Posted on 08/18/2013 5:52:51 AM PDT by SunkenCiv
Explanation: Skylab was an orbiting laboratory launched by a Saturn V rocket in May 1973. Skylab, pictured above, was visited three times by NASA astronauts who sometimes stayed as long as two and a half months. Many scientific tests were performed on Skylab, including astronomical observations in ultraviolet and X-ray light. Some of these observations yielded valuable information about Comet Kohoutek, our Sun and about the mysterious X-ray background -- radiation that comes from all over the sky. Skylab fell back to earth on 1979 July 11.
(Excerpt) Read more at 129.164.179.22 ...
In retrospect I think we should have gone to the moon instead.
I remember SkyLab. It was SO cool at the time...the first orbiting Space Station.
Those were great years, weren’t they!
I saw Skylab pass over one night. Very neat.
looking at that picture, thats a long way to fall back to earth.
where did it land? anywhere? or did it just incinerate?
Did Skylab fall out of orbit on its own or did they help it, like by firing retrorockets or something?
I think it would have been cool if it had stayed up there as a historical relic. Imagine boarding it fifty or a hundred years later.
i dont think it could stay up forever because eventually it runs out of helium so it sinks.
It would descend due to drag. There’s still a thin atmosphere at that altitude. It would need propellant to maintain speed and orbit.
Satellites and space stations stay aloft by orbiting the earth at escape velocity. They are moving so fast that the curved earth literally falls away beneath them faster than gravity can pull them down. It has nothing to do with helium. (Or were you kidding about that?)
That makes sense. I wish they had given it a nudge to keep it up there.
A nitpick (but I did like the helium line, somebody has to fall for it), if they were going that fast, they would escape. They are going fast enough so that the earth falls away (due to curvature) at the same rate the satellite would be falling.
I think the international space station (ISS) orbits at about 17,000 MPH, and escape velocity is about 25,000 MPH.
I left out that detail for simplicity’s sake but thanks for filling it in. So I guess that pretty much everything up there, unless it’s moving at precisely the velocity that would keep it in perfect orbit, is either spiraling towards or away from earth, and therefore doomed to become either Skylab or Major Tom eventually.
I think an object can spiral away but not escape (not moving fast enough), so after spiraling away for awhile, it reverses and spirals toward. Either it's moving fast enough, or it's Skylab. Might take a few hundred thousand years ;-)
Hmm, maybe an object can only spiral away if it’s accelerating — i.e. gaining kinetic energy. Which would mean an unpowered object like a satellite or space station could only spiral inward, though perhaps losing altitude at a very slow rate. The presence of any drag at all, even from a few air molecules here and there, would keep the case of maintaining a fixed orbit from being possible. Does this geekery sound legit to you? :-)
Yep. Spiraling out takes energy. While higher orbits require lower orbital velocity, it takes quite a bit of energy to elevate.
I'm sure I've misled as to escape velocity though. That 25,000 MPH is if the object is launched from the earth's surface, then loses propulsion (at low altitude). The farther away the object is from the earth, the lower the escape velocity, gravity is weaker as distance increases. I don;t know the relationship between escape velocity and orbital velocity ... maybe they are very close to the same value.
Yep. Spiraling out takes energy. While higher orbits require lower orbital velocity, it takes quite a bit of energy to elevate.
I'm sure I've misled as to escape velocity though. That 25,000 MPH is if the object is launched from the earth's surface, then loses propulsion (at low altitude). The farther away the object is from the earth, the lower the escape velocity, gravity is weaker as distance increases. I don;t know the relationship between escape velocity and orbital velocity ... maybe they are very close to the same value.
When taking tennis lessons at the time, the instructor liked to employ the “Skylob” ...
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