Wednesday, September 21, 2011

Where Will UARS Fall?

NASA Fri, 23 Sep 2011 07:45:08 AM PDT
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.
Dave's Note:  It's interesting that NASA's predictions are now falling more into line with those of Aerospace Corporation's of a late Friday, early Saturday eastern time reentry.  

NASA Thu, 22 Sep 2011 07:01:35 PM PDT
As of 9:30 p.m. EDT Sept. 22, 2011, the orbit of UARS was 110 mi by 115 mi (175 km by 185 km). Re-entry is possible sometime during the afternoon or early evening of Sept. 23, Eastern Daylight Time. The satellite will not be passing over North America during that time period. It is still too early to predict the time and location of re-entry with any more certainty, but predictions will become more refined in the next 24 hours.
NASA Thu, 22 Sep 2011 04:44:51 AM PDT
As of 7 a.m. EDT Sept. 22, 2011, the orbit of UARS was 115 mi by 120 mi (185 km by 195 km). Re-entry is expected sometime during the afternoon of Sept. 23, Eastern Daylight Time. The satellite will not be passing over North America during that time period. It is still too early to predict the time and location of re-entry with any more certainty, but predictions will become more refined in the next 24 to 36 hours.
Nasa's now defunct 20 year old UARS (Upper Atmosphere Research Satellite) is falling to earth. Pieces of the huge satellite may crash to the Earth this week, but no one's sure where they're going to land.

UARS, launched in 1991 aboard the Space Shuttle Discovery, will fall into the grasp of Earth's atmosphere around Friday September 23, plus or minus a day, according to NASA estimates.

“Re-entry is expected Sept. 23, plus or minus a day,” an agency spokesperson wrote in the most recent update. “It is still too early to predict the time and location of re-entry. Predictions will become more refined over the next two days.”
Most of the six ton satellite will burn up entering Earth's atmosphere, but it's thought as many as 26 major pieces may survive to fall to the ground.  This could happen anywhere between 57 degrees north and 57 degrees south.

“The risk to public safety or property is extremely small, and safety is NASA’s top priority,” NASA reports. “Since the beginning of the Space Age in the late-1950s, there have been no confirmed reports of an injury resulting from re-entering space objects. Nor is there a record of significant property damage resulting from a satellite re-entry.”

Current projections show UARS re-entering Earth's atmosphere just off the coast of Chile on a path that will take it northeast across central South America.  


This prediction, generated by Aerospace Corporation,  is based on September 20 data.  The yellow icon within the orange circle indicates the predicted re-entry point.  The blue and yellow orbital tracks indicate plus or minus 6 hours of uncertainty. So, as you can see, at this point it can come down just about anywhere.