NASA Working On Refueling Satellites 116
cylonlover writes "Geostationary satellites cost a fortune and, despite their sophistication, they break down or eventually run out of propellant to keep them oriented. This is unfortunate when the nearest garage is back on Earth, so NASA wants to remedy this with an orbital version of roadside service. The space agency is developing a service robot that can visit ailing satellites and refuel or even repair them on the spot. The refueling program is already at an advanced enough stage that a technology demonstrator called the Robotic Refueling Mission (RRM) was delivered to the International Space Station (ISS) in July of last year. The RRM was installed on a temporary platform outside the station. NASA's Goddard Space Flight Center wants a robot capable of carrying out what it calls the five 'Rs' – refueling, repositioning, remote survey, component replacement or repairing – on any satellite that might require its services."
Talk about Scope Creep (Score:5, Interesting)
I could almost see there being some value in refuel. Maybe also in reposition if a big change is involved (but why would you need to move it anyway?). Take a few pictures of it if you want, since that is fairly cheap.
However, when you start getting into repair you're talking about a massive increase in cost and decrease in reusability of the refueling ship.
And if you don't do repair, then you need to design the satellites to have components that last for decades but a fuel supply which lasts much less - why not just launch it with a lifetime fuel load?
Repositioning only makes sense if it was unplanned and needs more propellant than could be carried by the satellite. If you dock a ship to it and use that to move the satellite, then you need enough fuel to reposition the combined mass of both. It would be smarter to just refuel it and let the satellite move itself.
Oh, and unless you're really patient, moving from satellite to satellite takes a fair bit of fuel (a little nudge goes a long way if you're willing to wait, but with each orbit lasting a day it will be probably weeks between encounters if you don't want to do large burns).
I think that the only way private companies would sign up for this refueling service were if the cost of the service were basically subsidized on the backs of taxpayers. I could be wrong, and that would be wonderful, but this really seems like a solution looking for a product. Sometimes it really is cheaper to just make a new one.
Bonkers (Score:3, Interesting)
The whole "let's re-use spacecrafts" has been conclusively demonstrated to be Economic Nuts by the Space Shuttle program (1kg lifted by the shuttle is ten times more expensive than 1kg lifted by a throw-away rocket) . I have the definite feeling NASA wants to prove this once again, just in a different way.
But maybe we should read this message metaphorically ;-)
The orbit, itself (Score:5, Interesting)
More likely, the most valuable thing up there is not the satellite, it's the position it's occupying. Once upon a time, we tried to keep 2 degrees of separation between geosync satellites - meaning that there were 180 "slots" where one could be placed, and obviously fewer than that that could service any one location. The separation keeps dropping, but that makes the need for stationkeeping more precise, probably calling for more fuel, etc.
So the best thing here is to keep those geosync slots in use, and not chewing up an empty slot with a dead or useless satellite. I'll have to agree with what someone else said - that de-orbit should be a published option, as well.
Personally, I believe the best option is a big, gravity-gradient-stabilized boom, with some serious solar panel capacity on the outer side, battery capacity to match, and standardized electrical and mechanical hookups. Then rather than sending up complete satellites, lease hookups on the boom, and just send up an electronics package. In this case, the "service satellite" carries the package up, anchors and connects it, and does initial checkout.