What is required to survive a Martian dust storm? No excess generation allowed.

[Joseph Peterson]

Despite being a voracious reader of NSF topics devoted to human missions to/settlement of Mars I don't recall seeing this topic discussed in detail.  What I hope is accomplished is establishment of reference baselines which can be quoted in other threads similar to the solar farm size to refuel one Starship per synod of 500 kW from the Powering martian civilisation from ebay topic.

Establishing minimum requirements is going to require knowing, at a minimum, how many people need to be supported.  Additionally we want to consider the needs of plants and animals that need to be able to survive the storm.  While these details are open to debate my preference is to start with a standard starting point so we are all on the same page.  To this end I will define the biome population I currently believe is minimally viable for an early colonization mission.

Human population:  Total population of 12 including at least 1 doctor, 1 biologist, 1 botanist, 1 chemist, 1 geologist, 5 engineers of varied specialties, with the remaining 2 being wildcards of the specialty of your preference.
Plants:  A quarter acre(~1000 m³) single-layer-equivalent of varied food crops housed in an agricultural research lab.
Animals:  While I am fully aware that mice and rats are frequently used for biological research my working opinion is that rabbits can also breed quickly enough to provide a data set that will inform us how Mars' 0.38% G affects mammalian reproduction and development.  Additionally rabbit is a far more socially acceptable food and fur source than mice and rats.  Therefore it is my opinion it is wise to plan to support a fluffle of rabbits numbering 2-3 dozen.

Working from this limited information what do you believe is necessary to ensure the biome survives until solar power levels recover after an extreme 100 sol long dust storm?  I am particularly interested in the relationship between stored resources and power requirements.

[Slarty1080]

At the often quoted 32watts/square foot (344w/sqm) 1000sqm would require 344kw
No doubt this figure could by reduced a lot by use of high efficiency selective spectrum lights, by allowing the plants less light to survive if not flourish in the short term and other means, but it’s clear that there are going to be problems!

My suggestion would be to harvest everything possible as quickly as possible and freeze it. Freezing on Mars should not take much power. Maybe some near ripe crop could be kept alive for a limited period, but ultimately the fall back is dried / frozen food. Anything that is insufficiently ripe goes in the compost and you start again after the storm.

So in summary dried and frozen food is your backup. Plants will grow again just build in a margin to allow for this.

[Joseph Peterson]

As always there is a trade to be considered.  Plants naturally provide an oxygen source and CO2 scrubbing.  Allowing the plants to die during a dust storm means we need to replace this capability.  While it is eminently feasible to supply a reserve of lithium hydroxide canisters and O2 candles this does require a mass and power budget.  Perhaps these budgets would be better spent on an oversized solar farm that provides benefits during non-storm times.  344 kW is a pretty hefty power budget, especially when a dust storm has reduced solar power output to as little as 1%, but we don't necessarily need all of that power to keep the plants alive and my working assumption is we can shut down non-critical operations like ice mining and propellant production.  Perhaps we don't actually need to kill off all the plants in the manner that was depicted in National Geographic's Mars series.

[Slarty1080]

As always there is a trade to be considered.  Plants naturally provide an oxygen source and CO2 scrubbing.  Allowing the plants to die during a dust storm means we need to replace this capability.  While it is eminently feasible to supply a reserve of lithium hydroxide canisters and O2 candles this does require a mass and power budget.  Perhaps these budgets would be better spent on an oversized solar farm that provides benefits during non-storm times.  344 kW is a pretty hefty power budget, especially when a dust storm has reduced solar power output to as little as 1%, but we don't necessarily need all of that power to keep the plants alive and my working assumption is we can shut down non-critical operations like ice mining and propellant production.  Perhaps we don't actually need to kill off all the plants in the manner that was depicted in National Geographic's Mars series.

There are certainly some interesting trades. I would imagine that sufficient CO2 removal and O2 production capacity could be arranged via a fairly modest ECLSS like an over sized version of what is currently used on the ISS. I'm not sure of the exact power requirements but suspect it might be manageable on perhaps 2-4 kilopower units. This reference states 14.2kw required to keep a crew of 6 alive.
http://www.marsjournal.org/contents/2006/0005/files/rapp_mars_2006_0005.pdf

possibly supplemented by other storage and back up power options such as fuel cells, batteries and residual solar (even at very low levels). It would be interesting to identify the likely scenarios for solar power loss on Mars in terms of likelihood, duration and intensity.

I had not realised that killing off the plants had been suggested in National Geographic's Mars series, is this available anywhere? If used this would make the types of plant grown and especially the time to harvest a key factor.

Ultimately they will have to have multiple contingency plans for different scenarios no doubt shorter or lesser storms could be managed a lot more easily, but the worse case also needs to be considered and I suspect is manageable. Plants can be regrown within weeks and months.

[LMT]

re: power, we might take Antarctic electrical and thermal requirements as a rough baseline.

3.2 Comprehensive power generation concept

As an example, the following concept is based
on the power consumption estimates from
Antarctic research stations. Similar to proposed
stations on Mars, for Antarctic stations electricity
is required for light, pumps, and scientific
experiments. Based on Neumayer-Station III data,
which can host up to 40 people, this amounts to
70 kW – 300 kW. For heating, i.e. thermal energy,
another 70 – 150 kW are required for Antarctica.
For Mars, an even better building insulation
concept is required, reducing the required thermal
energy further.

Refs.

Baumgaertner, A. (2016). Power to Mars.

[Joseph Peterson]

There are certainly some interesting trades. I would imagine that sufficient CO2 removal and O2 production capacity could be arranged via a fairly modest ECLSS like an over sized version of what is currently used on the ISS. I'm not sure of the exact power requirements but suspect it might be manageable on perhaps 2-4 kilopower units. This reference states 14.2kw required to keep a crew of 6 alive.
http://www.marsjournal.org/contents/2006/0005/files/rapp_mars_2006_0005.pdf

possibly supplemented by other storage and back up power options such as fuel cells, batteries and residual solar (even at very low levels). It would be interesting to identify the likely scenarios for solar power loss on Mars in terms of likelihood, duration and intensity.

I had not realised that killing off the plants had been suggested in National Geographic's Mars series, is this available anywhere? If used this would make the types of plant grown and especially the time to harvest a key factor.

Ultimately they will have to have multiple contingency plans for different scenarios no doubt shorter or lesser storms could be managed a lot more easily, but the worse case also needs to be considered and I suspect is manageable. Plants can be regrown within weeks and months.

NG's Mars can be streamed here.  The specific episode where the plants die is S1 E5 - Darkest Days.  I had to set my script blocker to allow Brightcove video player but otherwise I didn't have to do anything to be able to watch.  While this episode focuses on psychological concerns the plants dying is memorable to me becasue of a 2014 MIT analysis of Mars One.

Baseline Mars One Habitat Architecture: A first
simulation of the baseline Mars One habitat indicated
that with no ISRU-derived resources, the first crew
fatality would occur approximately 68 days into the
mission. This would be a result of suffocation from too
low an oxygen partial pressure within the environment,
as depicted in Figure 8.

At the same time, the habitat would be put into a
state of high fire risk due to the oxygen molar fraction
exceeding the 30% safety threshold, as indicated in
Figure 9.

Further investigation revealed that this non-intuitive
result is primarily caused by the plants producing
excessive oxygen, increasing oxygen partial pressure to
outside their partial pressure control box, and causing
the pressure control assemblies to vent air. Because the
PCAs are not able to selectively vent a gas species, the
oxygen molar fraction remains the same after venting,
while the total atmospheric pressure reduces. Nitrogen
is then selectively introduced into the environment to
bring down the oxygen molar fraction. Over many
cycles of air venting and nitrogen being introduced for
oxygen molar fraction control, the nitrogen tank empties
on day 66 of the mission (see Figure 10).

When this occurs, the continually increasing oxygen
production by the plants increases the oxygen molar
fraction within the habitat beyond the fire safety threshold. At the same time, because nitrogen is no
longer available to make up for module leakage, the
habitat total pressure drops. The result is the
simultaneous decreasing of oxygen partial pressure and
increasing oxygen molar fraction.

Further analysis indicated that the oxygen
production of the plants in fact increases as crops reach
maturity. In this simulation case, all crops were grown
in batch mode, with lettuce being the first to reach
maturity at 30 days into the mission, followed by wheat,
which reaches maturity at day 62. Figure 9 depicts the
increase in oxygen molar fraction that occurs shortly
after these mission days.

https://dspace.mit.edu/handle/1721.1/90819

In short growing all the food locally produces significantly more oxygen than humans need to breathe.  The rabbits help mitigate this imbalance.  Furthermore food crop oxygen production accelerates as the plants approach maturity.  In the interest of maintaining a stable atmosphere inside the habitat it is wise to have multiple batches of crops approaching maturity at varied times. 

Hopefully this helps explain why I selected the agricultural research lab size I did and why I am concerned about ensuring their is sufficient power to keep the plans growing during a dust storm.

[Slarty1080]

Thanks for the post re the NG I will have to watch the whole thing. You raise some interesting points. I assume that the human v plant oxygen balance does not work because excess organic matter is produced. This might be rectified by composting waste which consumes a lot of oxygen under normal circumstances or adding herbivores as you suggest or even insects. However it would then make it very difficult to allow the plants to die as I suggested, because it would effectively also kill or at least seriously dislocate the entire ecosystem including microorganisms.

It might therefore be better to avoid any "reboot the entire ecosystem" option if it was in any way avoidable. I think this might only be avoidable by providing the power needed to maintain business as usual. Having said that it might be possible to manage on somewhat less power by lowering the temperature and or the light levels a bit to slow down growth. It's hard to say how effective this might be.

[Joseph Peterson]

Thanks for the post re the NG I will have to watch the whole thing. You raise some interesting points. I assume that the human v plant oxygen balance does not work because excess organic matter is produced. This might be rectified by composting waste which consumes a lot of oxygen under normal circumstances or adding herbivores as you suggest or even insects. However it would then make it very difficult to allow the plants to die as I suggested, because it would effectively also kill or at least seriously dislocate the entire ecosystem including microorganisms.

It might therefore be better to avoid any "reboot the entire ecosystem" option if it was in any way avoidable. I think this might only be avoidable by providing the power needed to maintain business as usual. Having said that it might be possible to manage on somewhat less power by lowering the temperature and or the light levels a bit to slow down growth. It's hard to say how effective this might be.

You're welcome and thank you for taking the time to help me clarify why I selected the plants and rabbits.  That MIT analysis has been critical in shaping how I think about Mars settlement but not everyone has read it.  In hindsight I probably should have added it to my original post.

With that sorted hopefully we can get into the question of just what is required to avoid an ecosystem reboot.

[Robotbeat]

No such thing as a 100 sol dust storm. I mean, do we have 100 day thunderstorms on Earth? Our plants wouldn't survive, either.

[Joseph Peterson]

No such thing as a 100 sol dust storm. I mean, do we have 100 day thunderstorms on Earth? Our plants wouldn't survive, either.

I'm not literally expecting a 100 sol dust storm.  100 sols was chosen so there should be plenty of margin.

I've already gone on at length about why we don't want all our plants dying.  Saying all the plants will die is not helpful.

[Phil Stooke]

This paper by Michael Smith:

https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2019JE006107

shows large global dust storms lasting on the order of 100 sols - peak obscuration by dust might be shorter but it can be fairly bad for 100 sols.  I wouldn't count out the possibility.

[Robotbeat]

This paper by Michael Smith:

https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2019JE006107

shows large global dust storms lasting on the order of 100 sols - peak obscuration by dust might be shorter but it can be fairly bad for 100 sols.  I wouldn't count out the possibility.

You're going to have to be more specific than that. I don't see any graphs that show total sunlight (including diffuse) over time. I don't think 100 sols is realistic for near-zero-sun.

Let's back up for a second.

My idea of how a Mars settlement would function:
1) most calories would be from vat-grown foods, not likely in greenhouses. Greenhouses primary would produce nice-to-haves that improve health and wellbeing of astronauts, not critical for survival.
2) Mars' cold climate and dessicating atmosphere mean that food can easily be stored essentially indefinitely just frozen in a cave somewhere. Or just bury a barrel of food. (Keep it from the sun so you don't have freeze/thaw cycles.)
3) The vast majority of power for Mars would be for making propellant for vehicles and perhaps secondarily for making structural materials like plastics and steel and maybe various chemicals. Something like 90-95% of power would be for those things. Some of this would be shared with vat food production.
4) There will be large amounts of propellant at the settlement at any one time. Propellant is methane and oxygen. Possibly CO or hydrogen for fuel, but most likely methane. Either way, ridiculous amounts of oxygen.
5) Any large buildings would need zero extra energy for heating. the near-vacuum makes really good insulation almost trivial, and the need to enclose everything (instead of having a billion out-buildings and houses you walk in between) means you're likely to have fewer, larger buildings than a similar sized settlement on Earth. Maybe just one or two main large enclosures. That helps reducing the surface area and would improve heat retention.
6) CO2 scrubbing can be done regeneratively fairly easily and with almost no energy input, especially if higher CO2 levels are tolerated for extenuating circumstances.

So you don't need 90-95% of energy during a dust storm. That alone would reduce the power required. You don't need heating, you don't need greenhouses (if the storm is going to last an extremely long time, you'll just have to replant almost everything). You can subsist on stored food and oxygen, for months. A small amount of power can be supplied by generators running on ISRU propellant normally used for rockets (you'd pause the vast majority of rocket launches) if in the depths of the dust storm (this being an extremely rare occurrence, like getting a hurricane in New York). You'd STILL get SOME power from the solar arrays, no matter how bad the storm (and the worst parts wouldn't and can't physically last more than a few days).

Unlike on Earth, you wouldn't get major damage to equipment from a storm. No major tornados, no hurricanes, no hail, no flooding, no forest fires, etc.

[spacenut]

First off, at what speed do most Martian dust storms blow?

Next, since the atmosphere is thinner, what does that translate into Earth equivalent?

Can the solar panels be mounted higher off the ground to avoid a lot of dust? 

Can they either have a small nuclear reactor or a battery bank to store excess electricity during the daylight hours to last for say several days or a week or more? 

Which would have less mass being transported from earth, a self contained nuclear reactor or equal power battery bank? 

Something to consider, a two year supply of dry or canned goods could be brought from earth for emergencies, along with medicines and vitamins for 2 years.  A greenhouse should provide all the plant based food for an outpost like this.  Rabbits is not a bad idea, but also chickens to provide not only meat, but eggs.  Birds might have fewer problems adjusting than mammals.  Worth at least a study. 
 

[Dalhousie]

Martian dust is more like smog than anything else.  Images can took impressive, but in reality visibility is still substantial. 

For example Viking 1 colour images taken on sols 282 and 324 showed the effects of a large dust storm (Tau between 5 and 6)  in a colour composite by Olivier de Goursac (https://www.planetary.org/space-images/20131231_sol282_324dust_storm197) look impressive but the horizon ~3 km distant is still visible.  Under Visual Flight Rules (VFR) helicopters are able to fly in visibility down to 3 km (CASA 2021) without reliance on external navigation aids or instruments.

Smith et al. (2018), in a study of visibility in Gale crater during the 2019 dust storm, concluded that visibility was reduced to less than three km.  Guzewich et al. (2019) refined this to 2.7 km. 

Ground operations are even less constrained.  Activities around the station should not be impeded with visibility down to a few hundred m, and some field work would also be possible provided it was at previously visited sites with a marked trail (vehicle tracks would be adequate).

The Martian, great movie that it was, isn't a a documentary!

[Robotbeat]

First off, at what speed do most Martian dust storms blow?

Next, since the atmosphere is thinner, what does that translate into Earth equivalent?

Can the solar panels be mounted higher off the ground to avoid a lot of dust? 

Can they either have a small nuclear reactor or a battery bank to store excess electricity during the daylight hours to last for say several days or a week or more? 

Which would have less mass being transported from earth, a self contained nuclear reactor or equal power battery bank? 

Something to consider, a two year supply of dry or canned goods could be brought from earth for emergencies, along with medicines and vitamins for 2 years.  A greenhouse should provide all the plant based food for an outpost like this.  Rabbits is not a bad idea, but also chickens to provide not only meat, but eggs.  Birds might have fewer problems adjusting than mammals.  Worth at least a study.

You wouldn't really need any special canned or dry food from Earth. You could just store food you made yourself. Mars' average temperature is about -80F, so storing stuff buried or deep in a cave means your food will essentially never go bad. In principle, it could last thousands of years (like mammoths frozen in the tundra). In reality, the quality will reduce over time, but it'll still provide calories and since -80F is extremely cold, it'd do a decent job of preserving micronutrients as well.

And the dust that settles on solar arrays can be removed, and the arrays flipped vertical or upside down at night to prevent accumulation.

[Joseph Peterson]

My idea of how a Mars settlement would function:
1) most calories would be from vat-grown foods, not likely in greenhouses. Greenhouses primary would produce nice-to-haves that improve health and wellbeing of astronauts, not critical for survival.

If you had bothered to read the opening post you'd know that the reference base I am trying to discuss contains an agricultural research lab.  That said, even assuming you are correct about vats killing all the algae is still a massive disruption to the biosphere.  Restoring ecological balance after the storm is easier said than done.

2) Mars' cold climate and dessicating atmosphere mean that food can easily be stored essentially indefinitely just frozen in a cave somewhere. Or just bury a barrel of food. (Keep it from the sun so you don't have freeze/thaw cycles.)

There is no guarantee that the agricultural research lab could provide enough food so the people and rabbits don't starve until after research has proven it is possible.  Assume that there is already stored food.  My concern is keeping the biosphere stable enough so recovery after the storm isn't a major PITA.

3) The vast majority of power for Mars would be for making propellant for vehicles and perhaps secondarily for making structural materials like plastics and steel and maybe various chemicals. Something like 90-95% of power would be for those things. Some of this would be shared with vat food production.

This thread is for determining what is needed to survive a dust storm.  Propellant, plastics, steel, and various chemical production during the dust storm isn't required to survive a dust storm.

4) There will be large amounts of propellant at the settlement at any one time. Propellant is methane and oxygen. Possibly CO or hydrogen for fuel, but most likely methane. Either way, ridiculous amounts of oxygen.

If you had bothered to read the thread and the MIT assessment of Mars One I quoted you'd know I'm far more concerned with the excess oxygen problem. 

5) Any large buildings would need zero extra energy for heating. the near-vacuum makes really good insulation almost trivial, and the need to enclose everything (instead of having a billion out-buildings and houses you walk in between) means you're likely to have fewer, larger buildings than a similar sized settlement on Earth. Maybe just one or two main large enclosures. That helps reducing the surface area and would improve heat retention.

Based on the size of the reference populations in the opening post it should be obvious that we aren't talking about large buildings.

6) CO2 scrubbing can be done regeneratively fairly easily and with almost no energy input, especially if higher CO2 levels are tolerated for extenuating circumstances.

CO2 scrubbers are an option if needed.  Then again keeping the plants and/or algae vats healthy enough so recovery after the storm isn't a major PITA might mean CO2 scrubbers aren't necessary.  Biology isn't a subject I am strong in though so I could use some help understanding what is required to keep the plants and/or algae vats healthy enough.

So you don't need 90-95% of energy during a dust storm. That alone would reduce the power required. You don't need heating, you don't need greenhouses (if the storm is going to last an extremely long time, you'll just have to replant almost everything). You can subsist on stored food and oxygen, for months. A small amount of power can be supplied by generators running on ISRU propellant normally used for rockets (you'd pause the vast majority of rocket launches) if in the depths of the dust storm (this being an extremely rare occurrence, like getting a hurricane in New York). You'd STILL get SOME power from the solar arrays, no matter how bad the storm (and the worst parts wouldn't and can't physically last more than a few days).

OK, but what I'm trying to figure out here are the requirements for survival.  I'm aware that killing all the plants is one option.  I'm also aware that restoring the ecological balance after the storm will take months.  If you really think that killing off all the plants is worth the work needed to restore balance then I'm open to a well reasoned argument.

Unlike on Earth, you wouldn't get major damage to equipment from a storm. No major tornados, no hurricanes, no hail, no flooding, no forest fires, etc.

No one was arguing otherwise. 

[Robotbeat]

Oh. Okay, biospheres are not a reasonable thing IMHO. I wouldn’t attempt it. Industrial life support from the beginning.

I was just establishing how *I* would do it.

A small research lab in a large settlement would be fine and could just use the backup generators.

[Joseph Peterson]

Oh. Okay, biospheres are not a reasonable thing IMHO. I wouldn’t attempt it.

Perhaps there is a better word but when I say biosphere I am talking about places where biological lifeforms live.  I consider humans to be biological lifeforms.  Therefore no biospheres means no humans on Mars.

Industrial life support from the beginning.

OK, but biospheres with greater diversity tend to be more stable over time.

I was just establishing how *I* would do it.

This is exactly what I feared this topic would devolve into if I didn't define a standard starting point.  This topic is not about everyone posting their own personal opinions on how "it" should be done.  This topic is about doing an in-depth analysis of one way to do "it."

A small research lab in a large settlement would be fine and could just use the backup generators.

Waiting to start research until after a large settlement has been built up means relying on imported food.  Importing food means the Starships required to import food aren't available to import other goods.  I don't want to drag this conversation even further off topic so I'm not going to list the other goods I'd prefer to be able to import but I will say I have a very long list.  Waiting to start research as you suggest and delaying importation of those other goods, and the expanding Martian economy they enable, is the opposite of fine in my book.

[LMT]

Martian dust is more like smog than anything else.  Images can took impressive, but in reality visibility is still substantial. 

For example Viking 1 colour images taken on sols 282 and 324 showed the effects of a large dust storm (Tau between 5 and 6)  in a colour composite by Olivier de Goursac (https://www.planetary.org/space-images/20131231_sol282_324dust_storm197) look impressive but the horizon ~3 km distant is still visible.  Under Visual Flight Rules (VFR) helicopters are able to fly in visibility down to 3 km (CASA 2021) without reliance on external navigation aids or instruments.

Smith et al. (2018), in a study of visibility in Gale crater during the 2019 dust storm, concluded that visibility was reduced to less than three km.  Guzewich et al. (2019) refined this to 2.7 km. 

Ground operations are even less constrained.  Activities around the station should not be impeded with visibility down to a few hundred m, and some field work would also be possible provided it was at previously visited sites with a marked trail (vehicle tracks would be adequate).

The Martian, great movie that it was, isn't a a documentary!

You could walk, yes.  We navigate under moonlight, after all. 

PV would fail there:  tau 5 transmission is < 1%.  Viking 1 could take the photo because it used the SNAP-19 RTG.

[libra]

Tape. Potatoes. Forgotten 1970's TV shows. No disco, ever. And avoiding the flying antenna... 

[Robotbeat]

Martian dust is more like smog than anything else.  Images can took impressive, but in reality visibility is still substantial. 

For example Viking 1 colour images taken on sols 282 and 324 showed the effects of a large dust storm (Tau between 5 and 6)  in a colour composite by Olivier de Goursac (https://www.planetary.org/space-images/20131231_sol282_324dust_storm197) look impressive but the horizon ~3 km distant is still visible.  Under Visual Flight Rules (VFR) helicopters are able to fly in visibility down to 3 km (CASA 2021) without reliance on external navigation aids or instruments.

Smith et al. (2018), in a study of visibility in Gale crater during the 2019 dust storm, concluded that visibility was reduced to less than three km.  Guzewich et al. (2019) refined this to 2.7 km. 

Ground operations are even less constrained.  Activities around the station should not be impeded with visibility down to a few hundred m, and some field work would also be possible provided it was at previously visited sites with a marked trail (vehicle tracks would be adequate).

The Martian, great movie that it was, isn't a a documentary!

You could walk, yes.  We navigate under moonlight, after all. 

PV would fail there:  tau 5 transmission is < 1%.  Viking 1 could take the photo because it used the SNAP-19 RTG.

Tau doesn’t include indirect light, which most of solar power in a dust storm like that would come from.

[LMT]

PV would fail there:  tau 5 transmission is < 1%.  Viking 1 could take the photo because it used the SNAP-19 RTG.

Tau doesn’t include indirect light, which most of solar power in a dust storm like that would come from.

No, that power story is false, whatever the NSF repetition.

The 2007 Opportunity power crisis makes plain how very little power is derived from diffuse light.  Power closely matches transmission.

Specifically:  "Tau jumped roughly from 2.9 (sol 1220) to 4.7 (sol 1235), cutting transmission by 84%.  Hence the 83% drop in daily PV output, and the crisis."

[Robotbeat]

PV would fail there:  tau 5 transmission is < 1%.  Viking 1 could take the photo because it used the SNAP-19 RTG.

Tau doesn’t include indirect light, which most of solar power in a dust storm like that would come from.

No, that power story is false, whatever the NSF repetition.

The 2007 Opportunity power crisis makes plain how very little power is derived from diffuse light.  Power closely matches transmission.

Specifically:  "Tau jumped roughly from 2.9 (sol 1220) to 4.7 (sol 1235), cutting transmission by 84%.  Hence the 83% drop in daily PV output, and the crisis."

nice try. The proportion from diffuse light is greater the worse tau is.

On the worst day Opportunity measured, when Tau was such that there’s much less than 1% direct light, the solar arrays still captured about 2-2.5%.

Your quote of yourself there is still in the regime where the majority of sunlight is direct, so doesn’t count as disproving the “NSF” “power story.”

The effect is more common on Earth than Mars as Earth often has cloudy days where almost all the light is diffuse.

[LMT]

On the worst day Opportunity measured, when Tau was such that there’s much less than 1% direct light, the solar arrays still captured about 2-2.5%.

The Opportunity power crisis was straightforward; power tracked closely to transmission, and even by your own estimate, the storm's diffuse light gave no significant power.  It's common expectation for PV on Mars.

[Joseph Peterson]

There are other topics for discussing power production.  This one is for power use.  Can you please take the power production conversation somewhere where it is on topic?

[LMT]

There are other topics for discussing power production.  This one is for power use.  Can you please take the power production conversation somewhere where it is on topic?

OP asks about power requirement, so people talk about power.  Your power requirement is much higher than Antarctic base requirement, due to your greenhouse spec.

Yet your greenhouse is too small to feed the crew.  High-intensity wheat could boost plot yield, but with exceptional power draw.

Some plausible requirements for greenhouse maintenance might be extracted from the EDEN ISS aeroponic extension of Neumayer-Station III.

[Joseph Peterson]

LMT this thread is about the demand side, not the supply side.  Take the supply side conversation elsewhere please.

[Joseph Peterson]

Since this has been a constant bone of contention I am going to repeat three words from the OP, agricultural research lab.

The goal is not to produce 100% of food requirements locally.  The goal is research.  What I expect to be learned is what unknown issues affect plant growth on Mars and which plants are affected.  I also expect to identify what problems need to be solved to maintain a stable biosphere.  Comments like, "Yet your greenhouse is too small to feed the crew." are not helpful in the slightest.

What would be helpful is a discussion of how to minimize the agricultural research lab's power requirements during dust storms.

[LMT]

LMT this thread is about the demand side, not the supply side.  Take the supply side conversation elsewhere please.

It's hard to make reasonable demand adjustments before you know the power supply deficit you're trying to survive. 

To move analysis forward -- and give a target for your minimizations -- you might ballpark a PV farm's low storm PV power and any plausible supplemental power.  You can use the 2007 Opportunity storm data and the 2018 storm data as reference datasets.  (Just convert optical depth to tau for comparison.)

Of course, you can set a target arbitrarily if you want, but this is a storm scenario, so plausible storm power parameters would frame the problem better.

[Robotbeat]

On the worst day Opportunity measured, when Tau was such that there’s much less than 1% direct light, the solar arrays still captured about 2-2.5%.

The Opportunity power crisis was straightforward; power tracked closely to transmission, and even by your own estimate, the storm's diffuse light gave no significant power.  It's common expectation for PV on Mars.

2.5% is definitely significant Power if you don’t need very much to begin with and your arrays are sized for propellant production which you can just not do during a dust storm.

[Slarty1080]

Since this has been a constant bone of contention I am going to repeat three words from the OP, agricultural research lab.

The goal is not to produce 100% of food requirements locally.  The goal is research.  What I expect to be learned is what unknown issues affect plant growth on Mars and which plants are affected.  I also expect to identify what problems need to be solved to maintain a stable biosphere.  Comments like, "Yet your greenhouse is too small to feed the crew." are not helpful in the slightest.

What would be helpful is a discussion of how to minimize the agricultural research lab's power requirements during dust storms.

Is it a remote agricultural research station? Or is it integrated with the base and propellant production? If propellant production is linked in any way it should stop to conserve power. But any practical solar arrangement is not going to be able to provide all of the light required for an agricultural research station during a major dust storm regardless of that.

I think the options are
1) Use some form of nuclear power
2) let the plants die and start the experiments again afterwards
3) Use backup power by burning Methalox
4) Use some other form of power storage like a cryogenic battery, conventional battery or a fuel cell powered by methanol and LOX
5) A mixture of the above

None of them are without draw backs and issues and which would be preferred is hard to say and will probably change over time as technologies develop. They will need to have a power research station before they can build a reliable agricultural research station.

[LMT]

On the worst day Opportunity measured, when Tau was such that there’s much less than 1% direct light, the solar arrays still captured about 2-2.5%.

The Opportunity power crisis was straightforward; power tracked closely to transmission, and even by your own estimate, the storm's diffuse light gave no significant power.  It's common expectation for PV on Mars.

2.5% is definitely significant Power if you don’t need very much to begin with and your arrays are sized for propellant production which you can just not do during a dust storm.

Scenario is not Mars Base Alpha, but a 12-man hab with power-hungry greenhouse.  The survival challenge only exists when power is constrained.

Re: greenhouse req, you could scale EDEN ISS numbers, and dim lights to PPF DLI 10, to ballpark a conventional req.  Zabel et al. 2016.

Refs.

Zabel, P., Bamsey, M., Zeidler, C., Vrakking, V., Schubert, D., Romberg, O., Boscheri, G. and Dueck, T., 2016. The Preliminary design of the EDEN ISS mobile test facility-an antarctic greenhouse.

[Joseph Peterson]

Is it a remote agricultural research station? Or is it integrated with the base and propellant production? If propellant production is linked in any way it should stop to conserve power. But any practical solar arrangement is not going to be able to provide all of the light required for an agricultural research station during a major dust storm regardless of that.

I think the options are
1) Use some form of nuclear power
2) let the plants die and start the experiments again afterwards
3) Use backup power by burning Methalox
4) Use some other form of power storage like a cryogenic battery, conventional battery or a fuel cell powered by methanol and LOX
5) A mixture of the above

None of them are without draw backs and issues and which would be preferred is hard to say and will probably change over time as technologies develop. They will need to have a power research station before they can build a reliable agricultural research station.

I suppose someone might think a remote agricultural research station is a good idea.  I can't see any reason why this would be better than an agricultural research lab that can easily share infrastructure and resources with the spaceport/propellant plant/ice mine complex.  If someone does want to argue in favor of a remote agricultural research station I hope they start a new thread to explore the topic.

The reason I started this thread is because, while there are plenty of conversations about how to provide power during a dust storm  spread across multiple threads, there is very little conversation about how much power is actually needed.  If I can't figure out how to get this thread mostly on topic I'm going to use the report to mod feature to ask the entire thread be deleted.  The way I see it is there is no reason to waste server space hosting yet another copy of the same old debates.

Killing off all the plants has consequences and costs.  I thought you and I had covered this sufficiently on page 1.

[Joseph Peterson]

Scenario is not Mars Base Alpha, but a 12-man hab with power-hungry greenhouse.

The scenario is an agricultural research lab where we learn what is needed to feed Mars Base Alpha.  What I hope people are thinking about are things like how to manage crop rotations so we don't have to deal with the consequences of an all the plants dying situation when a bad dust storm strikes. 

I read your links and neither are particularly helpful because of crop selection.  Do you happen to have anything more useful like information about winter wheat?

[LMT]

Scenario is not Mars Base Alpha, but a 12-man hab with power-hungry greenhouse.

The scenario is an agricultural research lab where we learn what is needed to feed Mars Base Alpha.  What I hope people are thinking about are things like how to manage crop rotations so we don't have to deal with the consequences of an all the plants dying situation when a bad dust storm strikes. 

I read your links and neither are particularly helpful because of crop selection.  Do you happen to have anything more useful like information about winter wheat?

Crop rotations?  It's a 100-sol crisis.  How many winter wheat harvests are you anticipating over 100 sols? 

You have info to calculate a conventional greenhouse survival power requirement.

[Joseph Peterson]

Crop rotations?  It's a 100-sol crisis.  How many winter wheat harvests are you anticipating over 100 sols? 

You have info to calculate a conventional greenhouse survival power requirement.

I really hate having to repeat myself.  We are not trying to harvest crops during the crisis.  We are trying to avoid an all the plants dying situation. 

You have been warned by moderators about using yourself as a source multiple times.  I already told you your links are not helpful because of crop selection.  Do you have anything useful to add to this conversation or are you going to repeat what happened on the Mars Colony Infrastructure thread?

[LMT]

Crop rotations?  It's a 100-sol crisis.  How many winter wheat harvests are you anticipating over 100 sols? 

You have info to calculate a conventional greenhouse survival power requirement.

I really hate having to repeat myself.  We are not trying to harvest crops during the crisis.  We are trying to avoid an all the plants dying situation. 

You have been warned by moderators about using yourself as a source multiple times.  I already told you your links are not helpful because of crop selection.  Do you have anything useful to add to this conversation or are you going to repeat what happened on the Mars Colony Infrastructure thread?

I posted info to calculate greenhouse survival power.  If you don't like the EDEN ISS power numbers or the min PPF DLI number, you can say so, but the strident tone is just odd.

[Joseph Peterson]

I posted info to calculate greenhouse survival power.  If you don't like the EDEN ISS power numbers or the min PPF DLI number, you can say so, but the strident tone is just odd.

If you would stop ignoring what I keep saying my tone wouldn't be strident.  For the third time neither link is helpful due to crop selection.  Do you have information for crops we want to be growing when a dust storm is approaching like winter wheat?

As to the EDEN ISS power numbers, did you even bother to read the Figure 18 caption?  If not it says, "Power demand during nominal operations for a single day-night cycle."  I'm trying to have a discussion about off-nominal operations.  That figure is useless for this conversation.  The PFF DLI numbers are also useless because we're trying to ensure the plants don't die during the storm, not ensure there is enough light for harvests during the storm.  If you want to use those sources then take them to the scaling agriculture thread.

[Robotbeat]

Crop rotations?  It's a 100-sol crisis.  How many winter wheat harvests are you anticipating over 100 sols? 

You have info to calculate a conventional greenhouse survival power requirement.

I really hate having to repeat myself.  We are not trying to harvest crops during the crisis.  We are trying to avoid an all the plants dying situation. 

You have been warned by moderators about using yourself as a source multiple times.  I already told you your links are not helpful because of crop selection.  Do you have anything useful to add to this conversation or are you going to repeat what happened on the Mars Colony Infrastructure thread?

alright, I’ll take your (kinda silly) constraints 100% seriously:

Okay, but 100 sols is like an entire growing season. If you want to keep the plants “alive” and unchanged for /research/ purposes, then basically you can’t reduce power requirements from nominal. So you just need constant power, provided however you like (backup methalox, nuclear, residual solar, whatever). Because if you’re doing science, changes in power will affect your results, so you need to plan for constant power. End of thread.

If it’s to feed the astronauts, then just do what humans do in winter, which is store up food from the growing season.  No reason to keep wheat alive during the middle of winter if you can just store seed or whatever.

[Slarty1080]

On page 1 I suggested a starting point for the power required for 1000sqm might be 344kw. How little power might be required below this normal level depends on many factors. (you might want to mention power levels in the thread title).

It would appear that many plants can survive low light levels with a photon flux of 5 mol/sqm/day compared to around 20 mol/sqm/day that might more normally be expected.
https://en.wikipedia.org/wiki/Daily_light_integral
 
This would allow the 1000sqm to be eliminated perhaps by as little as 86kw. But that begs the question of what experiments are being conducted doesn’t it? If plant survival is being tested then fine, but an experiment to measure growth or yield of various crops at a specific level of illumination under Martian conditions is going to be wrecked if the light levels change.

[Joseph Peterson]

alright, I’ll take your (kinda silly) constraints 100% seriously:

Okay, but 100 sols is like an entire growing season. If you want to keep the plants “alive” and unchanged for /research/ purposes, then basically you can’t reduce power requirements from nominal. So you just need constant power, provided however you like (backup methalox, nuclear, residual solar, whatever). Because if you’re doing science, changes in power will affect your results, so you need to plan for constant power. End of thread.

100 days is like an entire Russian winter.  Winter wheat is planted in autumn, survives the winter, then starts growing again come spring.  I know there are other plants that are capable of doing this.  Russians don't run electric lights during the winter to ensure their fields are productive so I have no idea where this "silly" constraint of having to maintain constant power over the course of an entire Martian year(687 Earth days) is coming from.  Your end of thread claim is therefore proven false.

Feel free to stop posting if you don't want to take this thread seriously.

If it’s to feed the astronauts, then just do what humans do in winter, which is store up food from the growing season.  No reason to keep wheat alive during the middle of winter if you can just store seed or whatever.

Once again the point of the agricultural research lab IS NOT FEEDING THE ASTRONAUTS.  The points are learning how to feed a growing settlement and maintaining a stable biosphere.  Sorry for shouting but this insistence that the agricultural research lab isn't an agricultural research lab and instead must be a greenhouse that is required to feed everyone is silly.  Why is it so hard to accept my words literally mean what they say?

[LMT]

I posted info to calculate greenhouse survival power.  If you don't like the EDEN ISS power numbers or the min PPF DLI number, you can say so, but the strident tone is just odd.

If you would stop ignoring what I keep saying my tone wouldn't be strident.  For the third time neither link is helpful due to crop selection.  Do you have information for crops we want to be growing when a dust storm is approaching like winter wheat?

As to the EDEN ISS power numbers, did you even bother to read the Figure 18 caption?  If not it says, "Power demand during nominal operations for a single day-night cycle."  I'm trying to have a discussion about off-nominal operations.  That figure is useless for this conversation.  The PFF DLI numbers are also useless because we're trying to ensure the plants don't die during the storm, not ensure there is enough light for harvests during the storm.  If you want to use those sources then take them to the scaling agriculture thread.

But you can't predict a dust storm months in advance.  Start date, severity, and duration are just unpredictable; your predictive crop-rotation notion isn't sound.

EDEN ISS gives a nice baseline for crop power.  For crisis power, just lower EDEN lighting power, dropping PPF DLI, again, to 10.  That's dim lighting, plausibly enough to "ensure the plants don't die", and obviously not "storm harvest lighting", or baseline growth lighting.  You need to understand PPF and DLI before trying to ballpark greenhouse survival.

[Joseph Peterson]

On page 1 I suggested a starting point for the power required for 1000sqm might be 344kw. How little power might be required below this normal level depends on many factors. (you might want to mention power levels in the thread title).

I originally was going to limit the thread to just power levels but then I got to thinking and realized that stored resources also need to be considered. 

It would appear that many plants can survive low light levels with a photon flux of 5 mol/sqm/day compared to around 20 mol/sqm/day that might more normally be expected.
https://en.wikipedia.org/wiki/Daily_light_integral

This is something that is more useful.  I'll be interested in seeing what I can find in the citations.
 

This would allow the 1000sqm to be eliminated perhaps by as little as 86kw. But that begs the question of what experiments are being conducted doesn’t it? If plant survival is being tested then fine, but an experiment to measure growth or yield of various crops at a specific level of illumination under Martian conditions is going to be wrecked if the light levels change.

Martian climate data is limited so there is the potential for unknowns but global dust storms typically happen roughly every 3 Mars years.  This means we have ~1900 sols between storms, or plenty of time to conduct growth and yield experiments.  Plant survival can be simulated easily enough between global storms by simply turning down the lights and, if needed, heat.

The question I am trying to answer is how much power and what stored resources are needed to survive what should be a worst case global dust storm.  If I can answer this question at the small scale defined in the OP then I know what is needed for a resilient Martian civilization that doesn't suffer a major catastrophe due to dust storms.

[Joseph Peterson]

But you can't predict a dust storm months in advance.  Start date, severity, and duration are just unpredictable; your predictive crop-rotation notion isn't sound.

The global storms we are concerned about for the purposes of this thread start in the southern hemisphere during summer, historically in Hellas Planitia.  Granted the reference storm is more severe than any ever recorded but significant global storms typically happen ever 3 Mars years.  Saying that it isn't possible to predict when a global storm should next occur is inaccurate.  Since we know which season to expect a storm in we can plan crop rotations accordingly.

Furthermore, since potential settlement sites under consideration are in the northern hemisphere we has weeks between the time the start of a storm is detected to prepare.  For example the 2018 storm was first detected on May 30th and officially became a planet-encircling dust event on June 19th.

EDEN ISS gives a nice baseline for crop power.  For crisis power, just lower EDEN lighting power, dropping PPF DLI, again, to 10.  That's dim lighting, plausibly enough to "ensure the plants don't die", and obviously not "storm harvest lighting", or baseline growth lighting.  You need to understand PPF and DLI before trying to ballpark greenhouse survival.

For the last time stop misrepresenting your unhelpful links.

[LMT]

The question I am trying to answer is how much power and what stored resources are needed to survive what should be a worst case global dust storm.  If I can answer this question at the small scale defined in the OP then I know what is needed for a resilient Martian civilization that doesn't suffer a major catastrophe due to dust storms.

It seems ISRU batteries can answer that question, at any required settlement scale, with modest cargo and little R&D.  Here no storm scenario demands rationing of stored resources or power, with possible exception of power to the heaviest industry.

[Joseph Peterson]

It seems ISRU batteries can answer that question, at any required settlement scale, with modest cargo and little R&D.  Here no storm scenario demands rationing of stored resources or power, with possible exception of power to the very heaviest industry.

Once again this thread is about demand, not supply.  I don't know and don't care why you have embarked on this personal crusade to attack me but STOP!!!

[LMT]

It would appear that many plants can survive low light levels with a photon flux of 5 mol/sqm/day compared to around 20 mol/sqm/day that might more normally be expected.
https://en.wikipedia.org/wiki/Daily_light_integral

This is something that is more useful.  I'll be interested in seeing what I can find in the citations.

This is survival with lowered PPF DLI, yes.  Previously a PPF DLI of 13 seemed the minimum for a strawberry crop; I used that crop as surrogate for all shade crops.  If PPF DLI 10 is insufficient for a crop, but sufficient for seedling survival, it seems plausible as a greenhouse survival target for reduced lighting power.

[Voidfloater]

I think we are assuming that all industrial processes stop during the dust storm. As a result, the only two power demands of the colony should be heating and life support.  I'm going to calculate the power supply required for life support assuming that plants produce negligible oxygen during the dust storm.

Humans, on average, consume about 2,000 calories of food a day, or about 8,400 kilojoules.  This chemical energy is produced by breaking down organic compounds into CO2 and H2O.  To control carbon dioxide levels, the base needs to convert the CO2 and H2O into O2 and CH4.  This process is inefficient and barring more precise numbers, I will assume that it takes 5 times more energy to convert CO2 and H2O back into O2 and CH4 than the other way around. 

So, for a base of 12 people, we consume 100,800 Kilojoules per day, or 100.8 Megajoules.  To convert the carbon dioxide and water waste back into oxygen (with methane as a byproduct), it will take 504 Megajoules of energy per day.  Converting to watts, the base needs 5830 watts per second to maintain oxygen levels.  Assuming that a solar power plant operates at 2% of baseline, to survive a dust storm the solar farm needs to produce at least 300 kilowatts of power.

[lamontagne]

I think we are assuming that all industrial processes stop during the dust storm. As a result, the only two power demands of the colony should be heating and life support.  I'm going to calculate the power supply required for life support assuming that plants produce negligible oxygen during the dust storm.

Humans, on average, consume about 2,000 calories of food a day, or about 8,400 kilojoules.  This chemical energy is produced by breaking down organic compounds into CO2 and H2O.  To control carbon dioxide levels, the base needs to convert the CO2 and H2O into O2 and CH4.  This process is inefficient and barring more precise numbers, I will assume that it takes 5 times more energy to convert CO2 and H2O back into O2 and CH4 than the other way around. 

So, for a base of 12 people, we consume 100,800 Kilojoules per day, or 100.8 Megajoules.  To convert the carbon dioxide and water waste back into oxygen (with methane as a byproduct), it will take 504 Megajoules of energy per day.  Converting to watts, the base needs 5830 watts per second to maintain oxygen levels.  Assuming that a solar power plant operates at 2% of baseline, to survive a dust storm the solar farm needs to produce at least 300 kilowatts of power.

So if we go back to the first page of this thread and take the 500 kW required for fuel production for 1 ship for one synod, there is a nice match.

[LMT]

I think we are assuming that all industrial processes stop during the dust storm. As a result, the only two power demands of the colony should be heating and life support.  I'm going to calculate the power supply required for life support assuming that plants produce negligible oxygen during the dust storm.

Humans, on average, consume about 2,000 calories of food a day, or about 8,400 kilojoules.  This chemical energy is produced by breaking down organic compounds into CO2 and H2O.  To control carbon dioxide levels, the base needs to convert the CO2 and H2O into O2 and CH4.  This process is inefficient and barring more precise numbers, I will assume that it takes 5 times more energy to convert CO2 and H2O back into O2 and CH4 than the other way around. 

So, for a base of 12 people, we consume 100,800 Kilojoules per day, or 100.8 Megajoules.  To convert the carbon dioxide and water waste back into oxygen (with methane as a byproduct), it will take 504 Megajoules of energy per day.  Converting to watts, the base needs 5830 watts per second to maintain oxygen levels.  Assuming that a solar power plant operates at 2% of baseline, to survive a dust storm the solar farm needs to produce at least 300 kilowatts of power.

You might add Mars-specific power requirements, such as O2 production, to scaled Antarctic baseline; e.g., Neumayer-Station III requirement:

300 kW electric,
150 kW thermal,
for a crew of 40.

[Robotbeat]

alright, I’ll take your (kinda silly) constraints 100% seriously:

Okay, but 100 sols is like an entire growing season. If you want to keep the plants “alive” and unchanged for /research/ purposes, then basically you can’t reduce power requirements from nominal. So you just need constant power, provided however you like (backup methalox, nuclear, residual solar, whatever). Because if you’re doing science, changes in power will affect your results, so you need to plan for constant power. End of thread.

100 days is like an entire Russian winter.  Winter wheat is planted in autumn, survives the winter, then starts growing again come spring.  I know there are other plants that are capable of doing this.  Russians don't run electric lights during the winter to ensure their fields are productive so I have no idea where this "silly" constraint of having to maintain constant power over the course of an entire Martian year(687 Earth days) is coming from.  Your end of thread claim is therefore proven false.

Feel free to stop posting if you don't want to take this thread seriously.

If it’s to feed the astronauts, then just do what humans do in winter, which is store up food from the growing season.  No reason to keep wheat alive during the middle of winter if you can just store seed or whatever.

Once again the point of the agricultural research lab IS NOT FEEDING THE ASTRONAUTS.  The points are learning how to feed a growing settlement and maintaining a stable biosphere.  Sorry for shouting but this insistence that the agricultural research lab isn't an agricultural research lab and instead must be a greenhouse that is required to feed everyone is silly.  Why is it so hard to accept my words literally mean what they say?

You said you wanted it to be a research agricultural station, so that means you want to control the variables or your research doesn’t really work. That’s how science is done. In that case, you want constant power (so the experiment can use a controlled amount and timing of light, heat, etc). So is it a research facility or not?

[Joseph Peterson]

I've been doing some searching and while I haven't found anything for winter wheat, I did find the attached paper about spring wheat which studied yields at DLIs ranging between 400-2080 μmol m^-2 s^-1(DLI between 1.4 and 7.5).  Minimum DLI for survival isn't address but there is compensation point in Fig 2 of 5 mol m^-2 d^-1(about 70 μmol m^-2 s^-1 or DLI=0.25) above which growth occurs.  Assuming similar DLIs for winter wheat and Slarty's figure of 344 kW from page 1 was based on a DLI of 25(the midpoint for efficient growth of tomatoes, peppers, and cucumbers from LMT's link) the extrapolates to a power budget of 3.4 kW needed for survival.

Edit: DLI calculations contain a stupid mistake, not multiplying by the photoperiod. 

[Joseph Peterson]

You said you wanted it to be a research agricultural station, so that means you want to control the variables or your research doesn’t really work. That’s how science is done. In that case, you want constant power (so the experiment can use a controlled amount and timing of light, heat, etc). So is it a research facility or not?

As you yourself said 100 days is roughly a growing season.  Are you claiming that it is not possible to run experiments that depend on a controlled amount of time, heat, light, etc if we have 1900 days between major global dust storms?

If that is not what you are claiming then why are questioning whether it is a research facility or not?

[Joseph Peterson]

This chemical energy is produced by breaking down organic compounds into CO2 and H2O.  To control carbon dioxide levels, the base needs to convert the CO2 and H2O into O2 and CH4.

That is one way to do it but it is not the only way.  There are a variety of chemicals that can be used for carbon dioxide scrubbing and the OP allows for stored resources.  Raptors run fuel rich so the propellant plant will produce an ample supply of excess oxygen which can also be stored.

[LMT]

I did find the attached paper about spring wheat which studied yields at DLIs ranging between 400-2080 μmol m^-2 s^-1(DLI between 1.4 and 7.5).

No, that's not the wheat PPF DLI.  The DLI is printed in the figures. 

DLI ranges up to 150.  This is the high-intensity wheat I mentioned in thread.

[Joseph Peterson]

I see what I was missing, multiplying by the photoperiod.  I hate it when I get flustered by trolls and make stupid mistakes.

Even still a DLI for survival of 10 is still to high.

[LMT]

I see what I was missing, multiplying by the photoperiod.  I hate it when I get flustered by trolls and make stupid mistakes.

Even still a DLI for survival of 10 is still to high.

The important thing is not to set PPF DLI too low; you might double-check unusually low numbers.

[Joseph Peterson]

If I had a basis for judging what is unusually low I would have caught the error sooner.  For now all I have a basis for is excessively high.  At least I know what not to look for.

[Slarty1080]

This chemical energy is produced by breaking down organic compounds into CO2 and H2O.  To control carbon dioxide levels, the base needs to convert the CO2 and H2O into O2 and CH4.

That is one way to do it but it is not the only way.  There are a variety of chemicals that can be used for carbon dioxide scrubbing and the OP allows for stored resources.  Raptors run fuel rich so the propellant plant will produce an ample supply of excess oxygen which can also be stored.

This is true. There is no need to convert CO₂ into anything, especially if it uses a lot of energy to do so. What is needed is air circulation and filtration through some media to capture the CO₂
https://en.wikipedia.org/wiki/Carbon_dioxide_scrubber
Oxygen requirements could be met from cryogenic storage and sufficient capture media could be provided so that it was not necessary to regenerate it during a dust storm. Alternatively a media that was easily regenerated with minimal power use might be chosen. All excess CO₂ could be vented into the Martian atmosphere.

[lamontagne]

Has the Melissa system been looked at in this regard as an option that has more control than the Mars One model?

Venting nitrogen has to be a really bad idea for Mars, cryogenic oxygen removal seems like a better idea.  Storing carbon, possibly as methane, and burning it and then venting the CO2 might be an alternative that uses stored energy rather than produced energy?  Separating out CO2 can be done regeneratively with much lower power requirements than condensing out the oxygen.

The transportation Starship, due to its very nature, will carry with it a life support system that is not dependent on food production and sized for the full crew.  Can this be the dust storm emergency system?

Might it make sense to divorce food production from life support, and therefore reduce the risk from failure of the food production system experiment? 

Life support is a absolute requirement, while food production is a nice to have?

[Slarty1080]

Has the Melissa system been looked at in this regard as an option that has more control than the Mars One model?

Venting nitrogen has to be a really bad idea for Mars, cryogenic oxygen removal seems like a better idea.  Storing carbon, possibly as methane, and burning it and then venting the CO2 might be an alternative that uses stored energy rather than produced energy?  Separating out CO2 can be done regeneratively with much lower power requirements than condensing out the oxygen.

The transportation Starship, due to its very nature, will carry with it a life support system that is not dependent on food production and sized for the full crew.  Can this be the dust storm emergency system?

Might it make sense to divorce food production from life support, and therefore reduce the risk from failure of the food production system experiment? 

Life support is a absolute requirement, while food production is a nice to have?

I don't see why any nitrogen would need to be vented? The big problem is that oxygen can only be regenerated from CO₂ at great cost in power which would be in short supply in a dust storm and there is plenty of CO₂ outside. LOX will be stored in large quantities anyway due to propellant requirements. In the regenerative CO₂ removal processes that I was referring to it is the removal media that can be regenerated not the oxygen.

Also the scenario under discussion assumes this is an agricultural research station and is not required to grow food for human consumption. (and yes some would be consumed no doubt, but the idea is to establish how low the power level can be rather than worry about food production)

[lamontagne]

Has the Melissa system been looked at in this regard as an option that has more control than the Mars One model?

Venting nitrogen has to be a really bad idea for Mars, cryogenic oxygen removal seems like a better idea.  Storing carbon, possibly as methane, and burning it and then venting the CO2 might be an alternative that uses stored energy rather than produced energy?  Separating out CO2 can be done regeneratively with much lower power requirements than condensing out the oxygen.

The transportation Starship, due to its very nature, will carry with it a life support system that is not dependent on food production and sized for the full crew.  Can this be the dust storm emergency system?

Might it make sense to divorce food production from life support, and therefore reduce the risk from failure of the food production system experiment? 

Life support is a absolute requirement, while food production is a nice to have?

I don't see why any nitrogen would need to be vented? The big problem is that oxygen can only be regenerated from CO₂ at great cost in power which would be in short supply in a dust storm and there is plenty of CO₂ outside. LOX will be stored in large quantities anyway due to propellant requirements. In the regenerative CO₂ removal processes that I was referring to it is the removal media that can be regenerated not the oxygen.

Also the scenario under discussion assumes this is an agricultural research station and is not required to grow food for human consumption. (and yes some would be consumed no doubt, but the idea is to establish how low the power level can be rather than worry about food production)

Earlier in the thread, a reference was made to Mars One, and the "in"famous MIT study that concluded that the crew would start dying after 68 days.  That conclusion was based on a system design that vented atmosphere when increased oxygen build up, eventually creating excess oxygen through nitrogen depletion.  Although I don't doubt the conclusions about Mars One's specific system it is clearly not the best possible design :-).

If we want to save the experiment, the crew being saved by other means, then I think the most important aspect might be maintaining sufficient heat to avoid the dead of the microbiome in the soil.  The death of the actual plants from light starvation might be secondary, as long as we have enough seeds to plant again?
Plants overproduce seeds to a tremendous degree, and seed survival is the way to go, as far as I understand farming.  Perhaps some soil freezing isn't so bad, as the bacteria and other microbial life clearly have means of surviving cold as well.  Dead plants are good food or the soil, as well.

[Joseph Peterson]

This is true. There is no need to convert CO₂ into anything, especially if it uses a lot of energy to do so. What is needed is air circulation and filtration through some media to capture the CO₂
https://en.wikipedia.org/wiki/Carbon_dioxide_scrubber
Oxygen requirements could be met from cryogenic storage and sufficient capture media could be provided so that it was not necessary to regenerate it during a dust storm. Alternatively a media that was easily regenerated with minimal power use might be chosen. All excess CO₂ could be vented into the Martian atmosphere.

I'd love to know about a media that is easily regenerated with minimal power use.  The lack of a good method for extracting CO₂ from Earth's atmosphere is the primary problem that is preventing me from attempting to replace fracked natural gas with methane made using the Sabatier reaction.

If we're storing CO₂ media for regeneration after the storm is over I think it would be better to send the CO₂ to the propellant plant or greenhouse.

[LMT]

The lack of a good method for extracting CO₂ from Earth's atmosphere is the primary problem that is preventing me from attempting to replace fracked natural gas with methane made using the Sabatier reaction.

You demand we stay on topic, while wandering off, yourself.  I gave you specific data and method to solve your greenhouse power problem.  So stay on topic, please, and try the solution algebra.

If I can't figure out how to get this thread mostly on topic I'm going to use the report to mod feature to ask the entire thread be deleted.  The way I see it is there is no reason to waste server space hosting yet another copy of the same old debates.

[Joseph Peterson]

The lack of a good method for extracting CO₂ from Earth's atmosphere is the primary problem that is preventing me from attempting to replace fracked natural gas with methane made using the Sabatier reaction.

You demand we stay on topic, while wandering off, yourself.  I gave you specific data and method to solve your greenhouse power problem.  So stay on topic, please, and try the solution algebra.

If I can't figure out how to get this thread mostly on topic I'm going to use the report to mod feature to ask the entire thread be deleted.  The way I see it is there is no reason to waste server space hosting yet another copy of the same old debates.

And as I've told you repeatedly optimal power and DLI for efficient crop growth is not helpful.  Stop misrepresenting your unhelpful links.

[LMT]

The lack of a good method for extracting CO₂ from Earth's atmosphere is the primary problem that is preventing me from attempting to replace fracked natural gas with methane made using the Sabatier reaction.

You demand we stay on topic, while wandering off, yourself.  I gave you specific data and method to solve your greenhouse power problem.  So stay on topic, please, and try the solution algebra.

If I can't figure out how to get this thread mostly on topic I'm going to use the report to mod feature to ask the entire thread be deleted.  The way I see it is there is no reason to waste server space hosting yet another copy of the same old debates.

And as I've told you repeatedly optimal power and DLI for efficient crop growth is not helpful.  Stop misrepresenting your unhelpful links.

Your only suggested DLI range -- up to 150, astonishingly -- is that of the very highest experimental light intensities ever recorded for a wheat crop.  As it says in the abstract, this was DLI "three times greater"... than that of sunlight itself. 

This is the extreme opposite of survival DLI -- e.g., 10 -- and irrelevant to the problem you posed.

OT fracking talk is even less relevant, obviously.

Biology isn't a subject I am strong in...

[Joseph Peterson]

I already recognized my mistake and edited the comment.  Stop harassing me troll.

[Twark_Main]

This is true. There is no need to convert CO₂ into anything, especially if it uses a lot of energy to do so. What is needed is air circulation and filtration through some media to capture the CO₂
https://en.wikipedia.org/wiki/Carbon_dioxide_scrubber
Oxygen requirements could be met from cryogenic storage and sufficient capture media could be provided so that it was not necessary to regenerate it during a dust storm. Alternatively a media that was easily regenerated with minimal power use might be chosen. All excess CO₂ could be vented into the Martian atmosphere.

I'd love to know about a media that is easily regenerated with minimal power use.

Basic lithium-hydroxide canisters (think Apollo) can be regenerated simply by heating them and exposing them to vacuum.

Not sure about the power use. I'm not sure it matters all too much, since after the storm is gone you have plenty of power available to regenerate them.

Even if it's "only" 50% energy efficient, then it still breaks even with the round-trip energy efficiency of the electricity -> methox -> electricity system. Here I am (generously) estimating an 80% efficient electrolysis+sabatier process and a 65% efficient combined-heat-and-power turbine generator.

Apollo LiOH canisters (which surely can be improved upon) would mass only 7 kg per person per 30 days. This compares very favorably to the battery mass needed to power a regenerative CO2 removal system for that same 30 day period.

[Phil Stooke]

Wind turbines?  Yes, I know, very thin atmosphere, but that's what was said about flight and now we have a helicopter.  Maybe Ingenuity can be reverse-engineered into a turbine,  Well, maybe something a bit bigger! - but as a backup to solar and basically just chugging away in the background trickling power into batteries, that might be worth adding to a base architecture.  I suppose there are studies, I just didn't look for them (yet).

[daedalus1]

Wind turbines?  Yes, I know, very thin atmosphere, but that's what was said about flight and now we have a helicopter.  Maybe Ingenuity can be reverse-engineered into a turbine,  Well, maybe something a bit bigger! - but as a backup to solar and basically just chugging away in the background trickling power into batteries, that might be worth adding to a base architecture.  I suppose there are studies, I just didn't look for them (yet).

No. There isn't hardly enough pressure to move a feather.

[Robotbeat]

Wind turbines?  Yes, I know, very thin atmosphere, but that's what was said about flight and now we have a helicopter.  Maybe Ingenuity can be reverse-engineered into a turbine,  Well, maybe something a bit bigger! - but as a backup to solar and basically just chugging away in the background trickling power into batteries, that might be worth adding to a base architecture.  I suppose there are studies, I just didn't look for them (yet).

No. There isn't hardly enough pressure to move a feather.

Wrong. People should check NASA research before unilaterally declaring something not possible or whatever.

https://ntrs.nasa.gov/citations/19990081125

Performance and Feasibility Analysis of a Wind Turbine Power System for Use on Mars
“Findings of this preliminary study show that turbine power output on Mars could be as high as several hundred kilowatts. The optimized conceptual design examined here would have a power output of 104 kW, total mass of 1910 kg, and specific power of 54.6 W/kg.”

[LMT]

Wind turbines?  Yes, I know, very thin atmosphere, but that's what was said about flight and now we have a helicopter.  Maybe Ingenuity can be reverse-engineered into a turbine,  Well, maybe something a bit bigger! - but as a backup to solar and basically just chugging away in the background trickling power into batteries, that might be worth adding to a base architecture.  I suppose there are studies, I just didn't look for them (yet).

Hello, astronomy Prof. Stooke.

The OP author gets upset when posters mention power supply here, but he's off talking about fracking and Sabatier reactors now, so why not.

--

One wind turbine targets 0.04 kW/kg, which isn't great, and it's designed for a high reference wind of 26 m/s (94 km/hr).  James et al. 1999.

Keep in mind, a dust storm produces the worst PV power deficit on just those days when atmospheric potential and triboelectric power harvest should be maximized.  A collector could be a useful, lightweight addition to a solar panel, providing extra kW reliably in the worst of the murk.  Have you seen Baumgaertner 2016, Melnik and Parrot 1998?

Refs.

James, G., Chamitoff, G., & Barker, D. (1999, August). Design and resource requirements for successful wind energy production on Mars. In Second International Mars Society Convention, Boulder, CO.

Baumgaertner, A. (2016). Power to Mars.

Melnik O, Parrot M. Electrostatic discharge in Martian dust storms. Journal of Geophysical Research: Space Physics. 1998 Dec 1;103(A12):29107-17.

[daedalus1]

Wind turbines?  Yes, I know, very thin atmosphere, but that's what was said about flight and now we have a helicopter.  Maybe Ingenuity can be reverse-engineered into a turbine,  Well, maybe something a bit bigger! - but as a backup to solar and basically just chugging away in the background trickling power into batteries, that might be worth adding to a base architecture.  I suppose there are studies, I just didn't look for them (yet).

No. There isn't hardly enough pressure to move a feather.

Wrong. People should check NASA research before unilaterally declaring something not possible or whatever.

https://ntrs.nasa.gov/citations/19990081125

Performance and Feasibility Analysis of a Wind Turbine Power System for Use on Mars
“Findings of this preliminary study show that turbine power output on Mars could be as high as several hundred kilowatts. The optimized conceptual design examined here would have a power output of 104 kW, total mass of 1910 kg, and specific power of 54.6 W/kg.”

That is very hard to believe. There is very little information in the link as to how this result came about. Though not wishing to dispute more learned people's results, I can't see how this is possible, there is insignificant wind speed at the Martian surface and it wil be at least a hundred times less effective than the same speed on Earth.

[Robotbeat]

Who told you Mars has insignificant wind speed?

Quit doing the thing where you over-correct from another misunderstanding. Just because Mars wind storms don’t throw stuff around to impale Matt Damon doesn’t mean the wind speed is insignificant. It’s significant enough to cause massive dust storms and move dunes all over the place.

The wind speed data is in Table 2 and comes from references 6 and 7.

[daedalus1]

Who told you Mars has insignificant wind speed?

Quit doing the thing where you over-correct from another misunderstanding. Just because Mars wind storms don’t throw stuff around to impale Matt Damon doesn’t mean the wind speed is insignificant. It’s significant enough to cause massive dust storms and move dunes all over the place.

The wind speed data is in Table 2 and comes from references 6 and 7.

Viking data. Winds average 10 to 20 mph which is the equivalent of 1 to 2 mph on Earth. During a dust storm they can be three times that, but they only occur for a short time every two years or so.

[Joseph Peterson]

What I hoped to see in this thread is a discussion of the demand side for both power and stored resources(This includes carbon dioxide scrubbing technology).  Supply side is better discussed here:

https://forum.nasaspaceflight.com/index.php?topic=39785.0

[daedalus1]

What I hoped to see in this thread is a discussion of the demand side for both power and stored resources(This includes carbon dioxide scrubbing technology).  Supply side is better discussed here:

https://forum.nasaspaceflight.com/index.php?topic=39785.0

Well I suggest you change the header because power is definitely required to survive a Martian dust storm.

[Robotbeat]

Who told you Mars has insignificant wind speed?

Quit doing the thing where you over-correct from another misunderstanding. Just because Mars wind storms don’t throw stuff around to impale Matt Damon doesn’t mean the wind speed is insignificant. It’s significant enough to cause massive dust storms and move dunes all over the place.

The wind speed data is in Table 2 and comes from references 6 and 7.

Viking data. Winds average 10 to 20 mph which is the equivalent of 1 to 2 mph on Earth. During a dust storm they can be three times that, but they only occur for a short time every two years or so.

1) actually look in the data table in that report. Of course it’s true if you set the wind turbine on the ground, the wind will be low. But wind speeds increase rapidly as you get higher. Look at what the proposal actually says before shooting it down
2) that’s precisely when you need the power most, though.m

It’s okay to admit your original claim is wrong and move on.

[Joseph Peterson]

Basic lithium-hydroxide canisters (think Apollo) can be regenerated simply by heating them and exposing them to vacuum.

Not sure about the power use. I'm not sure it matters all too much, since after the storm is gone you have plenty of power available to regenerate them.

Even if it's "only" 50% energy efficient, then it still breaks even with the round-trip energy efficiency of the electricity -> methox -> electricity system. Here I am (generously) estimating an 80% efficient electrolysis+sabatier process and a 65% efficient combined-heat-and-power turbine generator.

Apollo LiOH canisters (which surely can be improved upon) would mass only 7 kg per person per 30 days. This compares very favorably to the battery mass needed to power a regenerative CO2 removal system for that same 30 day period.

I vaguely recall looking into LiOH about a decade ago, then moving on because LiOH wasn't fit for what I needed.  It is an option for a stored resource that allows survival during a Martian dust storm though.  The question becomes are there better options?

[Joseph Peterson]

What I hoped to see in this thread is a discussion of the demand side for both power and stored resources(This includes carbon dioxide scrubbing technology).  Supply side is better discussed here:

https://forum.nasaspaceflight.com/index.php?topic=39785.0

Well I suggest you change the header because power is definitely required to survive a Martian dust storm.

Would you care to make a suggestion.  I specifically didn't use the word power in the title because there are already plenty of conversations on NSF about power generation and I was hoping to prevent this thread from repeating those conversations.

[LMT]

What I hoped to see in this thread is a discussion of the demand side for both power and stored resources(This includes carbon dioxide scrubbing technology).  Supply side is better discussed here:

https://forum.nasaspaceflight.com/index.php?topic=39785.0

Well I suggest you change the header because power is definitely required to survive a Martian dust storm.

Would you care to make a suggestion.  I specifically didn't use the word power in the title because there are already plenty of conversations on NSF about power generation and I was hoping to prevent this thread from repeating those conversations.

"Dark Greenhouse - The Seedlings"

[Robotbeat]

What I hoped to see in this thread is a discussion of the demand side for both power and stored resources(This includes carbon dioxide scrubbing technology).  Supply side is better discussed here:

https://forum.nasaspaceflight.com/index.php?topic=39785.0

Well I suggest you change the header because power is definitely required to survive a Martian dust storm.

Would you care to make a suggestion.  I specifically didn't use the word power in the title because there are already plenty of conversations on NSF about power generation and I was hoping to prevent this thread from repeating those conversations.

So add “no extra power allowed!” because it’s clearly the obvious solution.

[daedalus1]

Who told you Mars has insignificant wind speed?

Quit doing the thing where you over-correct from another misunderstanding. Just because Mars wind storms don’t throw stuff around to impale Matt Damon doesn’t mean the wind speed is insignificant. It’s significant enough to cause massive dust storms and move dunes all over the place.

The wind speed data is in Table 2 and comes from references 6 and 7.

Viking data. Winds average 10 to 20 mph which is the equivalent of 1 to 2 mph on Earth. During a dust storm they can be three times that, but they only occur for a short time every two years or so.

1) actually look in the data table in that report. Of course it’s true if you set the wind turbine on the ground, the wind will be low. But wind speeds increase rapidly as you get higher. Look at what the proposal actually says before shooting it down
2) that’s precisely when you need the power most, though.m

It’s okay to admit your original claim is wrong and move on.

Come on, no need for that last part of your comment.

If you look at the tables you will notice the atmospheric pressure goes down with altitude so making it less effective.

[Robotbeat]

Who told you Mars has insignificant wind speed?

Quit doing the thing where you over-correct from another misunderstanding. Just because Mars wind storms don’t throw stuff around to impale Matt Damon doesn’t mean the wind speed is insignificant. It’s significant enough to cause massive dust storms and move dunes all over the place.

The wind speed data is in Table 2 and comes from references 6 and 7.

Viking data. Winds average 10 to 20 mph which is the equivalent of 1 to 2 mph on Earth. During a dust storm they can be three times that, but they only occur for a short time every two years or so.

1) actually look in the data table in that report. Of course it’s true if you set the wind turbine on the ground, the wind will be low. But wind speeds increase rapidly as you get higher. Look at what the proposal actually says before shooting it down
2) that’s precisely when you need the power most, though.m

It’s okay to admit your original claim is wrong and move on.

Come on, no need for that last part of your comment.

If you look at the tables you will notice the atmospheric pressure goes down with altitude so making it less effective.

Actually, you were completely dismissive of wind. Evidence was provided that contradicts that dismissiveness. Pretty sure that it’s the dismissiveness that is unneeded.

And sure, almost like they took into account multiple variables when doing the study.

[Robotbeat]

The problem is that the question is kind of poorly posed. If it’s for scientific use, then the demand needs to be constant to maintain consistent controlled experimental conditions. If it’s to provide long term food and oxygen for astronauts, then the solution is to just store stuff and rely primarily on industrial life support.

[daedalus1]

Who told you Mars has insignificant wind speed?

Quit doing the thing where you over-correct from another misunderstanding. Just because Mars wind storms don’t throw stuff around to impale Matt Damon doesn’t mean the wind speed is insignificant. It’s significant enough to cause massive dust storms and move dunes all over the place.

The wind speed data is in Table 2 and comes from references 6 and 7.

Viking data. Winds average 10 to 20 mph which is the equivalent of 1 to 2 mph on Earth. During a dust storm they can be three times that, but they only occur for a short time every two years or so.

1) actually look in the data table in that report. Of course it’s true if you set the wind turbine on the ground, the wind will be low. But wind speeds increase rapidly as you get higher. Look at what the proposal actually says before shooting it down
2) that’s precisely when you need the power most, though.m

It’s okay to admit your original claim is wrong and move on.

Come on, no need for that last part of your comment.

If you look at the tables you will notice the atmospheric pressure goes down with altitude so making it less effective.

Actually, you were completely dismissive of wind. Evidence was provided that contradicts that dismissiveness. Pretty sure that it’s the dismissiveness that is unneeded.

And sure, almost like they took into account multiple variables when doing the study.

I was not "dismissive" of wind. I claim from the Viking data that at ground level the low wind speed combined with an ultra low atmospheric pressure will not be capable of producing any significant power. 7 milibars is practically a vacuum (try standing in it with just an oxygen mask for a few seconds). At altitude it will be even closer to a hard vacuum. Floating a heavy electrical turbine in a near vacuum would really be an amazing event.

[lamontagne]

Who told you Mars has insignificant wind speed?

Quit doing the thing where you over-correct from another misunderstanding. Just because Mars wind storms don’t throw stuff around to impale Matt Damon doesn’t mean the wind speed is insignificant. It’s significant enough to cause massive dust storms and move dunes all over the place.

The wind speed data is in Table 2 and comes from references 6 and 7.

Viking data. Winds average 10 to 20 mph which is the equivalent of 1 to 2 mph on Earth. During a dust storm they can be three times that, but they only occur for a short time every two years or so.

1) actually look in the data table in that report. Of course it’s true if you set the wind turbine on the ground, the wind will be low. But wind speeds increase rapidly as you get higher. Look at what the proposal actually says before shooting it down
2) that’s precisely when you need the power most, though.m

It’s okay to admit your original claim is wrong and move on.

Come on, no need for that last part of your comment.

If you look at the tables you will notice the atmospheric pressure goes down with altitude so making it less effective.

Actually, you were completely dismissive of wind. Evidence was provided that contradicts that dismissiveness. Pretty sure that it’s the dismissiveness that is unneeded.

And sure, almost like they took into account multiple variables when doing the study.

I was not "dismissive" of wind. I claim from the Viking data that at ground level the low wind speed combined with an ultra low atmospheric pressure will not be capable of producing any significant power. 7 milibars is practically a vacuum (try standing in it with just an oxygen mask for a few seconds). At altitude it will be even closer to a hard vacuum. Floating a heavy electrical turbine in a near vacuum would really be an amazing event.

There are a number of Martian windmill designs.  There are some seemingly solid papers on the subject.  There is a helicopter that flew on Mars.  That kind of proves that windmills could work.
However, they are not necessarily cost effective.  A little text on the subject: https://marspedia.org/Wind_turbine

[daedalus1]

Who told you Mars has insignificant wind speed?

Quit doing the thing where you over-correct from another misunderstanding. Just because Mars wind storms don’t throw stuff around to impale Matt Damon doesn’t mean the wind speed is insignificant. It’s significant enough to cause massive dust storms and move dunes all over the place.

The wind speed data is in Table 2 and comes from references 6 and 7.

Viking data. Winds average 10 to 20 mph which is the equivalent of 1 to 2 mph on Earth. During a dust storm they can be three times that, but they only occur for a short time every two years or so.

1) actually look in the data table in that report. Of course it’s true if you set the wind turbine on the ground, the wind will be low. But wind speeds increase rapidly as you get higher. Look at what the proposal actually says before shooting it down
2) that’s precisely when you need the power most, though.m

It’s okay to admit your original claim is wrong and move on.

Come on, no need for that last part of your comment.

If you look at the tables you will notice the atmospheric pressure goes down with altitude so making it less effective.

Actually, you were completely dismissive of wind. Evidence was provided that contradicts that dismissiveness. Pretty sure that it’s the dismissiveness that is unneeded.

And sure, almost like they took into account multiple variables when doing the study.

I was not "dismissive" of wind. I claim from the Viking data that at ground level the low wind speed combined with an ultra low atmospheric pressure will not be capable of producing any significant power. 7 milibars is practically a vacuum (try standing in it with just an oxygen mask for a few seconds). At altitude it will be even closer to a hard vacuum. Floating a heavy electrical turbine in a near vacuum would really be an amazing event.

There are a number of Martian windmill designs.  There are some seemingly solid papers on the subject.  There is a helicopter that flew on Mars.  That kind of proves that windmills could work.
However, they are not necessarily cost effective.  A little text on the subject: https://marspedia.org/Wind_turbine

An electric motor powering a helicopter does not prove that the wind turbines can happen.

[Robotbeat]

Hey, maybe you’re vastly smarter than all the authors of those papers, or maybe it’s not an obviously dumb idea. Anyway. Solar is probably better for the vast majority of cases EXCEPT if you’re in a dust storm.

[daedalus1]

Hey, maybe you’re vastly smarter than all the authors of those papers, or maybe it’s not an obviously dumb idea. Anyway. Solar is probably better for the vast majority of cases EXCEPT if you’re in a dust storm.

I'm not claiming to be smarter than anyone, just exercising logic to understand reality.
I agree with your last sentence.
Solar is cheap and the sun shines 50% of the time. For nighttime and the rare event of a dust storm, chemical or other electrical storage system is the solution.

[Slarty1080]

Moving on,

It seems clear that CO2 can be removed using some form of sorbent bed caustic, amide, molecular sieve arrangement that would not need to be regenerated during the dust storm. Oxygen levels can be controlled by adding oxygen from a LOX source as required. With 12 people and some animals present  excess oxygen production would be unlikely, especially if the plants were more dormant.

Power would still be required for air circulation through the sorbent beds, humidity control and monitoring etc. But heat and light would constitute the vast majority of the power required. Heat might or might not be an issue depending on the amount of insulation and the availability of waste heat from other power consuming devices (or even deliberately adding extra organic plant waste to anaerobic digester units to produce heat).

So to a reasonable approximation the problem boils down to how little light needs to be provided, assuming that the research aims can be set aside during dust storms as previously suggested.

Killing off the whole biosphere is not a good option, but there should be a range of intermediate options that can be adapted to the power that is available. The first would be to compartmentalize the environment in some way so that different areas can be treated differently. Some areas could be harvested and allowed to freeze slowly.

All animal life and much insect life might be encouraged to migrate towards heat and light oasis areas where increased numbers might be supported for limited periods. If these oasis areas were then themselves allowed to drop to minimum light and heat levels insects might well hibernate and plants become dormant.

Techniques might also be developed to determine what is most affected by light loss and how to minimize that problem. As an example the loss of one species might be counteracted by specifically holding reserves of that species for re-colonization or by inoculating soils and similar.

It is virtually impossible to come up with any concrete numbers as there are far too many variables from the types of crops being grown to assumptions about the variability in severity and duration of the power loss, to the acceptability or otherwise to various forms of environmental degradation that would occur and the speed with which different parts might recover (in 0.38g).

The best that can be said is the less power there was available and the longer the duration of the power loss the greater the damage and the greater the need for mitigation such as described above.

[Robotbeat]

An important note is that “biospheres” are unlikely to be a viable way of keeping astronauts alive at any time. If you’re doing a biosphere, you’re either doing it for experiment, for essentially a zoo, or you’re doing it on a massive, massive scale. There’s no particularly *practical* reason to do a Mars One or Biosphere2 style “biosphere.”

[Twark_Main]

Hey, maybe you’re vastly smarter than all the authors of those papers, or maybe it’s not an obviously dumb idea. Anyway. Solar is probably better for the vast majority of cases EXCEPT if you’re in a dust storm.

I'm not claiming to be smarter than anyone, just exercising logic to understand reality.
I agree with your last sentence.
Solar is cheap and the sun shines 50% of the time. For nighttime and the rare event of a dust storm, chemical or other electrical storage system is the solution.

... or wind. You forgot wind in your list, there.

I believe that methox + batteries will be used (they're needed anyway for other reasons), but dissimilar redundancy is a Good Thing. It's cheap insurance to erect a few turbines on the nearby ridge-line.

If something is critical to staying alive (heat, oxygen, electricity), you don't just want one or two ways to satisfy that need. You want ten ways. You want resiliency, even if it comes at the expense of some efficiency.

[Twark_Main]

excess oxygen production would be unlikely, especially if the plants were more dormant.

Plants consume (large amounts of) oxygen when they get insufficient light. This happens at night, for instance. This would also happen during long periods of low light.

This is something I haven't seen addressed yet in this thread.

[Slarty1080]

excess oxygen production would be unlikely, especially if the plants were more dormant.

Plants consume (large amounts of) oxygen when they get insufficient light. This happens at night, for instance. This would also happen during long periods of low light.

This is something I haven't seen addressed yet in this thread.

My point being that normally plants produce more oxygen than they consume, but this is unlikely to be much of a problem in low light as you say so there should never be a need to artificially remove oxygen from the atmosphere only add it.

There is likely to be a surplus of oxygen at any base due to the stoichiometric need for oxygen in the Raptor engine (fuel rich), but the production of stoichiometric amounts of oxygen from electrolysis due to the need for hydrogen. This will only likely to be made worse by the use of hydrogen for chemical processing to form plastics. So this issue is just a matter of having a big enough LOX tank considering the hundreds of tonnes of propellant needed the relatively modest requirements for plants should be well catered for.

Not only that but whatever need for oxygen there is at night should be reduced by the low temperature which slows plant respiration.

[Dalhousie]

Martian dust is more like smog than anything else.  Images can took impressive, but in reality visibility is still substantial. 

For example Viking 1 colour images taken on sols 282 and 324 showed the effects of a large dust storm (Tau between 5 and 6)  in a colour composite by Olivier de Goursac (https://www.planetary.org/space-images/20131231_sol282_324dust_storm197) look impressive but the horizon ~3 km distant is still visible.  Under Visual Flight Rules (VFR) helicopters are able to fly in visibility down to 3 km (CASA 2021) without reliance on external navigation aids or instruments.

Smith et al. (2018), in a study of visibility in Gale crater during the 2019 dust storm, concluded that visibility was reduced to less than three km.  Guzewich et al. (2019) refined this to 2.7 km. 

Ground operations are even less constrained.  Activities around the station should not be impeded with visibility down to a few hundred m, and some field work would also be possible provided it was at previously visited sites with a marked trail (vehicle tracks would be adequate).

The Martian, great movie that it was, isn't a a documentary!

You could walk, yes.  We navigate under moonlight, after all. 

PV would fail there:  tau 5 transmission is < 1%.  Viking 1 could take the photo because it used the SNAP-19 RTG.

Tau 5 is <1% direct sunlight.  What is the indirect value?   It is total irradiance that matters for PV and operations.

Note that solar power for Saturn orbiters has been considered even though irradiance is only 1.1.

Peak midday irradiance on earth is over 100,000 lux. For Mars under clear conditions it would be about 45,000 lux.  So 1% of that is ~450 lux,  equivalent to sunrise or sunset on a clear day on Earth.

By contrast full Moon under a clear size is 0.25 lux.

[LMT]

Viking 1 colour images taken on sols 282 and 324 showed the effects of a large dust storm (Tau between 5 and 6)...

PV would fail there:  tau 5 transmission is < 1%.  Viking 1 could take the photo because it used the SNAP-19 RTG.

It is total irradiance that matters for PV and operations.

No, landers' GaInP solar cells couldn't use redshifted storm light.  See the reference in the power thread.

[Joseph Peterson]

Thanks for the feedback. 

I did a minimal edit to the header inspired in large part thanks to Robotbeat.  I don't think the header is perfect yet but anything that precludes more talk of additional power generation is an improvement.

Note to Robotbeat:  I saw your cartoon and didn't laugh.  The fact of the matter is I have no problem utilizing stored power.  After all stored power is a stored resource.  What I am concerned about is minimizing stored power requirements, while at the same time ensuring the crops we choose to plant in the weeks before we know a severe global dust storm will strike allow the biosphere to return to nominal status once the dust storm passes.

[Joseph Peterson]

excess oxygen production would be unlikely, especially if the plants were more dormant.

Plants consume (large amounts of) oxygen when they get insufficient light. This happens at night, for instance. This would also happen during long periods of low light.

This is something I haven't seen addressed yet in this thread.

A propellant plant produces vastly more oxygen than needed.  With proper planning this excess oxygen supply will be much larger than the oxygen requirements of humans, animals, and plants that need extra oxygen due to insufficient light.  One of the goals I hope we can accomplish in this thread is to create a biosphere that doesn't consume all of the excess oxygen the propellant plant produces during an extreme dust storm.

[Joseph Peterson]

Martian dust is more like smog than anything else.  Images can took impressive, but in reality visibility is still substantial. 

For example Viking 1 colour images taken on sols 282 and 324 showed the effects of a large dust storm (Tau between 5 and 6)  in a colour composite by Olivier de Goursac (https://www.planetary.org/space-images/20131231_sol282_324dust_storm197) look impressive but the horizon ~3 km distant is still visible.  Under Visual Flight Rules (VFR) helicopters are able to fly in visibility down to 3 km (CASA 2021) without reliance on external navigation aids or instruments.

Smith et al. (2018), in a study of visibility in Gale crater during the 2019 dust storm, concluded that visibility was reduced to less than three km.  Guzewich et al. (2019) refined this to 2.7 km. 

Ground operations are even less constrained.  Activities around the station should not be impeded with visibility down to a few hundred m, and some field work would also be possible provided it was at previously visited sites with a marked trail (vehicle tracks would be adequate).

The Martian, great movie that it was, isn't a a documentary!

You could walk, yes.  We navigate under moonlight, after all. 

PV would fail there:  tau 5 transmission is < 1%.  Viking 1 could take the photo because it used the SNAP-19 RTG.

Tau 5 is <1% direct sunlight.  What is the indirect value?   It is total irradiance that matters for PV and operations.

Note that solar power for Saturn orbiters has been considered even though irradiance is only 1.1.

Peak midday irradiance on earth is over 100,000 lux. For Mars under clear conditions it would be about 45,000 lux.  So 1% of that is ~450 lux,  equivalent to sunrise or sunset on a clear day on Earth.

By contrast full Moon under a clear size is 0.25 lux.

An number that is oft-quoted is that Opportunity was producing 2.5% of rated photovoltaic power output prior to shutdown during the 2018 dust storm.  We can boost the available generated power available by any number of means including, but not limited to, sweeping dust off of the solar panels, bringing a nuclear reactor or dozens like kilopower, or burning methalox in a generator.  As long as we know how much power we need we can plan ahead and send multiple redundant backups that can provide the necessary power.

What I don't yet know is how much power we actually need.  Figuring out a reference value for how much power we actually need is the one and only reason I bothered to start this thread.  I am well aware that the restrictions I set in the OP are very limiting if all we care about is keeping a crew of a dozen alive.  In my mind those restrictions are OK.  What I really care about is creating a reference point that can be used to extrapolate what is needed to support thousands or millions.  The way I see it is if we are overly conservative now a Martian settlement numbering in the thousands will be grateful that we over-planned and gave them the excessive margins so they don't have to adopt of our underestimates later.

[daedalus1]

Hey, maybe you’re vastly smarter than all the authors of those papers, or maybe it’s not an obviously dumb idea. Anyway. Solar is probably better for the vast majority of cases EXCEPT if you’re in a dust storm.

I'm not claiming to be smarter than anyone, just exercising logic to understand reality.
I agree with your last sentence.
Solar is cheap and the sun shines 50% of the time. For nighttime and the rare event of a dust storm, chemical or other electrical storage system is the solution.

... or wind. You forgot wind in your list, there.

I believe that methox + batteries will be used (they're needed anyway for other reasons), but dissimilar redundancy is a Good Thing. It's cheap insurance to erect a few turbines on the nearby ridge-line.

If something is critical to staying alive (heat, oxygen, electricity), you don't just want one or two ways to satisfy that need. You want ten ways. You want resiliency, even if it comes at the expense of some efficiency.

You should read back, I didn't forget wind.

[lamontagne]

Can we use Canada as an example?

As I write this in November, everything about me in nature is shutting down.  A reduction in solar power far less dramatic than the one of a solar storm is driving nature into dormancy.  Most of the 'annual' plants will die, because that is the method they have developed for this period.  Others such as trees dry up and store energy in their roots.  Most life also slows down, and many have evolved complex ways of surviving the drop in temperature for the expected time.
I would expect this to happen during the Martian winter as well, and if a storm comes up and reduces sunlight further, it will take place during winter, and have little effect.  I guess that you would need to avoid very deep freezing, as that is not expected on Earth, so some minimum heating is required.  Frost on Earth never goes does bellow a few feet.  In the areas where it does, the ecosystem is basically too poor to support anything but the barest minimum surviving.

So i would suggest the best way to survive the dust storm might be to have the system already in dormancy, using seasonally adopted plants.  Not try to grow strawberries in December.

This doesn't really work if dust storms are entirely unpredictable and non seasonal.  Nature has evolved for billions of years on the basis of large scale predictability.

[daedalus1]

Can we use Canada as an example?

As I write this in November, everything about me in nature is shutting down.  A reduction in solar power far less dramatic than the one of a solar storm is driving nature into dormancy.  Most of the 'annual' plants will die, because that is the method they have developed for this period.  Others such as trees dry up and store energy in their roots.  Most life also slows down, and many have evolved complex ways of surviving the drop in temperature for the expected time.
I would expect this to happen during the Martian winter as well, and if a storm comes up and reduces sunlight further, it will take place during winter, and have little effect.

Martian dust storms are often global, so not restricted to winter.

[lamontagne]

Can we use Canada as an example?

As I write this in November, everything about me in nature is shutting down.  A reduction in solar power far less dramatic than the one of a solar storm is driving nature into dormancy.  Most of the 'annual' plants will die, because that is the method they have developed for this period.  Others such as trees dry up and store energy in their roots.  Most life also slows down, and many have evolved complex ways of surviving the drop in temperature for the expected time.
I would expect this to happen during the Martian winter as well, and if a storm comes up and reduces sunlight further, it will take place during winter, and have little effect.

Martian dust storms are often global, so not restricted to winter.

How uncooperative of them.  But are the storms seasonal in the sense that they are predictable, associated with perihelion or aphelion? Or might there be a base/settlement emplacement for which storm do correspond to winter in a reliable way?

Anyway, this means that a storm might come along at the height of summer and wipe out a crop in a least one hemisphere of Mars.  In about one month the available power will drop from summer to well bellow the worst possible winter on Earth.

So I guess that the answer would be to provide heat, or grow in a sufficiently insulated area, to ensure that ground does not freeze too deep, and store enough seeds for next year's crop.  Keep the habitat life support system independent from the farming/biosphere so it's only the plants that die.
It's going to be be very difficult to regulate that biosphere anyway, because it is so small and has so little inertia.  CO2 and oxygen concentrations may vary widely, as they already sometimes do in grow rooms on Earth.  Bacteria may do quite unexpected things, in particular if soil is used.

If the biome/much simplified food production system is in grow rooms rather than in greenhouses, the problem might be much less important.  The growth seasons are, I believe, quite short, with multiple crops per year, so you just skip a few crops and keep the lights off?

[guckyfan]

Martian dust storms are often global, so not restricted to winter.

Yes, but are they not an annual event? In the sense that they occur only once in the martian year, not twice and in the same part of the martian year?

[daedalus1]

Martian dust storms are often global, so not restricted to winter.

Yes, but are they not an annual event? In the sense that they occur only once in the martian year, not twice and in the same part of the martian year?

You are missing my point. It was in reply to someone suggesting that they might occur only in the winter. Obviously if they are global they cannot be only one season.

[Twark_Main]

Martian dust is more like smog than anything else.  Images can took impressive, but in reality visibility is still substantial. 

For example Viking 1 colour images taken on sols 282 and 324 showed the effects of a large dust storm (Tau between 5 and 6)  in a colour composite by Olivier de Goursac (https://www.planetary.org/space-images/20131231_sol282_324dust_storm197) look impressive but the horizon ~3 km distant is still visible.  Under Visual Flight Rules (VFR) helicopters are able to fly in visibility down to 3 km (CASA 2021) without reliance on external navigation aids or instruments.

Smith et al. (2018), in a study of visibility in Gale crater during the 2019 dust storm, concluded that visibility was reduced to less than three km.  Guzewich et al. (2019) refined this to 2.7 km. 

Ground operations are even less constrained.  Activities around the station should not be impeded with visibility down to a few hundred m, and some field work would also be possible provided it was at previously visited sites with a marked trail (vehicle tracks would be adequate).

The Martian, great movie that it was, isn't a a documentary!

You could walk, yes.  We navigate under moonlight, after all. 

PV would fail there:  tau 5 transmission is < 1%.  Viking 1 could take the photo because it used the SNAP-19 RTG.

Tau 5 is <1% direct sunlight.  What is the indirect value?   It is total irradiance that matters for PV and operations.

About 33% the top-of-atmosphere insolation if the Sun is at zenith, or roughly 25% if the sun is at 45°. I attached the relevant chart here.

[Twark_Main]

Hey, maybe you’re vastly smarter than all the authors of those papers, or maybe it’s not an obviously dumb idea. Anyway. Solar is probably better for the vast majority of cases EXCEPT if you’re in a dust storm.

I'm not claiming to be smarter than anyone, just exercising logic to understand reality.
I agree with your last sentence.
Solar is cheap and the sun shines 50% of the time. For nighttime and the rare event of a dust storm, chemical or other electrical storage system is the solution.

... or wind. You forgot wind in your list, there.

I believe that methox + batteries will be used (they're needed anyway for other reasons), but dissimilar redundancy is a Good Thing. It's cheap insurance to erect a few turbines on the nearby ridge-line.

If something is critical to staying alive (heat, oxygen, electricity), you don't just want one or two ways to satisfy that need. You want ten ways. You want resiliency, even if it comes at the expense of some efficiency.

You should read back, I didn't forget wind.

My mistake. I see now that you're inappropriately dismissing wind instead.

No matter since it's off-topic for the thread now (given the recent title edit), a consideration which also applies to the aforementioned "chemical or electrical storage systems."

[Twark_Main]

Martian dust storms are often global, so not restricted to winter.

Yes, but are they not an annual event? In the sense that they occur only once in the martian year, not twice and in the same part of the martian year?

You are missing my point. It was in reply to someone suggesting that they might occur only in the winter. Obviously if they are global they cannot be only one season.

That is very not obvious to me. It seems like you must be relying on many additional implicit unstated assumptions to arrive at that conclusion.

I, for one, still eagerly await an answer to guckyfan's question.

Is the trick here merely semantics? Are you reading "winter" and not immediately parsing it into "winter in the Northern hemisphere where the colony will be located?"

[daedalus1]

Hey, maybe you’re vastly smarter than all the authors of those papers, or maybe it’s not an obviously dumb idea. Anyway. Solar is probably better for the vast majority of cases EXCEPT if you’re in a dust storm.

I'm not claiming to be smarter than anyone, just exercising logic to understand reality.
I agree with your last sentence.
Solar is cheap and the sun shines 50% of the time. For nighttime and the rare event of a dust storm, chemical or other electrical storage system is the solution.

... or wind. You forgot wind in your list, there.

I believe that methox + batteries will be used (they're needed anyway for other reasons), but dissimilar redundancy is a Good Thing. It's cheap insurance to erect a few turbines on the nearby ridge-line.

If something is critical to staying alive (heat, oxygen, electricity), you don't just want one or two ways to satisfy that need. You want ten ways. You want resiliency, even if it comes at the expense of some efficiency.

You should read back, I didn't forget wind.

My mistake. I see now that you're inappropriately dismissing wind instead.

No matter since it's off-topic for the thread now (given the recent title edit), a consideration which also applies to the aforementioned "chemical or electrical storage systems."

I didn't "inappropriately (what is that comment for?) dismiss wind".
I argued logically that it wouldn't work on Mars. Some people argued that it would. That is what forums like this are for.

[daedalus1]

Martian dust storms are often global, so not restricted to winter.

Yes, but are they not an annual event? In the sense that they occur only once in the martian year, not twice and in the same part of the martian year?

You are missing my point. It was in reply to someone suggesting that they might occur only in the winter. Obviously if they are global they cannot be only one season.

That is very not obvious to me. It seems like you must be relying on many additional implicit unstated assumptions to arrive at that conclusion.

I, for one, still eagerly await an answer to guckyfan's question.

Is the trick here merely semantics? Are you reading "winter" and not immediately parsing it into "winter in the Northern hemisphere where the colony will be located?"

Yes I did make an assumption. It seems the big ones only start in the southern hemisphere when it is in summer. So ignore my previous comments.

[Robotbeat]

Viking 1 colour images taken on sols 282 and 324 showed the effects of a large dust storm (Tau between 5 and 6)...

PV would fail there:  tau 5 transmission is < 1%.  Viking 1 could take the photo because it used the SNAP-19 RTG.

It is total irradiance that matters for PV and operations.

No, landers' GaInP solar cells couldn't use redshifted storm light.  See the reference in the power thread.

That’s false. They’re usually triple junction cells that ABSOLUTELY DO USE RED SHIFTED LIGHT FOR POWER GENERATION. Can you quit doing this thing where you make a false claim and then cite yourself as proof?

[Robotbeat]

Thanks for the feedback. 

I did a minimal edit to the header inspired in large part thanks to Robotbeat.  I don't think the header is perfect yet but anything that precludes more talk of additional power generation is an improvement.

Note to Robotbeat:  I saw your cartoon and didn't laugh.  The fact of the matter is I have no problem utilizing stored power.  After all stored power is a stored resource.  What I am concerned about is minimizing stored power requirements, while at the same time ensuring the crops we choose to plant in the weeks before we know a severe global dust storm will strike allow the biosphere to return to nominal status once the dust storm passes.

I think we should just treat it like winter in a place like Minnesota where the crops die, the ground is frozen solid, and we just plant again in the spring. You use a buffer of oxygen and CO2 absorption capacity to return to normal.

[Dalhousie]

Martian dust is more like smog than anything else.  Images can took impressive, but in reality visibility is still substantial. 

For example Viking 1 colour images taken on sols 282 and 324 showed the effects of a large dust storm (Tau between 5 and 6)  in a colour composite by Olivier de Goursac (https://www.planetary.org/space-images/20131231_sol282_324dust_storm197) look impressive but the horizon ~3 km distant is still visible.  Under Visual Flight Rules (VFR) helicopters are able to fly in visibility down to 3 km (CASA 2021) without reliance on external navigation aids or instruments.

Smith et al. (2018), in a study of visibility in Gale crater during the 2019 dust storm, concluded that visibility was reduced to less than three km.  Guzewich et al. (2019) refined this to 2.7 km. 

Ground operations are even less constrained.  Activities around the station should not be impeded with visibility down to a few hundred m, and some field work would also be possible provided it was at previously visited sites with a marked trail (vehicle tracks would be adequate).

The Martian, great movie that it was, isn't a a documentary!

You could walk, yes.  We navigate under moonlight, after all. 

PV would fail there:  tau 5 transmission is < 1%.  Viking 1 could take the photo because it used the SNAP-19 RTG.

Tau 5 is <1% direct sunlight.  What is the indirect value?   It is total irradiance that matters for PV and operations.

About 33% the top-of-atmosphere insolation if the Sun is at zenith, or roughly 25% if the sun is at 45°. I attached the relevant chart here.

that's the value I use.

Thank you.  Do you know of a chart that extends out past Tau = 10?

If top of atmosphere is 588 W/m² then noon day irradiance at a Tau of 5 is 194 W/m²

[Twark_Main]

[snip]

My mistake. I see now that you're inappropriately dismissing wind instead.

I didn't "inappropriately (what is that comment for?) dismiss wind".
I argued logically that it wouldn't work on Mars.

I must have missed the "logical" part.

From what I saw you just said "gee the air is thin, guess we should give up" and then simply endlessly repeated yourself when presented with real counter-arguments. You also multiple times failed to comprehend that this was being put forth as a system primarily for use in dust storms.

...hence "inappropriately."

[Twark_Main]

Martian dust is more like smog than anything else.  Images can took impressive, but in reality visibility is still substantial. 

For example Viking 1 colour images taken on sols 282 and 324 showed the effects of a large dust storm (Tau between 5 and 6)  in a colour composite by Olivier de Goursac (https://www.planetary.org/space-images/20131231_sol282_324dust_storm197) look impressive but the horizon ~3 km distant is still visible.  Under Visual Flight Rules (VFR) helicopters are able to fly in visibility down to 3 km (CASA 2021) without reliance on external navigation aids or instruments.

Smith et al. (2018), in a study of visibility in Gale crater during the 2019 dust storm, concluded that visibility was reduced to less than three km.  Guzewich et al. (2019) refined this to 2.7 km. 

Ground operations are even less constrained.  Activities around the station should not be impeded with visibility down to a few hundred m, and some field work would also be possible provided it was at previously visited sites with a marked trail (vehicle tracks would be adequate).

The Martian, great movie that it was, isn't a a documentary!

You could walk, yes.  We navigate under moonlight, after all. 

PV would fail there:  tau 5 transmission is < 1%.  Viking 1 could take the photo because it used the SNAP-19 RTG.

Tau 5 is <1% direct sunlight.  What is the indirect value?   It is total irradiance that matters for PV and operations.

About 33% the top-of-atmosphere insolation if the Sun is at zenith, or roughly 25% if the sun is at 45°. I attached the relevant chart here.

that's the value I use.

Thank you.  Do you know of a chart that extends out past Tau = 10?

Sadly no.

They provide the equations in the linked paper, so with a little Excel someone should be able to make a chart that extends out past tau = 10.

Edit: aaand on second thought, I wouldn't do that. The equations in the paper rely on a polynomial fit, and that polynomial might diverge from the underlying model at tau > 6.

[daedalus1]

[snip]

My mistake. I see now that you're inappropriately dismissing wind instead.

I didn't "inappropriately (what is that comment for?) dismiss wind".
I argued logically that it wouldn't work on Mars.

I must have missed the "logical" part.

From what I saw you just said "gee the air is thin, guess we should give up" and then simply endlessly repeated yourself when presented with real counter-arguments. You also multiple times failed to comprehend that this was being put forth as a system primarily for use in dust storms.

...hence "inappropriately."

I mentioned in my argument Viking data including dust storm speeds which you conveniently left out of the reply.

[Robotbeat]

Nobody puts wind farms at ground level. Wind speed improves a LOT with height above the surface. That’s why tethered concepts or 200 meter tall wind turbines do very well. Even a modest height helps more than Viking. And wind speed changes in a pretty predictable way with height that can be well-modeled if you know the composition, pressure, and temperature of Mars’ atmosphere, which we do.

That’s why you should actually read that study posted instead of dismissing it without much thought. No one on earth puts a wind turbine close to the ground.

[daedalus1]

Nobody puts wind farms at ground level. Wind speed improves a LOT with height above the surface. That’s why tethered concepts or 200 meter tall wind turbines do very well. Even a modest height helps more than Viking. And wind speed changes in a pretty predictable way with height that can be well-modeled if you know the composition, pressure, and temperature of Mars’ atmosphere, which we do.

That’s why you should actually read that study posted instead of dismissing it without much thought. No one on earth puts a wind turbine close to the ground.

I'm completely aware of that. Neither you or I know the wind speed at 200 metres altitude on Mars. But i hazzard a guess that it is not significantly more than ground level and at 7 millibars would not make any significant electricity.

[Robotbeat]

Nobody puts wind farms at ground level. Wind speed improves a LOT with height above the surface. That’s why tethered concepts or 200 meter tall wind turbines do very well. Even a modest height helps more than Viking. And wind speed changes in a pretty predictable way with height that can be well-modeled if you know the composition, pressure, and temperature of Mars’ atmosphere, which we do.

That’s why you should actually read that study posted instead of dismissing it without much thought. No one on earth puts a wind turbine close to the ground.

I'm completely aware of that. Neither you or I know the wind speed at 200 metres altitude on Mars. But i hazzard a guess that it is not significantly more than ground level and at 7 millibars would not make any significant electricity.

your guess is worth nothing. Read the paper, they did the actual fluid dynamics.

[daedalus1]

Nobody puts wind farms at ground level. Wind speed improves a LOT with height above the surface. That’s why tethered concepts or 200 meter tall wind turbines do very well. Even a modest height helps more than Viking. And wind speed changes in a pretty predictable way with height that can be well-modeled if you know the composition, pressure, and temperature of Mars’ atmosphere, which we do.

That’s why you should actually read that study posted instead of dismissing it without much thought. No one on earth puts a wind turbine close to the ground.

I'm completely aware of that. Neither you or I know the wind speed at 200 metres altitude on Mars. But i hazzard a guess that it is not significantly more than ground level and at 7 millibars would not make any significant electricity.

your guess is worth nothing. Read the paper, they did the actual fluid dynamics.

If you know it why not just quote it?

[Robotbeat]

You can read just fine. But anyway, windspeed exactly at ground level is zero according to fluid dynamics due to finite viscosity.

It is obvious due to fluid dynamics, but here’s a source for that statement:
https://www.semanticscholar.org/paper/Testing-a-new-model-of-local-wind-erosion-and-dust-N.Deniskina/a38194aa34b2e932d1cc6ed9d88e2a6addd0b3e7

[Robotbeat]

Here’s the previously mentioned paper again. Tethered wind kite is a pretty mass efficient concept (important on Mars for obvious reasons… a heavy tower isn’t a lot of help) and it can access the much higher wind speeds of higher altitudes:
https://ntrs.nasa.gov/citations/19990081125

[daedalus1]

You can read just fine. But anyway, windspeed exactly at ground level is zero according to fluid dynamics due to finite viscosity.

It is obvious due to fluid dynamics, but here’s a source for that statement:
https://www.semanticscholar.org/paper/Testing-a-new-model-of-local-wind-erosion-and-dust-N.Deniskina/a38194aa34b2e932d1cc6ed9d88e2a6addd0b3e7

I've just found the paper and it quotes 3 m/s at 1 km, that's 7 mph. So barely more than ground level at 1 km. You are proposing 200 metres, so like I guessed....insignificant difference.

[Robotbeat]

You can read just fine. But anyway, windspeed exactly at ground level is zero according to fluid dynamics due to finite viscosity.

It is obvious due to fluid dynamics, but here’s a source for that statement:
https://www.semanticscholar.org/paper/Testing-a-new-model-of-local-wind-erosion-and-dust-N.Deniskina/a38194aa34b2e932d1cc6ed9d88e2a6addd0b3e7

I've just found the paper and it quotes 3 m/s at 1 km, that's 7 mph. So barely more than ground level at 1 km. You are proposing 200 metres, so like I guessed....insignificant difference.

oh shut. No I’m not. I’m proposing what the paper was proposing (actually I’m not even proposing it, only mentioning the proposal because it’s worth being considered, not dismissed out of hand lazily). I mentioned 200m only because that’s a typical height on Earth. The paper was proposing much higher heights.

You don’t get to dismiss a concept just because you intentionally misinterpreted something I said and refuse to look at ways the concept makes sense.

Read. The. frakking. Paper. I won’t be doing any more arguing with you about it until you do because you’ll just intentionally misinterpret what I say again.

Let’s focus on technical aspects, not on silly rhetorical tricks.

[daedalus1]

You can read just fine. But anyway, windspeed exactly at ground level is zero according to fluid dynamics due to finite viscosity.

It is obvious due to fluid dynamics, but here’s a source for that statement:
https://www.semanticscholar.org/paper/Testing-a-new-model-of-local-wind-erosion-and-dust-N.Deniskina/a38194aa34b2e932d1cc6ed9d88e2a6addd0b3e7

I've just found the paper and it quotes 3 m/s at 1 km, that's 7 mph. So barely more than ground level at 1 km. You are proposing 200 metres, so like I guessed....insignificant difference.

oh shut. No I’m not. I’m proposing what the paper was proposing. I mentioned 200m only because that’s a typical height on Earth. The paper was proposing much higher heights.

You don’t get to dismiss a concept just because you intentionally misinterpreted something I said and refuse to look at ways the concept makes sense.

Read. The. frakking. Paper. I won’t be doing any more arguing with you about it until you do because you’ll just intentionally misinterpret what I say again.

Let’s focus on technical aspects, not on silly rhetorical tricks.

My whole point is that it is impractical. The higher you go the close you are to a hard vacuum (as I've said previously). Mars is already near that at ground level. There is no way you are going to fly a kite at any significant height. An electric generator is a massive lump of metal also.

[Robotbeat]

Nah, read the paper. All that’s addressed in there.

On second thought, maybe we can power the base during a dust storm with all the handwaving you’re doing just to avoid reading the paper. Problem solved!

[daedalus1]

Nah, read the paper. All that’s addressed in there.

On second thought, maybe we can power the base during a dust storm with all the handwaving you’re doing just to avoid reading the paper. Problem solved!

You'd win an argument on insults lol.
But on this discussion we will have to agree to disagree as they say.

[Joseph Peterson]

Does anyone actually want to talk about what is needed instead of potential power generation solutions that can hypothetically provide for speculative needs?

If not I'll waste Chris' time with a PM asking that this topic be deleted.  Server space costs money.  Rehashing the same old supply-side arguments in a thread that is supposed to be about off-nominal demand is not something worth NSF paying to host.

[JohnFornaro]

Does anyone actually want to talk about what is needed instead of potential power generation solutions that can hypothetically provide for speculative needs?

If not I'll waste Chris' time with a PM asking that this topic be deleted.  Server space costs money.  Rehashing the same old supply-side arguments in a thread that is supposed to be about off-nominal demand is not something worth NSF paying to host.

I'll make a few wise cracks.  That usually gets threads deleted...

[Robotbeat]

Does anyone actually want to talk about what is needed instead of potential power generation solutions that can hypothetically provide for speculative needs?

If not I'll waste Chris' time with a PM asking that this topic be deleted.  Server space costs money.  Rehashing the same old supply-side arguments in a thread that is supposed to be about off-nominal demand is not something worth NSF paying to host.

The problem is your question is not precisely formed. The amount of demand required can be anywhere between zero and 100%, demanding on all kinds of stuff. You need to specify precisely what you’re exactly doing.

[Joseph Peterson]

The problem is your question is not precisely formed. The amount of demand required can be anywhere between zero and 100%, demanding on all kinds of stuff. You need to specify precisely what you’re exactly doing.

I asked for help reformatting the OP and got no replies.  It's not like I didn't specify the size of the habitat sections I would like to see a baseline crafted for but people keep ignoring that completely.  I've tried to steer the conversation away from useless points but that has failed spectacularly.

I am at a complete loss as to how to get the conversation on track. 

[Bob Shaw]

It really isn't a problem. If you're doing ISRU when power levels are positive, then just burn your stored fuel by running IC electrical generators when things get tough. You can also use that strategy at night and in winter. The only pinch points are early on, unless you've pre-landed either supplies or unmanned ISRU setup(s). Oh, and CO burns, too.

[Twark_Main]

I did... specify the size of the habitat sections I would like to see a baseline crafted for...

It's pretty straightforward based on the prior discussion, isn't it?

Based on a rabbit's CO2 output (383 umol CO2/min = 24 g/day), so ~46 rabbits equals one person. Let's call the entire rabbit population 1 additional person.

13 people for 100 sols (~103 days) consume:

  • 830 kg of food
  • 4700 liters (1250 gallons) of water
  • 1100 kg of oxygen (970 liters = 260 gallons as LOX)
  • 330 kg of LiOH canisters (Apollo baseline)

Of those, only the LiOH canister have to be brought from Earth (but they can be regenerated and reused).

[Twark_Main]

Now for the crops...

For 1,000 m² of crops you're looking at about 300 kW for the lights. If it runs 10 hours/day, that's 300 megawatt-hours of energy.

That's about 1200 tonnes of batteries (assuming a 2x capacity-per-mass improvement over Megapack). Clearly impractical.



Far more practical is methalox energy storage, which (assuming a 65% efficient turbine generator) will consume 141 tonnes of propellant. This is equivalent to about 13.7% of one Starship per synod.

So if you want to keep growing full-tilt during a dust storm, you need to add the cost of:

  • an additional 0.137 Starships-per-synod worth of methox mining & production equipment

  • an additional 300 kW of methox turbine generator capacity, and

  • additional solar power equivalent to powering 0.137 Starships-per-synod worth of methox production equipment.



Just how valuable is it to perform this "agricultural research" for 669 sols per Mars year vs. 569 sols per Mars year? Remember that agricultural research is not continuous, and experiments only last the length of one crop maturation cycle.



These numbers are for a population of only 12 people. How does this scale to a city of millions? If we optimistically assume 40 m^2/person at scale (NASA CELSS Breadboard Project), then the per-person numbers 'only' improve by 1.92x.

[lamontagne]

If we do not store or produce excess energy, then we would really need to find ways of reducing damage from long periods of low power.

It might be required to avoid planting crops that require multiple years to mature, so no fruit trees, just berries and bananas, no asparagus.  Perhaps no almonds and no olives either?  Wood products might be replaced by bamboo in most cases, and there are a number of possible sources for paper to replace the commonly used wood pulp.

The limitations might also mean that greenhouses as areas of production might represent too much risk, unless very efficient covers could be designed to ensure they can be kept above the freezing point despite the high thermal loses that transparent coverings represent.
 

[Robotbeat]

I’m fine with the claim that batteries are impractical as long as that’s taken with the caveat that that is only due to the arbitrary restrictions on the allowed solution space in this thread. In real life, you WILL have some power generated during the storm and you WILL have some excess power production otherwise (ie more than you can use).

[Joseph Peterson]

Forgive me for being an emotional wreck over the last few months.  I've known the end was coming for my most faithful friend, the kitty cat, Ruckus.  I tried, and failed, to create an emotional escape for myself in the form of this thread.  Similarly I failed to ensure Ruckus lived to a mere 15 years by an unacceptable margin.

Keep on failing to discuss the topic I tried to broach as I failed to ensure Ruckus din't take a premature dirt nap.  This thread is merely a conversation.  It no longer matters to me that the results will be even more deadly.  "LMT" it up to your hearts desires if that is your wish.  I've lost the drive to avoid that kind of obvious failure.

Life stinks, and to put it politely, then you die.  I was a fool to think anything else was possible.

[spacenut]

It makes no sense to colonize Mars without excess power production and storage for night use and dust storms.  Doesn't matter how it is done, solar, wind, battery, nuclear, or methane generators.  Which ever produces the most results with the least mass and energy drain. 

Food is going to have to be produced, starting out small scale, then expanding to grain crops, fruit trees, then larger nut trees as the colony expands and grows.  Power production will have to grow with the expanding colony. 

Solar will be the number 1 source of power to begin with.  Either methane/oxygen production for a night and wind storm generator or power wall type battery storage.  Mass here is the key due to Starships only being able to bring 100-150 tons per Starship/per synod. 

I think the excess heat off a methane generator could be used to heat greenhouses or habitats, as Mars is cold.  Power would be primary.  Also when methane burns it produces 2 water molecules and one carbon dioxide molecule.  This is good for plants.  The exhaust could be used to warm and provide moisture for plants.  The generator should NOT be an ICE generator, but a small turbine for efficiency and fewer moving parts as well as more complete combustion of fuel.  Excess heat off the turbine generator could also be used with an add on boiler system for additional power or heat.  '

Does anyone know what the smallest manufactured turbine's mass is, either a turbine or a very small jet engine?  An engine or turbine would have to be housed in a separate facility due to excess noise of operations.

[lamontagne]

Sorry for your loss, Joseph.
It is almost impossible to convey irony through the type of conversation that exists on the Internet.  It is also very difficult to convey empathy.  What we see on the screen often seems to have little to do with what is happening the other side of the keyboard.  I am reminded of an episode from my favorite space opera series, The Miles Vorkosigan Saga, in which most of the novel shows our Hero trying to identify the social risk from a technology involving cryofreezing, only to discover that ,in the end, Miles was really hoping to find a way to prolong his beloved father's life.

I honestly think that to save your plantation on Mars you need to let it go.  That's what we do in winter, keeping the seeds for the future spring and further harvest, limiting our energy usage (after all, in winter we are no longer using the fields around our cities, even though they are still receiving significant power from the sun).  And therefore overproducing during the summer.
And I think that among your 12 crew you really need a psychiatrist (or a parent), someone who is people oriented rather than task oriented.  Because we all are much less tough than we think.

[Robotbeat]

Forgive me for being an emotional wreck over the last few months.  I've known the end was coming for my most faithful friend, the kitty cat, Ruckus.  I tried, and failed, to create an emotional escape for myself in the form of this thread.  Similarly I failed to ensure Ruckus lived to a mere 15 years by an unacceptable margin.

Keep on failing to discuss the topic I tried to broach as I failed to ensure Ruckus din't take a premature dirt nap.  This thread is merely a conversation.  It no longer matters to me that the results will be even more deadly.  "LMT" it up to your hearts desires if that is your wish.  I've lost the drive to avoid that kind of obvious failure.

Life stinks, and to put it politely, then you die.  I was a fool to think anything else was possible.

Sorry to hear that. Really sucks.

Things get better even if it doesn’t always feel like that.

[Twark_Main]

Forgive me for being an emotional wreck over the last few months.  I've known the end was coming for my most faithful friend, the kitty cat, Ruckus.  I tried, and failed, to create an emotional escape for myself in the form of this thread.  Similarly I failed to ensure Ruckus lived to a mere 15 years by an unacceptable margin.

Keep on failing to discuss the topic I tried to broach as I failed to ensure Ruckus din't take a premature dirt nap.  This thread is merely a conversation.  It no longer matters to me that the results will be even more deadly.  "LMT" it up to your hearts desires if that is your wish.  I've lost the drive to avoid that kind of obvious failure.

Life stinks, and to put it politely, then you die.  I was a fool to think anything else was possible.

So sorry to hear about your beloved friend. I would be a wreck in that same situation. 

[Twark_Main]

I honestly think that to save your plantation on Mars you need to let it go.  That's what we do in winter, keeping the seeds for the future spring and further harvest, limiting our energy usage (after all, in winter we are no longer using the fields around our cities, even though they are still receiving significant power from the sun).  And therefore overproducing during the summer.

I'd suggest that it's not quite necessary.

Annual plants? Sure, harvest them. No reason not to.

Perennial plants? These should be able to survive an "overwintering" cycle: colder temperatures and lower light. These plants benefit from having multiple years to develop. So for fruit trees etc you'd be better off avoiding harvest.

[lamontagne]

I honestly think that to save your plantation on Mars you need to let it go.  That's what we do in winter, keeping the seeds for the future spring and further harvest, limiting our energy usage (after all, in winter we are no longer using the fields around our cities, even though they are still receiving significant power from the sun).  And therefore overproducing during the summer.

I'd suggest that it's not quite necessary.

Annual plants? Sure, harvest them. No reason not to.

Perennial plants? These should be able to survive an "overwintering" cycle: colder temperatures and lower light. These plants benefit from having multiple years to develop. So for fruit trees etc you'd be better off avoiding harvest.

Well, that might be the lowest limit that Joseph is looking for.  What is the lowest temperature for perennial plants, and how much power is required to keep them alive over a few months of cold.  As storms tend to be warmer than other times, perhaps the heat required is not be too exaggerated compared to the available supply.
Might make sense to have some of your your perennials inside the human habitat, rather than in greenhouses, anyway?

BTW, in these days on Monsanto seeds and designer plants that farmer's aren't even allowed to reseed, what is the area required to produce all the seeds for a harvest? What is the multiplication factor?  Aren't carrot, for example, largely clones that are reproduced in labs anyway, these days?  where does Monsanto get its seeds?

[Twark_Main]

I honestly think that to save your plantation on Mars you need to let it go.  That's what we do in winter, keeping the seeds for the future spring and further harvest, limiting our energy usage (after all, in winter we are no longer using the fields around our cities, even though they are still receiving significant power from the sun).  And therefore overproducing during the summer.

I'd suggest that it's not quite necessary.

Annual plants? Sure, harvest them. No reason not to.

Perennial plants? These should be able to survive an "overwintering" cycle: colder temperatures and lower light. These plants benefit from having multiple years to develop. So for fruit trees etc you'd be better off avoiding harvest.

Well, that might be the lowest limit that Joseph is looking for.  What is the lowest temperature for perennial plants,

Short answer? It depends on the plant.

https://en.wikipedia.org/wiki/Hardiness_zone

[Joseph Peterson]

The perennial plant conversation is definitely more along the lines of what I'm interested in. 

Fruits like apples and blueberries are winter tolerant.  Assuming we can train these plants to adopt to a 687 day year my hope is that we could plan their winter to match up with storm season.  In this case we'd only need enough heat to keep from killing the plants.

Tropical plants like coconut are most likely more difficult to keep healthy.  It won't surprise me if keeping tropical plants is too costly.  I am interested in finding out for certain though.

[Twark_Main]

Over-wintering behaviors in plants are primarily controlled by day length and color temperature (and temperature, of course).

Seems like in a controlled-environment indoor growing system, you could feed in the correct environment to induce over-wintering as dust storm season approaches.



Full-cycle perennial agriculture systems can create their own fertility, without relying on a separate pesticide & fertilizer industrial base. Seems like a good idea to make room for a few such systems, even if only for the sake of redundancy.

Think a more dense version of this:

[daedalus1]

The only issue plants will have on Mars is 1/3 gravity.
Light and temperature can be provided artificially. This is increasingly done on earth in enclosed containers.

[Barley]

Annual plants? Sure, harvest them. No reason not to.

Perennial plants? These should be able to survive an "overwintering" cycle: colder temperatures and lower light. These plants benefit from having multiple years to develop. So for fruit trees etc you'd be better off avoiding harvest.

Some plants are tropical perennials that are grown as annuals.  (E.g. tomatoes, peppers, egg plants, some varieties of kale, sweet potatoes, ... ).   Plant them and keep harvesting as long as it's convenient.  If you run low on power or the aphids take over the grow house kill them off and restart when you're ready.  They will also handle a 12 or 18 month growing season without difficulty.

To put it another way: We grow tropical crops in Iowa.  No reason we can't grow them on Mars using the same general pattern.

[Dalhousie]

The only issue plants will have on Mars is 1/3 gravity.
Light and temperature can be provided artificially. This is increasingly done on earth in enclosed containers.

How do you know it will be an issue?

[daedalus1]

The only issue plants will have on Mars is 1/3 gravity.
Light and temperature can be provided artificially. This is increasingly done on earth in enclosed containers.

How do you know it will be an issue?

Yes I missed the word 'potenial'.
I suspect it wont be an issue.

[Joseph Peterson]

The only issue plants will have on Mars is 1/3 gravity.
Light and temperature can be provided artificially. This is increasingly done on earth in enclosed containers.

How do you know it will be an issue?

Yes I missed the word 'potenial'.
I suspect it wont be an issue.

This concern is a large part of why I went with an agricultural research lab instead of a greenhouse in my OP.