An ion thruster I suppose would do the trick. Of course it would run out of Xenon after awhile, but ion engines have the highest fuel to force ratios short of a solar sail.
Actually come to think of it I am not sure it is much of a problem. If you were in a geosynchronous orbit, surely the solar pressure would push you away half the time, but push you back the other half, right?

Agree with the poster. I figure solar cells in space will not trump solar cells on the ground until we dramatically lower the cost of delivery to orbit. At the moment we SpaceX is quoting 4300 USD/Kg to orbit on a Falcon 9 (1.1 - still waiting on maiden flight Sept5), and maybe down to 1200 UDS/Kg for the not yet built or demonstrated Falcon Heavy. And that is to LEO, Solar Cells probably need GTO which is about twice as expensive. I can't imagine a space based array can be competitive at those prices.
Now if someone built a rail-gun based launcher, then maybe it could make sense.
And as AC mentioned, we are in the midst of a ground based solar cell revolution right now. Very cool...

He does know how to swear like Gates (at least like he used to). And he does have a newish vision.

Kind of light on Enterprise though. MSFT needs someone who can do both. It is a tall order.

Its being done at a lot of places including here:
http://www.opb.org/news/article/osu-researchers-make-electricity-sewage/

Will probably take decades to make it to common usage though. How often do they rebuild Sewage Treatment Plants?

I don't care how they dress. I thought the "Mohawk guy" on the Curiosity landing was pretty cool. So do most others I believe.

They should defund the Senate Launch System instead and fund more of these science programs. (Like a few more Mars Rovers).

because I am an idiot and a slow learner.

Nice. Seems a bit like rationalzation, yet the logic is undisputably there. Glad you had a good ride.

Hope you don't want to have kids.

Actually that last sentence doesn't parse. Are you saying that if ATK gets cut they wil somehow cause the selection process to be jettisoned? That sounds wrong...

It sounds like you know what you are talking about, ... so you are depressing me.

Although I am pretty sure SpaceX will build a human rated Dragon regardless of what the CCD program decides.

I think the Space Shuttle was just a big flop that only escaped being cancelled because the US Government has such deep pockets. In the end, in fact way before the end, it was a jobs program more than anything else. It set the space program back something like 20-30 years.
I don't understand why people can't just admit it was a horrible mistake. Actually, of course I do understand, so many valuable lifetimes of work were sunk into it.We have to pretend.... But we should have just been building cheaper rockets (which the two other programs on the table proposed) - or funding a Ramjet, or Roton, or almost anything else. The only really useful thing the Shuttle did was repair Hubble.

Imagine where we would be now if NASA had done something like COTS 20 years ago after Challenger blew up instead of building another Shuttle.

I think NASA showed that they hadn't a clue what they should do with their terribly expensively developed "National Assets". They are all now rusting hulks. And they are developing another one with no clue as to what it is for (jobs for retiring engineers maybe).
At least the commercial guys are likely to rack their brains out as to how they can get more money out of "their" assets.
And face it - if a war broke out and SpaceX had useful assets, who do you think would control them overnight?

Are you sure they have a chance? The article clearly states that they are to be selected form the *current 4*...

What is your logic here? You think it costs signifcantly less to turn Dream Chaser around than a Dragon Capsule? It looks an awful lot like a Space Shuttle to me for that.
The two who seem to be doing a lot for bringing the price down would be Blue Origin (who are banking on a seemingly unlikely SSTO), and SpaceX with their Resuable Powered Decent stages (which also seem pretty far away at this point). It takes a 130 million Atlas V to put a Dream Chaser into orbit last time I looked, where as the Dragon only needs a 60 million dollar Falcon 9. Although Dream Chaser *could* probably fit on a Falcon 9 and in either case you are looking at additional costs on top of the basic launcher.