Saturday, July 24, 1999 10:24 AM Doug Jones <email@example.com> wrote:
>> If my memory's correct, NASA already did have at least one
>> satellite with panels on it that used light pressure to maneuver.
>> This was in Earth orbit.
>> Anybody else recall this?
> Mariner 10 tilted its solar panels to null our sunlight torque and
> reduce propellant consumption, ca 1973.
That must be what I heard of.
> As for spacecraft lasting more than decades, radiation exposure in
> space degrades solar cells by inducing crystal dislocations. The
> dopants diffuse to the flaws, and the efficiency drops several
> percent per year. I don't think there is a floor to this process,
> but if you can periodically anneal the cells by heating to around
> 250 C, the radiation damage is greatly reduced.
> Trouble is, this would require some moving parts to scan a
> magnifying glass over the panels to do the annealing. As far as I
> knoe, it's never been done.
That's only if you're going to use them as solar panels. I assume if you were only going to use such panels for corrections, then you wouldn't need to do as much.
> It's difficult to do this for the control electronics, though they
> don't degrade as quickly as the solar arrays.
Well, I would suspect, any space vehicle of platform that would be built to last decades or longer would have to take into account periodic maintenance and replacement of parts. Or such redudancies would have to be built into to so as to account for this.
I bet with nanotechnology or some form of biotechnology, some of these problems can be "solved." (In quotes because we don't need a total solution, just one that works until something better comes along. I.e., I can live without a teleporter as long as my car is safe enough and gets me there in one piece in a reasonable amount of time, etc.:)
There are other problems with interstellar travel -- how this thread first started??? -- that need to be solved too, such as traveling at high speeds through the interstellar medium. It may even be that for the most part, nothing will happen, but what of nearing planetary systems, where there's bound to be more matter. Now, these are not insoluable and plenty of interesting solutions have been proposed, e.g., steering around detectable concentrations of matter.
BTW, I'm a genxer who is into both mind and space exploration. I think by exploring the latter, we kind of get a good idea of the former. Pushing to the limits in any area helps us to understand what we are. (This comment is not aimed at Doug.:)