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After over two decades of service, a retired American satellite is set to crash back to Earth as it re-enters the dense atmosphere surrounding our planet. The Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) was retired in 2018 and has since been in a gradually decaying orbit. Launched in 2002, RHESSI was responsible for observing solar flares and coronal mass ejections from its low-Earth orbit position.

As the 300-kilogram satellite re-enters Earth’s atmosphere on Wednesday, the US Defense Department is keeping a close eye on its orbit and trajectory. According to NASA, most of the spacecraft is expected to burn up during re-entry, with only a few components likely to survive. The risk of any harm to Earth’s inhabitants is low, with the odds estimated at 1 in 2,467.

RHESSI was originally launched into low Earth orbit aboard the Orbital Sciences Corporation Pegasus XL rocket and remained functional until its decommissioning in 2018. Throughout its operational life, the satellite provided valuable insights into solar flares and their related coronal mass ejections, which can release enormous amounts of energy into the solar atmosphere and affect our planet. RHESSI documented a wide range of solar flares, from minuscule nano flares to colossal super flares that are thousands of times larger and more powerful.

NASA states that RHESSI recorded over 100,000 X-ray events during its mission, enabling scientists to study the energetic particles in solar flares. The data gathered by the imager helped researchers understand the frequency, location, and movement of these particles, shedding light on where they were being accelerated. The satellite was ultimately decommissioned due to communication difficulties.

The latest projections predict that RHESSI will re-enter Earth’s atmosphere at 7:00 am on Wednesday, with an uncertainty of +/- 16 hours. The spacecraft’s impending crash serves as a reminder of the growing congestion and potential dangers in Earth’s orbit. As more debris accumulates in orbit, the risk of collisions and the subsequent creation of additional space junk increases, potentially leading to the feared Kessler Syndrome, which could significantly hinder our ability to explore and utilise space.