Viewers of the soon to be released film “Gravity,” starring Sandra Bullock and George Clooney, will find themselves up close and personal with what would happen if astronauts aboard the International Space Station were hit by celestial debris and set adrift in outer space. For NASA, this is a worst case scenario situation, one in which they have taken measures to avoid and to protect astronauts from. “Gravity” is a fictional account, but the reality is that the destruction of the ISS from a collision with space debris such as the movie depicts is a constant threat and NASA should be worried.
NASA is currently tracking over 500,000 pieces of “space junk” orbiting the Earth. Traveling at speeds of up to 17,500 miles per hour, space debris is a real threat, since even the smallest piece can do severe damage to a spacecraft or satellite. According to NASA, there are over 20,000 softball-size pieces of debris orbiting the Earth and approximately 500,000 pieces of debris the size of a marble or bigger. These numbers do not account for the millions of debris outside the Earth’s orbit that cannot be tracked.
But the size of the debris is only part of what makes it is so dangerous. The speed at which it is traveling through space can make even pieces as thin as a layer of paint do extreme damage. Several windows on the space shuttles have had to be replaced due to being hit by paint flecks caused by thermal stress, according to NASA. The question of whether NASA should be worried about the destruction of the ISS or other manned space crafts from space debris, as “Gravity” depicts, is one the organization has been answering since the beginning of the space program.
What is space debris? Like a celestial landfill, the debris in space is comprised of both man-made and natural elements. One the one hand, there are the natural particles, known as meteoroids, which orbit the sun. On the other, there is the artificial debris, which orbits the Earth. This man-made ‘trash,’ serves no useful purpose anymore and is known as orbital debris. Orbital debris can be anything from derelict spacecraft, parts of launch vehicles, and solid rocket motor effluents. Some orbital debris is material intentionally released during mission operations or when a spacecraft and launch vehicle separate. Some debris is created from explosions or collisions.
How long orbital debris will continue to orbit the Earth depends on how high the debris is from the Earth. The higher the altitude the longer the debris will stay in orbit. If debris is 500 miles above the Earth, its decay and eventual demise may take decades. Debris at altitudes higher than 620 miles, will last for centuries. But, for debris orbiting the Earth below 370 miles, it will fall to Earth within several years.
Should we be worried about falling debris? NASA has tracked on average one piece of fallen debris a day over the past 50 years. The most likely landing place for debris has been in the oceans. Other area where landing has occurred is in remote sections of Canada, Australia, and Siberia, where there is little or no population.
In the movie, ‘Gravity,’ the ISS is destroyed by a collision with space debris. But, NASA has placed enough safeguards on the space station to be able to say it is, “the most heavily shielded spacecraft ever flown.” Its most critical components are made to withstand high-velocity impacts from particles up to four inches in diameter. Astronauts are trained both on the ground and in space in how to perform in the event of a disaster. Special equipment on the station is constantly evaluating space debris and performing avoidance maneuvers.
Should NASA be worried about the destruction of the ISS from a clash with space debris as the movie ‘Gravity’ depicts? Yes and they know it. Currently, the United States and other countries with space programs are investigating the environmental and technical challenge of minimizing orbital debris. In 1988, the U.S created a National Space Policy, which continues to evolve to protect astronauts and the public today.
By: Lisa Nance