No space for Debris

 

 

Oh Little Sputnik, flying high With made-in-Moscow beep, You tell the world it’s a Commie sky, And Uncle Sam’s asleep

This was G Menon Williams, Governor of Michigan, at his humorous best. For, though the Sputnik that the former Soviet Union sent into space on October 4, 1957 weighed just 184.3 pounds, its political impact was huge. Some with keen memories had then picturesquely described it as the “bloodless Pearl Harbour.”

Well there’s been a lot of such bloodless events since spaceship Sputnik. Space experts have been warning for years that the number of satellites in planet orbits has been increasing at a dangerously high speed. This poses a major threat to other satellites – and yet no one paid heed to them until February 10. That was the day that two communications satellites – one Russian and the other American – disintegrated, spewing tonnes of space debris in the higher and lower orbits.

Says space expert Brian Weeden: “Collisions generate debris, greatly increasing the possibility of more of them. These significantly add to the expense of operating in space – a highly expensive business in itself. For instance, if the satellites were to be designed in a way so that they could protect themselves, the cost would rise proportionately. Their life in the orbit too would decrease, because to avoid collisions they would be forced to manoeuvre more frequently. Manned missions, such as space stations, would need to go to great lengths to protect humans.” The Kessler syndrome (named after a highly regarded NASA space debris researcher) is all about this phenomenon. Kessler had found that collisions create a chain reaction of further collisions.

Three major events over the last three years have hogged prime space in both general and specialist media. The first of this ominous threesome was the Chinese anti-satellite test in January 2007 – while the US last February destroyed an ailing spy satellite. More recently two satellites accidentally collided in the Earth orbit. The February 10, 2009 incident was the first of its kind.

All three events generated huge dollops of interest, gossip, paranoia and conspiracy theories – till, for the layman, it became pretty nearly impossible to tell fact from fiction. Only the expert can sift one from the other – and what we learn from him would set any earthling on edge.

Imagine for a second what would happen if a 10 mm piece of debris were to suddenly collide with our Edusat satellites. The threat is so real indeed that on March 11, 2009 crew members had to evacuate the international space station and take shelter in a docked Russian Soyuz space craft due to the threat from space junk. A collision can punch such a large hole in the spacecraft that the crew's very survival is endangered.

Till Russia and China began to take on US might in space, the threat of direct collision between satellites was low. Points out Nicholas Johnson, chief scientist of NASA's Orbital Debris Program Office at the Johnson Space Center in Houston: “When the year began there were nearly 17,000 pieces of man-made debris orbiting Earth.” But scientists at the American Physical Society conference in Los Angeles estimated their number at over 150 million. The statistics also reveal that nearly 45 per cent of the space debris was produced by the US. “We are in danger of a runaway escalation of this deadly stuff,” warns Massachusetts Institute of Technology physicist Geoffrey Forden. But so far no effective way has been found to get rid of it, so that collisions can be prevented. Satellites and spacecraft launchers can only try to minimise the quantity of the debris produced. These killer satellites not only pose a major threat to our space programmes, they threaten mankind’s survival itself. And what in the world will satellites do without people? “Follow debris mitigation rules”

Geoffrey Forden, orbital debris expert at MIT, tells Vikas Kumar about the need for greater debris monitoring How serious is the problem?

This collision has created a serious problem for the Iridium satellites, which by definition have a large overlap with the debris released in space. We’ll need to bear this in mind when we send out more satellites in the future.

There have been times when the satellites came close to colliding, but in the end did not. Do you have any observation or study on that?

My calculations show that some satellites (including non-operational satellites that have reached the end of their life) and a piece of space debris approach each other every three to four days within 800 metres – the distance that the orbital elements predicted for this collision. Near misses between two satellites are considerably rarer, but still happen every month or so.

Would the ISS face any threat?

The ISS does face an increased risk, but the increase from the debris created by this collision is rather small. This is because the ISS is at a considerably lower altitude.

What can be done to prevent future collisions?

First, all space-faring countries must follow the debris-mitigation rules that various international committees have agreed to. They should sign up with the Code of Conduct that the European Union is considering.

What could be the implications of frequent collisions?

Space is being used for a variety of purposes, most of which serve humanity. For instance, satellites are used to predict weather, and hence mitigate the danger from floods, drought and other disasters. It is quite possible that if too much of space debris is created, near Earth orbits will be rendered unusable. If that happens, people’s lives will be lost on Earth.