The 6.5-ton NASA Upper Atmosphere Research Satellite (UAR) expected to make an out-of-control re-entry into the Earth's atmosphere on Friday, September 23, is generating concerns about where exactly on the earth it will fall.
But NASA has meanwhile ruled out the Antarctica and has recently said that it is very unlikely to fall on the United States because it will not be passing over the United States or North America at the time of its expected re-entry into the Earth's atmosphere. Reports say that scientists are working to determine the trajectory of the craft but NASA officials have said that it is unlikely that space scientists will be able to determine where exactly on the Earth's surface the craft will fall more than two hours ahead.
According to a statement by NASA officials:
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 48 hours.
Mark Matney, a scientist at the NASA's Orbital Debris Program Office, told space.com that:
With re-entry we're always interested in day-by-day and hour-by-hour details…It's very difficult to predict how it's going to happen. With our models, we try to figure out what parts of the spacecraft — what materials — will interact with the atmosphere in terms of temperature and melting, and determine which of those will survive. But it's a very dynamic environment, the force is very intense.
However, officials have said that the UAR will enter the Earth's atmosphere somewhere between 57 degrees north and 57 degrees south, which means, in principle, that it could hit anywhere between northern Canada and South America (though the likelihood of the North American continent is very low) but the projection is being further refined as the decaying orbital path of the satellite progresses.
NASA has estimated that at least 26 pieces of the satellite, adding up to about 1,170 pounds, will hit the Earth, with the debris scattering over a 500-mile area. NASA has re-assured that the odds that the pieces will fall on densely populated area are low because only a very small fraction of the earth's surface is densely populated.
NASA calculates the odds that someone will be hit by falling craft debris as 1 in 3,200. NASA has also advised that if you find any piece of the craft in your locality do not touch it. Inform your local enforcement officials.