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Space Shuttle Heading Home
Reuters is reporting that the shuttle has been prepping for a return to Earth, stowing gear and checking systems. Their expected return is tomorrow morning, around 9am EDT. From the article: "During tests on Sunday a leaking power unit for the shuttle flight control system appeared to be in good enough shape for landing and the jets that steer the spacecraft worked fine, NASA engineers said. The shuttle crew was still awaiting word on whether Discovery's heat shield had passed a final inspection performed on Saturday, but scans conducted with cameras and sensors throughout the flight had so far turned up no damage."
If most of the mission is making sure that the shuttle they sent up can land safely (at least that's the impression we get from the news coverage), doesn't the whole ordeal become pointless?
One of the mission goals was to set up a -80 C freezer on the ISS. We have a couple in our lab (most bio labs do) -- they're primarily used to store biological samples. The -20 C freezer and 4 C refridgerater are also standard operating equipment in biology (or chemistry, I suppose), so it looks like they're gearing up to do some life sciences work.
Now, this brings up an interesting issue -- How do you operate refrigeration equipment in space? Especially that -80 C...it's a real power hog and probably outputs a lot of heat (in a closed air environment, is this a problem?). Does anyone know how cooling is done in space? Is it still based on condenser coils? Can they somehow utilize the "cold" of space for this purpose?
It is not at this time believed that the shuttle can be landed without a human pilot for the simple reason that the autopilot is not good enough to land on a runway.
Well, that's just wrong.
This mission is actually the first where the shuttle can be landed remotely, as reported here. Basically a cable was built that allows the ground to actuate some functions that orginally the crew had to do switch throws for.
What is interesting about the cable is that (if I recall correctly) it only cost a couple hundred thousand to fabricate, which is all that was keeping the orbiter from being able to land unmanned. The orbiter autopilot is quite capable of landing automatically as long as the crew drops the landing gear, and has been since the first flight in 1981.
I've flown in the motion based simulators the crew uses for training (I work for NASA), and have witnessed the autopilot land the orbiter. In fact, even when the thing isn't engaged it's providing the cues on the HUD for the pilot to follow down to the runway. The orbiter is surprisingly easy to land because of all of this help.
For some reason, the capability of the orbiter to do this was little known. It's not that surprising, though. Aircraft have been able to land themselves for some time. The crew typically lands the orbiter because it reduces failure modes and they are better able to cope with malfunctions.
Worst...sig...ever!
The shuttle can land itself without any hassle whatsoever. What prevents this from being done is the fact that the landing gear is manually activated. This was an intentional design element, as once the landing gear is activated there is no way to reverse the process. The fear was that if the computers fouled up and dropped the landing gear early, the excess drag would cause the shuttle to fall short of the runway. For this reason, they wait until the last minute (approx. 300 feet) to activate the system. As far as I know, the landing gear still requires an actual human to give the command, but the cable they installed allows this to be done remotely if the need should arise.
"So after all this, you make my case for me. To end this stalemate, you must die..."
Does it appear to anyone else that most of the time the astronauts are in space is spent determining if they can get back to Earth?
it is only after a long journey that you know the strength of the horse.