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ISS Orbit-Raising Attempt Fails
hpulley writes "ITAR-TASS reports that the Progress cargo ship currently docked at the ISS attempted an orbit raising burn this morning but the engine failed three minutes into the firing. Further burns are cancelled until they figure out the problem and meanwhile, the station continues to lose approximately a kilometer of altitude every week, with the rate increasing as the orbit decays. At present, the schedule says the next Progress, 20P, will be launched on December 21st, nearly 9 weeks from now. Normally the shuttle would also raise the orbit of ISS but it is not scheduled to launch until May 3rd at the earliest. Nominally the ISS orbits at 358km but if it drops to 300km, it may decay in a matter of days. It was down to 340km already on October 13th."
Reading the summary makes me think either the PR firm who wrote it doesn't understand acceleration, or expects us to be unable to.
The orbit could currently be decaying at 1km/wk, but that is less useful than saying the paperclip I just dropped is currently traveling at 15m/s.
In order to convey the predicament of the ISS the article should mention altitude, downward velocity, and acceleration.
4 missions per year does not mean 3 months lead time.
Astronauts train for over a year for their flights. Missions are being prepared for concurrently. I do not know what the required lead time is, but it's undoubtedly greater than 3 months.
Seth
$5 / month hosted VPS on linux = awesome!
It's not like the ISS is of use to anyone, thanks to it being in its current orbit. Like the Shuttle itself, it was a bad idea poorly implemented. You don't design and implement a space station just so a gaggle of nations can proudly say they have a presence in space, and you don't build a shuttle just because a bunch of Air Force pilots insist on flying a space ship home like an airplane. You do both to accomplish a purpose in space. What is our current mission in space? Besides lining the pockets of the Aerospace Industry, that is. Form follows function. If you don't have a concrete goal to accomplish, you'll never reach it. We have no business being in space without such a goal.
My suggestion: decommission the space station and shuttle, close down NASA, and give the money we currently spend on it to private individuals and companies to do something (tourism, manufacturing, mining, whatever) worthwhile with it. That is the only way mankind will reach the "new frontier", the same way we reached the old one: monitize it.
"My country, right or wrong; if right, to be kept right; and if wrong, to be set right." --Senator Carl Schurz (1872)
Why? Why have rocket motors built into the station, that you have to refuel? Would such a system be magically less prone to failure than the current system? Why not just use the partially-fueled rocket?
"And yes, things could be better if I were doing it"
Uh huh. Here's a nickel, kid.
Why yes, I AM a rocket scientist!
We obviously want the station properly decommissioned. But it needs to come down. What a waste.
This is my post. There are many others like it. If you don't like what you read here, go try one of the others.
You're forgetting about higher radiation exposure (isn't geosync above the Van Allen belts?). And the amount of extra fuel needed is pretty significant.
A better option would be to use a tether to give it thrust by pumping current through it. If they give it the right thrust, it can cancel the deceleration caused by the atmosphere. This would have the added advantage of getting them closer to true zero gee. One of the reasons they call it microgravity instead of zero gee when you're in LEO is because of the force imposed by that deceleration.
With Ion engines, the weight is neither in the engine nor in the reaction mass; it's in the solar panels. Ion engines require lots of power to operate, since the xenon is only a reaction mass. The ISS has a pretty tight power budget, and there is no way enough power can be diverted to Ion engines.
So, installing Ion stationkeeping engines on the ISS would also require installation of large new solar panels. The current system with Progress ships boosting the station is actually quite nice because the Progress space-robots are going to visit the station anyway - even if you had stationkeeping engines, you'd still have Progress ships visiting the station, laden with spare fuel and engines.
As for lowering the orbit of the station, well... It would degrade much more rapidly, requiring more power to keep it up - and power requirements increase exponentially. Also, the thin atmosphere would start ablating at the station, and as you pointed out, building the station aerodynamically might start making sense at some point. However, this would make the station incredibly more difficult to build.
I feel that the current solution with Progress space-robots boosting the station is a pretty good one.