BREMEN, Germany — NASA’s Orbital Debris Program Office expects to begin active work on how to remove debris in orbit on the strength of the new U.S. National Space Policy, according to the office’s chief scientist.
Nicholas L. Johnson said the office, which assembles data from the U.S. Air Force-run Space Surveillance Network, has been working on these issues for years, but only on an informal basis, with few resources and no formal mandate.
That changed on June 28, when President Barack Obama issued an updated space policy that specifically orders NASA and the U.S. Defense Department to “pursue research and development of technologies and techniques … to mitigate and remove on-orbit debris.”
Attending the 38th Congress of the Committee on Space Research (Cospar) here July 18-25, Johnson said it is too early to tell exactly how the new policy will be transformed into programs and budgets. But the specificity of the wording, he said, gives reason to conclude that NASA will be able to increase its efforts.
In addition to asking NASA and the Defense Department to research debris mitigation — making satellites and rockets less likely to break up in orbit, and removing satellites from the orbital highways upon retirement — the policy’s inclusion of orbital debris removal may take the NASA office in a new direction.
The policy also requires any U.S. agency seeking an exception to the debris-mitigation practices to notify the U.S. Secretary of State beforehand.
NASA’s most recent assessment of the orbital debris population gives no more reason for optimism than previous reports. In fact, the abnormally low solar activity of the last year has prolonged the orbital life of debris that likely would have been pulled into the Earth’s atmosphere if solar activity had been at predicted levels.
Even in geostationary orbit, where internationally accepted guidelines for moving retired satellites to a higher, unused orbit are widely accepted, spacecraft continue to be abandoned.
In 2008 and 2009 alone, four geostationary orbiting satellites — the U.S. EchoStar 2 and the Russian Gorizont 33, Raduga 1-5, Cosmos 2371 and Cosmos 2379 — were all left to expire on the geostationary arc without performing end-of-mission orbit-raising maneuvers. EchoStar 2 failed suddenly in orbit and could not be moved.
At least one satellite in 2010 — Intelsat’s Galaxy 15, which stopped responding to commands in April — is likely to join the more than 150 dead satellites and rocket stages that will drift for centuries at geostationary position.
International guidelines urge that satellite owners raise their geostationary satellites by some 250 kilometers above the geostationary belt 36,000 kilometers over the equator.
Satellite operators say it is often difficult to estimate how much fuel is remaining on their satellites, a fact that complicates the timing of the decision to move otherwise healthy, $200 million investments into forced retirement.
Space debris experts said that, as is often the case with Earth-bound pollution, orbital debris mitigation may require forced economic incentives before debris-mitigation practices are followed to the letter.
Johnson said observing debris-mitigation practices need not be viewed as putting handcuffs on experiments in space, even tests of anti-satellite munitions. From a strict debris-creation point of view, these exercises, if done in very low orbit, create debris clouds that burn up in the Earth’s atmosphere within a few months, as was the case during U.S. anti-satellite tests in the 1980s.
By NASA’s count, there have been 58 occasions of orbital debris being caused by intentional events. Fifty-two of them were intentional explosions by Russia or the Soviet Union, five were U.S.-caused events and one by China.
The Chinese anti-satellite test, in 2007, is viewed as particularly grievous because it occurred at 850 kilometers in altitude, which is much higher than the U.S. and Russian/Soviet tests. Debris at that altitude will remain in orbit for decades, if not a century or more.
