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

[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?