The observatory, which transformed the study of gamma-ray bursts and other high-energy cosmic events, was forced to shut down after atmospheric drag accelerated its descent. The spacecraft could no longer compensate for the increasing drag and entered safe mode on October 20, when it had reached an altitude of just 275 kilometres.
Following the development, the operations team at Pennsylvania State University in University Park sent a command that effectively ended Swift’s mission and prepared the spacecraft for its eventual atmospheric re-entry.
Like other satellites operating in low Earth orbit, Swift encounters atmospheric drag as it travels through the thin outer layers of Earth’s atmosphere. Increased solar activity recently intensified the effect, causing the observatory to lose altitude faster than anticipated.
A high-risk, fast-turnaround servicing mission intended to boost Swift’s orbit ended in August without an attempt to raise its altitude.
Before the servicing mission, Swift had temporarily paused its science observations to minimise atmospheric drag and extend its time in orbit. The team pursued the orbital boost mission during this period, but after it concluded, the spacecraft resumed observations and collected data on hundreds of targets.
These included remnants of stellar explosions, active supermassive black holes in distant galaxies and comets within our own solar system. However, restarting science observations increased atmospheric drag on the spacecraft, accelerating its descent once again.
A Lasting Legacy of Cosmic Discoveries
Launched in November 2004, the Neil Gehrels Swift Observatory was designed to detect gamma-ray bursts, brief but extraordinarily powerful explosions associated with cataclysmic events such as the collapse of massive stars and the mergers of compact stellar objects.
Its ability to rapidly identify these bursts and coordinate observations across multiple wavelengths enabled scientists to investigate their origins and study the extreme environments in which they occur.
Beyond gamma-ray bursts, Swift contributed to research on black holes, supernovae, stellar flares and other transient astronomical phenomena. Its observations helped astronomers investigate events unfolding across the universe, ranging from nearby stars to distant galaxies billions of light-years away.
Although the observatory’s science operations have ended, its extensive data archive will continue to provide valuable information for researchers studying high-energy cosmic events and other astronomical phenomena.
As Swift descends towards Earth, its mission is approaching its final stage with atmospheric re-entry. Most spacecraft components are expected to experience intense heating during the process, although the precise fate of individual components will depend on the conditions of re-entry.
Swift’s operational mission will therefore end after nearly two decades of observations, but the scientific record it leaves behind will continue to support research into some of the universe’s most energetic and transient events.
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