Satellite to fall out of sky, but probably not on you

Chunks of a 6-ton, bus-sized satellite are expected to fall out of the sky and land on Earth sometime this morning or early afternoon.

But don’t worry, the chances of you being hit are less likely than winning the lottery, according to a local aerospace engineer.

The 20-year-old Upper Atmosphere Research Satellite will be the biggest NASA spacecraft to fall from the sky in 32 years.

“Since 70 percent of the Earth is taken up by the ocean, the odds are very unlikely that any one person would be hit,” said Kira Abercromby, a Cal Poly aerospace engineering professor.

Abercromby worked at NASA’s orbital debris program office in Houston for eight years and has been following the satellite re-entry closely.

Abercromby said that space debris flies toward Earth on a daily basis, but most of it burns up in the atmosphere. In this case, 26 of the heaviest metal parts from the satellite are expected to reach Earth, the biggest chunk weighing about 300 pounds.

The satellite chunks are expected to land somewhere in the Pacific Ocean today. The odds that a human being will be hit by the debris is 1 in 3,200, NASA scientists have calculated.

But a randomly selected person of the 7 billion individuals inhabiting the planet faces a 1 in 21 trillion chance of being struck.

Abercromby said that older satellites weren’t designed with regard to how their re-entry might impact people living below. Now, however, satellites are designed to burn up in the atmosphere, or their propulsion can be controlled so they land in uninhabited areas.

The debris today could be scattered over an area about 500 miles long or wide. But given the planet’s geographical makeup, the chances of county residents needing to dive out of the way isn’t likely.

“I think, in this case, it will be interesting if we’re able to see a space debris shower here in San Luis Obispo, which is like a meteor shower, and could be seen during the day,” Abercromby said.

The only confirmed case of a person being hit by space junk was in 1997 when Lottie Williams of Tulsa, Okla., was grazed on the shoulder by a small bit of debris from a discarded piece of a Delta rocket. She saw a flash of light in the sky shortly beforehand.

“I told my students today that if they were hit by space debris, I’d give them an A,” Abercromby joked.

The Associated Press contributed to this story.