Heads up! Soviet-era probe to re-enter atmosphere this week, could make it to the surface

Fifty years ago, the former Soviet Union launched a probe to Venus. Except it never made it. Instead, the rocket engines shut off too early, and the probe was stuck in Earth orbit. Now, it's making its way back to Earth.

Venera 8, launched on March 27, 1972, was one of a pair of probes designed to study the surface of Venus. Four days later, it launched the second probe, which, after it was stuck in Earth orbit, was catalogued as Kosmos 482.

The probe is estimated to be around half a tonne and is expected to re-enter Earth's atmosphere around May 10, give or take a day and a half, according to a recent update from Marco Langbroek, who has been tracking the object for quite many years.

What's most interesting is that this lander (or re-entry capsule) was built to survive Venus's punishingly dense atmosphere. So, unlike rockets that we see re-enter Earth's atmosphere and break up (think Starship's recent mishaps), it's unlikely that this will happen with Kosmos 482.

But it's not a reason to panic, said Jonathan McDowell, an astrophysicist with the Harvard–Smithsonian Center for Astrophysics's Chandra X-ray Center.

"So you've got basically something the size of a small car plowing into the Earth at [240 kilometres] an hour," he said. "Let's not overstate it, right? It's not, like, evacuate the city kind of thing. But it's like a small plane crash or something like that: You don't want to be standing right underneath."

McDowell is well known for his extensive satellite- and debris-tracking database. In fact, it was he who first postulated back in 2000 as to what Kosmos 482 could be.

"Back in 2000, I was going through every object in the NORAD space object catalogue, trying to figure out what each object was, all 25,000 of them as there were at the time. And I came across this one and went, 'OK, this is something unusual.'"

It wasn't widely known what the object was at the time because the U.S. and the Soviet Union were in the midst of the Cold War, and many things were kept secret.

As for where it might crash, Langbroek recently told Spaceweather.com, "With an orbital inclination of 52 degrees, the Kosmos 482 descent craft could come down anywhere between 52 degrees north and 52 degrees south latitude," said Langbroek.

That covers much of the world at south and mid-latitude.

However, McDowell said that it's more likely to come down in the ocean, since Earth is mostly covered by water.

"The odds are … it'll be in the ocean or in an empty area. But there's ... some decent chance that it'll come down in an area where there are people, though, even in populated areas, most populated areas are not like people packed side by side. And so the chances are that it won't hurt anyone."

This is a somewhat familiar story.

In 1979, NASA's empty Skylab space station re-entered Earth's atmosphere after a few failed attempts to keep it in orbit. Much of it did burn up in the atmosphere, however debris fell over the Indian Ocean and in parts of Australia.

The big differences between the two are that Skylab wasn't built to withstand Venus' dense atmosphere, and it was 70 tonnes, not half a tonne.

Now, the belief is that Kosmos 482 is the descent craft, but it's not known for certain.

The launch consisted of several elements, including the rocket stage and the service module (which provides power among other things). The service module was believed to have re-entered Earth's atmosphere in 1981.

McDowell said that there's a possibility that what was labelled as the service module, which re-entered the atmosphere in 1981, was actually the lander and that Kosmos 482 could instead be the service module. In that case, it would most likely burn up in the atmosphere.

However, he said based on the size and density of the current object labelled as Kosmos 482, it's more likely to be the Venus lander.

Astrophotographer Ralf Vandebergh imaged Kosmos 482, which showed some sort of protuberance. He speculated that it could be the parachute, but that will likely never be confirmed as it will burn up in the atmosphere upon re-entry.

As this is an uncontrolled re-entry, it's difficult to determine exactly where or when this will re-enter Earth's atmosphere.

"Because we don't know when it's going to re-enter to within a few hours at best, even the day before, we won't be able to say, 'Here's where it's going to come down,'" McDowell said. "We'll have to find out after the fact."