November 26th, 2013

Space Debris Risk: Part II, Collision Risk

Posted at 1:00 AM ET

Space debris poses a serious risk to operational satellites, particularly in the low earth orbit (LEO) and geosynchronous orbit (GEO). Indeed, debris amounts are increasing as objects continue to collide with one another, producing more fragments. According to the U.S. Strategic Command’s Space Surveillance Network, more than 20,000 objects above ten centimeters in size are currently orbiting Earth. Of these, only some 1,000 are active satellites. For items measuring between one and ten centimeters, around 500,000 particles are thought to be orbiting Earth. Estimates suggest tens of millions of other particles smaller than one centimeter are circulating the planet. All this material is traveling at several kilometers per second, sufficient velocity to cause significant damage to operational satellites.

LEO

More than 13,000 objects above ten centimeters in size are currently estimated to be in the LEO and this number is expected to increase as collisions cause more debris. Indeed, a recent study by the inter-Agency Space debris Coordination Committee (IADC) found that catastrophic collisions will (conservatively) likely occur every five to nine years in the LEO over the next 200 years.

Despite end-of-life deorbiting strategies that now exist for the latest generation of satellites deployed in the LEO (that involve a controlled re-entry into the Earth’s atmosphere and subsequent burn up), no sustained debris mitigation measures are in place to catch existing space junk and pull it out of orbit.

Only a small number of satellites are currently insured in the LEO, given that the majority of satellites there are government owned (used in the main for Earth observation purposes). Swiss Re currently estimates the total value of insured satellites in the LEO at around USD1 billion. However, as more private companies move into satellite imagery and mapping, the value of insured assets in the LEO is expected to increase significantly. This could have significant implications for (re)insurers, particularly if attempts to reduce the amount of debris in the LEO do not achieve significant progress during this time.

GEO

Most insured satellites are currently located in the GEO due to the high number of commercial communication, broadcasting and meteorological satellites deployed here. According to Swiss Re, satellites in the GEO currently have an insured value of more than USD18 billion. Although the risk of collision in the GEO is currently lower than the LEO due to fewer inactive objects, the risk clearly does exist as illustrated by the near miss of Galaxy 15 in 2010 (which stopped responding to commands and drifted uncontrollably for several months before being stabilized).

In addition, the difficulty of finding a successful long-term debris removal strategy in the GEO means the risk could increase in the future as debris will remain at these altitudes indefinitely without human intervention. Estimates indicate more than 500 obsolete satellites, around 200 rocket bodies and thousands of smaller fragments litter the GEO.

Attaining a debris clearing mechanism in the GEO is therefore crucial to finding a sustainable solution for satellite operators and (re)insurers alike. Although most modern devices deployed to the GEO are being sent into a “graveyard” orbit some 300 kilometers above the region once their lifespan ends, the lack of a clearing solution for legacy debris means the collision risk is likely to rise over time as more satellites are deployed to the region.

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