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

[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.