Finally. Someone's talking about on orbit refueling/spacecraft repair.

[magnemoe]

Been reading the thread and thought of a scenario that might work.

The most costly failure (besides total launch failure) is a launch that results in the incorrect orbit being achieved. You end up with a brand new satellite in a totally unworkable location.

So this is where the strength of a totally reusable launch system comes into play. Say we have the F9R at it's operational peak design intention of 1st and 2nd stage re-usability. What if SpaceX developed a "rescue" craft payload? Basically an engine with good DV, tankage, throw it in a reusable bus based on Dragon and a way to grab our errant satellite and move it to it's intended orbit. . Keep the whole setup on standby at one of their launch facilities.

Now they are in a position to save someone's 200million dollar comsat for the minimal cost of a Falcon9 launch (which they are hoping to be less than $10mil in this configuration) and a reusable payload that needed minimal development. How many comsat owners would pay for that service?

Would be a great service to offer from a PR viewpoint even if it never actually gets used. "You launched with another provider and the rocket failed? No problem, we can fix that for you. Next time just consider using us in the first place" Heck, they could even offer it as a free service on their own launches. further reducing risk. "Well, our rocket didn't quite do it's job. No problem, we're warming up Thunderbird 1 to make the correction now. No charge, of course".

Note that this will probably be cost effective anyway, the correction probe does not need to be designed for long life, this is much of the reason why satellites is so expensive.

An future plan would be an vasmir or other high ISP transfer probe to shuttle satellites from LEO to GEO.

The repair and refuel module might be an optional part of this.

Darpa is probably thinking more of their recon satellites in LEO they are huge and have to use fuel to stay in orbit and do orbital changes.

They should be very cost effective to refuel.