On Tuesday, Feb. 10, and for the first time, two intact satellites collided in orbit. The wreck created a “massive” debris field 491 miles over Siberia and 270 miles over the NASA international space station.
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An Iridium commercial communications satellite, launched in 1997 and weighing 1,235 pounds, collided with a one-ton 1993 Russian Kosmos 2251 military satellite which appeared to be out of control.
NASA believes it will take several weeks before they have a full assessment of the damage.
“We knew this was going to happen eventually,” said Mark Matney, an orbital debris scientist at Johnson Space Center in Houston,В in an interview with the Associate Press.
Litter in orbit is now a greater hazard to space shuttle flights than lift-off or re-entry. В According to Nicholas Johnson, though, we should probably worry more about the Hubble Telescope. Johnson, an orbital debris expert at the Houston space center, said the risk of damage from the collision is greater for the Hubble Space Telescope and Earth-observing satellites, which are in higher orbit and nearer the debris field.
NASA estimates that of the 6,000 satellites launched since 1957, approximately half remain in operation. In addition, about 18,000 pieces of man-made objects orbit the earth as space litter. Most are the result of old satellites breaking up, long after they ceased to function.
And who is counting these floating bits? The military, saysВ The Washington Post:
The military can track space debris as small as a baseball. The U.S. Strategic Command monitors 18,000 distinct pieces of debris, according to Reggie Winchester, spokeswoman for the command. That number will jump by at least 600, the preliminary estimate for the number of pieces from Tuesday’s collision.В
Even a very small object packs tremendous kinetic energy at orbital velocities, which are on the order of 17,500 mph. Humphries said the space station has “bumpers” designed to shatter an object into tiny pieces before it can penetrate the pressurized interior.В
Said Humphries: “It gets down to probabilities. Space being very big, these pieces of debris being very small, the odds are very high that they’re not going to collide.”