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NASA's Fermi Spacecraft Dodged a Defunct Russian Satellite

Posted by Soulskill on from the evasive-maneuvers dept.

g01d4 writes "On March 29, 2012, NASA scientists learned that the space agency's Fermi Gamma-ray Space Telescope was headed for a potential conjunction (close approach) with Cosmos 1805, a defunct Russian satellite from the Cold War era. The team knew that the only way to move Fermi would be to fire thrusters designed to move the spacecraft out of orbit at the end of its operating life. On April 3rd, shortly after noon EDT, the space agency fired all thrusters for one second. When it was over, everyone involved 'just sighed with relief that it all went well.' By 1 p.m., the spacecraft had returned to its mission."

5 of 47 comments (clear)

  1. Bad headline by MasseKid · · Score: 1, Informative

    Dodged evidently doesn't mean it was going to hit it and they moved it out of the way. It was actually a "close approach" as stated in the summary (gotta love sensationalism, right?). Except, close approach actually means within 700' of the defunct satellite, which really isn't all the close at all.

    1. Re:Bad headline by DougOtto · · Score: 5, Informative

      From TFA:

      Though Fermi was expected to miss Cosmos by several-hundred feet, NASA scientists knew from experience that forecasting spacecraft positions a week in advance isn’t an exact science. For example, Iridium 33 and Cosmos 2251 collided in 2009 even though they were predicted to miss each other by approximately 1,900 feet. This was the first known satellite-to-satellite collision.

      --
      Solving Unix problems since 1989...
    2. Re:Bad headline by X0563511 · · Score: 5, Informative

      If there was any debris from the Cosmos (either directly from it, or from interactions with other junk or such) could be within that area.

      Our radar is not good enough to make it safe enough to pass by that closely.

      --
      For large sets, this will be our guide even unto death, for the LORD will work for each type of data it is applied to...
    3. Re:Bad headline by Anonymous Coward · · Score: 2, Informative

      700' is ridiculously close when you're going miles per second and the Earth's atmosphere is constantly changing, changing each object's orbits by similar amounts regularly due to drag.

      Heck, if the RADAR producing the data has a couple of microseconds of jitter in it's clock, the propagation estimates could be off by that amount....Basically, 700' is pretty close to the noise of our estimations for orbital objects like this, and it's just better to be safe than sorry. Not to mention, who knows what small pieces could have broken off of that satellite and be orbiting nearby it....

  2. Re:Orbital Envoirment Protection Agency.... by Anonymous Coward · · Score: 3, Informative

    If you want to be pedantic, no. "Geosynchronous" means that it has a 1-day orbital period but does not specify the inclination or eccentricity of that orbit. The correct term for what you're talking about is "geostationary".