Monday, August 17, 2009
All photos taken by: NASA
Millions of nuts, bolts, pieces of metal and carbon, and whole spacecraft from thousands of missions and/or launches form an orbiting garbage dump spinning around the Earth at speeds up to 22,000 mph.
In February 2009, a collision between a Russian and US satellite graphically showed the dangers of this growing mass of space junk. (Is there anywhere we won’t pollute?) Growing levels of concern regarding the possible “fallout” from this crisis have caused NASA and the European Space Agency to divert resources into monitoring space debris and researching ways to mitigate the damages. They have an eye on one day being able to safely remove this junk.
The NASA Orbital Debris Program Office estimates that 19,000 objects larger than 10 centimeters (3.94 inches) in diameter are known to exist. There are approximately 500,000 objects between 1-10 centimeters in size; and, probably in excess of tens of millions of particles smaller than 1 centimeter, say scientists.
According to one study there is an estimated four million pounds of space junk orbiting in low-Earth orbit. I always feel that studies such as this one tend to underestimate the potential dangers rather than looking at the facts and figures in realistic terms. Unfortunately, spacecraft, astronauts or spacecraft studying changes in our planet and atmosphere are now in danger of coming in contact with any of this space debris.
As usual, there’s good news and bad news. Here’s the good news: most space junk is located outside of the orbits of the International Space Station plus any space shuttles launched. The bad news: a recent NASA study forecasts a 10-fold increase in the probability of collision with debris over the next 200 years.
However, there were several factors that were not taken into consideration when the problem of 21st century space junk was first forecast. There was absolutely no account made for the fact that space exploration would accelerate. The predictions were made on no increase in space expeditions. The current predictions were also made prior to the 2007 intentional destruction of a Chinese weather satellite.
The Chinese ASAT test deposited more than 2,300 pieces of debris larger than 10 centimeters into some of the most heavily-used orbits where the world’s weather and climate monitoring satellites reside.
The satellite breakup and resulting debris cloud was “the most prolific and serious fragmentation in the course of 50 years of space operations,” according NASA’s Nicholas Johnson, Chief Scientist for Orbital Debris.
“There is an emerging consensus among the technical community that simply preventing creation of new debris is not going to be enough,” said Brian Weeden, Technical Consultant for the Secure World Foundation.
Weeden says that up until now, the debris mitigation process has been focused mainly on the technical aspects, but more and more attention is now being paid to the legal dimensions of space debris. A first step towards this end was the recent establishment of the United Nations Space Debris Mitigation guidelines.
“At some point we will need to actively remove debris from orbit. Fortunately, new studies are showing that removing as few as five or six objects per year could stabilize the debris population over the long term,” said Weeden.
“The big question right now,” added Weeden, “is which objects to remove first and what is the best method to do so.”