Space

Emergency disposal maneuver okayed for satellite at risk of exploding

Emergency disposal maneuver ok...
Artist's concept of Spaceway-1
Artist's concept of Spaceway-1
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Artist's concept of Spaceway-1
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Artist's concept of Spaceway-1
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Diagram of Spaceway-1

DirecTV has been granted permission by the US Federal Communications Commission (FCC) to send a damaged communications satellite in danger of exploding into an emergency disposal trajectory. The Boeing-built Spaceway-1 direct-broadcast satellite suffered a "major anomaly" last month that caused severe thermal damage to its batteries and must now be moved to an orbit where it will not pose a hazard to other spacecraft.

Orbiting space debris is a major and growing hazard and there has been a great deal of effort in recent years to both clean up dead satellites and to minimize the production of more debris. This not only includes the building of tougher spacecraft that won't shed bits and pieces but also making sure that damaged satellites are properly disposed of before they become a threat.

According to documents filed by DirecTV with the FCC, the 13,400-lb (6,080-kg) Spaceway-1, which is in a geosynchronous orbit 35,800 km (22,200 mi) above the Earth's equator, was damaged by an unspecified event in December 2019. Telemetry from the satellite was examined by Boeing engineers who concluded that the batteries on the 702-model satellite had suffered significant and irreversible damage.

Normally, this would not be a problem because Spaceway-1 is solar-powered and has enough capacity to avoid using the batteries. However, the satellite is approaching the season when it will periodically pass into the Earth's shadow. The concern is that the temporary switch to batteries will place the cells under such stress that they could explode – turning Spaceway-1 into a cloud of shrapnel circling the planet at hypersonic speed.

To prevent this from happening and avoid danger if it does, will use the remaining fuel on the satellite to move it into a disposal orbit 300 km (190 mi) above its present position, where it will be decommissioned and vent as much from its propellant tanks as possible – the move is expected to take 21 days, while the propellant venting will last seven days. It will need to be completed before February 21 when the next eclipse season begins.

Source: FCC

8 comments
piperTom
I'll ask the obvious question: if they will have propellant to vent after making the orbit 300 km higher, why not use that propellant to move the thing even higher?
paul314
I guess battery fires aren't just for laptops and phones and airliners...

@piperTom I would expect that there's a benefit to getting the thing into a known, well-predictable orbit rather than running the thrusters till empty (which they might not do at exactly the same time). And then vent so that any future bang has less to act on...
Expanded Viewpoint
I'm with Piper on this. Why not just send it far, far away from Earth, like out of the solar system, or crash it into the Moon, or send it on a course into the sun? We could also crash it into Mercury or Venus as those places are NOT hospitable to life forms. Just venting the propellants after parking it in a higher orbit is a complete waste, unless it's cost effective to try to salvage it at a later date, which I seriously doubt would ever be the case. By the time they got around to doing it, it would be akin to wanting to restore a Yugo.
eMacPaul
@Expanded Viewpoint, the propellant was intended for small orbital maneuvers. It doesn't have enough propellant to leave Earth's orbit (other than by crashing into the Earth).
paul314
300 km is less than 1% of the satellite's current orbital altitude. Tiny (relatively) amount of energy/fuel required to move up there and stabilize. Leaving the earth entirely would require energy/fuel closer to the amount it took to launch in the first place. Btw, geosynchronous orbit is a particularly valuable part of space real estate -- there are about 400 satellites up there (a little less than one degree spacing) and an explosion in place could render an orbital slot effectively unusable because the shrapnel would keep crossing and recrossing the original location.
Tony Morris
Why not send it down, to burn up on re-entry?
dls
Yes, why not lower it to burn up? Like we need more junk up there permanently!
christopher
The vented propellant is now going to cause friction on all the other satellites, which are then going to have to vent their own propellant to correct their orbits, making more propellant pollution to cause more friction, and so on...