Quote from: marcon on 07/23/2015 11:56 pmFor all non-German speakers: [...](just to elaborate on what was mentioned above) Thx Marcon. I thought about writing a translated transcript but decided its not worth it since he doesnt mentions anything new. Your summary is way better than either nothing or a transcript. Thx.
For all non-German speakers: [...](just to elaborate on what was mentioned above)
We know now first hand that they are not aiming low. 2-5 reuses would only help to make their competetive situation better which is already very good.
Again, using existing solar panels on Mars, how big an area would 100kw of solar panels cover? Of course it will only work effectively 8-10 hours a day whereas a small nuke unit will go 24-7.
10kg per m^2 for just the arrays sounds really high given modern thin films.Thin films just placed on the ground would have lower efficiency per square meter due to dust and lack of reflectors... but probably significantly better per kilogram.The cells in IKAROS were 25 micrometers thick - if they were amorphous silicon, that's something like 58 grams per m^2!It might need to be somewhat thicker on Mars due to wind, but even so, I think you could do way better than 10kg per m^2.
The weight will come more from good uv protection than the panel itself.
So it might be months before the first MCT can return.
Quote from: Jimmy Murdok on 08/15/2015 12:00 pmThe weight will come more from good uv protection than the panel itself. Not necessarily. UV protective coating can be thin and invisible. I learned that when I built a roof for my terrace. The transparent polycarbonate panels come with an UV coating on one side. You don't even see that. The panels need a marking for the side that goes up. If you mount them wrong side up they don't last.
Not that I know much about this, but hard UV straight from the Sun is rather different from the bit of it that gets through our atmosphere.
It hinges on the mass of the ISRU equipment and power systems. If a complete automated deployment turn-key system capable of refueling the MCT-Lander in 1 synod will fit within one such Lander then I see no reason to ever abandon any mechanically sound lander.Rather you go right into propellant production, return the first vehicle and leave the ISRU equipment in place. This achieves the two most important goals, 1) Have propellant in place before crew is risked, 2) Validate the entire round-trip flight of the vehicle before crew is risked.The only reason to temporarily or permanently 'strand' an expensive vehicle on Mars is if the ISRU equipment is so massive that it needs to be broken-up over multiple landers, but all of my estimates show that it should easily fit within one landers 100 mT capacity (and finish in 1 synod), provided that the return propellant mass is not some absurd amount like 1000 mT.