QuoteI just don't see this happening in 9 years. You'd probably need multiple design iterations for the entire process to work, and there are only 3 transfer windows left before the process *has* to work if the 2024/5 mission date is to be met.....Yeah, and they're going to utilize each one. 2024/5 doesn't leave a lot of margin, but that's the "if everything goes according to plan" date. When Musk gives that kind of date, usually it's the earliest it can be done, not the "we'll definitely be able to do it by then" date. Which means you should probably expect it to slip.But again, Musk has repeatedly said they're going to mine water. I really don't think they'll mess around with liquid hydrogen. Instead, they'll double-down on getting water extraction to work. And some of that they can test here on Earth before sending it to Mars.
I just don't see this happening in 9 years. You'd probably need multiple design iterations for the entire process to work, and there are only 3 transfer windows left before the process *has* to work if the 2024/5 mission date is to be met.....
Quote from: Pipcard on 06/04/2016 11:01 pmQuote from: MikeAtkinson on 06/04/2016 10:49 pmWe don't know that any water mining will be done robotically, that is an assumption based on the rather dubious proposition that SpaceX won't send a crew until there is a fully fueled return BFS waiting on the martian surface.The idea (originating from Mars Direct) was to ensure the safety of the crew.As Zubrin said in "The Case for Mars" (pg. 70-71):"To ensure our Mars crew would not be stranded, the ERV would fly one launch opportunity, or twenty-six months, prior to the launch of the astronauts. Thus all the propellant would be made before the crew ever left Earth, and since the propellant plant was flown to Mars integrated with the ERV there was no question about landing 'within a hose length.' The plumbing that would deliver the Mars-manufactured propellant from the chemical synthesis unit into the ERV's fuel tanks would be hardwired, installed on Earth.""if the ERV [Earth Return Vehicle] is sent first, the crew will know before they even leave Earth that they have a fully functional Mars ascent and Earth return system waiting for them on the Martian surface, one that has already survived the trauma of landing. In contrast, a crew that lands with their ascent system can only guess in what shape their Mars ascent vehicle will be after they've hit the surface."SpaceX did test fire F9 engines after they've been through supersonic retropropulsion in conditions relevant to Mars EDL systems development, so the latter might not be a problem.The ERV doesn't have to be fully fuelled before the crew leaves Earth. It merely needs to have landed safely and be producing propellant at a rate that means it will be fully fuelled by the time the crew needs to use it to launch back to Earth. No doubt there will be margins to take account of any possible breakdown after the crew has set off for Mars. Set against that is the possibility of the crew making repairs and the additional output of any further ISRU equipment they bring with them. If additional margins and/or redundancy is required you can always send two ERVs on the first trip, or perhaps an ERV and a dedicated ISRU propellant production lander.
Quote from: MikeAtkinson on 06/04/2016 10:49 pmWe don't know that any water mining will be done robotically, that is an assumption based on the rather dubious proposition that SpaceX won't send a crew until there is a fully fueled return BFS waiting on the martian surface.The idea (originating from Mars Direct) was to ensure the safety of the crew.As Zubrin said in "The Case for Mars" (pg. 70-71):"To ensure our Mars crew would not be stranded, the ERV would fly one launch opportunity, or twenty-six months, prior to the launch of the astronauts. Thus all the propellant would be made before the crew ever left Earth, and since the propellant plant was flown to Mars integrated with the ERV there was no question about landing 'within a hose length.' The plumbing that would deliver the Mars-manufactured propellant from the chemical synthesis unit into the ERV's fuel tanks would be hardwired, installed on Earth.""if the ERV [Earth Return Vehicle] is sent first, the crew will know before they even leave Earth that they have a fully functional Mars ascent and Earth return system waiting for them on the Martian surface, one that has already survived the trauma of landing. In contrast, a crew that lands with their ascent system can only guess in what shape their Mars ascent vehicle will be after they've hit the surface."SpaceX did test fire F9 engines after they've been through supersonic retropropulsion in conditions relevant to Mars EDL systems development, so the latter might not be a problem.
We don't know that any water mining will be done robotically, that is an assumption based on the rather dubious proposition that SpaceX won't send a crew until there is a fully fueled return BFS waiting on the martian surface.
Go back to that Max Fagin (former SpaceX intern) retropropulsion thesis defense video.Whole vehicle lands, but only an upper portion returns to Earth. If the propulsion is in the upper portion (Dragon 2 heritage) the left behind cargo section can be used for most anything; habitation, cargo, or perhaps a dual purpose.How about some cargo sections hauling expandable & repurposeable tanks full of distilled water (thinking Thin Red Line's expandable tank tech.) AKA, 'how to ship hydrogen and oxygen without cryocollers', and the cargo bay volume vould be repurposed for colony use later.
Thirdly, the robotics is hard and is special purpose to the initial landing. It is probably at least an order of magnitude (perhaps two orders of magnitude) harder than Curiosity. The robotics would almost certainly be the long pole with a 2022 launch this would be really hard. The chances are that it would not work perfectly the first time. Correcting the robotics could easily take several attempts, each of which are hard to do before launch of the next synod. Worst case SpaceX could take a decade before they got the ISRU robotics correct, each year burning through a $1B or two.
Quote from: MikeAtkinson on 06/05/2016 05:56 pmThirdly, the robotics is hard and is special purpose to the initial landing. It is probably at least an order of magnitude (perhaps two orders of magnitude) harder than Curiosity. The robotics would almost certainly be the long pole with a 2022 launch this would be really hard. The chances are that it would not work perfectly the first time. Correcting the robotics could easily take several attempts, each of which are hard to do before launch of the next synod. Worst case SpaceX could take a decade before they got the ISRU robotics correct, each year burning through a $1B or two.I think this is a valid concern but I am expecting Musk thinks he can hack this in time. Asked about driving AI he called it a "solved problem" and said widespread class 4 (handless, not requiring attention) driving was 2 years away technically. So maybe he thinks ISRU robotics won't be that hard? You'd expect a lot more visible precursor work but if there is work going already, SpaceX is very tightlipped about it!
In line with the philosophy of reuse mfck articulated...I could see the MCT being "partially strippable"... if you had cabins for 100, but are only returning 20 people why carry all of that back? if the fittings, panels, wiring, plumbing etc was designed to be modular and reusable it could be removed by humans and used in outfitting the base.
If they simply install a large (but very lightweight) crane
This would be pretty easy to automate.
As Zubrin said in "The Case for Mars" (pg. 70-71):"the ERV would fly one launch opportunity, or twenty-six months, prior to the launch of the astronauts. [...]the crew will know before they even leave Earth that they have a fully functional Mars ascent and Earth return system waiting for them on the Martian surface [...]"
Thirdly, the robotics is hard
Remember Mars has a atmosphere and has water cycles (water vapor and water ice, does not have liquid phase). So to mine all the water you need, you compress the air and liquefy the water vapor in the atmosphere. Admittedly you would have to compress a lot of atmosphere for a little bit of water but the advantage is you do not have to go out and dig it up! Once the quantities needed become very high then comes the mining of water. But for the initial methalox manufacture for the return trip this method would be an easy one to implement and would not require complex equipment just plenty of power. Compressing gas takes a great deal of energy. But you need the atmosphere compressed for other parts of the methalox manufacture as well.
The point about driving AI is not driving per se, although that's a useful part of the overall problem... it's that they implemented something that learns. ...with two years of learning time the units might be better than when they arrived...
Quote from: oldAtlas_Eguy on 06/06/2016 02:39 amRemember Mars has a atmosphere and has water cycles (water vapor and water ice, does not have liquid phase). So to mine all the water you need, you compress the air and liquefy the water vapor in the atmosphere. Admittedly you would have to compress a lot of atmosphere for a little bit of water but the advantage is you do not have to go out and dig it up! Once the quantities needed become very high then comes the mining of water. But for the initial methalox manufacture for the return trip this method would be an easy one to implement and would not require complex equipment just plenty of power. Compressing gas takes a great deal of energy. But you need the atmosphere compressed for other parts of the methalox manufacture as well.Not really possible to get water by compression. Water vapour is about 0.03%, so for every kg of water you would need to compress and liquefy 3 tonnes of water <air>.
Quote from: Robotbeat on 06/06/2016 01:27 amIf they simply install a large (but very lightweight) crane You presumably mean a power-shovel or dragline. A crane isn't mining equipment.
Quote from: Robotbeat on 06/06/2016 01:27 amThis would be pretty easy to automate.It really isn't. It takes a lot of finesse to run a bucket at the end of a flexible line. Even a basic bucket excavator would be better. But a bucket-wheel might the best option for robotic operation.