Today might be a great day to watch the sky for more then just weather. You might just see a falling satellite this afternoon. NASA’s Upper Atmosphere Research Satellite (UARS) is scheduled to re-enter the Earth’s atmosphere sometime today or tonight. UARS finished its productive research life nearly six years ago and has been falling towards the atmosphere ever since.
This satellite is not being controlled during its de-orbit, so scientists are unsure of where and when it will re-enter. UARS has been constantly tracked by the Joint Space Operations Center of U.S. Strategic Command at Vandenberg Air Force Base, Calif., which works around the clock detecting, identifying and tracking all man-made objects in Earth orbit, including space junk. As of late yesterday night, September 22, 2011, the best guess was that it would re-enter late this afternoon or early evening, Eastern Daylight Time. Assuming re-entry does occur at that time, it won’t be over North America. However, the orbit of this satellite ranges from 57deg south latitude to 57deg north latitude, which pretty much covers most of the populated parts of the world, so someone is going to get quite a fireworks show.
While most space debris burns up completely in the atmosphere, due to its size, parts of UARS are expected to reach the ground. It is likely that the debris will fall into the ocean and never cause any concern, however since its re-entry is uncontrolled, it is possible that debris could reach land. Please know that the risk of anyone being hurt by this falling debris is incredibly small. In the last 60 years, since the beginning of the Space Age, there have been no confirmed reports of any injury from falling debris.
If the debris does hit land, rather then water, the debris field is expected to be nearly 500 miles long. If you think you have found a piece of UARS, do not touch it, contact authorities for assistance.
Re-entry prediction updates should be coming in throughout the morning to pin point the target zone and time. If you would like to track UARS in realtime, check out the NORAD data. (Keep in mind all of the tracking websites have been getting overloaded the last 24 hours so give it a few minutes to load.)
UPDATE Friday 11am from NASA UARS website: As of 10:30 a.m. EDT on Sept. 23, 2011, the orbit of UARS was 100 miles by 105 miles (160 km by 170 km). Re-entry is expected late Friday, Sept. 23, or early Saturday, Sept. 24, Eastern Daylight Time. Solar activity is no longer the major factor in the satellite’s rate of descent. The satellite’s orientation or configuration apparently has changed, and that is now slowing its descent. There is a low probability any debris that survives re-entry will land in the United States, but the possibility cannot be discounted because of this changing rate of descent. It is still too early to predict the time and location of re-entry with any certainty, but predictions will become more refined in the next 12 to 18 hours.
Update Friday 8PM from NASA UARS website: As of 7 p.m. EDT on Sept. 23, 2011, the orbit of UARS was 90 miles by 95 miles (145 km by 150 km). Re-entry is expected between 11 p.m. Friday, Sept. 23, and 3 a.m., Sept. 24, Eastern Daylight Time (3 a.m. to 7 a.m. GMT). During that time period, the satellite will be passing over Canada, Africa and Australia, as well as vast areas of the Pacific, Atlantic and Indian oceans. The risk to public safety is very remote.
Final Update Saturday 4am from NASA UARS website: NASA’s decommissioned Upper Atmosphere Research Satellite fell back to Earth between 11:23 p.m. EDT Friday, Sept. 23 and 1:09 a.m. EDT Sept. 24. The Joint Space Operations Center at Vandenberg Air Force Base in California said the satellite penetrated the atmosphere over the Pacific Ocean. The precise re-entry time and location are not yet known with certainty.
