NASA’s Swift observatory is days from reentry, but where its surviving pieces will come down remains unknown, Space.com reports. Its declining orbit confines the possible landing area to roughly 21 degrees north or south of the equator, a region made up mostly of open ocean.
Swift spent more than 20 years contributing substantially to knowledge of the cosmos, but its orbit is now deteriorating too quickly for it to recover. NASA launched an effort to save it in July, hoping to keep it operating longer. The plan called for a spacecraft designed and built by startup Katalyst Space Technologies to lift Swift into a more stable, higher orbit.
The rushed mission didn’t succeed. Several months into the flight, the Katalyst spacecraft started tumbling uncontrollably, leaving Swift without the orbital boost it needed.
NASA attributed the faster descent to increased atmospheric drag after Swift resumed science observations at the last minute. In its October 23 update, the agency said the observatory had begun “to sink rapidly.” Its altitude had dropped to just 171 miles by mid-October, when it was “no longer able to compensate for the effects of the increased drag.”
Only fragments are expected to make it through reentry; most of the observatory should burn up. Darren McKnight, senior technical fellow at LeoLabs, told Space.com that the surviving debris was unlikely to endanger anyone on the ground.
“It is unfortunate that Swift was not ‘reorbited,’ but from a reentry hazard perspective it is a small portion of the stuff coming back in,” McKnight said.
The parts most likely to reach the ground are Swift’s pointing equipment and its tougher optical components. Dean Sladen, quality manager at aerospace parts supplier Accu Components, told Space.com the probable survivors were its “six heavy reaction wheels, the spinning flywheels it used to aim itself, along with tougher telescope parts such as lenses and mirrors”.
Swift isn’t expected to cause damage on Earth’s surface. Still, it accounts for only one spacecraft in the continuing stream of space debris falling back to the planet.
As more debris accumulates in orbit, the amount coming down through the atmosphere grows year by year. Examples include stray Chinese rocket stages and long-missing Soviet satellites.
