Space & Innovation

Zombiesat Attack! Solar Storm Fries Satellite's Brain

After April's powerful solar storm, a satellite has stopped communicating with Earth. It's now adrift and dubbed a "zombie satellite," potentially interfering with other satellites in the neighborhood.

What was Nicole saying? Something about the reasons why we should "care about the sun"? Right on cue, my Discovery News colleague has been proven right; it appears that a communications satellite has been hit by a solar storm, killing its ability to talk with Earth. It's now drifting past other geostationary satellites, at an altitude of 36,000 kilometers (22,400 miles), risking interruption of their services.

SLIDE SHOW: What happens when a solar storm hits our atmosphere? A beautiful auroral display erupts, exhibiting the power of the sun's influence on Earth.

In the satellite communication game, there's a name for satellites that go brain dead and start to drift. They're called zombie satellites or "zombiesats." Industry experts are very familiar with zombiesats and know how to deal with them, but that doesn't mean they're not a problem.

Galaxy 15, owned by Intelsat, has been out of communication since April 5 and attempts to send commands to the satellite have failed. The satellite's manufacturer, Orbital Sciences Corp. suspect it was the huge solar storm thatslammed into our planet in early April that did the damage. Although there's little chance of the satellite bumping into other satellites (it's not that crowded up there, yet), Galaxy 15′s situation is "unprecedented" according to industry officials.

As opposed to other zombiesats that just die and drift, Galaxy 15′s systems are fully functioning, with its telecommunications payload (the equipment that relays customer's transmissions around the globe) fully "on." And yet the satellite itself refuses to accept commands from Earth.

Yesterday, controllers fired a powerful signal at the satellite in an attempt not to control it, but to switch it off as it is posing a threat to other satellites in its orbital neighborhood.

If Galaxy 15 drifts too close to other satellites, it can steal their signal, thereby interrupting other vendor's services to customers on Earth. That's not too good for business, hence the increasingly desperate attempts to "kill" the satellite's power.

There are dozens of zombiesats trapped in geostationary orbit, but they all tend to drift toward two points: 105 degrees west and 75 degrees east. These are locations where the slight irregularities around the Earth's equator exert a slightly altered distribution of gravitational calm; they are the equivalent of gravitational "valleys." And it is to one of these valleys that Galaxy 15 is currently heading.

So it would appear that the sun claims another high-tech victim, emphasizing the importance of missions such as NASA's Solar Dynamics Observatory (SDO) and improved space weather prediction methods. After all, there's a huge investment orbiting above our heads.

Images: An artist's impression of a solar storm (NASA/SDO), the Galaxy 15 satellite before launch in 2005 (Orbital Sciences).