You may recall that in 2008, rather than risk the chance of a large piece of a failing spy satellite would fall on populated areas the government blasted it out of the sky. The physics of such a shot were complicated and the Navy had a less than 10 second window to hit the satellite as it passed overhead of its ships in the Pacific Ocean. But it worked.
Now word comes that a five year-old Intelsat TV satellite is meandering across Earth's orbit and any attempts to control it have proven futile. At issue now is that the satellite could smash into other satellites or ramble into other satellite orbits and abscond with its signals. That is possible because while the satellite is uncontrollable it is still broadcasting.
Intelsat said its Galaxy 15 satellite " experienced an anomaly on 5 April 2010" and that the system's traffic, which provides transmission capacity for cable programmers in was moved to Intelsat's Galaxy 12 satellite. Published reports say no major service problems have occurred yet from the likes of DirecTV and Comcast. Intelsat and Orbital Sciences Corporation, the manufacturer of the G-15, are conducting a technical investigation, Intelsat says.
Whether or not this rogue satellite hits something or has to be destroyed it again raises the topic of what to do about the growing amounts of space junk orbiting the Earth.
The chief of US Strategic Command last year said the US was decades behind where we should be to protect assets in space from such debris. The most serious debris comes from a couple of large events in the past few years. The intentional destruction of the Chinese Fengyun-1C weather satellite in January of 2007 and the accidental collision of American and Russian spacecraft in February of 2009 have increased the cataloged debris population by nearly 40%, in comparison with all the debris remaining from the first 50 years of the Space Age, experts say.
The United States Space Surveillance Network, managed by U.S. Strategic Command, is tracking more than 19,000 objects in orbit about the Earth, of which approximately 95% represent some form of debris. However, these are only the larger pieces of space debris, typically four inches or more in diameter. The number of debris as small as half an inch exceeds 300,000. Due to the tremendous energies possessed by space debris, the collision between a piece of debris only a half-inch in diameter and an operational spacecraft, piloted by humans or robotic, has the potential for catastrophic consequences, experts say.
More recently problems have been avoided by proactive action. In January for example, French space scientists said they had moved one of the key Earth-observing satellites out of its orbit with four NASA satellites to avoid potential collisions.
The French satellite, known as PARASOL (Polarization and Anisotropy of Reflectances for Atmospheric Science coupled with Observations from a Lidar) was flying in a constellation of satellites known as the A Train. The A-Train satellite formation consists of NASA's Aqua, CloudSat, CALIPSO, and Aura.
The French Space Agency (CNES) said that after collecting observations synchronous with the other satellites from the A-Train for almost 5 years, PARASOL was moved to a lower orbit 2.4 miles (3.9 km) under the A Train after CNES noted PARASOL orbit tracks slowly drifting eastward over the past these past few months.
CNES's said its decision to position PARASOL to a lower orbit was motivated by safety reasons to minimize the risk of collision, should PARASOL begin to fail (PARASOL, flew within about 10 minutes of the others). While the expected duration of the PARASOL mission was 2 years, it will reach 5 years in March 2010.
In the new orbit, observations from PARASOL will no longer be simultaneous with the others, except for only a few days at regular intervals, NASA said.
The A Train has already had experience with avoiding space junk. NASA has noted that the Aqua satellite in November successfully performed its first ever Debris Avoidance Maneuver to avoid a piece of the Chinese Anti-Satellite missile test debris from January 2007.
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