The Difficult Search for Dangerous Space Junk
By Jon Sindreu, Nov. 11, 2022, WSJ

Officials are getting spooked by all the extra clutter. In orbits lower than 375 miles, re-entry into the Earth naturally happens after a few years, but these will be crowded by Starlink alone. Many players will need to go higher, and set up “deorbit”
plans that regulators—and sustainability-minded investors—find solid.

Companies’ requirement to keep enough fuel in reserve on their satellites to navigate them down into the atmosphere, or higher into a graveyard orbit, is likely to start getting enforced. But a percentage of them will break down, creating demand for
trash-removal companies. Also, there are financial benefits to sending a robot up there: It can extend the lifespan of a satellite that has run out of fuel, holding it in place with its own propulsion system until decommissioning time.

That still leaves satellite operators and trash-removal firms with a fundamental problem: Their information on an object, including position, shape and mass, involves a lot of guesswork.

Most observations come from ground radars, which firms access through government agencies like the U.S. Space Command. But this data is often several hours old and can miss the mark by miles, so satellites and stations can’t swerve out of the way of
approaching debris with full confidence. For removal missions, this will mean accommodating extra fuel and allowing for the possibility that an object is spinning faster than estimated, making it impossible to grab.

And this is for pieces larger than 10 cm, which according to the ESA number above 30,000 and are the only ones visible from Earth. Mathematical models suggest there are a million additional fragments measuring between one and 10 centimeters, and 100
million even smaller than that, often traveling many times faster than a bullet. Yet the ISS’s “Whipple shield” can be pierced by anything larger than one centimeter.

“We have a catastrophic 9-cm gap in our knowledge,” said Alex Fielding, CEO of Privateer Space, a venture he set up last year with Apple co-founder Steve Wozniak. “If this was how it was in traffic, you’d never want to cross the street.”
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OBJECTS IN ORBIT AROUND THE EARTH
Dead satellites: 2,050
Functioning satellites: 6,800
Debris tracked by surveillance Networks: 32,560
Estimated debris greater than 10 cm: 36,500
Estimated debris between 1 cm and 10 cm: 1,000,000
Estimated debris between 1 mm and 10 cm: 130,000,000 -------------------------------
Privateer’s solution is to get more data. Its Wayfinder application combines both official sources and observations from satellite operators to create a near-real-time “Google Maps of space” that companies can use to narrow margins of error.
Wayfinder was recently updated with a collision-assessment tool, and a partnership announced last week with telescope-maker Celestron will allow amateur astronomers at home to feed into it. Privateer is planning to establish a network of monitoring
satellites too.

However, ClearSpace CEO Luc Piguet warns that, while improving space maps to include big chunks of debris will be valuable, providing more data on smaller objects will prove much harder and comes with its own risks. “If you don’t know with a high
level of certainty where the object is, you may do maneuvers that aren’t really required,” he said.

However the debates over space trash continue, any company aspiring to profit from the final frontier will need to better understand the risks of the terrain. The alternative is a true tragedy of the commons that ends a promising new space age before it
has really begun.

https://www.wsj.com/articles/the-difficult-search-for-dangerous-space-junk-11668162607

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