> The heat differential from night to day is the hardest engineering part.
Well, aside from getting a significant payload into orbit.
... and getting it to the moon
... and landing it
... and moving around
... and navigating the regulatory maze so you can:
... store, work with, and transport hazardous propellants
... actually do engine tests
... actually do test launches
... transport your test or launch stack across national borders
Okay, good point. I'm stepping outside my area of expertise, but here's my intuition:
Radiative cooling and thermal isolation seem to be fairly well understood. They can also (unlike many, many other parts of the problem) be tested on Earth. Basically, any satellite needs to deal with this stuff, and designers have been dealing with it for a long while.
Now, if you add lunar dust to the mix, sure, that's a complicating factor, but I don't see it being as bad as some of the other things I mentioned.
Launch vehicles are a service now. If I were to work on this, I wouldn't work on a launch vehicle, just the package that could survive the launch & landing.
> a) Most likely nobody will be able to claim the prize.
I'm pretty sure that Armadillo could do it if they decided to. They've spent about $3M to date on their development, but they're attacking a very different problem of (eventually) manned VTVL.
I'm still trying to get my head around how funding for this, and subcontracting / collaboration would work.
The heat differential from night to day is the hardest engineering part. The launcher from earth is just a matter of money.