NASA’s Neil Gehrels Swift Observatory is expected to re-enter the atmosphere around 3:30 a.m. Eastern on Wednesday, Nov. 4, NASA says, citing a U.S. Space Force prediction. That estimate has an uncertainty of 11 hours either way, so it could happen any time from Tuesday afternoon to Wednesday afternoon.

Should Canadians worry?

No. Swift weighs about 3,200 pounds (roughly 1,450 kg), and NASA expects most of it to burn up. Any pieces that survive can only land between 20.6 degrees south and 20.6 degrees north latitude, a band around the equator that’s mostly ocean and lies well south of Canada. NASA puts the chance of anyone anywhere being hurt at about 1 in 2,100. You can follow updates on NASA’s Swift blog.

Why it’s coming down

Swift has no engine, so drag from the thin upper atmosphere slowly lowered its orbit. Solar activity heated and expanded the atmosphere, which made the drag stronger than expected, Spaceflight Now reports.

NASA tried to save it. It paid Katalyst Space $30 million USD (about $42 million CAD) to send a robotic spacecraft, LINK, to grab Swift and push it higher. LINK launched in July on the last Pegasus XL rocket, but a power switch tied to its orientation control failed about a week later, and NASA called off the capture in August. Swift made its last observation on Oct. 20.

What it did

Swift was built for a two-year mission and lasted nearly 22. It was designed to catch gamma-ray bursts, which NASA calls “the most powerful explosions in the cosmos,” and to swing around quickly and alert other telescopes when one went off. Spaceflight Now tallies its record:

  • more than 2,000 gamma-ray bursts and more than 1,400 supernovas observed
  • about 12 terabytes of data, cited in roughly 7,000 scientific papers
  • the first afterglow from a short gamma-ray burst, in 2005
  • a 2008 burst 7.5 billion light-years away that was briefly bright enough to see with the naked eye

Why it’s worth your time: You can follow a famous spacecraft’s last day as it happens, with no risk to anyone here. It’s also a reminder that old satellites in low orbit don’t stay up forever, and that rescuing one in space is still very hard.