A dead NASA satellite likely crashed uncontrollably into Earth yesterday

No need to panic, NASA said prior to the RHESSI satellite reentry.
Chris Young
An artist's impression of NASA's RHESSI satellite.
An artist's impression of NASA's RHESSI satellite.


A retired 660-pound (300 kilograms) NASA satellite is thought to have crashed into Earth yesterday, April 19.

NASA and the U.S. Department of Defense estimated that the space agency's Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) satellite performed an uncontrolled reentry through Earth's atmosphere at some point around 9:30 p.m. EDT on Wednesday, give or take roughly 16 hours.

Harvard astronomer and astrophysicist Jonathan McDowell pointed out on Twitter that "RHESSI should have reentered by now. No new info from Space Force yet, though."

NASA's RHESSI reenters Earth's atmosphere

NASA's RHESSI satellite studied the Sun from Earth's orbit for almost two decades — it was launched in 2002 and was decommissioned in 2018 — before finally reentering our atmosphere this week.

RHESSI was launched to orbit by a Pegasus XL rocket and it was designed to study solar eruptions and coronal mass ejections (CMEs). To do so, it used a spectrometer that detected high-energy X-rays and gamma rays before they could be blocked by our atmosphere.

Over its lifetime, the satellite observed more than 100,000 X-ray flashes and it also helped astronomers to gain a better understanding of the Sun's shape.

NASA explained in a blog post that the dead satellite will have mostly burned up while reentering Earth's atmosphere. It has so far not disclosed the reentry location, though it has stated that the risk of anyone being hurt is low. "The risk of harm coming to anyone on Earth is low — approximately 1 in 2,467," the space agency wrote.

The growing problem of space debris

The reentry of RHESSI is one of several high-profile reentries that have occurred in recent months and years. China's space program has been criticized, for example, for allowing four of its Long March 5B rocket boosters to fall uncontrollably to Earth between 2020 and 2022.

Debris from a SpaceX Falcon 9 rocket launch, meanwhile, rained down over a sheep farm in Australia last year.

Space debris is a growing problem, with international space agencies keeping track of more than 30,000 pieces of space junk in orbit.

One group of astronomers has even organized against the surge in satellite launches, mainly due to SpaceX's Starlink satellite mega-constellation. They warn that such a large amount of satellites and space debris in orbit hinders science and could also lead to disastrous consequences, such as Kessler Syndrome.

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