Hi there, Hubble, glad to hear you're doing okay Astroboffins the world over drew a collective sigh of relief to hear that the Hubble Space Telescope has been formally returned to service. The “all clear” came on Friday, and over the weekend, NASA set the spacecraft back to work: “The observations were of the distant, star-forming galaxy DSF2237B-1-IR and were taken in …
On Monday NASA warned that the Kepler space telescope, discoverer of hundreds of exoplanets. The problem is that the telescope is nearly out of fuel and there's no way to give the tanks a top up.
Maybe it's time for satellites like this to include some sort of fueling port and then have a robot or manned capsule be able to refuel them? NASA builds them tough and they seem to exceed expectations as far as usable life, so provision for refueling probably ought to be part of the design.
It's been discussed here before and it's just not viable. It would cost so much to do a refuelling mission that you are actually better off just to go for a replacement. In the intervening timetech will have moved on so for your one space mission you can improved things a great deal by replacing the machine in orbit.
Maybe one day we could lauch a tanker which would float round refuelling sats but in reality that probably not very feasible either.
Fuel would be something useful to throw up in launch tests. Space X could have taken something to go and refuel the Hubble instead of a car(!), assuming the refuelling craft wouldn't be overly expensive.
A fuel port while maybe not viable may have been viable in the time between Hubble's launch and today. For anything launched today, refuelling might be more viable in 28 years.
That assumes the fuel port wouldn't add too much cost, weight or complexity, of course.
To refuel something you have to stop next to it. Stopping takes the same amount of fuel as speeding up. So Tesla's rocket would need to carry another rocket the same size to de-accelerate to match Keppler.
But then you would need another half-dozen rockets bolted to the first rocket to lift the second rocket - that would be a big fsckign rocket.
To let someone more elegant that I explain it: Space is big. You just won't believe how vastly, hugely, mind-bogglingly big it is. I mean, you may think it's a long way down the road to the chemist's, but that's just peanuts to space.
It's far enough that launching a "fuel ship" would probably take a decade or more to get there (and longer to get back, so there goes a manned option). Any KSP pros out there able to put some numbers together to confirm or refute my ill-informed guess?
Couple that with how complex orbital operations are (along with how counter intuitive they are) and its just not practical.
An alternative is to have a fuel depot in medium orbit with fuel from the Moon, Titan or wherever, and then tank up the space probes to the max before going to the operational position. Journeys to refuel a satellite is unlikely to be cost effective in the foreseeable future even without technological advances making the satellite obsolete.
"Kepler is now at over 270% of its intended lifetime"
That's good, but Opportunity had a planned 90 sol lifespan, and made it to at least 5594 sols before it's recent shutdown, (that's sixty two times longer than it's original mission). There's still a good chance it'll recover and will keep on roving on.
Big problem for Hubble is that since they grounded the Space shuttle they can't tow it back to a higher orbit any more.
With its orbit being as low as it is, it is just catching the top of the atmosphere, so it does experience drag. It's not going to stay up for many more years before turning into a fireball.
The telescope was designed to be serviceable and eventually retrievable by the Space Shuttle. That limited the altitude at which it was deployed to allow the shuttle to get to it.
One of the last things that was done on the final shuttle servicing mission was to attach a docking collar to the telescope base which would allow a future visiting space craft to attach itself to the scope. What this craft would be doing was not explained in too much detail, except to state that a rocket engine on the craft could change the telescope's orbit or de-orbit it in a controlled manner (important as much of the mirror would make it through re-entry and it's very massive). It's not a great stretch to conceive of a "service module" that could take over the navigation and pointing functions of the telescope and be attached to it when we see the gyros and momentum wheels on the telescope starting to fail again. This would also maintain the orbit. When the module is used up then it could be replaced with a second unit.
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