More than 750,000 pieces of dangerous debris
are currently orbiting the Earth, traveling at speeds up to 17,500 miles per
hour. This debris is called “space junk”?—?and it includes disused satellites,
fuel tanks, spent rocket stages, everyday rubbish from past space stations, lost
tools from spacewalks, along with natural debris from space. Junk can range in
size from dust to very tiny fragments (called ‘bullets’) to full-size
satellites (‘cars’). There are a couple of relatively famous pieces of space
trash. One is the glove that floated away from the Gemini 4 crew during the
first spacewalk by U.S. astronauts. The other is the camera Michael Collins
lost during the Gemini 10 mission.
Most space junk comes from orbiting satellites
and the rockets that shot them into place. Gradual
wear and tear or sudden collisions cause these to disintegrate into tiny
fragments that continue to orbit at tens of thousands of kilometres an hour.
Besides such accidental break-ups, satellite interceptions by surface-launched
missiles have been a major contributor in the recent past.
The main problem with space trash is the danger
it poses to working satellites, International Space Station and manned
spacecraft. Because of their very large orbital speeds,
even small pieces of debris can be deadly. Objects in low Earth orbit (LEO)
travel seven times faster than a rifle bullet. At that speed, a one-millimeter
piece of debris can damage a satellite if it hits a vulnerable area, and debris
larger than about one centimeter can seriously damage or destroy a satellite in
Experts have been growing increasingly concerned that this space
junk could cause Kessler Sydrome, a collision that could cascade into a snowball
effect of collisions. Each time a collision occurs it adds an incredible amount
of debirs fragments, and each of those fragments then goes on to
trigger further collisions. In the hypothetical doomsday scenario, this runaway
cascade continues until LEO is completely clogged.
That would dramatically impact our way of life back on Earth
– no mobile phones, no GPS, no accurate weather forecasting, no satellite
For these reasons, NASA has created a space
surveillance network. Ground stations track larger pieces of space trash so
that collisions with working satellites or the Space Shuttle can be avoided.
Future plans include a cooperative effort among the governments of many nations
to stop littering space and to possibly clean up the trash already there.
While NASA and many other space agencies worldwide
agree that space junk is a huge problem, there is still no concrete solution to
getting rid of it. The current strategy used by NASA is simply cutting down on
how much new junk is produced?—?there are now guidelines for how to prevent collisions and
how to leave less junk behind. However,
it’s clear that very soon, we will need to start removing this debris from our
atmosphere or the consequences will be serious. Scientists are working on a range of clean-up solutions, including
cables, nets, harpoons, sails and robotic arms. All are designed to
capture pieces of space junk and tug them down into Earth’s atmosphere where they
will burn up and disintegrate