NASA Tracking Satellite Heading for Earth

NASA says there could be a spectacular show on Friday if someone spots the re-entry of an old satellite. But that is a big if. The space agency is down-playing any danger associated with a 20-year-old, school-bus-sized piece of space junk crashing into a populated area.

But there is still a chance that someone will spot one of the 26 pieces NASA estimates will survive atmospheric re-entry and land somewhere between northern Canada and southern South America. The agency puts those odds at one in 3,200. So not great but not impossible either.

The reason for such uncertainty of the return of the Upper Atmosphere Research Satellite is twofold. Sun and rockets. With the solar cycle heating up things are moving faster in space, including orbiting satellites. Solar activity is making it difficult for NASA to pin point the exact time and location of UARS falling to Earth.

Because the satellite was launched on space shuttle Discovery in 1991 it doesn’t have fuel left to push the thrusters to help NASA guide falling debris like this away from people.

Those two factors are making careful prediction of the de-orbiting satellite more difficult. But NASA is hopeful that the pieces will land in the ocean or in desert areas.

NASA is working closely with the Air Force’s Joint Space Operations Center to pinpoint the re-entry locations. By the time the satellite is getting ready to drop into Earth’s atmosphere scientists should have a better picture what to expect. NASA estimates the debris footprint will be about 500 miles long.

Mark Matney from NASA’s orbital debris program says the motion of the satellite is unpredictable but he believes it will come to Earth sometime on Friday. He says, “It’s coming in a little faster than we anticipated.” And since it is an uncontrolled re-entry there is still a lot of uncertainty.

NASA and the joint space operation center will give public updates daily until Friday when updates will come 12, 6 and 2 hours before impact.

Medium-sized pieces of space debris fall to Earth about once a week, generally landing in the ocean. But some of the pieces of this satellite could weigh up to 300 pounds and pack quite a punch if they hit solid ground.

NASA reminds people who find chunks of the satellite in the next few days or weeks to call local law enforcement to report them. After all the burned up satellite is government property. So don’t try to sell it on eBay.