The sky-watching world was thrown into a spin this week with multiple reports of space debris falling onto Australian farms.
Experts say as more satellites go up, it is only logical more will come down.
- The biggest pieces of space junk seen in Australia since 1979 were recently found in NSW
- Researchers in Queensland are using wind tunnels to predict where space junk could land in the future
- Experts say there are likely many more pieces of space junk in Australia, but the likelihood of finding them is “pretty small”
Mark Rigby, a former curator of the Sir Thomas Brisbane Planetarium, agrees.
“The number of operational satellites has almost doubled in the last 18 months. That’s phenomenal,” he said.
But if you’re planning a “space debris” hunt, do not get your hopes up.
“Fortunately, most of our earth is covered in ocean. So, most space junk actually comes down harmlessly, and a lot of space junk vaporises before it even reaches the surface of our planet,” Mr Rigby said.
But sometimes it lands in a cow paddock.
James Stirton discovered wreckage from a rocket on his family property in south-west Queensland, near Quilpie in 2008.
At the time, he and his wife Sue took calls from all over the world and hosted visits from researchers keen to inspect the round fuel cell that landed near his cattle in the scrub.
“They checked it over for radiation, and wanted to take it away, and I said, ‘No, it’ll stay here’,” he explained.
The space wreckage, officially named 2006-047-C, lived in a farm shed until the couple retired.
It is now on permanent display at Charleville’s Cosmos Centre.
Ever the pragmatic farmer, Mr Stirton said his discovery did not lead to any further space-craft exploration on his property.
“It was during the drought years, so we had plenty of other things to do,” he said.
“And I figured it’d only happen once in my lifetime, so no, I never thought I’d find any more space junk.”
But he did.
“A few years later we found another one,” he said.
“Actually, I don’t think we’ve ever told anyone about that second find,” Ms Stirton laughed.
Serious area of study
A specialist project at the University of Southern Queensland was launched earlier this year focusing on space junk.
“We’re starting to see more and more of this stuff happening,” Fabian Zander, senior research fellow at the University of Southern Queensland, said.
“I’d like to hope that there’s not too many more [incidents] like the SpaceX one… but we need a better understanding of the demise and the dispersion of things that re-enter the atmosphere.”
He said while most controlled re-entries aim for the “space graveyard” in the South Pacific, some non-functional satellites could come down anywhere.
“Even the impact of the sun shining onto the object can change the force and the trajectory of it,” he explained.
“The Earth’s atmosphere expands and retracts slightly depending on the weather.
“When something’s orbiting the upper reaches of the atmosphere the effect is marginally different depending on the particular atmospheric conditions, and that can’t be predicted with any certainty at this stage.”
But he said there was no need to worry about getting hit by “zombie” satellites when you stepped outside.
“There’s only ever been one person that’s been hit by space junk,” he said.
“A lady named Lottie Williams in the USA got hit by a piece on her shoulder, and it didn’t hurt her at all.”
Space junk hunting we will go?
Mr Rigby said the recent findings might inspire people to go hunting for debris, but the chances of finding something were “pretty small”.
“Even if you use satellite imagery to find those Skylab pieces that came down in 1979, that are no doubt still out there, you’re trying to find things that might be a meter across — or even smaller — in a vast country.
“So, I’d say good luck to you.”
I have also cautioned on the possible hazards.
“There may be space junk that’s come down that still has some toxic material. With these things, it’s quite often best to contact authorities if you found something you think is space junk.
“Get it checked out first before you go handling it.”
And if you find something, don’t get too attached to it.
“It still belongs to the originating country,” Mr Rigby said.