An old NASA space telescope is expected to crash back to earth Wednesday after a failed rescue attempt — nearly 22 years after it was launched.

The Swift Observatory — a 3,200-pound orbiting installation — will fall from the sky around 3:30 a.m. EST, give or take 11 hours, the US Space Force predicts.

Most of the telescope will likely burn up in the atmosphere, but a handful of pieces made of denser-than-lead tungsten and some mirror parts could survive reentry, according to NASA’s Brad Cenko, the mission’s chief scientist.

Any intact pieces will likely land in the ocean — but the re-entry window for stray wreckage spans every continent outside Antarctica, and possible landing sites include most of the US and China and nearly all of Australia and Africa.

Still: “The risk of harm coming to anyone on Earth is unlikely — approximately 1 in 2,100,” said NASA in an announcement.

Swift blasted off on Nov. 20, 2004, to search for some of the biggest explosions in the universe: gamma ray bursts and supernovas.

Its cosmic cremation has the Swift team mourning, yet full of gratitude for the observations the telescope made during its 22 years in orbit. 

“We’ve known this day would come since before Swift was launched. At least in low-Earth orbit, what goes up must come down. And that end is catastrophic,” said Pennsylvania State University’s John Nousek, an astronomer who led the control team.

Intense solar activity over past few years dragged Swift down faster than usual.

NASA hired Katalyst Space a year ago to mount a rush rescue.

But the company’s three-armed robot named Link ran into trouble after Launching in July and got no closer than 7 miles to 9 miles (12 kilometers to 15 kilometers) to the telescope. Link plunged back to Earth in September.

Swift resumed observations once the rescue attempt was called off, discovering even more gamma ray bursts and other ultrahigh-energy events. But by late October, the telescope was too low to remain steady for observations, and its systems were shut down.

Its final tally: more than 2,000 gamma ray bursts and 1,400 exploding stars, not to mention a slew of comets, asteroids and star-shredding black holes. The telescope’s superpower was its ability to swivel swiftly — thus its name — toward erupting celestial events.

NASA considered Swift a first responder for the Hubble and Webb space telescopes and others that would follow its alerts and provide deeper investigations.

Scientists are still figuring out how to fill the gap.

With Post wires