Miles O'Brien: Communication crisis with Mir

Miles O'Brien

CNN Space Correspondent Miles O'Brien spoke with CNN.com about an alarming 20-hour radio communication blackout with the Mir space station. The glitch heightened concerns over whether the aging unmanned orbiter poses a threat to populated areas on the ground.

Q: Can you explain the possible cause or causes of the blackout?

O'BRIEN: Sources close to the Russian control team speculate that a spurious command was sent to the motion controlling device in the core module of the space station Mir. The spurious command, for whatever reason, put Mir in an improper orientation, such that the solar rays are not pointing perpendicular to the sun.

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As a result, those solar arrays stopped producing energy, the batteries were draining slowly, a brownout ensued and the communications system went down. This is the best guess they have now.

Now the question is where did this command come from? Did someone push a wrong button at the Russian Mission Control? Did some software melt down and create a stray command on its own? It's possible that a solar flare might have created this spurious command. The sun is at the peak of its 11-year cycle right now. It's bombarding the planet with solar flares.

In any case, they feel it's a situation they can designate as a one-time fluke event, and thus it does not heighten their concern too much.

Q: Has contact with Mir been lost before or has Mir been in danger of falling from orbit before?

O'BRIEN: There have been problems like this numerous times over the 15-year history of Mir, where the solar arrays have ceased making power, the batteries have been depleted or the motion control system shut down.

The big difference is that in the past it occurred with people onboard the station. They were there to troubleshoot the situation and get things up and running again. In this case, it was unoccupied and it took some time before anyone on the ground realized that there was a problem.

On the one hand, it's nice to know no one is up there in harms way. But on the other hand, you don't have anyone to troubleshoot things as quickly as you would if it were manned.

The folks at Russian mission control were saying that this is as serious a problem as they've encountered in the history of Mir. Now that is saying a lot when you consider that Mir has had two collisions, one of which caused a module to be shut down completely. It caused a quick decompression of that module. It's still sealed off. And there was a fire up there too.

Q: If Mir were to fall over the Earth, how would its debris trail compare to that of Skylab in 1979 or other large spacecraft?

O'BRIEN: Even if everything goes according to their plan for an orderly descent early next year, that is, assuming a crew doesn't have to go up there to help out, nothing as big as this has ever been de-orbited.

Skylab was much smaller by mass. Mir is more than 200,000 pounds. What makes Mir even more intriguing and ominous -- it's a very gangly spacecraft. It has all these school-bus sized modules sticking out of a core center, kind of like a tinker-toy arrangement. And it's got all these wings that are the solar arrays.

No one is certain what is going to happen as that strange-shaped object begins to hit the atmosphere. Which way will it tumble? How will it break up? How many pieces will remain intact? All of that is complete guesswork. There's no computer models out there that would give you a real sense of what would happen.

Skylab by comparison was a very streamlined, aerodynamic vehicle. It was just kind of a single module that was built into a Saturn 5 rocket. It didn't have the gangliness of Mir and thus was more predictable. Even though it was coming down in an uncontrolled fashion, it nevertheless was very predictable as to where it would go when it started to hit the atmosphere.

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Office of Space Flight - Mir

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