NASA’s RHESSI spacecraft set to reenter Earth’s atmosphere after 21 years in orbit

The RHESSI spacecraft, retired by NASA, is set to reenter Earth's atmosphere in April, nearly two decades after its launch.[0] The spacecraft was launched in 2002 from aboard an Orbital Sciences Corporation Pegasus XL rocket with a mission to image the high-energy electrons that carry a large part of the energy released in solar flares.[1] RHESSI was equipped with an imaging spectrometer, which recorded the sun’s X-rays and gamma rays.[2] From its low-Earth orbit, the satellite captured images of high-energy electrons that carry a large part of the energy released in solar flares, providing vital data for scientists to understand the physics behind these energetic events.[3] 

With nearly 100,000 X-ray events documented, RHESSI's mission enabled researchers to scrutinize the active particles within solar flares.[4] With over 100,000 X-ray events documented, RHESSI has unearthed essential insights into solar flares and the consequential coronal mass ejections, which discharge colossal amounts of energy into the solar atmosphere within minutes.[5] RHESSI also stepped outside its primary mission to help scientists improve their measurements of the sun’s shape, and showing that terrestrial gamma-ray flashes – bursts of gamma rays emitted from high in Earth’s atmosphere over lightning storms – are more common than previously thought.[4] 

NASA decommissioned RHESSI in 2018 after 16 years of operations due to issues with the spacecraft's communication.[6] The risk of harm to anyone on Earth due to its reentry is estimated to be low, at 1 in 2,467. NASA anticipates that the majority of the spacecraft will incinerate while passing through the atmosphere, while certain parts are predicted to withstand reentry.[7] NASA did not reveal the exact spot of the object's impact on Earth due to uncertainty. However, the probability of it posing a threat to human life is minimal, with odds of around 1 in 2,467.

Among the vast swarm of space debris orbiting our planet, RHESSI was merely a single component. Presently, over 30,000 fragments of space junk are being monitored by space surveillance networks. The reentry of RHESSI into Earth’s atmosphere highlights the growing problem of space debris, with international space agencies keeping track of more than 30,000 pieces of space junk in orbit. Satellites and space junk can cause damage to spacecraft and pose a risk to astronauts in orbit. 

The reentry of RHESSI also serves as a reminder of the importance of studying the sun and its effects on Earth. Solar flares and coronal mass ejections can have effects on Earth, including the disruption of electrical systems.[8] Understanding the underlying physics of these events is crucial for predicting their impacts and developing strategies to mitigate any damages they may cause. RHESSI played a vital role in advancing our understanding of these energetic events during its 16-year mission.[0]

0. “A disused satellite is crashing back down to Earth and it could hit us” indy100, 19 Apr. 2023,

1. “NASA says 660-pound satellite heading to Earth; chances low it will hit someone” WHIO, 19 Apr. 2023,

2. “Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) Spacecraft To Reenter” Space Ref, 17 Apr. 2023,

3. “Defunct NASA spacecraft returns to Earth after 21 years” CNN, 19 Apr. 2023,

4. “NASA: Spacecraft reenters atmosphere Wednesday; chance it harms anyone 1 in 2,467”, 18 Apr. 2023,

5. “NASA says risk of harm from falling satellite is low” The Hill, 19 Apr. 2023,

6. “660-pound NASA spacecraft is hours away from crashing into Earth after more than a decade studying the sun” CBS News, 19 Apr. 2023,

7. “Defunct NASA Satellite Disintegrates Over Northern Africa” Gizmodo, 20 Apr. 2023,

8. “Fireball Finale: RHESSI's Fiery Reentry After 16 Years of Solar Observation” SciTechDaily, 18 Apr. 2023,

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