Falling satellites: should we worry?

NASA predicts that the debris is due to fall back to Earth sometime between Sept. 23 and 25th.

Get a snapshot view of NASA's Upper Atmosphere Research Satellite (UARS), which will fall to Earth in 2011, in this SPACE.com infographic.
Source: SPACE.com: All about our solar system, outer space and exploration

Update -- 9.23.2011 (11:15 AM ET): Scientists are predicting that the Upper Atmosphere Research Satellite will land sometime Friday afternoon or early evening, Eastern time. The latest calculations show that during that time it will not threaten the North American region, which includes the United States, Canada and Mexico, reports the Associated Press.

Last week, NASA warned that large fragments from a satellite may survive when it re-enters the atmosphere sometime between September and early October. Now the agency has revised their forecast and predicts that the debris is due to fall back to Earth sometime between Sept. 23 and 25th.

Scientists came up with the latest projection after factoring in some newly detected atmospheric conditions, primarily the fact that the sun has become more active as of late. The effect of this is that it creates more atmospheric drag for satellites in a stage of decaying orbit.

Researchers are still gathering data and tracking the satellite as it approaches it's descent. But here are a few facts that we do know:

  • The Upper Atmosphere Research Satellite weighs six tons and will disintegrate into pieces as it barrels down from the skies. The biggest chunk is expected to weigh 300 pounds.
  • The geographic range of where it'll land will likely be anywhere in latitude between northern Canada and southern South America.
  • An analysis shows that satellite bits will likely scatter within an area of 500 miles (800 kilometers)
  • There's a chance that people in the U.S. will get to see debris passing through the skies as UARS makes a final drop.

Now here's the part that's got more than a few people on edge about this whole situation:  There's a 1 in 3,200 chance that the debris will actually strike a human earthling.

Personally, I think the possibility is so remote that it's not worth losing sleep over. But I can see how the circumstances surrounding this possible life-threatening event strikes at the core of people's anxieties -- rational or not.

Here's why this whole satellite-going-rogue business is so scary:

  • It's going to happen (fall to earth) and there's no way to prevent it.
  • It's unpredictable. No one can pinpoint the exact location of where it's going to land. Otherwise we can just draw an X at the specific coordinates and evacuate the area around that spot.
  • People are left defenseless. Unless we all can walk around with some impenetrable shield hovering over us then, yeah, we're sitting ducks.

Fortunately NASA does offer some semblance of reassurance. They've repeatedly reminded the public that throughout the history of plummeting space junk, no one has ever been hit. And since UARS was launched in 1991, the agency has enacted stringent safety requirements to avoid these kinds of scenarios.

"Now, they have to save enough fuel to either put the satellite in a graveyard orbit or guide it back in" to Earth in a controlled manner, Victoria Samson, Director of the Secure World Foundation, told SPACE.com. "That wasn't actually standard operating procedure back then."

In the meantime, NASA will continue to monitor the situation closely and provide constant updates along the way. There's even a website for users to track the satellite's location in real-time.

(via Space.com)

This post was originally published on Smartplanet.com