A dead NASA satellite will plummet to Earth on Friday (Sept. 23), and while the
NASA"s Upper Atmosphere Research Satellite, or UARS, is set to make an uncontrolled re-entry into Earth"s atmosphere on Friday. However, it is still too early to tell exactly where the 6.5-ton spacecraft will fall. Scientists will likely have a much better idea of where the debris will land about two hours before the impact, NASA officials said.
But, NASA was able to rule out
"Re-entry is expected sometime during the afternoon of Sept. 23, Eastern Daylight Time," agency officials said in a statement. "The satellite will not be passing over
In the meantime, NASA and the U.S. Air Force will be closely monitoring the satellite and its decaying orbit.
"With re-entry we"re always interested in day-by-day and hour-by-hour details," Mark Matney, a scientist with NASA"s Orbital Debris Program Office, told SPACE.com. "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."
Current predictions of the potential impact zone cover a giant swath of the planet — anywhere between the latitudes of northern
"It"s partly a matter of not knowing enough," said Ray Williamson, executive director of the Secure World Foundation, an organization dedicated to the peaceful use of outer space. "The shape of the structure is not perfectly spherical, so when it heats up and starts to break up, it will break into odd pieces. Once it begins to break up, then they can get a better sense of where this is roughly going to hit."
Scientists at NASA"s Orbital Debris Program Office estimate that at least 26 large pieces of the bus-size satellite will endure the scorching heat of re-entry. Approximately 1,170 pounds (532 kilograms) of material are expected to reach the ground, NASA officials said.
These pieces of debris will likely be scattered over a 500-mile (804-kilometer) long path. But agency officials have been quick to stress that there is very little chance that satellite chunks will smash into towns or cities.
Instead, it"s much more likely that the debris will fall over water or remote, uninhabited areas, NASA officials said.
"There"s always a concern," Matney said. "But, populated areas are a small fraction of the Earth"s surface. Much of the Earth"s surface has either no people or very few people. We believe that the risk is very modest."
For comparison, when NASA"s space shuttle
NASA has calculated the odds of anyone anywhere in the world being hit by a piece of the UARS satellite at 1 in 3,200. But, the chance that you personally will get hit is much more remote, on the order of 1inseveral trillion, Williamson said.
Still, if anyone happens to stumble upon a piece of the defunct satellite on the ground, agency officials stress that for safety and legal reasons, it is best to leave the material where it is, and alert the authorities.
"If you find something you think may be a piece of UARS, do not touch it," NASA officials said. "Contact a local law enforcement official for assistance."