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A Brief History of the Space Station
HyperbolicParabaloid writes "A story about the history of the International Space Station, and its utility or non-utility for space exploration. One interesting insight: after the Challenger explosion it became obvious that we would never refuel a rocket with volatile fuel at a space station because the threat to the station would be so great. And did you know that to accomodate the Russians, the space station is in an orbit that makes it almost useless as a jumping off point to anywhere?"
From Glory to Sideshow: The Space Station's Story
By WILLIAM J. BROAD
Published: February 3, 2004
In 1989, when the first President George Bush announced his plan to send American astronauts back to the Moon and on to Mars, he called the proposed space station "our critical next step in all our space endeavors." It would be a base in the weightlessness of space where big rockets would be assembled and blast off on voyages of exploration: "a new bridge between the worlds."
Now, with the outpost hurtling through space 240 miles above Earth and with 16 nations struggling to complete the most challenging engineering project of all time, the station has suddenly become a $100 billion dead end.
The current President Bush made no mention of it as a steppingstone in his speech on Jan. 14 reviving the call for missions to the Moon and Mars. Instead, he spoke of it as a site of biomedical research and an "obligation" that the United States had to help finish.
Mr. Bush gave no clear indication how, or whether, the United States planned to use the station after its prospective completion in 2010. With NASA focusing its efforts and its budget on the Moon and Mars, the station's prospects are uncertain.
"I'm worried that they're going to cut off the space shuttle before we have another vehicle that can fly," said Senator Bill Nelson, a Florida Democrat who is the only current member of Congress to have flown in space. "And that will drastically reduce space station use."
What happened? How did the station go from star to sideshow? Experts cite a litany of factors: cost overruns, design changes, new perceptions of technical risk after the shuttle disasters and shifting national priorities. For instance, orbital changes to accommodate Russia after the cold war made it harder to use the station as a launching pad.
The tale has no real bad guys, the experts say, but many false promises.
"It was always a steppingstone to the stars," said Dr. Howard E. McCurdy, a space historian at American University. "It was sold as all things to all people."
Dr. Alex Roland, a former NASA historian now at Duke University, said a moral of the story was that Congress and the public needed to work harder to hold the space agency accountable for its dreams.
"They keep getting trapped in their own rhetoric," he said. "They're willing victims of it. But as public policy it's a disaster because it feeds unrealistic expectations."
At the start of the space age, visionaries invariably saw outposts in earth orbit as jumping-off points. Dr. Wernher von Braun, in a famous 1952 article, told of a huge inhabited wheel. "From this platform," he said, "a trip to the Moon itself will be just a step."
In 1968, Stanley Kubrick's movie "2001: A Space Odyssey" featured a giant outpost in Earth orbit that was a way station to the Moon and Jupiter.
Finally, after decades of fantasies, President Ronald Reagan proposed in 1984 that the United States actually build a space station. It too was envisioned as a hub for colonies on the Moon and Mars. For Mr. Reagan, the station also represented a way to challenge the Soviet Union. In the cold war, Moscow made human outposts a hallmark of its space activities.
But Congress did not vote construction money to pay for either Mr. Reagan's vision or that of the first President Bush. Not until 1993 did a new a new vision for space take shape, this one emphasizing harmony over rivalry. That September, President Bill Clinton announced that Russia had joined the station effort as a full partner. Its giant rockets were seen as a boon for the project and a good backup if the shuttles should again fail catastrophically, as the Challenger did in 1986.
"One world, one station," said Daniel S. Goldin, NASA's administrator at the time.
There was just one problem. For the Russian rockets to reach the grand unified station, it would need a different orbit.
Shuttles flying out of Florida usually go into an or
Organic free-range music... yum!
And did you know that to accomodate the Russians, the space station is in an orbit that makes it almost useless as a jumping off point to anywhere?
While this may be true, the ISS was already to be in a horribly useless orbit to begin with, Russians or not.
Because of a weakness in the shuttle and the immense weight of the station, the station is in a perpetually decaying orbit. That is, to say that the shuttle, each time it docks with the station, has to fire its boosters while docked in order to push it back to a higher orbit. If the shuttle doesn't go back to the statio within the next few years, the ISS will go the way of SkyLab. (The Progress and Soyez ships do not have enough power to push the ISS high enough.)
Why put the station in such a poor, low orbit? Because the shuttle can't fly that high.
A recipe for disaster if I ever heard one.
"And did you know that to accomodate the Russians, the space station is in an orbit that makes it almost useless as a jumping off point to anywhere?"
I'm sure the astronauts currently living on the station are quite thankful for this as the United States does not have another vehicle and they would all be dead if Russia could not reach them now that the shuttle has been grounded for a year. Should China and/or Japan enter into this endeavor from a launch vehicle point of view, being accessible is hardly a detriment to the utility of the station.
Clearly, the utility of being able to reach the station from Asia for existing missions far outweighs the utility of using the station as a departure point for missions that have yet to be defined. Besides, the station design is that of a scientific laboratory, not of an orbital drydock. Having already ruled out refueling, can you imagine constructing a transport vehicle in the middle of that tangle of trusses and solar panels? If both construction and refueling are out of the picture, what's left? A snack bar? Seriously, that thing isn't even designed to handle an espresso machine.
Terminal velocity is the maximum speed you'd reach if you fell off the ladder at the top. Gravity would be pulling you down, air friction would be pushing you up, eventually they balance and you reach a maximum speed. In a vaccuum you'd keep accellerating till you hit the ground.
You're talking about escape velocity.
Yes, you would, that's the idea of the space elevator that's brought up from time to time. But you'd be expending energy constantly on your way up.
Think of it more that you fire a bullet straight up, how fast would it have to be going to leave earths gravitational well? You expend your energy all at once - like the big engine on a rocket. That's escape velocity.
I don't need no instructions to know how to rock!!!!
What? Fuel? Who says you need to use liquid fuels? Try solids that can be lit and relit in space. The fuel cores could be sent on shuttles without as much worry about volatility than liquids. There is one way to stop a burn in space--stop the oxidizer (you're in vacuum, figure it out).
Hmm. I'm not sure it's that easy. I'm pretty sure that solid-fuel rockets have the oxidizer mixed in with the fuel and are fully self contained. The SRBs on the Shuttle, for instance, have nothing pumping an oxidizer in.
There are (in my experiences) two types of propulsion engineers--those who love solid fuels, and those who hate them.
On the positive side, it keeps you from messing with those nasty hypergolic fuels like hydrazine.
On the negative side, once you light it, there's no easy way to stop it until it's out of fuel--it's like a big highway flare. IIRC, if the shuttle needs to abort early in the launch sequence, the only thing to do is to jettison the SRBs and let them go flying merrily on their way (to be destroyed later by range safety).
Liquid fuels can be throttled or shut off. A solid booster's thrust can only be controlled by how the fuel is poured in the casing (star patterns and whatnot give high initial thrust, then back off), and not easily shut down.
Actually, the parent post is closer to being correct. The Van Allen belts have their lower edge up around 1200-1400 km. The station is orbiting at a much lower altitude than that (mean altitude somewhere around 380 km). That low altitude is mostly driven by the capability of the shuttle, which can't go a whole lot higher than that (especially at the inclination that the station is at). It'd be nice to put the station higher, since that would cut down atmospheric drag a lot, and thereby seriously reduce the amount of stationkeeping (aka "reboosting") they would need to do.