Going Solar...the best solution for Mars.

SpaceNut · 2018-06-16 09:04:23

So we need 4 x 2625 panels(1) and battery(2) sets (10,500)to obtain the 200 kwhr storage for a hope of a storm not lasting longer than 4 days with a storm blockage of sunlight that is below 3%. To which with no backup power and severe power rationing would kill the crew shortly after the temperatures drop to below freezing and co2 level reach satuation.
The 8.82 mega whr build from would need to have time and surplus management to be able to build up a sort of goods in the form of Co2, Water, Methane, Oxygen and food when not in storm mode all while providing return fuel for the BFR, science exploratory power, habitat needs of co2 scrubbing, oxygen, water, food growth power for greenhouse, food processing to meals, refiguration of foods, cooking of foods, canning& preserving of foods, lighting, heating and cooling. Which is sort of what we are trying to get numbers for in the Air. Shelter. Water. Food. by Oldfart1939 topic.
https://en.wikipedia.org/wiki/Photovolt … er_station
Keep in mind the farm on mars is 2.3 times larger since the level of energy getting to mars is that much less if earth panels were used due to panel effiency differences.
Still need to also make a battery building to house and climate isolate them from mars as well.
Here is a comparible farm:
https://www.eastbaytimes.com/2018/04/18 … -richmond/

ebt-l-solarfarm-0419-1.jpg?w=940

https://gizmodo.com/5943708/this-is-wha … looks-like

louis · 2018-06-16 10:10:39

I think domestic and solar farm panels are often in the 15% range of efficiency. It's likely Mars panels would be more like 25%, because the cost is really an irrelevance in relation to overall mission cost, so Space X can afford to buy the most efficient. So your 2.3 might be more like 0.7 if comparing with standard solar farms on Earth.

Build time could be far quicker than on Earth because weather conditions are much more clement than on Earth, so you don't need the sturdy structural support. I have proposed using lightweight PV panelling that can be rolled out and attached to two taught wires supported by lightweight poles. Alternatively they could just be laid on the ground and weighted by rocks. I think robot rovers could be programmed to undertake this task quickly - in a matter of a few days.

Here's a link to an existing lightweight flexible PV panel system that achieves over 20% efficiency (I think this is the one kbd linked to before). Bit of a game changer.

https://flisom.com/technology/

I would also expect a proportion of the PV set up to be in the form of Orbital ATK fans or similar. Maybe they would make up 5% of the complete array and be able to deploy immediately after landing.

You make reference to greenhouse food production and other power draws, but in the context of Mission One a lot of those are add-on extras that can be ditched. Really, propellant power production and life support are the two indispensables.

I don't foresee any issues with PV energy unless Mission One lands in the middle of a serious worst-case dust storm. In those circumstances one would make use of the chemical batteries (I'm thinking around 70 tonnes) and the supplies of air and water brought from Earth (maybe around 50 tonnes).

SpaceNut wrote:

So we need 4 x 2625 panels(1) and battery(2) sets (10,500)to obtain the 200 kwhr storage for a hope of a storm not lasting longer than 4 days with a storm blockage of sunlight that is below 3%. To which with no backup power and severe power rationing would kill the crew shortly after the temperatures drop to below freezing and co2 level reach satuation.
The 8.82 mega whr build from would need to have time and surplus management to be able to build up a sort of goods in the form of Co2, Water, Methane, Oxygen and food when not in storm mode all while providing return fuel for the BFR, science exploratory power, habitat needs of co2 scrubbing, oxygen, water, food growth power for greenhouse, food processing to meals, refiguration of foods, cooking of foods, canning& preserving of foods, lighting, heating and cooling. Which is sort of what we are trying to get numbers for in the Air. Shelter. Water. Food. by Oldfart1939 topic.
https://en.wikipedia.org/wiki/Photovolt … er_station
Keep in mind the farm on mars is 2.3 times larger since the level of energy getting to mars is that much less if earth panels were used due to panel effiency differences.
Still need to also make a battery building to house and climate isolate them from mars as well.
Here is a comparible farm:
https://www.eastbaytimes.com/2018/04/18 … -richmond/
https://www.eastbaytimes.com/wp-content … .jpg?w=940
https://gizmodo.com/5943708/this-is-wha … looks-like

Last edited by louis (2018-06-16 10:20:44)

Oldfart1939 · 2018-06-16 10:25:46

I don't foresee any issues with PV energy unless Mission One lands in the middle of a serious worst-case dust storm. In those circumstances one would make use of the chemical batteries (I'm thinking around 70 tonnes) and the supplies of air and water brought from Earth (maybe around 50 tonnes).

Louis-

You can dance around this issue as much as you like, but no astronaut is going to set foot in a BFS unless there is a realistic power supply available. If I were some 20 years younger, I would be making my application NOW to be a mission commander because of my scientific background and record of extreme outdoor activities (Winter mountaineering, rock climbing, U.S. Army military experience, and the fact I'm also a certificated Private Pilot). Your attitude is one of extreme wishful thinking, and that's what get's people killed.

louis · 2018-06-16 12:58:40

Oldfart, sounds like you would have been a perfect candidate...as long as you're not too tall.

I don't think I'm wishful thinking at all. Travelling with a couple of hundred tonnes of PVs, batteries and emergency supplies is not "wishful thinking" - it's planning.

Nuclear reactors have their own issues. You definitely need to take a minimum of two. There are safety issues about operating them...are they going to be activated on board the BFS? What about the waste heat? How much are they going to weigh? What happens when you want to go exploring...

Oldfart1939 wrote:

I don't foresee any issues with PV energy unless Mission One lands in the middle of a serious worst-case dust storm. In those circumstances one would make use of the chemical batteries (I'm thinking around 70 tonnes) and the supplies of air and water brought from Earth (maybe around 50 tonnes).

Louis-
You can dance around this issue as much as you like, but no astronaut is going to set foot in a BFS unless there is a realistic power supply available. If I were some 20 years younger, I would be making my application NOW to be a mission commander because of my scientific background and record of extreme outdoor activities (Winter mountaineering, rock climbing, U.S. Army military experience, and the fact I'm also a certificated Private Pilot). Your attitude is one of extreme wishful thinking, and that's what get's people killed.

SpaceNut · 2018-06-16 13:11:30

The rovers efficiency are the 35% panels so there will be growth of the farm and no they can not just lay on the ground due to thermal gradient, dust and rock build up on them would increase the damage to them as the wind would make the sand dust like sanding paper to them say nothing about the added mass on the panels due to being flat as it acumilates and attenuation of power output.

www.spaceflightinsider.com/missions/atk-provide-ultraflex-solar-arrays-insight-lander/
ultra flex solar panels

https://www.orbitalatk.com/space-system … tsheet.pdf

Sure the ATK fan with tracking would be optimal as these collapse into a small package but they still need a base to make them stand up for correct positioning towards the sun. This is like having 10 rovers on a stick to face towards the sun.

Not to be confused with these
http://www.aktsolar.co.uk/index.php/en/products or

ATK mega flex panels used on some cygnus cargo ships

The ATK/Orbital has be aquired by Northrogrumman
http://www.northropgrumman.com/Capabili … fault.aspx

The sum of batteries in a large room still has not been addressed either.

louis · 2018-06-16 14:16:51

Like Musk, I think Mars's future will be PV-based. Whilst I accept and have always accepted that there are some strong arguments for their use on Mission One, I think otherwise they are a very restrictive technology. They will reinforce Mars dependency on Earth, rather than allow a swift transition to ISRU. We hear claims about automated operation, but we know that in nuclear power stations on Earth, in reality, hundreds of people have to be employed monitoring all the processes. A malfunction of a nuclear power facility could have serious health and safety effects on a colony.

Putting everything together, I think nuclear is the wrong choice for Mars. It's not a very good one for Earth either, as the people of Japan discovered.

I'd like to see a link to these formal NASA reports of solar insolation being reduced by more than 80% of normal because I genuinely have not seen that yet. What is received by a solar panel rover is not the same as the amount of insolation.

This is purely a Mission One problem. Beyond that point there will be copious supplies of methane and oxygen available to maintain any desired level of power.

Anyone advocating nuclear needs to address a list of questions. Where's your nuclear reactor going to be sited? How many are you taking? How heavy will it be? Are you going to keep it on the BFS? Or take it off? Are you going to bury it? How close to it can humans safely get? Are you going to rely solely on nuclear power? How does that work if you go exploring? If you are taking PV how much? What do you do with the significant

You seem to be suggesting that the reactors are offloaded (a significant challenge in itself) at 1.5 tonnes a time. How close to the habs can you place them?

We're going to need a lot more than 100 KWe if we are producing propellant for a return trip. I don't think we've bottomed out how much exactly. If it's I Mw then your nuclear system alone (but you might also be taking PV and probably batteries for your rovers as well) will be over 150 tonnes.

Flisom flexible PV panelling will give you 1200 Kwhs per sol for 10,000 sq metres at 5 tonnes (encapsulated) or the equivalent of 48.9 Kws continuous. For 150 tonnes of PV you would get nearly 1.47 Mws continuous equivalent. Because nearly all the PV power would be going into propellant production, the intermittency of PV is not really an issue here.

kbd512 wrote:

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

SpaceNut · 2018-06-16 16:55:12

https://www.nasa.gov/

https://mars.nasa.gov/

https://mars.nasa.gov/news/8350/nasa-en … r-science/

https://mars.nasa.gov/news/8348/opportu … ust-storm/

https://mars.nasa.gov/news/8349/media-t … portunity/

https://www.nasa.gov/feature/jpl/nasa-e … or-science

https://mars.nasa.gov/weather/storm-watch-2018/

RobertDyck · 2018-06-16 17:43:58

louis: Nuclear is an option that gained a bad reputation based on ignorance. America chose to develop nuclear reactors for navy ships, then use those designs for commercial power. There are several problems with that. Ship reactors were designed to operate without maintenance of the core for years at a time, refuelling required shutting the reactor down for 3 months at a time. You may be able to do that with a navy ship, but not commercial power plant. Furthermore, fuel required enrichment. Enrichment is expensive, but significantly reduces mass carried by the vessel. That mass reduction holds no benefit what so ever for a ground based power plant. But a power plant cannot shut down. Furthermore, these old designs resulted in a significant proportion of uranium absorbing a neutron to be transmuted into a different element, and the reactor was not designed to use those other elements as fuel. This created significant radioactive waste. Modern reactor designs use these other trans-uranic elements as fuel. Furthermore, a thorium reactor starts with 100% Th-232 as fuel, requiring a two-step reaction. 1) absorb a neutron to become Th-233, then a few days to decay to U-233, then that uranium is split by another neutron. Modern thorium reactor designs do not provide enough neutron radiation to sustain a reaction. After all, splitting uranium releases on average 3 neutrons with each atom split, so a uranium reactor only requires 1/3 of the neutrons to hit another U-235 atom. But with thorium, 2/3 of the neutrons must be productively used, one to transmute thorium into uranium, the other to split uranium. This requires a small high-intensity neutron radiation source to keep the reactor going. That neutron source is mounted on an arm so it can be quickly and easily removed, allowing the reaction to die. It's a safety feature. But it also means 100% of raw fuel is fissile. And U-233 absorbs neutron radiation more readily than either Th-232 or U-235, so U-233 is consumed as quickly as it's produced, and extremely little is transmuted into undesired trans-uranics. When fuel rods (Th or U) become contaminated with too much fission fragments (nuclear waste) that waste product "poisons" the reaction. So fuel rods have to be replaced. Reprocessing separates unused fuel from waste, so unused fuel can be made into fresh fuel rods. This dramatically reduces nuclear waste. And fission fragments are high radioactive elements that decay quickly. Fast decay means they can be stored for months, then the vast majority becomes non-radioactive. The non-radioactive material can be separated from still "hot" radioactive.

This research was proceeding, but unfortunately anti-nuclear activists campaigned against research to effectively eliminate radioactive waste. They actually campaigned against reactors that use trans-uranic elements as fuel, against reprocessing facilities, against any advancement.

As for Japan, their reactors were designed to use plutonium as fuel. The most plentiful trans-uranic in waste from American nuclear reactors was plutonium, so Japanese reactors were designed to use that waste as fuel. The problem is they designed Fukushima class reactors to survive either an earth quake or tsunami, but not both. But Japan is an island, any major earth quake will cause a tsunami. They realized this, designed a new model of reactor to resolve this. A new reactor was under construction, Fukushima was scheduled to be shut down just 3 months after the accident. If they had completed construction that much sooner, the accident wouldn't have happened.

Mars: MGS already mapped deposits of thorium. It's an indicator mineral for uranium, but why not use the thorium itself?

In the thread "updating Mars Direct", I suggested taking mobility components from Curiosity rover (new components) and bolting them to a SAFE-400 reactor. That reactor is the same as SP-100, but newer and lower mass, designed by the same team. The result would be the same mass as Curiosity. Wheels, suspension arms, motors, nav-cam, navigation computer, but the body and RTG and science instruments replaced by the reactor. A self-driving reactor is easy to get out. Of course that's sized for a science mission, not settlement.

I should also point out, Mars Direct included a nuclear reactor on the ERV, delivered without crew. The reactor would be parked in a bottom of a crater a safe distance from the ERV before the reactor is turned on. Crew would ride in the hab, with solar. Crew would never ride with a reactor. Radiation from uranium is mild; in 1987 I saw a video that was old at that time, showing Canadian nuclear reactor workers filling fuel rods, they stuffed yellow cake uranium oxide powder into stainless steel tubes using their fingers. They wore the same loose plastic gloves you get with oven cleaner, white lab coat, paper filter mask over their nose/mouth, lexan eye protection, and plastic shower cap over their hair. That's all they needed. Uranium is that safe before it goes into the reactor. The dangerous stuff is the fission fragments, after atoms are split. You want a concrete wall several feet thick between you a fuel rod as it comes out of a reactor, or 12 foot deep pool of water. A reactor that has never, ever been turned on is so safe that the casing of the reactor is all the protection you need. Once the reactor is turned on... But transporting the reactor to Mars in a vehicle without crew is a definite safety feature.

Last edited by RobertDyck (2018-06-16 23:02:46)

louis · 2018-06-16 18:22:20

I was thinking more of scientific papers like this one which states:

"From a photovoltaic system design point of view, the intensity, frequency, and duration of these storms may be viewed as partially cloudy and cloudy days for which additional energy storage in the photovoltaic system must be taken into account."

Hardly in line with the apocalyptic stuff being touted here by the pro-nuclear lobby!

http://large.stanford.edu/courses/2017/ … 102299.pdf

There's nothing in your links that I would say amounted to proper scientific evidence.

SpaceNut wrote:

https://www.nasa.gov/
https://mars.nasa.gov/
https://mars.nasa.gov/news/8350/nasa-en … r-science/
https://mars.nasa.gov/news/8348/opportu … ust-storm/
https://mars.nasa.gov/news/8349/media-t … portunity/
https://www.nasa.gov/feature/jpl/nasa-e … or-science
https://mars.nasa.gov/weather/storm-watch-2018/

ADDED:

Here's another paper on "Design considerations for Mars photovoltaic systems".

The abstract states:

"Of major concern are dust storms, which have been observed to occur on local as well as on global scales, and their effect on solar array output. While atmospheric opacity may rise to values ranging from three to nine, depending on storm severity, there is still an appreciable large diffuse illumination, even at high opacities so that photovoltaic operation is still possible. If the power system is to continue to generate power even on high-optical-opacity (i.e. dusty atmosphere) days, it is important that the photovoltaic system be designed to collect diffuse irradiance as well as direct. "

So, it there you can't just read over from opacity to solar array output.

I think a bit of common sense backed by the science is required. If there really are "blackout" conditions - case not proven in my view - then they are going to be v. shortlived. At all other times PV panels can operate during dust storms albeit at much reduced levels - perhaps as low as 80% of the "normal" average figure at times, though that will be at the extreme.

Last edited by louis (2018-06-16 18:45:02)

SpaceNut · 2018-06-16 19:22:26

The paper as written for earth useage not of mars as clouds of moisture are not the same as dust and dirt in the air.
This earths https://en.wikipedia.org/wiki/Dust_storm
https://en.wikipedia.org/wiki/List_of_d … rs_or_less

https://phys.org/news/2015-09-fact-fict … torms.html

Mars Imagery, factural measurements are not a paper, as they are the truth and not a guestimate as to what might be...

POWER REQUIREMENTS FOR THE NASA MARS DESIGN REFERENCE ARCHITECTURE (DRA) 5.0

https://www.techworm.net/2015/09/nasa-r … storm.html

https://mars.jpl.nasa.gov/gallery/dusts … 02807.html

louis · 2018-06-16 19:34:51

I gave you a reference to a scientific paper relating specifically to Mars insolation. They equate dust storm conditions to "cloudy or partly cloudy days" . They mean you would generally expect comicant reductions in insolation...probably in the 20-60% mark, with it occasionally going lower to 80%

SpaceNut wrote:

The paper as written for earth useage not of mars as clouds of moisture are not the same as dust and dirt in the air.
This earths https://en.wikipedia.org/wiki/Dust_storm
https://en.wikipedia.org/wiki/List_of_d … rs_or_less
https://phys.org/news/2015-09-fact-fict … torms.html
Mars Imagery, factural measurements are not a paper, as they are the truth and not a guestimate as to what might be...
POWER REQUIREMENTS FOR THE NASA MARS DESIGN REFERENCE ARCHITECTURE (DRA) 5.0
https://www.techworm.net/2015/09/nasa-r … storm.html
https://mars.jpl.nasa.gov/gallery/dusts … 02807.html

RobertDyck · 2018-06-16 19:46:33

Massive dust storm on Mars knocks out NASA's Opportunity rover

The solar-powered rover has not been responding with ferocious winds and swathes of dust blocking sunlight to the red planet.
A huge dust storm is raging on Mars and has knocked out NASA's Opportunity rover as harsh conditions overwhelm the planet and blocks out the sun.
Officials are hoping the solar-powered rover will make it through the storm, which has already engulfed a quarter of the red planet and is expected to expand over the coming days.
On the other side of Mars, another rover called Curiosity, which is nuclear-powered, is beginning to detect increasing levels of the dust.

RobertDyck · 2018-06-16 19:48:26

Do you have exact numbers? Exactly how much solar power was reduced by dust storms experienced by Spirit and Opportunity? Exact amount and dates.

Last edited by RobertDyck (2018-06-16 23:03:44)

louis · 2018-06-16 19:57:56

No I don't. I don't think anyone else does here. Some of the best data goes back to the Viking Landers I believe.

I've seen a figure quoted of a 40% reduction during summer dust storms (presumably an average).

RobertDyck wrote:

Do you have exact numbers? Exactly how much solar power was reduced by dust storms experienced by Sprint and Opportunity? Exact amount and dates.

RobertDyck · 2018-06-16 20:14:22

Mars Rovers Caught in Severe Dust Storm

July 20, 2007: Having explored Mars for three-and-a-half years in what were missions originally designed for three months, NASA's Mars rovers Spirit and Opportunity are facing perhaps their biggest challenge.
For nearly a month, a series of severe Martian summer dust storms has affected the rover Opportunity and, to a lesser extent, its twin, Spirit. The dust in the Martian atmosphere over Opportunity has blocked 99 percent of direct sunlight to the rover, leaving only the limited diffuse sky light to power it. Scientists fear the storms might continue for several days, if not weeks. "We're rooting for our rovers to survive these storms, but they were never designed for conditions this intense," says Alan Stern, associate administrator of NASA's Science Mission Directorate, Washington.

louis · 2018-06-16 20:22:22

That's a press release not a scientific paper.

RobertDyck wrote:

Mars Rovers Caught in Severe Dust Storm
July 20, 2007: Having explored Mars for three-and-a-half years in what were missions originally designed for three months, NASA's Mars rovers Spirit and Opportunity are facing perhaps their biggest challenge.
For nearly a month, a series of severe Martian summer dust storms has affected the rover Opportunity and, to a lesser extent, its twin, Spirit. The dust in the Martian atmosphere over Opportunity has blocked 99 percent of direct sunlight to the rover, leaving only the limited diffuse sky light to power it. Scientists fear the storms might continue for several days, if not weeks. "We're rooting for our rovers to survive these storms, but they were never designed for conditions this intense," says Alan Stern, associate administrator of NASA's Science Mission Directorate, Washington.

RobertDyck · 2018-06-16 20:29:10

louis wrote:

That's a press release not a scientific paper.

From NASA. If you want to challenge that further, find the power production figures (table or graph) for Opportunity during that dust storm, including July 20, 2007.

Ps. Spirit experienced the same dust storm, but power was not reduced as much. Rather than posting from my own faulty memory, I'll just say "not as much". However, on that day Opportunity did experience 99% power reduction, and right now it lost so much power that JPL lost contact.

Last edited by RobertDyck (2018-06-16 20:32:19)

SpaceNut · 2018-06-16 21:15:50

The tau and the telescope view are for differnet days as the storm was approaching

may 30th Opportunity’s batteries were delivering 645 watt hours
may 31

jun 1st Opportunity’s energy levels had dropped to 345 watt hours
jun 2nd Opportunity’s drops farther to 133 watt hours this is at a tau of 5 ish for solar being able to charge the battery

while the current storm had an estimated tau of nearly 11 as of June 6
jun 6th

science operations on June 8 suspended

jun 9th

jun 11 Two days later, a final transmission came in from Opportunity showing the energy level had dropped to just 22 watt hours, which would be expected to trigger a low-power fault mode in which everything but the mission clock is turned off.

Opportunity rover on June 12 but did not hear back probably because the charge in its batteries has dropped below 24 volts.

“The good news there is the dust storm has warmed temperatures on Mars. We’re also going into the summer season, and so the rover will not get as cold as it would normally.

The 2007 was a tau of 5.5 for the same rover:
Operations Strategies for the Mars Exploration Rovers During the 2007 Martian Global Dust Storm

estimated that the dust in the atmosphere prevented over 99.6% of direct sunlight from reaching the surface at the peak of the storm. Data collected indicated that solar array energy output was reduced to approximately 15% of maximum.

Oldfart1939 · 2018-06-16 22:32:32

"And meanwhile, the entire solar powered Mars research station died from extreme temperatures in the now unpowered habitats. The reserve batteries were exhausted and oxygen production ceased. The entire solar array was covered in thick layer of Mars dust."

The foregoing hypothetical statement is simply what GW, SpaceNut, RobertDyck, kbd512, and I are forecasting would happen without any substantial nuclear system available as backup. And I am a Musk supporter, too. Not all of his plans are completely rational, however.

Last edited by Oldfart1939 (2018-06-16 22:33:39)

SpaceNut · 2018-06-16 22:54:45

The 15% to 20% (30kwhr to 40 Kwhr) of the 200kwhr levels would be enough for a nuclear reactor to be the back up for a habitat to be able to survive even in a total black out that lasts days, sure we might want to do a bit of power rationing to help keep the batteries from going dead but that might be enough.
That level targets well with the kilowatt reactors that Nasa is designing that are self contained molten salt. That said 3 or 4 of them at the 10 kw size is plently.

Edit removed, the hr on the kilowatt reactor as thats not the sizing needed as its a continous run device.

kbd512 wrote:

The 100% scale design is 10kWe. I believe they're testing a 10% scale design (1kWe) because that's the output power level that the test site can accommodate without modifications of any kind. The 100% scale design will weigh 1,544kg complete (core, cooling, shielding, control). It's almost entirely metal, with very little in the way of ceramics or plastics, so the masses of the individual components are fairly well known quantities.
NASA’s Kilopower Reactor Development and the Path to Higher Power Missions
Take note of how well KiloPower trades with PV and batteries, with respect to mass, even at landing sites favorable for using PV power. That whole 50% further from the Sun than the Earth is turns out to be a real bummer.

Oldfart1939 · 2018-06-16 23:28:21

SpaceNut wrote:

The 15% to 20% (30kwhr to 40 Kwhr) of the 200kwhr levels would be enough for a nuclear reactor to be the back up for a habitat to be able to survive even in a total black out that lasts days, sure we might want to do a bit of power rationing to help keep the batteries from going dead but that might be enough.
That level targets well with the kilowatt reactors that Nasa is designing that are self contained molten salt. That said 3 or 4 of them at the 10 kw size is plently.

Agreed!

SpaceNut · 2018-06-17 07:55:16

A good repost that puts insitu into perspective:

kbd512 wrote:

Louis,
There are no mines to provide the raw materials for solar panels on Mars. Whether you import nearly ready-to-use solar panels or fission reactors from Earth, or spend years setting up the machinery to manufacture either on Mars using raw materials that are imported from Earth, you're still 100% dependent on energy production technology imported from Earth. No factories on Earth are set up in a day, a week, a month, or even a year. Simply designing the factory takes a year or more in most cases. On top of that, all raw materials and manpower that required to produce the finished products are readily available on Earth.
Go read about how long it takes to set up a factory to do anything here on Earth. Tesla still can't produce cars at their target rate with all the resources available to them. The manufacture of batteries and solar panels is not easy or simple and it's extraordinarily resource and manpower intensive. The colonists on Mars need to produce their own air, water, food, and textiles using equipment imported from Earth. That is the single most important step for permanent colonization. The second step required is to produce the construction materials on Mars, which is mostly concrete / steel / glass. Several decades later, the importation of electrical equipment from Earth will become cost prohibitive.
The major difference between solar panels and batteries or fission reactors are that as the power requirements to support activities like food production, mining, and manufacturing increase d, nuclear power requires a lot less resource importation to operate and provides reliable power. Here on Earth, fission reactors are operational 90% of the time or better and output levels of 90% of rated capacity or better. There is not one single solar power plant on Earth that has ever achieved rated capacity, nor will there ever be, and we're 50% closer to the giant fusion reactor that supplies the solar power. The real only argument between solar and fission power advocates seems to be which nuclear reactor to use and how close it should be sited to the point of use.
Some of us want to fly in small fission reactors and spend the rest of our time on useful activities like finding available natural resources, propellant production to get our spaceships back so we can use them to ship more stuff to Mars, air / water / food production to sustain the colonists living on Mars, and collecting or mining raw materials so we can build more habitable structures to put more people on Mars. We're not particularly enamored with the idea of tending to solar arrays and batteries and would rather have robots spend their time knocking the dust off the arrays so we continue to use opportunistic solar power when it's available. We want to drop a few nukes in hand-dug bore holes, connect the power cables, turn 'em on, and start making 24/7 electrical power so we can spend the rest of our time building giant solar farms, digging giant bore holes for people / animals / food crops to live in, and the never ending list of other tasks that need to be done.

louis · 2018-06-17 09:49:01

A 99% power reduction does not equate to a 99% insolation reduction. You have to establish the insolation levels separately.

RobertDyck wrote:

louis wrote:
That's a press release not a scientific paper.
From NASA. If you want to challenge that further, find the power production figures (table or graph) for Opportunity during that dust storm, including July 20, 2007.
Ps. Spirit experienced the same dust storm, but power was not reduced as much. Rather than posting from my own faulty memory, I'll just say "not as much". However, on that day Opportunity did experience 99% power reduction, and right now it lost so much power that JPL lost contact.

louis · 2018-06-17 09:54:38

So how much electricity do you think 75 tonnes of top-notch lithium batteries could produce? Zero or something. If something, how much?

At a conservative 200 Wh per kg I make that 15000 KWhs.

Why do you need to take along nuclear power facilities, with all the complexity of handling that implies?

Oldfart1939 wrote:

"And meanwhile, the entire solar powered Mars research station died from extreme temperatures in the now unpowered habitats. The reserve batteries were exhausted and oxygen production ceased. The entire solar array was covered in thick layer of Mars dust."
The foregoing hypothetical statement is simply what GW, SpaceNut, RobertDyck, kbd512, and I are forecasting would happen without any substantial nuclear system available as backup. And I am a Musk supporter, too. Not all of his plans are completely rational, however.

GW Johnson · 2018-06-17 10:57:58

Louis:

Your prejudices against nuclear power are irrational (so are the anti-nuclear prejudices of most of the world's brainwashed public). Besides, it's NOT either/or. Most of us are saying "take both".

A reactor of 100 KWe weighs less than batteries capable of 100 KWe, and will operate for many years, while tons upon tons upon tons of batteries are required to operate for weeks. It's that simple.

Your attitudes about the risks posed by Martian dust storms are also irrational. It is pointless to demand citations from scientific or engineering papers when you have the historical evidence right in front of your face.

You have not said one word about my example of the 1969 dust storm that blanketed the entire planet for 9+ months (it was already going on when Mariner 9 got there, and dissipated 9 months after the probe's arrival). I infer that you have nothing you can say about it. It does not take very many tiny particles per cubic meter to totally obscure all beam radiation, and most diffuse radiation, when the slant path length through them is 20+ km in length! Simple physics, man! OF COURSE it was almost totally blacked out down there! How could it NOT be?

I'm not an astronomer. I haven't kept up with dust storms on Mars. I don't know how many near-planet-wide obscuration events there have been since the 1969 event. But the current event seems to be falling into that category, so that's at least 2 in about 50 years. What that means is that the probability of having one during any particular 2 to 4 year stay on Mars is significantly nonzero! That's just statistical math, man! You cannot argue with it without making a complete fool of yourself!

All right, since the statistics are significantly larger than zero, you are ETHICALLY OBLIGATED to design-in adequate power for your crew on Mars in conditions of near total darkness for extended periods of time (approaching a year).

As for your fears of how unsafe nuclear power is, consider that since SSN-571 Nautilus was launched in 1954 (an event I personally remember, by the way), NOT ONE accident was ever experienced with a compact pressurized-water reactor on any ship or submarine in the US Navy, despite two sinkings (Thresher SSN-593 and Scorpion SSN-589) into the deep sea far beyond the crush depth of any of the pressure hulls. Such a compact pressurized water design is not identical to, but very similar to, what would be needed on Mars. As for isolation, bulldoze an earthen berm around it. Don't start the thing until you have it emplaced. Simple!

The ONLY blot on that US Navy record was the experimental sodium-cooled reactor installed in SSN-585 Seawolf. It leaked with radioactive sodium fires inside a pressure hull at sea. It was replaced with the pressurized-water design, and NEVER EVER had another problem! The ship served many, many years flawlessly after that.

Amazing what the safety record can be when safety is prioritized over cost by edict from the top. Hyman Rickover was a real SOB, but his insistence on safety and reliability FIRST above all really paid off.

Commercial power plants are built and operated by outfits for which the bottom line is the god they worship above all, and safety regulations are complied-with only under duress. This shows in the Three Mile Island incident, which released a very minor amount of radiation, and the Fukushima incident, which has released (and continues to release) a huge amount. Chernobyl was in a class by itself: no one in their right mind today would use a graphite pile reactor with no containment at all.

The point here is: TAKE BOTH! You're gonna need the nuke when the long darkness comes (and it will). You cannot ship enough batteries to get through that.

GW

Last edited by GW Johnson (2018-06-17 11:04:54)

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