I am including in this blog the following article that was written by my good friend Phil Naranjo for our previous blog which has now been deleted. I thought that it was particularly relevant given current interest in the movie Gravity:
Yesterday, Chinese space officials published a white paper outlining the country’s long-term space exploration plans. What’s notable about the paper is that it makes a somewhat uncharacteristic mention of China’s efforts to mitigate space debris. This is particularly surprising when you consider the massive space debris problem China’s military created in 2007. As a gesture aimed primarily at the United States, the Chinese deployed an anti-satellite (ASAT) weapon against a senescent weather satellite named Fengyun (meaning ‘wind and cloud’) 1-C. The ASAT (basically a missile) closed on its prey and struck at 5 miles/second, shredding poor Fengyun 1-C into millions of shards of shrapnel.
Fengyun 1-C was in what’s known as a sun synchronous polar orbit meaning that it crossed the equator at about the same local time during each orbit. This type of orbit is common to certain weather and environmental satellite as well as spy satellites. Its destruction was meant to send a clear message to Washington that China had arrived as a major space power. Ironically, earlier that year, China had lobbied the Bush administration to sign on to a space weapons ban. Some speculate that the test was also an effort to strong-arm the stubborn Bush administration into an agreement. Whatever the motives, it’s clear that China did not anticipate the extent to which it would end up polluting low earth orbit, potentially endangering its own space efforts.
According to Nicholas Johnson from NASA’s Orbital Debris Program Office, the explosion distributed debris across a vast swath of orbital space covering 125 to 2,300 miles in altitude, with the bulk of the debris concentrated at 530 miles. NASA estimates that there are over 35,000 pieces of debris greater than 1 cm in orbit. At smaller sizes, there are likely millions of pieces, each posing a lethal risk to other satellites (and space explorers). The high altitude and small size of the debris ensures that it will remain in orbit for hundreds of years.
To get a sense for the scale of the problem, I plotted the orbits of 6,800 pieces of debris from Fengyun 1-C, currently tracked by US Strategic Command, using a shareware program called Heavensat. Here, you’ll see two plots. The first shows an azimuth/elevation plot of the night sky above Seattle, Washington (USA) on December 30th, 2011 at 7:10 PM PST. Each piece of debris (some as small as 4 inches across) is labelled Fengyun 1-C DEB, where the DEB stands for debris. The time and date are not particularly important. You could pick any random date/time and see the same constellation of space debris somewhat evenly distributed across the heavens.
The second image is a Mercator projection of the Earth showing a snapshot of the lat/long positions of each piece of debris. Again, notice how evenly the debris is distributed. You get real sense for how much of a pollution problem this one weapons test created. In fact, the International Space Station was threatened by a collision with Fengyun 1-C debris as recently as April 2011. Reminiscent of some massive, WWI-era trans-oceanic minefield, this debris cloud will continue to threaten orbital operations for many generations to come. The full impact of this environmental disaster will only be known to future historians tasked with chronicling the fate of its victims.