Satellite killers: Meteoroids vs. space junk

STANFORD (US) — Billions of tiny meteoroids do more damage to satellites and other spacecraft than all the space junk orbiting Earth, according to new research.

At any given time there are somewhere in the neighborhood of 22,000 pieces of debris 10 centimeters or larger zipping along in orbit at speeds of seven kilometers per second, according to the U.S. Air Force.

But Sigrid Close, an assistant professor of aeronautics and astronautics at Stanford University, says minuscule particles weighing on the order of a billionth of a gram or less and measuring less than one five-hundredth of an inch can—and do—damage spacecraft, at roughly once per year—a number larger than that associated with space debris.

Close is a member of a 13-person panel that produced a National Research Council report warning of the dangers of space junk and recommending ways to deal with it.

“One of the issues we raised was that everyone is focused on the impacts of the larger particles and nobody is looking at the mechanism for electrical failures and anomalies associated with small, fast particles, even though it appears as though this is how satellites are failing,” Close says.

“This would occur from very fast-moving particles and could happen from particles as small as a nanogram. Why are spacecraft having anomalies during high-speed meteor showers?”

Graduate students Theresa Johnson and David Strauss worked with Ivan Linscott, a senior Stanford researcher with Close’s team, conducting an experiment to try to detect radio frequency emission from plasmas, which are produced when a meteoroid or debris particle hits a spacecraft.

Their preliminary results suggest that radio frequency emissions are indeed produced when a particle weighing less than a billionth of a gram and traveling upward of 20 kilometers per second smacks into a spacecraft and produces ionization.

“Now the question is, what is the mechanism behind this? Can these radio frequency emissions cause a satellite to fail or cause an anomaly on the satellite even when you never see a momentum transfer?” Close asks.

In other words, can a particle too tiny for its impact to be felt by a spacecraft still cause the spacecraft to malfunction? Stay tuned.

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