I have posted before about the problem with all the space junk in orbit around the Earth. It is estimated that there are over a hundred million pieces of space junk including old satellites, rocket boosters, fragments of rockets, and fragments of metal and paint. About twenty thousand pieces are more than four inches in diameter. One-half a million pieces are between four-tenths of an inch and four inches in size.
An object, including pieces of space junk, in Earth orbit travels at four miles a second. A fleck of paint traveling at that speed has the same impact as a five hundred pound object traveling sixty miles an hour. So even tiny pieces can inflict significant damage on solar cell panels, penetrate pressurized compartments and even create new pieces of space junk.
If space launches continue to spew junk into space, at this rate we may reach a point where it is impossible to launch a vehicle to Earth orbit without it being damaged by junk. If we are going to continue to explore and exploit space we have to reduce the production of space junk and find a way to remove it from orbit.
A few weeks ago I posted a story about an experiment being conducted by the Japan Aerospace Exploration Agency (JAXA) to deal with space junk. The JAXA partnered with a fishing net company to create a tether with woven stainless steel and aluminum wires. The tether was about two thousand three hundred feet long. The intention was to test the idea of attaching a tether to a fragment of space junk and to letting the tether create a drag as it moved though the electromagnetic field around the Earth. As the tether dragged the satellite down, its orbit would decay and it would burn up in the atmosphere.
The tether was carried aloft by a cargo ship bound for the International Space Station in December. The mission plan called for the tether to be unreeled from the cargo vessel but it apparently failed to deploy as planned.
A few weeks ago, a JAXA mission tried to use a mini rocket to carry a satellite to orbit. A small, experimental rocket called the SS-520-4 was intended to carry six and half-pound satellite, called TRICOM-1, to orbit but failed. The SS-520-4 rockets have been used to reach six hundred miles above the Earth, known as the edge of space. The SS-520-4 in the failed experiment had an extra stage added that was intended to allow it to carry the attached satellite all the way to Earth orbit.
Last February, JAXA launched the Hitomi satellite. It was much bigger than earlier Japanese scientific satellites at forty-six feet and two and three quarter tons. The Hitomi satellite was designed to analyze X-rays emitted by black holes and colliding galaxies. Contact with the satellite was lost a month after launch. After efforts to restore communication failed, JAXA abandoned the mission, concluding that the solar panels of the satellite had broken off at their bases.
The recent failure of these three missions is a serious blow to the JAXA.
