When scientists at the Joint Space Operations Centre at Vandenberg Air Force Base in California detect a potential collision between orbiting satellites and debris, they alert Nasa’s Goddard (unmanned missions) or Johnson (manned missions) space centres. Last year, Goddard handled eight collision-avoidance manoeuvres. Here’s how one of them played out.
29 MARCH: JSpOC scientists alert Goddard that Nasa’s R6,9 billion Fermi Gamma-ray Space Telescope faces a close encounter with Cosmos 1805, a defunct Soviet spy satellite, in seven days, on April 4.
30 MARCH: The updated forecast has the two objects passing the same point in space within 30 milliseconds.
3 APRIL: Fermi stows its delicate solar panels and antenna and orients itself to face the direction of orbit. It alters its orbit, accelerating with a 1-second blast from its end-of-life thrusters, and resumes normal operations within an hour.
4 APRIL: The conjunction arrives, and the satellite misses Fermi by nearly 10 km.