Re: How do they know where MIR will contact earth?

Greetings:

You can keep up to date about the MIR and other space stations on the following web site:
http:// www.space.com/news/spacestation/index.html

The following 3 news briefs from the web site explain what is proposed to do with the controlled MIR deorbit, the possible outcomes and then compares the hopefully controlled MIR deorbit with the uncontrolled reentry of Skylab in 1979.

The stories about the deorbit of MIR are under the topic "Abandon Ship" on the web site.

Briefly the following are abstracted text about the deorbit of the MIR space station from the web site:

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Current Mir Crew Says It Is The Last

Aug 15 1999 14:59:49 ET

When the Russian Mir space station is vacated Aug. 28 by its current crew, no one else will return. That is if you believe the current crew, two Russians and a Frenchman.

However, that contradicts the official position of the Russian Space Agency. It has always been that another crew will go back up to prepare the space station for its fatal plunge back into the atmosphere. According to a report from the BBC over the weekend, the three crew members believe they will be the last aboard and that everything from Aug. 28 on will be controlled automatically. The current crew is installing a new computer that is designed to control Mir much as an autopilot would. It would then guide Mir into the Indian Ocean, away from any humans.

Not everyone is certain the computer is enough to keep Mir from crashing into Earth, out of control. The "final" crew that has been planned all along by the Russians is supposed to help control the space stations re-entry before they abandon the station. Whether the computer can handle the re- entry is critical. The space station is so large that much of it will not burn up when coming back into the atmosphere. Figuring out where it will land is important.

Funds to run the Mir space station officially run out shortly after the crew of three now aboard leave. Unless additional funding is found, either by the Russian government or by private investors, the station will be officially abandoned.

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Home At Last!

Aug 27 1999 20:42:49 ET
KOROLYOV, Russia (Reuters) -- Two Russians and a French cosmonaut returned to Earth on Saturday from the Mir space station, which may be dumped next year if Moscow fails to raise funds to keep its 13-year-old orbital laboratory running.

A spokesman for Mission Control in the town of Korolyov outside Moscow said a landing capsule with Russians Viktor Afanasyev and Sergei Avdeyev and Frenchman Jean-Pierre Haignere, possibly Mir's last full-time crew, safely touched ground at 0035 GMT.

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When Space Stations Fall...

By Stewart Taggart
Special to space.com

Aug 27 1999 06:24:38 ET
As Russia's aging Mir station bids goodbye to what may be its last occupants this week, the question is, what happens next?

Russian officials haven't said definitively. But if the 125-ton space station is allowed to fall back into Earth's atmosphere -- probably next year -- not all of it can be expected to burn up on re-entry.

But the station still has fuel on board, and can be remotely controlled from Earth. Therefore, ground controllers can be expected to steer Mir over an ocean, and not over inhabited areas.

"Mir will be a controlled reentry, assuming that it takes place," says Roger D. Launius, NASA's chief historian in Washington. "It will be brought down whenever and wherever controllers want."

The contrast with NASA's out of fuel and out-of-control Skylab, which crashed back to Earth just over 20 years ago -- on July 11, 1979 -- couldn't be more great, he says. "Skylab was an uncontrolled re-entry," Launius said. "There was no way to fire thrusters and make it either re-enter the atmosphere or to reboost to a higher orbit."

The original plan was for Skylab to stay in orbit long enough for the space shuttle fleet to become operational in 1978. Shuttles would deliver extra rockets, and the 77-ton Skylab would either be guided to a specific re-entry trajectory or boosted to a higher orbit.

Instead, the space shuttles weren't ready in time. The $2.5-billion Skylab essentially became an orbiting piece of metal beyond anyone's control. Higher than normal solar flare activity also intervened, causing additional atmospheric drag and pulling Skylab even more quickly toward Earth.

During Skylab's final days, NASA engineers were reduced to merely guessing where on Earth the station's remnants would fall. In India, astrologers did a booming business. The world kept a worried vigil. Around 2:35 a.m. in the morning of July 11, 1979, Skylab re-entered Earth's atmosphere, falling largely over the eastern Indian Ocean. Parts of it fell over suburban Perth, Western Australia and over Australia's mostly vacant western desert.

No injuries were reported. Souvenir hunters fanned out. Few did better than 17-year-old Stan Thornton of Esperance, Western Australia.He scooped a few pieces off the roof of his home and caught the first flight to San Francisco,where he collected a $10,000 prize from the San Francisco Examiner. Meanwhile, Australian Prime Minister Malcolm Fraser wrote a letter to US president Jimmy Carter, praising the scientific research Skylab had done during its active lifespan. Even so, he said, he would have preferred Skylab hadn't fallen on his country. He then suggested tongue-in-cheek a trade be made of Skylab wreckage in return for higher Australian beef export quotas to the US market.

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It will be interesting to see what happens when MIR is deorbited and how it all works out.

Best regards, Your Mad Scientist
Adrian Popa