An Assessment of the Impact of the January 2007 Chinese ASAT Test on the LEO Environment

Over the past several decades there has been increasing concern regarding the growth of the orbital debris population in the Low Earth Orbit (LEO) environment. Even under the best of circumstances the debris population may be expected to increase under conditions of ambient use by the space-faring nations of the world. It is easy to see that such a situation will obtain since the operational lifetimes of most on-orbit systems are typically less than a decade, while their orbital lifetimes may be many decades to hundreds of years or more. Historically, very little has been done regarding the removal of defunct orbital systems. Making matters worse, there have been many cases of spontaneous explosion of derelict upper stages on orbit. In such an event, a single large “hazard to navigation” becomes hundreds to thousands of pieces of orbiting shrapnel. As the numbers of debris objects increases, for whatever reason, so does the threat of collision with high-value operational assets. Thus, given the importance of minimizing orbital debris in LEO, it is obvious that any nation conducting anti-satellite (ASAT) tests should do so in a responsible fashion – minimizing the long-term deposition of large numbers of orbital debris objects at operational LEO altitudes. It is the thesis of this paper that the January 2007 ASAT test conducted by the Chinese government was particularly careless in this regard. In support of this statement, Oceanit’s LEO environment model, PODEM (patented in 2004), was employed. The Chinese ASAT test was conducted successfully at an altitude of about 850 km producing large numbers of debris objects. Results, based on an approximation to this recent event, utilizing the PODEM model, suggest that many debris pieces may remain in the LEO environment for hundreds of years. By contrast, debris ranging in size from one to several centimeters may be expected to drift down, due to drag, through lower LEO altitudes producing a transient spike in hazard within a few years to a decade. The International Space Station (ISS) is a particular concern. By comparison and in contrast, several hypothetical cases of debris deposition in LEO at lower altitudes are illustrated. The current research concludes that the Chinese ASAT test has unnecessarily exposed valuable LEO systems to an enhanced hazard over a long time scale.