Despite Dust Storms, Solar Power is Best for Mars Colonies
Written by Ian O'Neill
Now you see it... Spirit's solar panels collected a lot of dust in two years (NASA/JPL)
Dust — a solar panel's worst nightmare.
Is sending solar-powered robots to the Red Planet a bad idea? Mars is a very dusty planet, and Mars dust sticks to everything, especially solar arrays. After all, Phoenix's death was probably hastened by a Sun-blocking dust storm, and rover Spirit was battered by the combined solar panel-coated dust layer plus dust storm, nearly draining its batteries (as can be seen in the comparison above, after two years on the Martian surface, Spirit's dusty layer was already an acute problem).
However, a NASA-sponsored MIT think-tank has weighed up the future energy needs of a manned settlement on Mars and arrived at an interesting conclusion…
It sounds like the "nuclear space debate" continues. Thinking back to when Galileo was launched toward Jupiter in 1989, or when Cassini was sent to Saturn in 1997, huge protests erupted from critics, Cape Canaveral neighbours and anti-nuclear organizations. The argument was that should there be a launch accident, the radioactive material contained inside the radioisotope thermal generators (RTGs) could be scattered through the atmosphere and over a wide area on the ground (i.e. death and destruction). While this is a scary thought, NASA engineers were very quick to point out that RTGs are virtually indestructible, even under extreme conditions during an explosion and atmospheric re-entry.
The motivation for sending plutonium (non-weapon grade Pu238) on board missions to Jupiter and Saturn has even been called into question, spawning wild conspiracy theories such as "Project Lucifer." Therefore, it seems only sensible that NASA should want to carry out an in-depth study of all energy production techniques before committing to a potentially unpopular (and therefore politically damaging) nuclear source for future Mars colonies.
With the help of energy specialists from the Massachusetts Institute of Technology (MIT), NASA commissioned a study of how future manned Mars settlements can be powered. Will nuclear generators need to be constructed? Or can solar panels fulfil our proto-colony's energy needs (regardless of the dust situation)?
Interestingly, if positioned in the correct location, solar arrays might function just as well, if not better, than the nuclear options. Solar panels could provide all the energy a fledgling colony needs.
The MIT researchers assessed 13 different energy generation systems and compared solar and nuclear options. In a presentation last month at the International Astronautical Congress in Glasgow, MIT engineer Wilfried Hofstetter compared nuclear fission reactors, RTGs, Sun-tracking solar panel arrays and non-tracking thin-film solar arrays laid atop the Martian landscape.
Like any space travel endeavour, efficiency is paramount; astronauts will need to utilize every last energy-generating ounce of equipment sent to Mars (including back-up systems).
It would appear that a large solar panel array can match nuclear generators, only if they are situated at a latitude of 0-40° north of the Martian equator. Southern latitudes have much less solar energy available for most of the year.
So what's the best plan of action? According to Hofstetter, a Mars mission should be able to transport several 2 metre-wide rolls of thin-film solar panel arrays. Rolling out an array of these thin-film rolls could supply ample energy to a colony. For example, if the array is positioned at 25° north, measuring 100×100 metres, 100 kilowatts can be generated. The MIT researchers even calculated it would take two astronauts 17 hours to construct the array (alternatively they could get a robot to do it).
Commenting on this Mars energy solution, Colin Pillinger, planetary scientist with the Open University, UK (and head Beagle 2 scientist) said the solar array's old foe — dust — shouldn't be too much of a problem after all. "Dust storms tend to start in well-known places in the southern hemisphere as it warms up, so it shouldn't be too difficult to avoid them," he said.
So the skies may be clear for solar energy on Mars after all. Even though dust storms causes problems for our robotic explorers, manned expeditions may be able to avoid them all together. Besides, I don't see why astronauts couldn't pack some brushes to wipe down the arrays should dust become a problem…
Source: New Scientist
Filed under: Mars
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November 20th, 2008 at 9:17 pm
Why on earth (or mars really) aren't the land based mars explorers equipped with some kind of vacuum cleaner for the solar panels? It shouldn't be that hard to keep the panels free of dust, should it?
November 20th, 2008 at 9:23 pm
The main issue with the rovers is that they have surpassed their lifespan ×10 – NASA didn't think dust would become a problem 5-years down the line as the rovers weren't expected to live past 5 months…
So it's not so much NASA didn't realise dust would be a problem, they just didn't think the rovers would last long enough to gather this much dust!
Some great engineering, but it would be sad if Spirit succumbed to a dust-coated demise…
November 20th, 2008 at 9:35 pm
well a colony would be able to squeege the panels, and i think the rovers could add an extra ounce of weight and have a little windshield wiper system to wipe of the dust. they could live 100x the mission goal
November 20th, 2008 at 10:24 pm
jason Says:
November 20th, 2008 at 9:35 pm
"…they could live 100x the mission goal"
Sadly, I think congress would cut funding for them long before then. In fact, that almost happened just last month to our intrepid little explorers.
As for the main article – exactly! Solar panels would be great for colonies because they can be maintained – wiped down, repaired etc. RTG's are super reliable too, so really it comes down to what is easier to get there and safest to have around for the amount of energy produced by each.
I could envisage that both technologies would have a part to play in any future colony as requirements and circumstances dictate.
November 20th, 2008 at 10:27 pm
Personally I think nuclear energy , wind and solar energy are great ideas for planets like mars. As far as I can see without going into other sources of energy that we experiment with, the nuclear option would be one of the best ideas for power on mars, at least used to power a command center.
November 20th, 2008 at 11:40 pm
Solar is the best route up until Ceres, after that, the distance / energy relationship of the sun doesn't provide enough energy to reach furthur out. Nuclear would likely be for the places like the Galilean moons and beyond.
November 20th, 2008 at 11:48 pm
I agree with Damien about nuclear energy and I'm reluctant to trust "scientific" think tanks and committees now that scientists have shown themselves to be as open to ideological bias as any of the "soft" fields of study.
The global warming debate has been an eye opener, with scientists calling for "denialist" colleagues to be decertified by their professional organizations and so on. Nauseating.
Nuclear power is not as clean as solar power but for the power requirements needed for a safe productive colony (or mission) nothing else is close.
November 21st, 2008 at 12:13 am
It seems that dust on the photovoltaic cells would be a minor problem for a Mars colony. NASA could either A. Devise some sort of automated system to periodically blow or wipe the dust from the panels, or B. Just have some of the colonist wipe them off occasionally.
Seems simple enough, but I could be wrong…
Either way I agree that solar power is the best option to juice a future colony.
November 21st, 2008 at 12:27 am
You know I think they might have overlooked the whole windscreen wiper thing.
Does anyone know for sure?
November 21st, 2008 at 12:28 am
The windscreen wiper idea sounds O.K. but would be improved by using a rotating brush in place of a squeegee type wiper……….Solar power sounds wonderful, but how is the generated power stored for use at night ?Surely the weight of batteries needed to supply a manned colony would be far in excess of being an acceptable payload to the detriment of being able to carry other more essential supplies……..food…..water…..air….habitat…..etc
November 21st, 2008 at 4:20 am
Solar Power plus battery weight plus eventual demise of the rechargeable batteries makes an RTG (nuclear) power source in my humble opinion a no brainer. No silly wipers, no EVAs to "wipe" (how often do you do that in a storm?). The two Vikings used them until congress ordered them turned off. Voyager still uses them (launched over 30 years ago) and will be operating further decades into the stars. Lets design an all purpose excellent 50 year RTG and make enough of them so these silly solar toys can be put to rest. So what is there to figure out?
November 21st, 2008 at 4:27 am
Why not use some kind of windshield wipers for the solar panels?
November 21st, 2008 at 4:27 am
whoops…I should have read before posting. sorry.
November 21st, 2008 at 6:54 am
Something we seem to forget is the energy density of solar is really low. 100 meters by 100 meters is 10 KM^2……..that's a lot of solar panels. So it would take that much to just get 100 kilowatts with solar, while the reactor on a modern navy ship can produce 100 times that at least. I'm sorry but given the amount of money it costs get stuff there and the trouble with martian dust, solar just doesn't cut. Long term, there is really nothing but nuclear. It's unfortunate that some people just don't get that.
November 21st, 2008 at 7:13 am
I am actually more curious about the "Lunar Dust Buster" concept for the solar panels. Do we know if NASA is actively looking into this as a possible solution for solar panels on the Moon or Mars? (http://science.nasa.gov/headlines/y2006/19apr_dustbuster.htm)
November 21st, 2008 at 7:29 am
I'm thinking a can of compressed air would probably work very well. Less mechanical devices than a motorized brush – which would also drain the battery. Just blast the dust away.
November 21st, 2008 at 7:51 am
How many cans of compressed air do you think they will need, Dark Gnat?
Did I understand correctly that we should build some type of nuclear generator that would last 50 years? So what do we do with the waste product? We know nothing about the planet and we are already contaminating it!!
Solar energy is a "store-type" system, right?
Why do they need to do an EVA for dusting in a dust storm?
November 21st, 2008 at 8:07 am
[quote]Did I understand correctly that we should build some type of nuclear generator that would last 50 years?[/quote]
Yes you did, because other than fossil fuels there is nothing else with a high enough energy density and reliability (granted in space reliability isn't the problem, but on practically any planet or moon it will be) to be useful.
[quote] So what do we do with the waste product?[/quote]
Reprocess it for reuse in the reactor and what cannot be reprocessed perhaps can be reused as RTGs.
But really, modern reactors don't make that much waste. Yes, the waste storage pools in american reactors are full, but that took more than 30 years for this to happen and that was without reprocessing.
November 21st, 2008 at 8:27 am
We need a combination.
Solar panels for the main power, a few RTG's to serve as backup (and booster for when experiments require the extra power).
By the time theres enough colonists and waste to worry about, mars bases should be self sufficient.
November 21st, 2008 at 8:28 am
I can't believe NASA never thought of dust being a factor when they built these robots! It just goes to show that sometimes we get caught up in the technical details without considering practicality.
I agree that Nuclear could be a solution, but it takes anything from 6 to 12 years to get a reactor fully functional. And like the others have said – what happens to the radioactive waste?
We've already created enough waste on Earth. We shouldn't start spreading it all over the solar system now.
The idea of compressed air is an idea, however, how will it be refilled?
I think all the solutions to cleaning the panels are a start, but they all have their pitfalls. Good luck for the brains at NASA for figuring this one out!
November 21st, 2008 at 8:59 am
I can't remember where I read this but about a hundred years ago, scientists thought there was no more science left……..
Look how far we have come, and in reality I thing we are still so-so very new to science that we do not even qualify for diapers stage.
So, YES, those smart guys at NASA will figure this one out…… And, I hope I am here to see it happen that there ARE colonies on Mars running on energy that is as "Green" and our planet will be in the near future.
November 21st, 2008 at 9:10 am
Well Ian if I was on Mars, I'd rather be doing some science than spending my day dusting panels.
A combo of power sources like what Maxwell said is the best way to go. It would be stupid to rely on one type of power source anyway in the first place.
November 21st, 2008 at 9:30 am
Steve! Reality is that dust will be everywhere, and the colonies on Mars are going to spend a considerable time cleaning everything; their selves, equipment inside the compound and out. I see no difference that they will need to once in a while go out and do some dusting of some solar panels. And one more thing, the Rovers have functioned for five years with one true dusting from a Dust Devil….. That's a pretty good record if you ask me.
Re-use of nuclear fuel is a complicated process; included are water which will be most important for the colonies survival (now we have to build depositories for that contaminated water), equipment that could only be used for the cleaning process (at what cost and how do we get it there?), buildings that will need to be constructed (at what cost and how how long will it take to build them?). Also keep in mind that the safety of the colony is most important (since science is most import, time is an issue so at what distance will they need to do all of this?).
November 21st, 2008 at 9:31 am
Hmm, if dust is the big problem, what about something like a Hot Air Balloon made out of Solar Panels and tethered to the ground by it's power cable? This get's the thing off the ground potentially away from the bulk of the problems and if you're really savvy, you put it on a long enough cable that it sits above dust storms and the like and isn't affected by overhead clouds.
November 21st, 2008 at 9:40 am
100 KW from an area the size of about a football field and a half? That sounds respectable to me. Real estate on Mars is bound to remain cheap for a few centuries to come….
With humans around to attend to it, dust might not be a huge problem… like a couple of days work every year, or thereabouts. Remember, Spirit has been out there for five years.
November 21st, 2008 at 10:00 am
@Silver Thread:
I like your idea, I see three problems, though:
1) the weight of the power cable – it needs to be lifted
2) only a small portion of the balloon's envelope would face the sun – it would probably have to be GIGANTIC
3) the atmosphere on Mars is very thin – to achieve the necessary lift, the balloon may have to be GIGA-GIGANTIC.
somebody with some spare time and the knowledge about material properties might do the sums, just for the fun of it…
November 21st, 2008 at 10:12 am
Quote
I don't know, Feenixx, the minute someone finds minerals or precious stones on Mars, which I believe there was plenty of time for their creation, then business men from the private sector will be scrambling to get a piece!!!
One hundred, two hundred is a long time. I think we will be on Mars much much sooner.
I liken it to the Gold Rush in America. Moneys will be available for new ventures.
November 21st, 2008 at 10:24 am
"outcast Says: …Something we seem to forget is the energy density of solar is really low. 100 meters by 100 meters is 10 KM^2……..that's a lot of solar panels."
A small point here. 1km (kilo metre) is 1000 metres so 100 metres is .1 km. and 100m x 100m is .01 km^2
November 21st, 2008 at 10:57 am
Yeah well, if we can unfurl things in space we can send solar panels in rolls to Mars. What ever the amount we need doesn't make a difference. It is much easier than the alternative.
November 21st, 2008 at 1:39 pm
RTG is a silly option. A brayton cycle fission reactor uses much less radioactive materials and produces several times more energy, and waste heat can be used to keep the colony nice and warm.
I wonder if this MIT thinktank considered the energy required to sustain and keep warm a small Mars colony during
THE COLD NIGHT.
However, a 4 kW solar array powers my home and the batteries provide power for 4 days with no sunlight. But I cannot run an electric heater without running out of juice within a few hours.
A solar powerd Mars colony my be possible.
Although if you want to save weight, and money, and provide heat, nuclear fission will be needed.
November 21st, 2008 at 6:19 pm
"A small point here. 1km (kilo metre) is 1000 metres so 100 metres is .1 km. and 100m x 100m is .01 km^2"
100 meters times 100 meters is 10000 meters squared, which is 10 km^2. Run 100 * 100 through a calculator if you don't believe me.
"Re-use of nuclear fuel is a complicated process; included are water which will be most important for the colonies survival (now we have to build depositories for that contaminated water)"
Not all of the methods use water, there is one that doesn't
http://en.wikipedia.org/wiki/Nuclear_reprocessing#Pyroprocessing
"equipment that could only be used for the cleaning process (at what cost and how do we get it there?), buildings that will need to be constructed (at what cost and how how long will it take to build them?)."
Both of which are a one time investment, and don't even need to be built right away. Like I said, it took the old, far less efficient generation 2 nuclear reactors in the US 30 years to fill up their waste reservoirs without any kind of reprocessing. With modern nuclear reactors it would take even longer., and even then that assumes we use a full scale 1 GW reactor, which at the moment isn't even necessary.
"Also keep in mind that the safety of the colony is most important"
Actually even the old generation 2 nuclear plants are a lot safer than the coal plants we like to depend on. Coal claims thousands of lives every year through mining accidents and air pollution related respiratory ailments. And besides, as KG6ya rightly points out the nights on Mars are really really cold, can solar provide enough power at night to run a power hungry heater for 12 hours +? I doubt it.
"And, I hope I am here to see it happen that there ARE colonies on Mars running on energy that is as "Green" and our planet will be in the near future"
In reality countries in western europe (namely the UK and Germany) that tried to ditch nuclear and invested heavily in wind and solar are finding themselves stuck with looming energy shortages, which is causing them to build more coal power plants (which is causing more air pollution) and buy nuclear generated electricity from France. Thinking that solar and wind and other such low density, intermittent power sources can provide enough electricity for us no matter what is an unfortunate fantasy.
November 21st, 2008 at 7:08 pm
Can anyone estimate the mass of an RTG and the mass of solar cells and overnight batteries for say 100 KW continuous power generation ?
November 21st, 2008 at 7:52 pm
Has anyone found a link to Hofstetters presentation ?
November 21st, 2008 at 8:40 pm
outcast
"100 meters times 100 meters is 10,000 meters squared, which is 10 km^2. Run 100 * 100 through a calculator if you don't believe me."
And, 100 feet x 100 feet is 10,000 square feet – Not almost 2 square miles. You are confusing area measure with linear measure.
November 21st, 2008 at 9:38 pm
I heard an interview where a NASA rep was asked about this exact problem. She said that they did not think it would be a significant problem over the projected life of the mission, and that every ounce of the payload was carefully calculated for maximum scientific value. A wiper or vibrator would have meant an experiment left behind.
NASA has made a few blunders in the past ("The thrust value was Metric? Are you sure?") but they did know there is dust on Mars. Some of you are being "armchair quarterbacks".
In future manned missions, the cost of the payload and maintenance will be compared for all possible generators. It sounds like they have already begun the work.
As for waste, it is one small generator. For a small colony, it would not be contaminating the entire planet. They won't be driving Martian SUV's commuting from the suburbs. They won't have 15,000 watts of Christmas lights outside the habitat, or a 52 inch plasma TV.
November 22nd, 2008 at 2:36 am
"And, 100 feet x 100 feet is 10,000 square feet – Not almost 2 square miles. You are confusing area measure with linear measure."
My bad. My point is still valid though.
November 22nd, 2008 at 7:13 am
[quote]You keep talking about coal, Outcast, but Wiki says it is a fossil fuel created from plants, Yes, what you say is right, that it contributes to the carbine dioxide in the atmosphere which is bad here on Earth.[/quote]
My point was that solar and wind can never be used as primary sources of power for human settlements/cities/countries, and I used the example of Germany having to build more coal plants as proof.
At least here on Earth, we can still use fossil fuels to make up the difference without going nuclear, but on the moon/Mars/asteroid belt we don't have that choice (Mars is the exception, but not initially).
[quote]Why take our problems to Mars? We are starting with a clean slate.[/quote]
By using nuclear we are not taking problems to Mars, we are using our best option.
November 22nd, 2008 at 12:12 pm
Ok I see your point, Outcast. And just a liitle bit of nuclear energy won't hurt. Right?
November 23rd, 2008 at 2:32 am
Hi, Outcast says ,and I just cannot let this pass unchallenged, that 100 meters X 100 meters equals 10,000 meters squared. GREAT MATHS BUT TOTALLY INCORRECT..100 X 100..meters. IN FACT EQUALS ONLY 10,000 Square meters and this is not even in the same ballpark as 10,000 X 10,000 (10,000 squared ) this is a figure that makes my calculator want to go into overload and close down.
November 23rd, 2008 at 8:17 am
"Hi, Outcast says ,and I just cannot let this pass unchallenged,……"
Someone else already pointed that out, and I accepted I made a mistake. Plus the way you present it does not cast you in a good light.