US concern about Russian & Chinese satellites trajectories
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Nearly 400 satellite crash notices sent to Russia, China[/SIZE][/FONT]
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BY STEPHEN CLARK
SPACEFLIGHT NOW
Posted: June 15, 2011
[/SIZE][/FONT]TONBRIDGE, England -- Since instituting a new policy to inform commercial and international satellite operators of collision threats, the U.S. Air Force has issued hundreds of notifications to Russia and China warning of possible crashes between their satellites and other objects in orbit, according to a U.S. State Department official.
[FONT=Verdana, Arial, Helvetica, sans-serif][SIZE=-2]This artist's rendering shows the distribution of objects in orbit above Earth. Image not to scale. Credit: European Space Agency
[/SIZE][/FONT]Frank Rose, a deputy assistant secretary of state for space and defense policy, said the Air Force has sent 252 warnings to Russia and 147 notices to China over the past year.
Speaking Monday at an international space security conference in Prague, Rose said U.S. Strategic Command's Joint Space Operations Center issued 677 warnings to U.S. government and private sector satellite owners in the same time period.
Satellites in low Earth orbit speed around the planet at more than 17,000 mph. At such high velocities, kinetic impact energy from a collision has an explosive effect, creating new debris and destroying the satellite.
Since the beginning of 2010, satellite owners and operators have maneuvered their satellites more than 100 times in response to the Air Force notices, according to Rose, who works in the State Department Bureau of Arms Control, Verification and Compliance.
"Such notifications are themselves an important confidence building measure, and they also provide the basis for pursuit of other bilateral [transparency and confidence-building measures] in diplomatic, military-to-military, and scientific channels," Rose said.
Not only do the warnings promote trust, they also guard against further collisions between spacecraft that could generate more debris, producing a scenario where the amount of junk grows exponentially.
"Debris begets debris," said Gen. William Shelton, head of Air Force Space Command. "We have not found a way that is either technically nor economically viable to eliminate debris."
The notifications arose out of the U.S. National Space Policy released by the White House last year. The policy document called for mitigating the threat from orbital debris and building trust among private and international operators.
The paper specifically mentioned disseminating tracking information to commercial and international entities as part of renewed focus on preserving the space environment and the responsible use of space.
The Air Force tracks more than 22,000 objects in orbit, and experts believe there are thousands more too small to be spotted from existing radars. About 1,100 of those objects are active satellites.
"That number is projected to triple by 2030, and much of that is improved sensors, but some of that is increased traffic," Shelton said in April. "Then if you think about it, there are probably 10 times more objects in space than we're able to track with our sensor capability today. Those objects are untrackable, yet they are lethal to our space systems -- to military space systems, civil space systems, commercial -- no one's immune from the threats that are on orbit today, just due to the traffic in space."
A Chinese test of an anti-satellite weapon in 2007 and the collision of a dead Russian satellite with an Iridium communications craft in 2009 unleashed thousands of new pieces of debris in low Earth orbit a few hundred miles above Earth.
Hundreds of operational satellites pass through that region of space, including the space shuttle and International Space Station.
After the 2009 collision, the Air Force began sharing collision warnings with a wider group of operators. Most orbital tracking data is publicly available, and the military offers additional support services to organizations and governments who sign formal agreements.
The Air Force began sending email collision warnings to all operators in early 2010.
