WRAL WeatherCenter Blog

Trouble at 22,300 Miles Up

Posted December 6, 2007

Anomaly -- It's such an innocent-looking word, but as anyone who follows the US space program knows, it might as well only have four letters.

As you may know, most of the satellite pictures we use on air and on WRAL.com come from a pair of geostationary satellites.  These multi-million-dollar satellites -- known as GOES-West and GOES-East -- orbit the earth at an altitude of 22,300 miles.  Each satellite orbits the earth such that it "hovers" above the same point on the earth's surface at all times.  To keep them that way, the folks in charge of the satellites have to occasionally move them a bit to correct for drift in position and other effects. (For a more detailed explanation, see the Wikipedia article associated with this blog entry.)

They were performing one of these "station keeping maneuvers" with GOES-East on Tuesday afternoon when one of those dreaded anomalies occurred.  Ever since then, the spacecraft is having trouble maintaining a proper attitude.  In other words, the satellite folks are having trouble keeping it pointed in the right direction.  As you might imagine, this is a problem.

What does that mean for us?  Well, fortunately, an older incarnation of GOES-East is still in orbit and in good working order.  Before Tuesday, it had been collecting images of South America and the southern Atlantic, but it's since been re-positioned in order to collect the same imagery we got from GOES-East before the anomaly occurred.  While some of the more advanced products are not available temporarily, most of the basic images we're used to seeing from GOES-East are available once again.

As for GOES-East, NESDIS -- the government agency in charge of the satellites -- says that it's "safe" and that it's been repositioned so that it will receive plenty of solar power.  Hopefully, with a full battery, they'll be able to correct this nasty anomaly.


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  • nsj Dec 9, 2007

    rsmath - It looks like the NESDIS folks have figured out the cause of the GOES-12 "anomaly":

    "Engineers have confirmed the cause of the attitude disturbances on GOES-12 that started after the North/South maneuver. We believe there is a leak in the oxidizer line of thruster 2B."
    -- From http://www.spaceref.com/news/viewsr.html?pid=26264

    They go on to say they will try to bring GOES-12 back into normal operating mode on Monday. In the meantime, NESDIS and NASA engineering teams are drawing up plans to move GOES-13 (not scheduled to be put into active use for another year or two) into place as GOES-12's replacement.

  • Made In USA Dec 9, 2007

    Interesting rsmath! I appreciate that info! Learning something new every day is a good thing!!

  • rsmath Dec 9, 2007

    Satellites have stationkeeping thrusters - chemical-based or some of the newer ones use ionized gas. A satellite is allowed to drift in a "box" in the sky - when the satellite reaches towards an edge of the box, a stationkeeping maneuver is made to move the satellite more securely inside its "box".

    I don't know what caused the GOES-E failure, but some TV satellites have lost attitude control due to loss of a on-board CPU processor, loss of gyros that stabilize the satellite platform, loss of earth-lock sensor (a part of the satellite no longer can face towards Earth since the sensor can't tell the satellite where Earth is located), stuck stationkeeping thrusters, or tin-whiskers shorting out something in the satellite.

  • Made In USA Dec 8, 2007

    Good story Nate. I had no idea that these satellites can be corrected in regards to their position. I wonder how they can do that. Do they have small boosters that can steer them?

  • loudnoises Dec 8, 2007

    NASA does not operate nor maintain the GOES satellite system. NOAA/National Weather Service does.

  • mrtwinturbo Dec 7, 2007

    anyone who follows the US space program knows, it might as well only have four letters.......would that word start with f?