Japan’s H-2A rocket that blasted off on May 18 sent a Japanese satellite, Shizuku, and a South Korean satellite, Arirang-3, into orbit. But it also left behind space junk, the accumulation of which is starting to create big problems above the atmosphere.
The amount of space debris has steadily increased since its start on Oct. 4, 1957, when the Soviet Union launched Sputnik 1, the first artificial satellite to enter orbit.
Now, the "garbage problem" could rise at an explosive rate.
Countries are now trying to figure out ways to take care of the problem, but progress has been slow.
"We know that it will eventually impede the development of space, but if we just leave space debris out there anyway, then some day we suddenly won't be able to go into space anymore and our development there will hit a brick wall," said Seishiro Kibe, director of the Innovative Technology Research Center of the Japan Aerospace Exploration Agency (JAXA).
An estimated 22,000 pieces of debris with a diameter of 10 centimeters or more are floating around in space. Information, such as orbital path, size and origin, is known for about 16,000 of them.
There are also about 1,000 satellites in operation. The continued accumulation of space debris could interfere with the satellites' orbital paths, leaving them nowhere to operate.
Debris has always been a part of space development.
For example, two minutes after the H-2A rocket lifted off on May 18, the vehicle's solid rocket boosters separated. The covering over the payload at the launch vehicle's nose detached, followed by the stage-one engine.
Those components soon fell back to Earth.
But other parts that detached, such as the stage-two engine, uncoupled when the vehicle neared the satellite's orbit. The parts remained there and will circle the Earth as space debris. Some will fall and burn up in the atmosphere, but it is common for other debris to continue traveling around the planet for years or even decades.
Also floating in orbit are lens caps for satellite cameras and clasps that held their folded solar arrays in place. Hammers and other tools used by astronauts on spacewalks are also floated around Earth, but their number has decreased recently.
The pieces may be small, but they can cause serious damage. A chunk of aluminum only 1 cm across and orbiting at 10 kilometers per second is far more powerful than a bullet from a gun.
STRENGTHENED MONITORING TO AVOID COLLISIONS
There are two ways to observe space debris from Earth. Debris in a low orbit up to 1,000 km high is tracked by radar. Debris in stationary orbit approximately 36,000 km up and moving in sync with the Earth's rotation seems immobile to viewers on the ground, making them observable through a telescope, just like celestial objects.
A global observation network is needed because space debris on the other side of the Earth cannot be observed from any given point on the ground.
But the only countries with observation networks capable of tracking all orbits around the Earth are the United States and Russia. Even still, the smallest objects they can discern are 10 cm wide, and their networks have numerous blind spots.
Japanese satellites rely on data from the United States to avoid collisions with space debris. Europe has initiated a collision prediction and monitoring project to protect satellites from space debris, meteors, asteroids and other objects.
Space has also been a laboratory for military experiments. From the 1960s to the 1980s, the Soviet Union repeatedly conducted experiments crashing satellites into each other. The United States did the same later on.
In 2007, China launched a ballistic missile from the ground to shoot down one of its own satellites at an altitude of roughly 865 km. The impact scattered space debris, including more than 2,600 pieces with a diameter of at least 10 cm.
There have also been accidents. In February 2009, the Russian communications satellite Kosmos 2251, which was out of service, collided with Iridium 33, a U.S. communication company's satellite, shearing off small pieces.
From the ground, 1,313 fragments 10 cm or larger have been observed and registered as space debris.
NO AGREEMENT ON CLEANING UP THE MESS
"If left in place, the amount of space debris will continue to grow," one published study says.
Satellites destroyed by space debris turn into large amounts of more debris, which then collide with other satellites and space debris. This so-called Kessler syndrome, a phenomenon in which a chain of destruction creates explosive growth in space debris, thus rendering space useless, is becoming more likely.
The United Nations Committee on the Peaceful Uses of Outer Space decides on treaties comprising agreements relating to space. However, a fundamental rule of the committee is that passage requires unanimous approval by its members. Only four treaties, including the Outer Space Treaty of 1967 and the Liability Convention of 1972, have been adopted so far.
With no treaty prescribing obligations to clean up space debris, countries are taking it upon themselves to do so.
Prime Minister Yoshihiko Noda and U.S. President Barack Obama on April 30 reached an agreement to examine ways to share monitoring data on space debris, satellites and other objects for the security of both countries.
Among the matters up for discussion at the June meeting of the U.N. Committee on the Peaceful Uses of Outer Space will be guidelines on how to reduce the amount of space debris. Chairing the meeting will be Yasushi Horikawa, a technical adviser to JAXA, marking the first time Japan will chair the committee.
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