Weighing approximately 3,200 pounds (1,452 kg), the $500 million Swift satellite met its fiery end less than three months after a rescue spacecraft failed to move it into a higher orbit.
The US Space Force confirmed that Swift re-entered Earth’s atmosphere at 7:39 a.m. EST (1239 GMT). According to NASA, the observatory entered the upper atmosphere at approximately 22 times the speed of sound over Indonesia’s North Sumatra province, around 200 miles (322 km) north of the equator.
NASA had expected the intense frictional heat generated during re-entry to destroy most of the satellite well above Earth’s surface. However, some fragments were expected to survive the descent. The space agency reported no damage or injuries on the ground caused by falling debris.
The precise distance between the re-entry location and Medan, North Sumatra’s capital and largest city, was not immediately clear. Medan is home to approximately 2.5 million people, while the province has a total population of around 16 million.
Before the satellite's return, the US Space Force had assessed the danger to populated areas as very low, estimating the probability of anyone on Earth being harmed at one in 2,100.
Dean Sladen, an aerospace engineer at Britain-based industrial parts supplier Accu Components, had said before the re-entry that only a "handful of small, scorched fragments are expected to make it down, nothing recognizable as a telescope."
"Satellites this size re-enter the atmosphere regularly, and in nearly 70 years of spaceflight no one has ever been killed by falling debris," Sladen said in an email.
He also warned that the risk of an accident caused by falling space debris increases over the longer term, highlighting the growing importance of designing satellites to return safely to Earth.
NASA's Neil Gehrels Swift Observatory was primarily developed to investigate gamma-ray bursts, the most intense explosions of energy in the universe. Its multi-wavelength system featured three telescopes designed to observe these cosmic events.
Since its launch in 2004, Swift had expanded its scientific contributions beyond gamma-ray bursts. The observatory studied hundreds of supernova explosions, black holes tearing apart stars, stellar X-ray flares, asteroids and comets. Its observations contributed to approximately 7,000 published scientific papers.
Despite being designed for a two-year operational lifespan, Swift remained in service for nearly two decades. The observatory ceased operations on October 20 after spending months drifting towards orbital instability. It did not have its own propulsion system, making it difficult to correct its orbit as its altitude continued to decline.
In July, NASA partnered with Arizona-based startup Katalyst to launch a specially developed rescue spacecraft named LINK. The mission was designed to rendezvous with Swift, attach itself to the observatory and pull it into a higher, more sustainable orbit.
However, the rescue attempt encountered problems shortly after LINK reached space. The spacecraft began spinning uncontrollably, preventing it from carrying out the planned operation.
By mid-August, mission managers had abandoned the rescue effort, leaving Swift to continue its descent towards Earth.
The satellite's re-entry over Indonesia brought an end to a mission that had significantly expanded observations of gamma-ray bursts and several other astronomical phenomena. Its scientific legacy includes thousands of research papers, while its final descent has also drawn attention to the challenges of safely disposing of ageing satellites in Earth's orbit.
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