Swift normally slews rapidly to observe transient targets such as gamma ray bursts with its suite of telescopes. Principal investigator S. Bradley Cenko at NASA's Goddard Space Flight Center said that while the Burst Alert Telescope will continue detecting gamma ray bursts, the spacecraft will no longer slew to follow up these events with its other instruments. This change limits Swift's ability to carry out multiwavelength observations but helps preserve the observatory for a future reboost.
Enhanced solar activity heats Earth's upper atmosphere and causes it to expand, increasing drag on spacecraft in low Earth orbit and slowly lowering their altitude over time. Swift has operated in orbit for about 21 years, and its average altitude has been steadily declining as a result of this atmospheric drag. Many missions eventually reenter the atmosphere at the end of their lifetimes, but NASA is pursuing a different path for Swift.
The agency has contracted Katalyst Space Technologies of Flagstaff, Arizona, to carry out a mission that will boost Swift into a higher orbit. The planned servicing effort aims to extend the observatory's scientific lifetime while demonstrating an orbital reboost capability that could be applied to a broader class of spacecraft. NASA sees satellite servicing and orbit-raising as an important step toward maintaining valuable space assets and reducing the need for replacement missions.
To maximize the chances of a successful reboost, Swift's average altitude must remain above about 185 miles, or roughly 300 kilometers. As of early February the spacecraft's orbit had already dropped below about 250 miles, around 400 kilometers, prompting the team to modify operations to slow the descent. By keeping the observatory in a drag-minimizing attitude and limiting slews, the mission team is working to preserve sufficient altitude for the upcoming servicing flight.
Mission planners anticipate that the reboost spacecraft will launch in the summer. Cenko said the team is transitioning Swift's operations now to provide the widest possible margin for the servicing mission. If successful, the boost to a higher orbit will allow Swift to continue its role in rapidly detecting and studying changes in the high energy universe.
Swift studies gamma ray bursts, which are among the most powerful explosions known, along with other energetic cosmic phenomena. The observatory has provided nearly daily observations of these fleeting events and has helped scientists investigate their origins and environments. Extending the mission's life would enable continued rapid-response observations and maintain a key asset for time sensitive astrophysics.
NASA encourages the public and scientific community to follow developments as the reboost mission approaches. The agency notes that the Swift mission remains an important part of its portfolio for studying the dynamic universe, even while operations are constrained to support orbital preservation. Additional information about the observatory and its science is available through the mission's web resources.
Related Links
NASA Neil Gehrels Swift Observatory
Stellar Chemistry, The Universe And All Within It
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