Swift (MIDEX 3, Explorer 84, Neil Gehrels Swift Observatory)

Swift (MIDEX 3) [NASA]

Swift is a first-of-its-kind multiwavelength observatory dedicated to the study of gamma-ray bursts. The main mission objectives are:

• Determine the origin of gamma-ray bursts.
• Classify gamma-ray bursts as well as search for new types.
• Determine how the blastwave evolve and interacts with the surroundings.
• Use gamma-ray bursts to study the early universe.
• Perform a sensitive survey of the sky in the hard X-ray band.

Swift carries three instruments:

• BAT (Burst Alert Telescope)
• XRT (X-Ray Telescope)
• UVOT (Ultraviolet and Optical Telescope)

During its nominal 2-year mission, Swift is expected to observe more than 200 bursts with a sensitivity ~3 times fainter than the BATSE detector aboard the Compton Gamma-Ray Observatory. Swift's Burst Alert Telescope will detect and acquire high-precision locations for gamma ray bursts and then relay a 1-4 arc-minute position estimate to the ground within 15 seconds. After the initial burst detection, the spacecraft will "swiftly" (approximately 20 to 75 seconds) and autonomously repoint itself to bring the burst location within the field of view of the sensitive narrow-field X-ray and UV/optical telescopes to observe afterglow. Swift will provide redshifts for the bursts and multi-wavelength lightcurves for the duration of the afterglow. Swift measurements will be of great interest to the astronomical community and all data products will be available to the public via the internet as soon as they are processed. The Swift mission will represent the most comprehensive study of GRB afterglow to date.

Swift remains fully operational, but orbital decay gives it a 50% chance of uncontrolled reentry by mid-2026, increasing to 90% by the end of 2026.

A mission to reboost the Swift observatory was launched in July 2026. The Link mission was to launch, rendevous and dock with the Swift observatory to raise its orbit and to prevent reentry of the still working observatory. Although the launch was successful, Link suffered attitude control problems and was found to be unable to perform the docking and re.boosting of Swift.