Mir takes aim at fiery descent tonight
| • | Hawai'i residents can watch Mir re-entry on Web |
| • | Graphic of Mir's de-orbit plan |
Associated Press
MOSCOW — Ground controllers powered up Mir's computerized orientation system yesterday and fired thrusters to begin stabilizing the station before a fiery descent into the South Pacific tonight that will end its 15-year existence.
At Mission Control headquarters outside Moscow, officials issued commands to regain full control of Mir. The station's onboard computer had been sending data to Earth but not receiving information, said a spokeswoman, Olga Soshnikova.
Mir's primary computer includes its attitude control system, which had to be activated to align the station. Russian space officials had let the uninhabited Mir drift in a slow rolling motion to conserve fuel and battery power.
Thrusters were fired shortly after computer control was regained to stop the tumble, Soshnikova said.
The next task was to align the station's solar panels with the sun, to soak up energy to recharge Mir's batteries. That was to done during the 15-minute window controllers have to communicate with the station during each orbit.
The 15-year-old Mir, which officials say is decrepit and too expensive to operate any more, has been left to drift in a slow rolling motion since the end of January to save its batteries and fuel for re-entry. It slowly descended on its own into the new orbit over several weeks.
Russian space officials have acknowledged that switching on the dormant systems could be tricky.
In December, Mission Control lost contact with the station for more than 20 hours because the batteries suddenly lost power. Space officials managed to retain contact with Mir during several subsequent power losses, but each of those incidents disabled its central computer for days.
Mission Control experts have a backup — using the onboard computer and separate radio communications of the Progress cargo ship docked at the station.
If Mir's position can't be stabilized, the re-entry process will become uncontrollable.
If the process goes smoothly, Progress will fire its engines twice for about 20 minutes, at around 2:30 p.m. Hawai'i time today and 4 p.m. Hawai'i time during consecutive orbits. That will slow the station and change its orbit from round to elliptical.
Then, at around 7 p.m. Hawai'i time, Progress engines will fire one last time for 23 minutes to send the station hurtling into the South Pacific between Australia and Chile.
Most of Mir is expected to burn up in the atmosphere during re-entry, but up to 27.5 tons of debris are expected to reach Earth in an oblong debris zone centered roughly around 44 degrees south latitude and 150 degrees west longitude.
That spot in the Pacific Ocean is more than 2,000 miles south of Tahiti; about 2,500 miles east of New Zealand; and more than 3,000 miles southwest of Chile's Easter Island.
Space officials were confident of a safe descent, pointing to their experience in dumping dozens of Progress ships and other spacecraft into the same area of the Pacific.
But the 143-ton station is the heaviest spacecraft ever dumped, and its size and shape make it difficult to exactly predict the re-entry.
"It's an experiment," Mir cosmonaut Valery Ryumin said on Echo of Moscow radio. "No one has experience at this."
