rational defense
an unlikely collision; a real problem
18 02 2009
Two satellites collided in orbit Feb. 10 for the first time in history.[1] Nearly 500 miles above the vast emptiness of northern Siberia, Iridium 33 (NORAD ID 24946) – a communications satellite operated by the U.S. Company — and Cosmos 2251 (NORAD ID 22675) — a supposedly decommissioned Russian communications relay satellite — crashed into each other just before 1700 UTC on Feb. 10. At orbital velocities in excess of 15,000 miles per hour and impacting on nearly perpendicular orbits, the kinetic energy of the impact instantly tore the two satellites apart and left some 600 pieces of debris in orbit.[2]
Though this altitude is close to the most heavily populated band of low earth orbit (LEO), the collision is still, statistically speaking, extraordinarily unlikely — often likened to two ping pong balls floating in the Pacific Ocean accidentally colliding. Even though U.S. Strategic Command has cataloged and tracks some 18,000 objects orbiting the earth (only a few hundred are operational satellites), the chances of collision are extremely low because of the immense distances and vast swaths of empty space involved, and the timing and spatial alignment must all come together perfectly. (Indeed, the U.S. military attempts to plot and forecast potential collisions and help satellite operators avoid even near misses, though this effort is not as systematized as it might be.)
In short, there is a reason it has not happened before.
But that is also changing. Conspiracy theories aside, the long-term the trajectory is clear: LEO will only get more crowded. As that happens, systematic international coordination and cooperation will become increasingly necessary. (The international community already has standards for debris-mitigation in satellite launches and orbital insertions.) Much like confronting climate change, the sooner meaningful, comprehensive action is taken, the more manageable the traffic control and debris challenges will be.
And these challenges are already very real. It is not just about preventing useful satellites from colliding. The debris that such a collision — or the Jan. 11, 2007 Chinese test of an anti-satellite weapon (ASAT) — creates can endanger other satellites and even manned spaceflight efforts. Though the skin on certain parts of the International Space Station already shows signs of minor impacts, something smaller than a bolt traveling at orbital velocities could actually cause potentially catastrophic damage to the Station or another manned spaceflight.
Indeed, some experts have estimated that as few as a dozen events like the Feb. 10 collision or the Chinese ASAT test could effectively render whole swaths of LEO essentially unusable. As such, more comprehensive international efforts to manage traffic in space, monitor debris and forecast potential impacts are necessary.
RD is not about to suggest that space is about to become the next Antarctica, where all the nations of earth can agree not to place military assests. There may not be weapons in space yet in the traditional sense, but LEO is better likened to airspace in the 20th century. Its military value is not only undeniable, but inescapable — already demonstrated quite clearly by the persistent orbits of RQ-1 Predators, MQ-9 Reapers and RQ-4 Global Hawks around the world controlled from the continental United States by satellite and every time the American Global Positioning System guides a Joint Direct Attack Munition precisely to its target.
Space is critical for modern military endeavors and as such will be exploited for military means. Adversaries will attempt to leverage space-based assets for military means and deny the use of those assets to the enemy. Defensive measures for satellites may well eventually include defensive weaponry. Space-based ballistic missile defenses (where the platform would be in the ideal position for an intercept) have also been discussed.
Indeed, as the collision of Iridium 33 and Cosmos 2251 aptly demonstrates, an apparently incuous and even long-since decommissioned satellites also have the potential to be an effective ASAT. Though to have a true ASAT, precision maneuvering, guidance and targeting capabilities not necessarily inherent in the average satellite would be necessary, it would be impossible to ensure that every satellite put in orbit does not have these capabilities disguised beneath its interior.
The reality is that any treaty to ban the weaponization of space is effectively unverifiable due to the realities of the orbital environment. Without verifiability, no rational state could have reasonably full confidence in the treaty, which would only encourage clandestine ‘cheating’ to hedge against others doing the same.
Nevertheless, it does not mean that international cooperation on traffic management and debris monitoring and mitigation should not extend to discussions of preventing a devastating exchange of ASATs that could ruin LEO not just for the belligerants, but for all mankind.
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1 While there have been some impacts of small pieces of space debris with each other and even larger objects and anything in orbit is regularly peppered with microscopic matter, this is the first time two actual satellites have collided.
2 According to early estimates.
Categories : space
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