Orbital debris is defined as any man-made Earth-orbiting object which is non-functional with no reasonable expectation of assuming or resuming its intended function or another function for which it is or can be expected to be authorized, including fragments or parts thereof.
International Academy of Astronauts
Welcome,
We have come here to take a closer look at the Earths immediate surroundings. As you may know, a lot of exciting things have been going on lately in Earth orbit. We have witnessed the arrival of the first element of the International Space Station (ISS), the first satellite network (the Iridium constellation) has just been installed, and a short time ago the first PC in space passed by. These newcomers belong to the category of operational spacecraft, a category which comprises only 5% of all man-made objects orbiting Earth. Let's leave this glorious category aside for the time being. The remaining 95% (orbiting waste) will be our topic for today.
We have transgressed the boundary/interface called sky. We are confronted with a hardware problem. Space junk - the thousands of objects remaining after EOL (a satellites End of Life) - poses a threat to the machines which are working up here. Explosions and collisions have already occurred, and will continue to occur. Are we interested? With great scoops like Iridium and ISS at hand, it seems artificial to focus on the leftovers. The risks being run by satellites, let alone the world population, are hard to notice from the ground. And whether or not the space debris problem offers an illuminating metaphor for hardware and software situations on Earth is open to discussion. We have little to go by. But why not let the question mark serve as an incentive? Some perspectives on the wider context, the habitat, of the above-mentioned blissful technologies can fuel our discussions. Enjoy your visit.
Indications of a degrading environment
Satellites will transform Planet Earth into a clean, peaceful whole, which is just what it looks like when viewed from outer space. It therefore comes as an annoying surprise to find that satellites are making a mess of their own environment. This is due to a rather primitive mechanism of waste accumulation, the piling up of dead satellites and rocket stages. The total number of defunct man-made objects (> 1 cm3) in Earth orbit is estimated at 100,000. This is annoying, as this junk causes the livability of Earth orbit to decrease. In early December of 1998, the crew of the shuttle Endeavor, on a mission to build the International Space Station, cancelled EVA (Extra Vehicular Activity, i.e., a space walk) at the last minute, and went eight kilometres out of their way to avoid a rocket stage which had been launched the month before. Impacts on spacecraft, as well as more than 60 fractured Space Shuttle windows, are further indications that we have to regard these objects as possible causes of collision. And this danger can only be expected to intensify. First of all, because more artificial moons are being sent up, and thus more future waste. Secondly, because debris tends to break up into fragments: one broken machine is good for up to 200 new objects. On February 15th, 1998, the upper stage of the Meteor 2-16 exploded in Lower Earth Orbit and caused a Tsyklon third stage to break up into 80 fragments. Analysts calculated ejection velocities ranging from 15 m/s to more than 250 m/s. We don't hear about it often, but satellites are transforming their own habitat into a minefield.
|