Mars InSight lander

louis · 2018-11-27 17:04:22

I think that Space X and NASA have cordial relations. I don't think either wishes to make an enemy of another. Space X have huge resources - I am sure they would be happy to pay over the odds for the right technology. But as I have remarked before: during WW2 very complicated airplanes would be developed from scratch in half a year. It's as much a matter of will as anything else. I think if Space X is prepared to throw $50 million at developed of a Mars-rated LOX/CH4 plant it will happen and it will work.

I don't really agree with your "baby steps" approach. That wasn't how the USA got to the Moon within 7 years from a standing start.

NASA would have done much better to have a very focussed approach to getting to Mars after the Moon landings rather than striking out in a multiplicity of directions. It has to be asked why NASA didn't develop reusable rockets. Why was it left to private sector companies?
I suspect that reusable rocket technology could have been developed maybe in the 1990s.

kbd512 wrote:

Louis,
I'm betting that you need to send someone into space before you can even think about sending them to Mars.
I'm betting that you need to know where a good source of water is located on Mars if you must make propellant to return the astronauts you send to Mars back to Earth by using that water, or just the rocket if you don't care about the astronauts.
I'm affirming that I've seen no patents indicating that SpaceX has done any work on a LOX/LCH4 plant. The absence of patents is not an indication that such technology doesn't exist, but virtually all government agencies and private corporations that wish to retain intellectual property for their own use file patents with our patent office. So far as I can tell, the only meaningful work on that technology comes from NASA and their contractors or affiliated university programs. The enabling solar and nuclear power technologies to provide reliable power without excessive weight come from NASA and their contractors.
Each and every time you attempt to ignore or besmirch the achievements and contributions of NASA to Mars exploration, the more and more you'll see NASA's name written all over the technologies that enable space exploration. SpaceX's development and implementation of reusable rockets is an accomplishment that deserves high praise, and I have given them full credit for that incredible achievement. However, virtually every key technology required to live on Mars comes from NASA and their contractors. The transportation solution (reusable rockets) is a baseline requirement for sending humans to Mars. After that, everything else comes into play (reliable power, reliable long duration life support, the ability to obtain oxygen and water from Mars, the ability to grow food, the ability to make propellants, the ability to keep humans healthy in space for several years). That's where public space agencies from the US and Canada, European Union, Russia, and India are required.
I wish every effort to go to Mars nothing but the best, whether it comes from NASA, ESA, ROSCOSMOS, SpaceX, or anyone else. I also think there's a logical progression of activities that lead up to sending humans somewhere besides Earth. The first step is to study the place you want to go. The second step is for America to restore its human space flight capabilities. The third step is to prove the ability to live in deep space for at least as long as it takes to get to where you want to go. The final step is actually going to the place you want to go to. It seems like you want to skip over all those intermediate steps and that's not a recipe for success if past experience is any indicator.

RobertDyck · 2018-11-27 17:50:44

In the 1960s and '70s NASA believed in space planes. Greater control during atmospheric entry and landing. Air Force developed Dyna-soar in the '50s, NASA worked various lifting bodies in the '60s. In 1968 they expected to build a fully reusable TSTO shuttle, orbiter based on X-24A or HL-10. Nixon slashed their budget so we got Shuttle instead. In early '90s Senator Graham had the air force work with Lockheed Martin to build DC-X. After it worked they handed it over to NASA who used it as a test bed for tank technology for X-33 and Venture Star until they crashed it.

NASA wasn't against reusable, they just wanted aerodynamically controlled landing. And their usual contractors didn't want to control cost.

Last edited by RobertDyck (2018-11-27 20:20:59)

RobertDyck · 2018-11-27 18:01:14

Back to InSight
8393_D000M0000_596535424EDR_F0000_0106M1-stretch_web.jpg

SpaceNut · 2018-11-27 18:37:25

Louis, Space x did buy technology to get to where it is at; as well as much needed training and expertise until they were able to hire it long ago. But it does not matter how much they will or would pay for the tech if they can not engineer it for their own build and use; as its just integrating it if they do buy.

Robert Dyck the lifting body is not dead as the sierra Nevada group has got the DreamChaser almost ready for human taxiing to the ISS as well as cargo soon and its reusable.

Now back to the waiting for more news on Insight...and more great images too.

kbd512 · 2018-11-27 18:43:16

Louis,

The airplanes in WWII were designed in a short period of time out of necessity. That necessity was to stop the killing ASAP. Apart from whatever is going on in your head, which I believe to be a bad case of "gotta-get-there-itis", there is no such necessity for going to Mars. Those WWII aircraft were also expected to last a handful of missions before they were replaced with new aircraft or destroyed in combat. That's why we made tens of thousands of them. Most of them had a lot of operational issues and required legions of support personnel who spent every hour of the day that the aircraft wasn't in the air making sure those planes would be ready for their next mission. As someone who has spent time in a naval aviation squadron, I assure you that very little has changed in the intervening years. Aircraft still require many hours of maintenance per hour of flight time. As the aircraft age, the maintenance hours only increase. The fact that a few of those old warbirds are still around today is more a testament to the craftsmanship of the women and men who built them and the dedication of their support personnel than how reliable they were as aircraft. That type of usage won't work at all for Mars because there aren't any hangar bays on Mars to repair busted birds.

In point of fact, we did go to the moon in 7 years with baby steps. We didn't begin the next phase of flight testing until the problems that needed to be resolved was adequately addressed, either. Every aspect of the mission was incrementally tested.

NASA doesn't get a choice in what missions they will undertake. Former President Nixon told NASA they could have a reusable spacecraft and a space station, so that's what they set out to build, and build it they did. NASA did attempt to develop truly reusable spacecraft, in the 1990's oddly enough and using a landing sequence just like that of the SpaceX Falcon boosters, but the funding rug was pulled out from underneath them by the politicians. This idea you have stuck in your head that NASA gets to do whatever it wants with its money has no relation to reality. NASA is a government agency that is subject to the decisions of the President and Congress.

Incidentally, NASA was developing nuclear thermal rocket engines to go to Mars in the 1960's. By 1974, all ground testing was complete. The last step was to qualify the engine in space by flying it as the third stage of a Saturn V. Former President Nixon killed the NTR program and that was that- no more Mars missions. That's as close as we ever were in decades past to going to Mars.

Void · 2018-11-27 20:14:17

I guess I am actually very impressed by the potential of this probe. A bit of a coward previously, but they seem to have a likelihood to pull it off.

I would say that we are extremely fortunate at the timing of that recent global dust storm. Not likely to have one soon to interfere with InSight. Really a good thing.

I will be very excited if they can get even a crude notion of what the Mars interior is like, per layers and temperatures. I am also interested in water.

http://now.northropgrumman.com/nasas-in … onization/
Quote:

Commenting on the findings, NASA reported that InSight “will provide crucial data on how much heat escapes the planet and where liquid water could exist near its surface.” If InSight can determine whether Mars is seismically “alive,” it could aid in humanity’s search for extraterrestrials.

While higher latitudes apparently could be mined for ice, I would rather see discovery of potential for liquid water not too far down. Most likely brines. Brines would be fine. They would contain water and important useful chemicals. Some drilling and processing would be required, but not mining. Mining will be troublesome if it is required.

And anyway, a start near the equator of Mars should be much preferred.

https://newatlas.com/mars-water-equator-nasa/51565/
Quote:

he team improved the spatial resolution of the old Mars Odyssey data on the region from 320 miles (520 km) to 180 miles (290 km), using image-reconstruction techniques that allowed a view of hydrogen distribution twice as clear as that afforded by the unrefined data.
The higher resolution data revealed a surprising abundance of hydrogen consistent with relatively small buried water ice deposits at the Martian equator, though the team are unsure how they could persist in this environment.
It is possible that the deposits formed a long time ago, when Mars' axis was more tilted than it is today, allowing the atmospheric circulation of an ice and dust mixture from the polar regions that subsequently settled at the present day Martian equator.

However, even if such deposits were protected by a layer of hardened dust, it is unlikely that they would survive to this day, as Mars atmosphere has not been tilted by the degree needed to form equatorial ice deposits for hundreds of thousands to millions of years.
Water ice deposits are not the only explanation for the hydrogen abundance. The signal could also have arisen from the detection of significant quantities of hydrated salts buried beneath the surface. However, the team are unsure how such a deposit could form.

……

Now then I go off the deep end just a bit.

I would like them to identify the possibility that there may be a strongly planet wide water table of very briny water below the surface of Mars. One that could replenish the moisture in "significant quantities of hydrated salts buried beneath the surface", at or near the equator.

Such deposits might occur if upwelling brines from across higher elevations of the planet donated the salts, and the water slowly evaporated, to be replaced sufficiently by moisture of brines below.

……

Obviously that also requires periodic water melts somewhere that can replenish the hydration. That may require a planet which on occasion has a better climate than is now. Or maybe it is an extremely slow process, very slow flows, and per the supposed lake found under a polar ice cap is fed in that manner.

Optimistic? Sure.

…..

It may be that we will find out. I hope so.

Mars is not Earth. Typically the emphasis is on how Mars is less than Earth. But perhaps we might find that in some ways it may be better than Earth for these things.

It has had billions of years without tectonic disturbances for needed channels for brine flow to develop.

As for heat, it does not appear to have much for tectonics. Surely that process for the Earth serves to cool off the interior of the Earth.

For Mars, it might not have.

It is obvious however from the lack of hot steam vents, that water and hot spots do not converge much, to the point of current steam eruptions. Perhaps due to the water seeking a lower place, and the hot spots building up high places.

……

Or Mars is indeed somewhere between the Earth and the Moon per cooling off.

However, there may be other heat sources. I will not tire you again with that.

If insight works as desired, that will either turn my water off, or let it flow.

…..

The best news then would be we would have a better understanding. Pretty much a good thing.

Done.

Last edited by Void (2018-11-28 16:49:27)

kbd512 · 2018-11-28 16:39:05

Void,

I see InSight as our money maker. Although we want InSight to tell us where the water is, it could also tell us if Mars has Methane trapped below the surface. If mass quantities of methane are found on Mars, then we don't have to expend energy to make it. Here on Earth we pump the methane out of the ground, we don't make it from scratch. That's why there's no technology used by industry to make methane from H2O and CO2. Technically there is, but that pilot plant is about the size of a football field and weighs many hundreds of tons. Don't tell Louis, though, or he'll think someone from SpaceX can come along, wave their magic wand, and transform it into something that can be craned off of Starship.

Presuming aerocapture / aerobraking at Mars and chemical propulsion, each ton of mass we deliver to the surface of Mars requires a minimum of 226 tons of propellant and delivery vehicle launched from Earth. Most of that, meaning more than 90%, is propellant.

So, how will InSight help us solve this problem?

We need to know exactly where everything that's buried is to avoid drilling dry wells, which is what InSight will help us do. InSight carries the same technology used by the fracking industry to assure that a dry well never happens.

The ice drill used at Lake Vostok to obtain samples of the water from that sub-glacial lake weighed 100kg, consumed 1kWe of power in operation, and drilled to a depth of 2km in 100 days. If that device doesn't make apparent why it is that you want to drill for your resources whenever possible, then I don't know what would. That drill was first tested in Gypsum to determine its ability to drill through soft rock. There were no additional drill pipe segments used because the drill bit was suspended in the hole by a power cable and anchored to the side of the hole while it drilled.

An earlier proposal I put forth in another thread for ice drilling involved using a Pu238 heated carbide drill head to assist with the drilling process and to create hydraulic pressure to force superheated steam to the surface and into a Titanium collection tank. However, the Rodriguez Well at the South Pole does the same thing without using nuclear technology. It provides drinking water for the scientists there and has done so for the past couple of decades. The alternative was heating snow on the surface, but that was far more energy intensive. Some of the steam generated in the process is piped back into the hole to melt more ice beneath the station. It's fracking for water.

NASA is working on a lightweight version of a 15t hard rock drill used in Australia, or at least that's where their research team lifted the idea from. The drill used in the outback has a coil of stainless steel tubing that it feeds into the bore hole, rather than individual pipe segments, and drills at a rate of 1m/min. NASA's version weighs a few kilograms and consumes far less power, but the basic concept is the same. Instead of using a metal tubing of some kind, NASA's device forms a composite tube from a lightweight flat tape as the drill operates. That was tested in simulated Mars regolith and also drilled at a rate of 1m/min. Compressed CO2 was used to blow material out of the bore hole / tube. NASA wants to put their drill on a Curiosity-sized rover that contains a reel of tape / tube and a water tank. The agency has already done some initial field experimentation with a prototype ATHLETE style rover here on Earth.

Incidentally, regolith mixed with frozen water is as hard and strong, or stronger, than concrete. As a result, NASA decided to test what the best way to drill through frozen regolith was and came up with a hammer drill that combines percussive force and rotation to quickly drill through rock or rock hard (frozen) regolith with very little energy expenditure and less material to blow out of the bore hole. NASA's final drill product uses between 100W and 150W of power, which is far less power than ice melters or gypsum roasters would require, but NASA is also researching gypsum and regolith mining using water jetting instead of explosives.

NASA's minimum water requirement is 16t (4,226 gallons) for their lander.

SpaceX's minimum water requirement is 100t (26,417 gallons) for their lander.

Here's the backup for this:

Kris Zacny - Mining Water on Mars - 21st Annual International Mars Society Convention

Void · 2018-11-28 16:50:53

Agreed.

SpaceNut · 2018-11-28 18:10:45

If they do find methane the amount of water to make fuel drops real quickly.

The one probe will not tell the story of the entire planet but it will give good data for that local.

louis · 2018-11-28 18:32:36

Well there was certainly no necessity of getting to the Moon before the Soviets but it was treated like a wartime priority project.

Anyone who has an understanding of Martyn Rees's list of possible threats to humankind (many of which increase as our technological capabilities advance) will realise we need a second home - and quick! I believe that the development of robot army capability is going to seriously destablise the world. When something the size of a gnat can sneak in and disable all your defences, you have instant instability and instability is often what leads to war. Mini flying robots are going to completely change the nature of war and blur the boundaries between espionage and war - especially when coupled with cyber warfare. Because we have two v. large and powerful (and cheating) non-democracies in the world (China and Russia) we can't get sensible international agreements to control these sorts of menace.

As Musk himself has pointed out we also face a serious AI threat to humanity because humanity has failed to understand the problem, as (correctly, in my view) defined by Musk and others.

kbd512 wrote:

Louis,
The airplanes in WWII were designed in a short period of time out of necessity. That necessity was to stop the killing ASAP. Apart from whatever is going on in your head, which I believe to be a bad case of "gotta-get-there-itis", there is no such necessity for going to Mars. Those WWII aircraft were also expected to last a handful of missions before they were replaced with new aircraft or destroyed in combat. That's why we made tens of thousands of them. Most of them had a lot of operational issues and required legions of support personnel who spent every hour of the day that the aircraft wasn't in the air making sure those planes would be ready for their next mission. As someone who has spent time in a naval aviation squadron, I assure you that very little has changed in the intervening years. Aircraft still require many hours of maintenance per hour of flight time. As the aircraft age, the maintenance hours only increase. The fact that a few of those old warbirds are still around today is more a testament to the craftsmanship of the women and men who built them and the dedication of their support personnel than how reliable they were as aircraft. That type of usage won't work at all for Mars because there aren't any hangar bays on Mars to repair busted birds.
In point of fact, we did go to the moon in 7 years with baby steps. We didn't begin the next phase of flight testing until the problems that needed to be resolved was adequately addressed, either. Every aspect of the mission was incrementally tested.
NASA doesn't get a choice in what missions they will undertake. Former President Nixon told NASA they could have a reusable spacecraft and a space station, so that's what they set out to build, and build it they did. NASA did attempt to develop truly reusable spacecraft, in the 1990's oddly enough and using a landing sequence just like that of the SpaceX Falcon boosters, but the funding rug was pulled out from underneath them by the politicians. This idea you have stuck in your head that NASA gets to do whatever it wants with its money has no relation to reality. NASA is a government agency that is subject to the decisions of the President and Congress.
Incidentally, NASA was developing nuclear thermal rocket engines to go to Mars in the 1960's. By 1974, all ground testing was complete. The last step was to qualify the engine in space by flying it as the third stage of a Saturn V. Former President Nixon killed the NTR program and that was that- no more Mars missions. That's as close as we ever were in decades past to going to Mars.

SpaceNut · 2018-11-28 19:11:22

And yet Russia wants to take part in the lunar gateway and missions to the surface of the moon....

Back to Mars Insight and what it will see for man that we require to know.

kbd512 · 2018-11-28 20:16:28

Louis,

1. The Apollo Program came about at a time when there was an international, ahem, "launch package" measuring contest. If another country came along with a serious space program, then you can bet your last dollar that we'd compete against them. Russia's entire economy compares unfavorably to that of California. China is effectively locked out of space exploration cooperation because they won't stop stealing our IP and using it for military purposes. In simple terms, China has no intention of cooperating with anyone to do anything unless there's a military application in it for them. Russia can be on excellent terms with the West whenever it decides to quit invading its neighbors in a misguided attempt to recreate the Soviet Union. Similarly, if Russia's neighbors decide they want to be part of Russia again, the US won't lift a finger to stop it. It's that whole use of military force and communist ideology to achieve territorial expansion that we're opposed to. That was a running theme throughout the Cold War. The communists started an insurgency, subsequently started murdering their own countrymen, and naturally we'd oppose them and their self-destructive ideology.

2. We have an answer to the miniature flying terminator robots. It's called "frickin layzurs"! Our immediate future air defense plans call for incorporation of these devices on aircraft with substantial internal power generation capability, like the F-22 / F-35 / B-1 / B-2 / B-21, and into vehicle-based short range surface-to-air defense systems. It's not a cure-all, but there's no such thing as leading the target with a laser.

3. You're the one who wanted to use robots to build everything on Mars. Well, guess what? That entails rather clever machines that are, in all probability, the product of AI-driven design and operation. There's no escaping technological innovation. It's here to stay. It's far more likely that one of the yahoos in a third-world country gets button-happy with their ICBM launch button or that some well-intentioned idiot in a genetic research laboratory kills us all with a designer dingleberry virus than space rocks or AI. If none of that happens, then mosquitos still kill about 700,000 people every year, with or without war, with or without space rocks, and with or without SkyNet becoming self-aware.

RobertDyck · 2018-11-28 21:24:37

louis wrote:

Well there was certainly no necessity of getting to the Moon before the Soviets but it was treated like a wartime priority project.

Even more than kbd512 said. When Sputnik launched, no one had an ICBM. America's most advanced rocket was Redstone, an intermediate range ballistic missile. Nothing could cross an ocean. Most nations felt safe because any navy would take weeks if not months to reach them. Sputnik was launched on the Soviet's first ICBM. What most world leaders saw (and Soviet generals intended) was a demonstration that the Soviets could drop a nuclear bomb literally anywhere on the world. And the Soviets were years ahead of any technology the US had. So to be safe, many nations allied with the Soviets. That included economic trading, resources. To avoid the Soviets being the world leader, the US had to demonstrate superior technology. It was about winning allies.

JFK said "We choose to go to the Moon in this decade and do the other things, not because they are easy, but because they are hard". He meant that literally. Every time the US tried to do something, the Soviets did it first. So when you're losing, move the goal posts. That goal would require so much technological innovation that the Soviet lead was irrelevant. The US could catch up and pass them. That was necessary to retain international allies.

And some worried the Soviets would put a nuclear missile launch facility on the Moon. We know now that's rediculous, ground launched ICBMs are far more practical, but at that time the high ground was a tactical advantage. Landing on the Moon demonstrated to allies the US could take out a Soviet Moon missile base. Again, all about defence and allies.

The US barely made it first.

Last edited by RobertDyck (2018-11-28 21:30:06)

RobertDyck · 2018-11-28 21:49:30

Facebook group for Royal Astronomical Society of Canada.
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SpaceNut · 2018-11-28 22:10:57

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InSight's battery can power the lander for up to 16 hours on a single charge, but, even so, InSight needed to get its own solar array up and running — or its life on Mars would be very, very short, Green said. About 16 minutes after the landing, enough time will have passed for the dust to settle.

Each of InSight's two solar wings are 7 feet (2.2 meters) wide. About 6.0 m (19.7 ft) wide with solar panels deployed. Power is generated by two round solar panels, consisting of SolAero ZTJ triple-junction solar cells made of InGaP/InGaAs/Ge arranged on Orbital ATK UltraFlex arrays.

The science deck is about 1.56 m (5.1 ft) wide and between 0.83 and 1.08 m (2.7 and 3.5 ft) high (depending on leg compression after landing) with the Lander mass 358 kg (789 lb).

SpaceNut · 2018-12-07 18:45:43

Sound from Mars heard for first time on Earth

On Friday, NASA released audio of the Martian wind, the first time sound has been recorded on another planet's surface. Scientists estimated the northwest wind to be 10-15 mph. An air pressure sensor and seismometer detected the vibrations on December 1.
"Capturing this audio was an unplanned treat," Bruce Banerdt, of NASA's Jet Propulsion Laboratory, said in a press release. "But one of the things [the InSight mission] is dedicated to is measuring motion on Mars, and naturally that includes motion caused by sound waves."
The raw recording is a low pitched, barely audible purr. When it's cranked up two octaves, it sounds like a stiff breeze ricocheting off the walls of an alley on a windy day.

You can hear the audio in this YouTube clip posted by NASA:

If that was the ture wind speed it makes possble windmills...

SpaceNut · 2018-12-07 19:03:24

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"The 4,588 watt-hours we produced during sol 1 means we currently have more than enough juice to perform these tasks and move forward with our science mission."
The 4,588 watt-hours InSight generated on its first sol, or Martian day, from solar power is well over the 2,806 watt-hours generated in a day by NASA's Curiosity rover, which runs on a nuclear system called a radioisotope thermoelectric generator. Coming in third was the solar-powered Phoenix lander, which generated around 1,800 watt-hours in a day, according to NASA officials.
After sending back its first photo of the landing site and extending its two solar arrays, each of which is about 7 feet in diameter (2.2 meters),

RobertDyck · 2018-12-07 21:59:47

SpaceNut wrote:

If that was the ture wind speed it makes possble windmills...

Mars has very high speed winds, but very low air density. That low density means very little force from wind. Any windmill would have to be very flimsy to make use of very low wind force.

louis · 2018-12-08 05:11:54

Some useful figures there.

So on the basis of a diameter of 2.15 metres for the PV array, that gives an area of about 4.5 sq. metres.

On the basis of that area we have a power output of about 1 KweH per sq. metre per sol.

So a PV array of 100 metres by 100 metres, 10,000 square metres, would generate 10,000 KweH or 10 MweHs. I would estimate that with that you could generate steady power throughout the day (using batteries, or methane/oxygen generation) of say 0.5 Mwe or 500 KweHs for a human mission to Mars. However with a PV powered mission you would design it so that power was used mostly at PV peak, rather than lose lots of power to battery generation. So, you'll probably see power being used at 2Mws during the peak period - that would be when you heat water, run the dishwasher, produce propellant, recharge rover batteries etc. You'd probably see power used in the range of maybe 250 Kwes to 2,000 Kwes.

I don't think anyone's yet done a calculation of how much energy would be used in generating 1000 tons of propellant over a 2 year period at constant power. This discussion suggests 2.1 MweHs per ton:

https://www.reddit.com/r/spacex/comment … needed_to/

So 2100 MwHs in total, which works out over a 700 sol period at 3 MwHs per sol or 122 KwHs constant power.

So it looks like a 10,000 sq. metre PV power system with constant insolation could do the job with plenty to spare, to allow for dust storm debacles. But what season are we in at the moment on Mars (at the InSight Lander location)? Of course that has to be taken into consideration (although variation is less on Mars than on Earth).

SpaceNut wrote:

https://img.purch.com/w/660/aHR0cDovL3d … JheXMuSlBH
"The 4,588 watt-hours we produced during sol 1 means we currently have more than enough juice to perform these tasks and move forward with our science mission."
The 4,588 watt-hours InSight generated on its first sol, or Martian day, from solar power is well over the 2,806 watt-hours generated in a day by NASA's Curiosity rover, which runs on a nuclear system called a radioisotope thermoelectric generator. Coming in third was the solar-powered Phoenix lander, which generated around 1,800 watt-hours in a day, according to NASA officials.
After sending back its first photo of the landing site and extending its two solar arrays, each of which is about 7 feet in diameter (2.2 meters),

Last edited by louis (2018-12-08 06:12:55)

elderflower · 2018-12-08 05:28:27

Do Insight's solar panels track the sun in one dimension, two dimensions or not at all (fixed orientation). An array could produce quite a lot more power by tracking, even in just one dimension, than a static unit of the same size. On the other hand that means a structure and control system. I don't know which would be more advantageous.

louis · 2018-12-08 06:22:10

I think all the evidence suggests that for a Mars Mission tracking equipment is impractical. If you added say 5kgs of tracker to a one sq. meter panel, you'd end up with 50 tons of equipment for a 10,000 sq. metre facility - and getting all that equipment off board the BFR Starship, laying it out and maintaining it would become a far more complex challenge...it would also consume power presumably, so that has to be taken into account as well.

I've seen no suggestion that the InSight Lander's PV system is tracking the sun. The figure of 1 KweH per square metre (see above post) sounds right to me for PV laid flat. .

elderflower wrote:

Do Insight's solar panels track the sun in one dimension, two dimensions or not at all (fixed orientation). An array could produce quite a lot more power by tracking, even in just one dimension, than a static unit of the same size. On the other hand that means a structure and control system. I don't know which would be more advantageous.

SpaceNut · 2018-12-08 09:52:34

You only need one to track and the others to follow via connecting rods to each unit dropping the mass. If I find tracking info will post as that is usually at least 30% more energy even after deduction of the trackers use.

louis · 2018-12-08 10:19:15

Just realised I made a gross error in my power calculations above because the lander has two panel sets not one! So the power output figures need to be halved...

So, for clarification...I would correct the key para to read:

"So a PV array of 100 metres by 100 metres, 10,000 square metres, would generate 5,000 KweH or 5 MweHs. I would estimate that with that you could generate steady power throughout the day (using batteries, or methane/oxygen generation) of say 0.25 Mwe or 250 KweHs for a human mission to Mars. However with a PV powered mission you would design it so that power was used mostly at PV peak, rather than lose lots of power to battery generation. So, you'll probably see power being used at 1Mw during the peak period - that would be when you heat water, run the dishwasher, produce propellant, recharge rover batteries etc. You'd probably see power used in the range of maybe 125 Kwes to 1,000 Kwes."

To produce 1000 tons of propellant you need an averaged constant of around 122 Kwes throughout the sol for 700 sols (although of course that's the average - the power intake could vary to some degree). So a 10,000 square metre PV field could meet that requirement, but you would need possibly to increase it slightly to allow for the impact of any prolonged dust storms.

SpaceNut · 2018-12-08 11:36:07

Louis for post #69, The power rate for insight was for a total power of both arrays, so your numbers are inflated. The area of a circle is pi times the radius squared (A = π r²) but you have 2 of them for the total power recieved. For a single area of 3.8 sq meters per panel. The other part of that comes from not only the hours that it outputs but its efficiency of the cells and if they are non tracking and stationary.

SpaceNut · 2018-12-08 11:55:08

The windmills would use cloth fibers for the prop blades with semi flexible rods to support them. Most likely they would e carbon fiber or polyester materials for each to keep them light mass with permanent magnet power creation. We know that the more blades a windmill uses for the slight breeze that the more it spins to create power.

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