Archive for June, 2009

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Space Debris: How do we safeguard our future?

Iridium-Cosmos Debris cloud as it would be on July 10
Iridium-Cosmos Debris cloud as it would be on July 10

Satellite Collision simulation


The first accidental hypervelocity collision of two intact spacecrafts occurred on 10 February 2009 when Iridium 33, a US Operational communication satellite and Cosmos 2251, a Russian decommissioned communications satellite collided at 1656 GMT as they passed over northern Siberia at an altitude of 790 km leaving two distinct debris clouds in much of the Low Earth Orbit which are now dispersing and pose danger of future collisions.

The present incidence has generated a lot of concern in the space community (We were at the United Nations Committee for Peaceful Uses of Outer Space recently) especially as the Iridium constellation is in a region of high spatial density and the Iridium constellation has 70 satellites in the operational altitude regime – at even the current situation, there are approximately 3,300 additional catalogued objects that whiz through the Iridium constellation’s altitude each day.

The effects of such debris clouds after collision would pose a significant risk to the access to space both in the short-term and long-term. Although tracking results from the Iridium Cosmos incident show that the debris created is short lived (and would re-enter the Earth’s atmosphere within the next 5-10 years depending on solar activity), incidents such as this could potentially lead to an “ablation cascade” where future collisions would create further and more energetic space debris objects that may be extremely dangerous for human space flights. The figure above depicts the predicted evolution of the Iridium and Cosmos debris planes by July 10 (six months after the collision)! 

Photo Credit with thanks: NASA, Orbital Debris Program Office