Retired spacecraft will reenter Earth's atmosphere with some risk to humans, NASA says

A retired NASA spacecraft poses minimal yet possible risk to people on the ground when it is expected to reenter Earth's atmosphere Wednesday after nearly 21 years in orbit.

The Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) spacecraft monitored solar flares and powerful coronal mass ejections in low orbit above the Earth from its launch in 2002 until it was decommissioned in 2018, according to an announcement from NASA.

RHESSI recorded more than 100,000 X-ray events during its career, which helped scientists learn more about the energy of solar flares, the government agency explained.

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The Department of Defense has predicted that the unused spacecraft will return into the atmosphere at approximately 9:30 p.m. EST on Wednesday, give or take 16 hours, NASA said.

NASA experts noted that there is approximately a 1 in 2,467 chance that someone can be harmed by the debris as the 660-pound spacecraft burns up during its descent.

Between 200 and 400 tracked objects enter Earth's atmosphere annually on average, according to the National Oceanic and Atmospheric Administration's National Environmental Satellite, Data and Information Service.

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Space debris has been accumulating around the Earth since the launch of satellite Sputnik 1 on Oct. 4, 1957, though most of it burns up upon reentry and most pieces land in the ocean.

One piece of space junk falls to Earth every day, according to data recorded over the past 50 years, though there have been no confirmed deaths or serious injuries as a result.

China drew criticism last month when a second-stage booster from one of its rockets burned up and disintegrated in an uncontrolled entry over Texas on March 8.

"This was an uncontrolled entry, meaning it was not steered, rather its orbit decayed and lowered naturally," U.S. Space Command said of the Chinese space debris. "This type of behavior reinforces the need for better international norms regarding high-risk controlled reentries."

Fox News' Julia Musto contributed to this report.