Going Solar...the best solution for Mars.

Antius · 2017-10-17 05:10:20

Good post from GW. It is always useful when someone puts extra time in to do arithmetic on these concepts.

A small mobile PWR reactor would work well for water mining. Something the size of a road tanker, that can be towed to different locations between uses. The heat exchanger can be a single loop design with the boiler on its side and vertical steam separator. Decay heat removal can be accomplished by radiating through the skin of the towed reactor. If the vehicle is 3m wide and say 10m long and radiates at 200C, then using steffan-boltzmann with an emissivity of 0.9, gives a maximum decay heat dumping capability of 177kW. If sustained decay heat levels are about 1% of operating power, that would mean a mobile reactor of this type would have maximum operating power of 17.7MW.

That is about enough to melt and warm up about 30 litres of water per second. The reactor would be partially shielded by a water blanket, which would also serve as a reflector. It would generate relatively high levels of external radiation while active, so should only be activated remotely. Since refuelling would be extremely difficult on Mars and fuel is only a modest part of system mass, it would make sense to design a system that uses an elongated core with a movable reflector, such that core life can be decades.

If the base is relatively close to the glacier, we could pump the water back using polypropylene/polyethylene pipes that can be rolled up and dragged to new drilling points.

Antius · 2017-10-17 05:23:33

A stored heat engine is another option that might beat Li-ion battery power in terms of performance. Molten silicon can store up to 1MWh of thermal energy in 1m3. Charging would involve the use of heating elements and is not rate limited in the way that batteries are. As a working fluid, we could use liquid CO2, compressed to at least 5.1 bar. With a conversion efficiency of 30%, 300kWh of mechanical power would keep your digger going for 6 hours before recharging.

The enthalpy change of boiling of CO2 is relatively poor, so you would need to keep a bowser of compressed liquid CO2 close to your digger and refill regularly. You would need more liquid CO2 than the equivalent volume of diesel here on Earth, because heat transfer rates will limit the peak temperature of the CO2 in the engine. But again, this is not rate limited in the way that recharging batteries is. Liquid CO2 can be produced by compressing and refrigerating Martian air and stored in carbon steel tanks indefinitely at ambient Martian temperatures. So this is a good way of storing intermittent energy that can then be used to power diggers and air tools when needed. Not suitable for powering transportation due to the relatively low energy density, but it would work for applications close to a base.

If a rover could carry a flexible solar array and a compressor, it would be interesting to compare the performance of a stored heat engine to Li-Ion batteries. An RTG might be useful in this way. During the night, the RTG could power a small heat engine that could compress CO2 into a cylinder where it would liquefy. During the day, the vehicle would use direct heat from the RTG to boil the CO2 in a heat engine, generating propulsive power.

Last edited by Antius (2017-10-17 05:45:33)

SpaceNut · 2017-10-17 18:46:46

I have posted this in the Running on Compressed Air?

SpaceNut · 2018-04-01 19:05:00

I am wondering is a solar mission for one or two is possible since the moxie unit and other scrubbers would allow for it to happen or at least I think it could.

louis · 2018-04-02 03:52:49

I think a solar mission is possible for 100 people and Musk seems to agree. Maybe not on the first mission, however. That is much more like to be in the range of 6-10 individuals.

The extended solar panels can generate enough electricity in flight.

It's unclear whether Musk intends to start propellant production robotically before humans land. From what I can tell, it seems not. But given the latest estimate is that the first pioneers will have with them as cargo something like 500 plus tonnes (there appear to be two cargo landers followed by one humand and one cargo), then that is a lot to play with.

I think PV panels can be laid out robotically on Mars and kept clean robotically as well (with robot rovers rolling along giving little blasts of gas to clear them of dust) as required. The lack of strong winds, rain and other hazards on Mars means they can be laid out with minimal structure.

Space X might carry some Mars-adapted versions of the Orbital ATK to provide initial PV power on Mars.

It's interesting to consider what the unloading priorities might be...here's some suggestions:

1. Inspection robot rovers to scout all around the landing site. In communication with the humans in their BFR.

2. ATK rovers - a few robots with ATK fans attached to set up the initial PV power facility.

3. A rover carrying a small inflatable hab which will be the first home for the humans on Mars.

4. First humans deploy to land in a pressurised rover. The rover has the capability to attach power lines to the ATK facility and then docks in the hab's pressurised air lock. Following checks first humans can deploy in the hab.

SpaceNut · 2018-04-02 17:18:21

One could only hope but what if we were to design for a 1 flight to and back with what we have is it even possible with the pieces that we have and for what we can adapt...

louis · 2018-04-02 17:22:20

I can only think that Musk/Space X are determined to build a huge amount of failsafeness into Mission One by landing 500 tonnes of cargo.

The propellant production plant is going to be large. With failsafe replacements, maybe that will take up 100 tonnes.

SpaceNut wrote:

One could only hope but what if we were to design for a 1 flight to and back with what we have is it even possible with the pieces that we have and for what we can adapt...

SpaceNut · 2018-06-13 21:13:30

The little rover that has been on mars for 15 years has just tolds us why solar can not be the only power for man to be available.

AAyARkb.img?h=587&w=799&m=6&q=60&o=f&l=f&x=442&y=314

Each frame corresponds to a tau value, or measure of opacity: 1, 3, 5, 7, 9, 11.”

Gigantic dust storm on Mars silences NASA's Opportunity rover

The main issue with the power loss is with the rover's battery-powered heaters, which protect it from the bitter Martian cold. If the storm persists for too long and Opportunity gets too cold, that could spell its doom. The other rover on Mars, Curiosity, is nuclear powered and unlikely to be affected by the storm. During another dust storm in 2007, Opportunity basically shut down operations and went into survival mode for a few weeks. But this storm is much worse.

Void · 2018-06-13 21:51:58

I suppose I shouldn't, but here I am.

I was told by others previously that a dust storm on Mars could not block the solar flux sufficiently to be a threat. Apparently sometimes it can.

You have two alternatives that I can see.
1) Alternative Energy Sources.
2) Hybernation Mode.

#1 could include:
-Energy from O2 and CO extracted from the atmosphere.
-Fission
-Fusion
-Geothermal

I think that in the early days of Mars, only fission would be sensible as a survival backup. It would most likely have to be small scale compared to the solar production of energy. It is likely that getting the fuel from Earth to Mars would be complicated by several factors.
As a small scale method, I would think that it is not that much better than Hybernation.

#2 In my opinion is the way to go. Store food, Oxygen, and yes fuel, and also try to store thermal energy in reservoirs.

The last part, thermal energy in water reservoirs (Ice and mechanically covered), would be a good solution to use waste heat anyway, and excess solar thermal energy, as in non dust storm situations it might be very electrically productive to vent heat from the reservoirs during a Martian night. It should be very easy to charge such a reservoir with heat during the day, and from industrial waste heat.

If you have enough storage for a very long dust storm period, then your settlements should be OK.

Later perhaps some items from #1 may be implemented as they become practical from Insitu, and technological advancements.

But that is just me. Typically my ideas are sent to the lower parts of hell on this site.

Done.

Last edited by Void (2018-06-13 21:55:33)

kbd512 · 2018-06-14 05:42:31

SpaceNut,

Yikes! If that picture taken from the same spot and time of day, then that's just crazy. The Sun is barely brighter than a star. A megawatt class PV farm would be reduced to a few tens of kilowatts of output in a dust storm that severe. Some kind of LOX/LH2 fuel cell or nuclear power source is required to contend with a storm like that. The most energy dense batteries available won't cut it.

louis · 2018-06-14 07:42:33

Well let's take this step by step. Pictures can mislead as much as they inform.

1. According to the following site, the pics are "simulated" so make of that what you will...

https://news.nationalgeographic.com/201 … e-science/

2. The sun pics look dramatic but the important issue is how much solar radiation gets through. "Once the atmosphere becomes full of dust, only 20% of the solar radiation can reach the surface of the planet," says Vittorio Formisano, Istituto Fisica Spazio Interplanetario, Rome, Italy...

http://www.marsdaily.com/reports/Mars_E … s_999.html

That's my recollection from various sources. I think the 99% figure being bandied about is probably in relation to direct sunlight.

Certainly if the 20% figure is true, that would allow you to function on the basis of PV even without storage as long as you plan for dust storms. But more of that later...

3. The dust storm issue is really an issue for Mission One since as time goes everything will tend to the average and there will be plenty of time to store energy in various forms. It's potentially catastrophic only if you rely entirely on PV without storage on Mission One and you have the misfortune of experiencing an extended dust storm. It's not an issue for longer term survival, because dust storms do eventually stop. It's then a question of "making hay while the sun shines" ie converting PV power into storable energy reserves. In the main, that would be methane-oxygen in my view. And of course that fits in nicely with the need to produce propellant on the Space X model.

4. The density and frequency of dust storms does vary greatly. The NASA missions to date are about investigating interesting sites, not about establishing a human base. Clearly the location you choose for a human base would be one that had a low potential for high dust density so as to avoid regional dust storms. Global dust storms cannot be avoided of course, but it is my understanding that they still vary in intensity across the planet so you look for areas where the intensity is going to be near a minimum.

5. The Space X mission scheduled for 2022-2024 would involve the landing of about 700 tonnes of supplies.

Let's take a look at what that would mean if say that included 100 tonnes of state of the art batteries...At a conservative estimate of 200Whs per Kg, that would represent 20,000 KwHs.

If a hab for six people could be kept ticking over at 12 Kws (quite doable in my view), that would keep you going for 68 sols.

An alternative approach would be to bring just over 5 tonnes of air (maybe 10 tonnes with cylinder weight included) with you, to help keep your six person crew alive for those 68 sols. Then you wouldn't have to spend large amounts of energy on making/recyling air (so you could reduce the battery requirement).

You can operate a base minimally. No need for hot showers - the crew can "bathe" with wipes, as they do on the ISS. No need for cooking. Preserve power wherever you can. No general lighting. Limited time spent on coms and computers... But that is all in extremis and I doubt would ever be required.

Another point - dirty water and urine can likely be recycled for some water uses with static filters:

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

That's certainly something that could be investigated.

However let's look at a realistic scenario...

I think you could probably take maybe 50 tonnes of batteries and maybe 50 tonnes of compressed air and water etc and be satisfied you could stay alive for 300 sols, without any PV intake. Remember, heating would be a minimal requirement for a hab, as aerogel style insulation is incredibly effective and there is minimal heat loss in the low pressure atmosphere on Mars. Probably your major energy usage would be the fridge.

No dust storm on Mars has lasted longer than 9 months, which I think equates to 300 sols or thereabouts.

100 tonnes out of a 700 tonne mission to ensure failsafeness is reasonable I think.

But the reality is that with 20% of average insolation you would easily be able to cover the basic life support requirements. What you couldn't do is keep a Space X style propellant plant in operation (well not unless you brought 5 x the standard amount of PV equiipment required). You might need to think in terms of maybe 40% over standard PV capacity to cover the eventuality of a major dust storm, so that you can produce enough propellant over a 600 sols period (ie raising production when the dust does disperse).

See? No need for hysterics! And let's not forget you have to double up your nuclear reactor to ensure failsafeness on a first Mission. You can't risk the lives of your crew on the assumption that a single nuclear reactor won't ever fail.

GW Johnson · 2018-06-14 08:52:44

There are two fundamental problems with dust storms on Mars relative to solar power, and they are linked.

(1) Dust in the air reduces sunlight intensity. Depends on the storm, but reduction can easily be 80%. It can be 100% (seen by me in west Texas dust storms). Duration can be hours to months. Months were seen with the storm that blanketed the planet when the 1969 orbiter mission arrived.

(2) Even after the dust storm ends, you have to clean the dust off your solar panels. If you cannot, you will not get power out of them. Getting too cold while unable to generate solar power is what killed the other small rover Spirit.

Linkage: humans can clean dust off solar panels, but they must have lots of energy to survive the potentially-months of no effective solar power during a long storm. Long blackouts like that preclude banking on batteries or fuel cells. They occur unpredictably and erratically, and that's a fact, Jack!

Conclusion: You need nuclear-generated energy. PERIOD. Bring both. Size the nuclear to be just enough to live on. The sum total of both sources is how you live and make propellant.

It also means you bring enough supplies to eat, drink, and breathe all during the storm. And if you are doing any greenhouse growing of food, you will have to power the greenhouse lighting and heating, too! That's in addition to lighting and heating the living spaces. And powering communications (and all the other) gear.

GW

Last edited by GW Johnson (2018-06-14 08:57:50)

louis · 2018-06-14 14:20:59

See my post above (#186).

Regarding your points:

I am sure you didn't mean to imply 100% obscuration (ie dead of night light levels) goes on for months, or even weeks, or even days on Mars because obviously that is not the case. I would accept bad storms can result in 80% reduction of insolation.

This is a multi-billion dollar mission, so there will be no shortage of "get-it-right" money. I think there will be ways of ensuring at least part of the PV set up can deal with dust accumulation. Probably anti-accumulaton measures would be incorporated in special orbital ATK style fan PV arrays.

Can we agree Mission One will not be dependent on food production? It might be a potential add on for producing fresh salad vegetables but in no way will the crew be dependent on the success of food production for survival. Survival will be ensured by plenty of dried food, energy bars, vitamin and mineral supplements, cereals, frozen meals and vaccuum packed meals.

Air and water supplies can be taken to Mars on Mission One to ensure crew survival during an extended dust storm. Likewise a large battery load - say 50 tonnes can be used to provide any necessary energy supplies in addition to what a PV array could extract at 20% of normal insolation.

Essentially all you really need to cover is heating, lighting, IT and coms, some pumps and refrigeration. That could all be v. minimal. There is perhaps the question of keeping the return BFRs warmish...that might be a requirement. Not sure what that would take. It might be the largest energy take.

I accept you can make an argument for nuclear but it isn't v. flexible and you will need to take two same size reactors because there is no way you can allow no power back up.

GW Johnson wrote:

There are two fundamental problems with dust storms on Mars relative to solar power, and they are linked.
(1) Dust in the air reduces sunlight intensity. Depends on the storm, but reduction can easily be 80%. It can be 100% (seen by me in west Texas dust storms). Duration can be hours to months. Months were seen with the storm that blanketed the planet when the 1969 orbiter mission arrived.
(2) Even after the dust storm ends, you have to clean the dust off your solar panels. If you cannot, you will not get power out of them. Getting too cold while unable to generate solar power is what killed the other small rover Spirit.
Linkage: humans can clean dust off solar panels, but they must have lots of energy to survive the potentially-months of no effective solar power during a long storm. Long blackouts like that preclude banking on batteries or fuel cells. They occur unpredictably and erratically, and that's a fact, Jack!
Conclusion: You need nuclear-generated energy. PERIOD. Bring both. Size the nuclear to be just enough to live on. The sum total of both sources is how you live and make propellant.
It also means you bring enough supplies to eat, drink, and breathe all during the storm. And if you are doing any greenhouse growing of food, you will have to power the greenhouse lighting and heating, too! That's in addition to lighting and heating the living spaces. And powering communications (and all the other) gear.
GW

GW Johnson · 2018-06-14 14:40:46

Life support for the occupied spaces WILL NEVER BE MINIMAL, Louis. It will be one of the larger power draws that there is, comparable to the propellant production, actually. Until later, when a really big propellant plant gets built.

I agree that you bring at least two reactors, not one. I prefer three, so that if one fails, you still have a backup. Same sort of thinking applies to the solar, so you need to double or triple all your earlier estimates for solar. See how the payload capacity quickly disappears?

I quite agree that food, water, and oxygen will need to be shipped to Mars for the first manned mission. To do otherwise is horribly unethical! It's just what you have to do. Experimenting with greenhouses and the like is just that: experiments. You CANNOT count on any of that for the first mission, probably not the first several missions. The odds of failure are a lot longer than the odds of success. Murphy's Law!!!!

I wouldn't count on a min of 20% insolation during a dust storm. As I said, I have seen insolation go to 0% right here in Texas during our dust storms. To do otherwise is VERY HIGHLY UNETHICAL!!! So I disagree with you. You really do have to plan for 0% insolation, and for time scales up to 9 months, at least.

GW

Last edited by GW Johnson (2018-06-14 14:44:54)

kbd512 · 2018-06-14 17:03:11

Louis,

The only thing that's hysterical here is the logic you use to avoid the use of nuclear power. Why can't you just plainly state what your aversion is to using nuclear power? Whatever bothers you is clearly not math or logic based, so what is it?

NASA publishes reports on solar irradiance incident on the surface of Mars. They actually have that information because they have instruments to measure that attached to all those robots JPL sends there and have been measuring it for many years now. If the dust in the atmosphere blocks 90%+ of the Sun's light from reaching the surface of the planet, that means exactly what was stated. It does not mean light is still transmitted through some other means. It means it's dark outside during a severe dust storm.

Maybe you'd bring 100t of batteries and air tanks to avoid what's so blatantly obvious to everyone else. And what does "operate a base minimally" mean, apart from doing nothing useful on the surface of Mars? Here's some solar panels and batteries, now just sit there on Mars and do nothing. Don't cook, don't show, don't wash clothes, and just forget about exploring anything or making the propellants required to get home. Astronauts already drink their own piss. If you keep working on inventive ways to make life difficult, nobody else will ever want to go there.

If BFS delivered a dozen of the 10kWe output KiloPower fission reactors, even presuming two of the reactors fail or were damaged in transit, that's still 100kWe of continuous output for a total mass of 18,258kg for the dozen complete reactor units, plus whatever mass is required for the PMAD (which is always present with solar or nuclear).

A small robotic vehicle can plant these small fission reactor in the ground for added shielding, like radioactive palm trees. The 1,544kg mass for the complete reactor is not something the people at DoE pulled out of their rear ends to fuel an argument between the space fans in the peanut gallery, such as you and I. JPL said, "We want reliable 24/7 electrical power for mission planning purposes." DoE responded, "We think we can provide something like that using small and simple fission reactors." The mass figures are based upon scaling of actual existing 10% scale hardware that's being tested there.

Solar vs. Fission Surface Power for Mars by Michelle A. Rucker (NASA) September, 2016

louis · 2018-06-14 17:22:06

GW Johnson wrote:

Life support for the occupied spaces WILL NEVER BE MINIMAL, Louis. It will be one of the larger power draws that there is, comparable to the propellant production, actually. Until later, when a really big propellant plant gets built.

Well, I am arguing that for a major, intense dust storm scenario, you will have an emergency back up of on board supplies of air and water (plus food of course) - so there will be no required power draw with regard to those items at all for 300 sols (if necessary).

Any required power draw will relate to heating, lighting, pumps/filter systems, IT equipment, coms, waste management and refrigerator. They will all be pretty minimal. For a crew of six in a single hab, how much lighting do they need? V. minimal. Head band LED lights can be used for reading. Low level lighting can be used for generally getting around the hab. I'd think you could probably be talking about a max of 0.5 Kws continuous. Heating? Well, bodies exude quite a bit of heat and the habs will be state of the art, heat-retentive with aerogel or similar linings. I've read stuff on this before and was surprised at how low heat loss would be on Mars. I doubt the heating requirement would be much above 1 or 2 Kws, when you take into account body heat loss from six people and waste heat from batteries and equipment. A refrigerator might be something like 0.7 Kw, or more depending on size (but let's not forget it's effing cold outside as well so you might be able to use the cold from outside to minimise energy use in refrigeration!). A microwave oven might be used for an hour per day = an average of 0.03 Kw (virtually nothing). Laptops and computers? Six laptops on continuously (not really required) would be as little as 0.12 Kws. I guess the hab would have some more major computer power to deal with coms, life support and so on...so maybe add on another 1 Kw for that (probably generous). Mars-Earth messaging, communication with satellites? Well Curiosity electrical power is a max of 110 Watts...so let's give a generous 0.2 Kws for emergency communication with Earth. Waste management? I don't know...virtually nothing over a sol I imagine. Pumps and filters? Well let's give that a generous 1 Kw continuous. I'm struggling to get above 5Kws continuous average or about 12,250 KwHs over 100 sols. That would require about 62 tonnes of batteries to provide at 200Whs per kg. But I suspect for a Mars Mission we could improve on the 200 Whs figure so it's probably a conservative figure.

GW Johnson wrote:

I agree that you bring at least two reactors, not one. I prefer three, so that if one fails, you still have a backup. Same sort of thinking applies to the solar, so you need to double or triple all your earlier estimates for solar. See how the payload capacity quickly disappears?

Solar is inherently modular, so there is no issue in terms of absolute back-up there. Of course what you have to do with solar is to plan for known intermittency (sol/night sequence), unknown intermittency (dust storms) and variability (seasonal). I don't think there is any problem with maintaining life support (in combination with battery plus methane storage and also imported supplies). The only real question mark is over propellant manufacture which is a huge task in comparison with life support. My best guess is that you need to add 40% to "normal" PV production to cover a "worst case" dust storm scenario.

GW Johnson wrote:

I quite agree that food, water, and oxygen will need to be shipped to Mars for the first manned mission. To do otherwise is horribly unethical! It's just what you have to do. Experimenting with greenhouses and the like is just that: experiments. You CANNOT count on any of that for the first mission, probably not the first several missions. The odds of failure are a lot longer than the odds of success. Murphy's Law!!!!

Well we agree on something then!

GW Johnson wrote:

I wouldn't count on a min of 20% insolation during a dust storm. As I said, I have seen insolation go to 0% right here in Texas during our dust storms. To do otherwise is VERY HIGHLY UNETHICAL!!! So I disagree with you. You really do have to plan for 0% insolation, and for time scales up to 9 months, at least. GW

I think you need to give some evidential basis for a "0% insolation over 9 months" scenario. Never seen anything like that and I've done a lot of searches on the issue over the years.

SpaceNut · 2018-06-14 17:35:45

https://en.wikipedia.org/wiki/Opportunity_(rover)

This class of rover has two rechargeable lithium batteries weighing 7.15 kg (15.8 lb) each, each composed of 8 cells with 10 amp-hour capacity .
In Eagle crater the cells were producing about 840 watt-hours, but by Sol 319 in December 2004, it had dropped to 730 watt-hours.
During its first winter power levels dropped to under 300 watt-hours per day for two months, but some later winters were not as bad
When fully illuminated, the rover triple junction solar arrays generate about 140 watts for up to four hours per Martian day

NASA noted that as the storm blotted out the sun, Opportunity’s power supply dropped steadily: from 645 watt-hours, to 345, and finally to merely 22 watt-hours — little more than what a large iPhone’s battery holds.

It’s been 4 days since a signal was heard from Opportunity. The storm, which was first detected on May 30, now blankets 14-million square miles (35-million square kilometers) of Martian surface -- a quarter of the planet an area greater than North America.

Louis you need to remember that the solar panel does not put out power until its above the 70% levels with it charging the batteriy during the around or aproximate 3hr period of a day and that will not be achieveable once the amount of light drops.

The previous storm had an opacity level, or tau, somewhere above 5.5; this new storm had an estimated tau of 10.8 as of Sunday morning. See the image from earlier in the page.

NASA’s Opportunity rover is fighting for its life in a Martian dust storm

The growing storm image:

Since the storm began two weeks ago, the amount of light the spacecraft receives has dropped to less than 1 percent of normal levels. Energy production has fallen from hundreds of watt-hours a day to almost nothing.
Mars Exploration Rover project manager John Callas, team is operating under the assumption that the charge in Opportunity's batteries has dipped below 24 volts and that the rover has entered a low-power fault mode, when all subsystems except the mission clock are turned off.
Opportunity's batteries — even though they are 15 years old, they are still working at 85 percent of their capacity.
The clock is programmed to rouse the rover at periodic intervals to check whether light levels are sufficient to wake up — a state called “solar groovy.” But the storm is still growing and should encircle the planet in a matter of days. NASA expects that it will be weeks, if not months, before the dust clears enough to allow the spacecraft to turn back on.

Void · 2018-06-14 17:36:03

This, Olympus Mons has the best solar their is on Mars I think, but of course at a price.
http://www.dailygalaxy.com/my_weblog/20 … lcano.html

While I still agree that the first settlement needs to be in close proximity to a deep deposit of ice, I also note the above as fact.

We also don't know what the dust storm situation will be like during ramp up of atmospheric pressure. So for a long term projection of distribution of human activity, I recommend a close look at what the large volcano's offer for solar and other resources.

For instance it may be possible that weather forecasts could eventually warn the bulk of the population when to situate to a particular configuration. Included in that could be some kind of a months long refuge in the mountains where perhaps particular types of productivity could continue during a large storms.

Per a mass driver, it is possible that ice could be delivered from the lowlands to the highlands, if that is the only way to procure sufficient water at those locations.

......

Other tricks in the lowlands are ice covered reservoirs. That is they could hold not only heat but Oxygen.

It is possible even now to pull air to breath out of water.

http://news.bbc.co.uk/2/hi/science/nature/4665624.stm

In the case of a reservoir with a layer of ice 110 feet thick, then the imposed pressure is ~1 bar. However unlike Earth water which would contain ~20% Oxygen and ~80% Nitrogen and other gasses, this reservoirs water could contain almost 100% Oxygen dissolved, therefore up to almost 5 times as much Oxygen. And of course it would hold heat for quite a long time, depending on it's size. And so it would be possible to use it as an Oxygen source and energy source during a long dust storm. Food could be kept stored frozen on Mars quite easily. No need to grow much during a dust storm, if you prepare well.

As for fuel, I would think liquid fuels stored in tanks, perhaps in the reservoir might be a good plan. Another source of energy.

And yes small scale nuclear fission, but I bet it will come at quite a price, at least until it can be obtained insitu on Mars.

So, in the lowlands hibernation during a long dust storm.

Last edited by Void (2018-06-14 18:01:16)

SpaceNut · 2018-06-14 18:39:02

Not disrespecting your post #184 but some of this has been sort of answered in our collective posts.

I was told by others previously that a dust storm on Mars could not block the solar flux sufficiently to be a threat. Apparently sometimes it can.
You have two alternatives that I can see.
1) Alternative Energy Sources.
2) Hybernation Mode.
#1 could include:
-Energy from O2 and CO extracted from the atmosphere.
-Fission
-Fusion
-Geothermal

Not likely to have fusion as we are still developing it, cold fusion or LERN might be possible once we can refine the ores.
Nuclear fission is sort of the plan already in a mixed power delivery for redundancy but also for expansion of power supply being able to be used to which you do concur with..

The CO2 /Oxygen storage for later power creation is do able with nuclear but not so much under solar, but storage comes with added mass delivery for a possible use.

I am unaware of any geothermal vents being visible from the surface or orbit as of yet but after larger scale borring machines arrive, it could be plausable if mars still has some heat left in the core to create uildsame units that we have on earth once we can build it with insitu sources.

If going with solar only, the battery size for hibernation AKA power rationing will not be plausible due to not being able to predict how long of a duration or its intensity will be needed for hybernation or rationing but with nuclear support the chance that either would be needed are less of a risk for mans survival.

Of course backup food and water stores would be wanted with or without a storm as well as a fuel reserve for future useage..

Void · 2018-06-14 21:17:20

Well, I appreciate your attention to the matter.

Quote:

Not disrespecting your post #184 but some of this has been sort of answered in our collective posts.

Not at all feeling rude or wanting to convey rudeness, but as a reply to the above quote: Really I was assured by other members that during a dust storm solar panels would work well enough so that dust storms would not be a threat. So my post although unintentionally redundant, was intended to respond to your report that actually the dust storms could be killers. A miserable end to one of the human races greatest dreams. So, if I overdid it, so what. It's very important. Just consider it a review of materials with a new much greater concern at hand. I see that my communications were in part misunderstood.

Let me attempt to communicate better.

The CO and O2 chemistry that I mentioned would be the very minor amount of those chemicals dissolved into the Martian atmosphere.
The hopes of tapping it efficiently are not great. Primarily because it has not been researched and experimented with. I did suggest a mechanical "Gill" that might be worth a try to see if it worked at all, but like many things I mention it gets sidelined.
While a gill for that may seem rather stupid, remember that fish breath Oxygen dissolved in water. And there is not that much of it.

As for Nuclear Fission, I realize that it will be important twice.
1) In the initial settlement of Mars, small fission reactors from Earth will be very important. Although people throw the idea around like it is an easy solve, I don't think that in general nations or owners of nuclear fuels will be likely to part with them in bulk for a small price. So apart from the transport costs, I would expect these small reactors to go for a high price. Except for a necessary backup emergency power source, or as the very first starter settlements, I think the cost could be too high to do it in bulk.
2) Much later when Insitu ore reserves can be processed it can become very important.
3) Fusion? Well when it arrives, then maybe that. But it may be quite a complex technology to implement on Mars.
4) Geothermal? Well the jury is out.
One thought is that Mars being small it, is also cold from cooling off faster than Earth. That makes fair sense.
Another alternative is that since it does not appear to have or have had much plate tectonics, it may not have cooled off as fast as might be supposed. Suppose the crust being thicker and of lighter materials that that of the Earth, convection of the heat is inhibited, stopping the magnetic field, prohibiting plate tectonics, and the heat only leaking out in certain locations such as just possibly Olympus Mons. We are just going to have to find out.

My real point was that for a lowland settlement subject to serious dust storms, hibernation is probably the only survival option until insitu nuclear of any kind can be implemented. Items #1, #3, #4 are very improbable as a useful solution at this time. #2 has limited use. Along with stockpiled chemical supplies, and energy supplies, and frozen or dried foods.

I have in the last post before this one, mentioned that a reservoir of water with a thick ice layer could be of assistance in storing energy long term and Oxygen. One other thing that could be done with such reservoirs when energy was plentiful, is to dump fuel chemicals into them to stimulate life. Chemosynthetic farming. Obviously if you are splitting CO2 and/or H20 for the Oxygen, then you are going to end up with Carbon, CO, H2.

I am not going to bother to find the articles about it tonight but it appears that the chemosynthesis that appears around undersea volcanism is as highly productive as surface photosynthesis. The reason that the bottom waters are not as productive as the surface, is that there is not as much volcanism as there is sunshine.

I have also mentioned that a Martian civilization might do well to have some settlement down in the icy lowlands, and some up high on places like Olympus Mons which will have the best solar energy resources, the least subject to blockage from dust storms.

So to simplify it.
1) Icy Lowlands? Then prep for hibernation during dust storms.
2) Highland Volcanos? Try for a more solar continuous economy, but be prepared to retreat into lava tube shelters with provisions if the dust storms still block the light. The thing is, likely Olympus Mons has the best solar flux on the surface of the planet.

And of course I want settlements of both types.

With weather forecasting, it may be possible to evacuate many of the people from the lowlands to the highlands for serious dust storms.

And another point I made is that if Mars is to be terraformed with a denser atmosphere, what will the dust storm problem be like if the atmospheric pressure is higher? 20 mb? 50 mb? 100 mb? 333 mb.

Plans really need to be made to cope with a planet with a persistent and lasting dust storm problem.

I think I answered very well on this.

Done

Last edited by Void (2018-06-14 21:48:08)

louis · 2018-06-15 06:48:53

SpaceNut wrote:

Louis you need to remember that the solar panel does not put out power until its above the 70% levels with it charging the batteriy during the around or aproximate 3hr period of a day and that will not be achieveable once the amount of light drops.

Are you referring to Opportunity or more generally? Opportunity's experience relates to v. low power numbers. Clearly a Mars base woudl be operating with much higher numbers. As far as I know PV panels can operate at low lights like 20% of normal insolation.

Oldfart1939 · 2018-06-15 10:25:26

After shaking my head for a long time, I decided to once again involve myself in this issue. I am certain that if NASA is involved in the Mars missions, as I am certain they will be, there will definitely be some Nuclear Reactors sent for RELIABLE POWER. One thing seemingly overlooked is the amount of power required for installation of any solar arrays. I'm trying to be nice here towards Louis, since he seems irrationally attached to solar and negative towards nuclear. But as GW stated about having backup of 3x the calculated needs, and that Murphy's laws are involved--I simply state that Murphy was an optimist.

We simply need to look right here on Earth for the applicability of Solar Power; not every state here in the USA has enough sunlight for widespread solar applications. Only the "sunshine states" of the southern tier have sufficient irradiance for exploitation: Arizona, Southern California, Nevada, Texas, and New Mexico. Other southern states have too much cloud cover and other forms of bad weather that make utter reliance on solar power impracticable.

I don't have any bad mojo towards solar; but am unwilling to bet the entire farm for it's success on Mars as the only system without a 100% reliable backup.

louis · 2018-06-15 13:10:22

It's not just me who's pro-solar! It's me and Musk!! Yes Musk - you know, the guy who has the most advanced Mars Mission on the planet.

As already indicated, you can take batteries as back up - a lot of batteries...maybe 50 tonnes, maybe 70 , maybe 100 tonnes. In a Mission landing 800 tonnes, that is perfectly possible. Combined with importation of air and water at maybe 50 tonnes, that will keep you going for 100s of sols with no PV array input.

As already indicated, PV is modular by design. So the need for back up from a total system failure does not apply. But you do need to provide over-capacity to cope with a prolonged dust storm. I have suggested probably 140% of 100% at "normal" insolation levels for a 600 sols or thereabouts mission.

The only really bad scenario for solar is if you land in the middle of a dust storm, that will force you to make use of emergency power (batteries immediately).

I think a significant amount of the PV system will deploy automatically as fans like Orbital ATK systems. The energy requirement would be minimal. The rest could be deployed by rovers, but they are unlikely to use more than 1000 KwHs I would have thought to put up a full array. I think it is also possible you could deploy the arrays on the BFRs which will be sizeable in themselves.

Nuclear reactors have their own issues.

Oldfart1939 wrote:

After shaking my head for a long time, I decided to once again involve myself in this issue. I am certain that if NASA is involved in the Mars missions, as I am certain they will be, there will definitely be some Nuclear Reactors sent for RELIABLE POWER. One thing seemingly overlooked is the amount of power required for installation of any solar arrays. I'm trying to be nice here towards Louis, since he seems irrationally attached to solar and negative towards nuclear. But as GW stated about having backup of 3x the calculated needs, and that Murphy's laws are involved--I simply state that Murphy was an optimist.
We simply need to look right here on Earth for the applicability of Solar Power; not every state here in the USA has enough sunlight for widespread solar applications. Only the "sunshine states" of the southern tier have sufficient irradiance for exploitation: Arizona, Southern California, Nevada, Texas, and New Mexico. Other southern states have too much cloud cover and other forms of bad weather that make utter reliance on solar power impracticable.
I don't have any bad mojo towards solar; but am unwilling to bet the entire farm for it's success on Mars as the only system without a 100% reliable backup.

SpaceNut · 2018-06-15 17:14:49

Multiply the rover numbers for the size of the daily need to be reached for the wattage of the panels that you will bring and the same for the batteries as tonnage is only a launch and landing issue for the mass of each. Having excess batteries to store a charge does not work as the wattage still comes form the panels that is stored so they must match.

The rover batteries are 2 x 24v each to give a buss power of 48 volts with a 10 amp-hour or a total 480 whr of capacity to make use of for the entire day. The panel sends when new 840 watt-hours and drops to 730 watt-hours just after a single year on mars. These are the near best of both parts for use, still within a percent or 2 at most as spending to much really does not change it all that much. As you can see the converting from what the cells recieve to what can be store and put are are not the same number due to efficiecy losses.

So you want from the batteries say 50 kwhr a day just for life support that will be about 105 sets of batteries and the same is true for the panel count to be able to provide the energy over the course of a day. So in the dust storm we are only getting 22 watt-hours so multiple the panel count and see how low the amount of power will be; which is just 2.31 kwhrs so if we need 50 kwhr which is 2 kw used in each hour and we got 2.3 kwhr power will be on for about 1 hour before the battery is dead.

That said if that was as bad as it would get and we could get that low level generated garenteed then we need to have 25 times as many sets of each 105 panel battery combination to be able to meet the survival level.

Now that we know that is the goal for safety then we can look at the tonnage of the complete system of 2625 panel battery sets.
Battery mass of a set was weighing 7.15 kg (15.8 lb) for a mass of 18.77 mT and until we have more numbers for the panels mass and converters for charging and for providing the power we will not know how much mass the total will be but then again the volume of all of that in what ever manner it will be packed is the next issue to solve.

Sure when not in sand storm events that last for months we will have a surplus of power which will cause the batteries and panels issues for over charging if we are not consuming enough not to meantion we will experience battery cell barrier issues as well as they could be damaged by the severe draw down that a storm will cause..

louis · 2018-06-16 06:25:06

I am finding it difficult following all that technical stuff Spacenut!

I worked on the basis of 200Whs storage per Kg. So that would be 200 KWhs per tonne. I think that's quite a conservative figure. That would provide. 4 sols' worth at about 2 Kws. For 100 tonnes, that would be 400 sols' worth of emergency power.

As soon as PV power returned to normal, you would top up your batteries, before powering up all the other energy users like the propellant production facility.

SpaceNut wrote:

Multiply the rover numbers for the size of the daily need to be reached for the wattage of the panels that you will bring and the same for the batteries as tonnage is only a launch and landing issue for the mass of each. Having excess batteries to store a charge does not work as the wattage still comes form the panels that is stored so they must match.
The rover batteries are 2 x 24v each to give a buss power of 48 volts with a 10 amp-hour or a total 480 whr of capacity to make use of for the entire day. The panel sends when new 840 watt-hours and drops to 730 watt-hours just after a single year on mars. These are the near best of both parts for use, still within a percent or 2 at most as spending to much really does not change it all that much. As you can see the converting from what the cells recieve to what can be store and put are are not the same number due to efficiecy losses.
So you want from the batteries say 50 kwhr a day just for life support that will be about 105 sets of batteries and the same is true for the panel count to be able to provide the energy over the course of a day. So in the dust storm we are only getting 22 watt-hours so multiple the panel count and see how low the amount of power will be; which is just 2.31 kwhrs so if we need 50 kwhr which is 2 kw used in each hour and we got 2.3 kwhr power will be on for about 1 hour before the battery is dead.
That said if that was as bad as it would get and we could get that low level generated garenteed then we need to have 25 times as many sets of each 105 panel battery combination to be able to meet the survival level.
Now that we know that is the goal for safety then we can look at the tonnage of the complete system of 2625 panel battery sets.
Battery mass of a set was weighing 7.15 kg (15.8 lb) for a mass of 18.77 mT and until we have more numbers for the panels mass and converters for charging and for providing the power we will not know how much mass the total will be but then again the volume of all of that in what ever manner it will be packed is the next issue to solve.
Sure when not in sand storm events that last for months we will have a surplus of power which will cause the batteries and panels issues for over charging if we are not consuming enough not to meantion we will experience battery cell barrier issues as well as they could be damaged by the severe draw down that a storm will cause..

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