Tag: Satellites

ClearSpace-1: The First Space Garbage Collector

The European Space Agency has awarded an 86 million euro contract to ClearSpace to carry out the first removal of space debris from Earth’s orbit.

According to a ClearSpace press release announcing the contract,

ClearSpace-1’s mission is to develop a robot-like spacecraft with four articulated arms which will ultimately enable space debris to be removed safely. ClearSpace-1’s first task scheduled for 2025 after launching from the Kourou space centre in French Guiana, will be to bring down the Vespa (Vega Secondary Payload Adapter) left by the Vega rocket placed in orbit in 2013, the size of a 112 kg satellite. With its articulated arms, the robot will remove Vespa and move it closer to the earth’s atmosphere where it will burn up and disintegrate.

ESA Director General Jan Wörner said of the plan,

Think of all of the orbital captures that have occurred up until this point and they have all taken place with cooperative, fully- controlled target objects. With space debris, by definition no such control is possible: instead the objects are adrift, often tumbling randomly. So this first capture and disposal of an uncooperative space object represents an extremely challenging achievement. But with overall satellite numbers set to grow rapidly in the coming decade, regular removals are becoming essential to keep debris levels under control, to prevent a cascade of collisions that threaten to make the debris problem much worse.

Would Wooden Satellites Decrease Space Junk?

There was a flurry of stories recently about a Japanese plan to create satellites made out of wood. Apparently, the intent is to reduce the amount of debris created when a satellite re-enters the earth’s atmosphere. The BBC captured the typical reporting on the idea thusly,

Space junk is becoming an increasing problem as more satellites are launched into the atmosphere.

Wooden satellites would burn up without releasing harmful substances into the atmosphere or raining debris on the ground when they plunge back to Earth.

“We are very concerned with the fact that all the satellites which re-enter the Earth’s atmosphere burn and create tiny alumina particles which will float in the upper atmosphere for many years,” Takao Doi, a professor at Kyoto University and Japanese astronaut, told the BBC.

“Eventually it will affect the environment of the Earth.”

ArsTechnica, responding to coverage by the BBC and others, noted that while wood might have some potential benefits as a material to make satellites out of, reducing space junk is not really one of them.

Most of the coverage seems to present wooden satellites as helping with the space junk problem because of the fact that wood would burn up when it de-orbits. But this stuff is space junk precisely because it doesn’t de-orbit. All of our plans for handling the existing abundance of space junk involve finding a way to induce it to leave orbit. Wood won’t make any difference here.

The one point that wood might have in its favor, noted in some of the coverage and by Doi himself, is that it won’t leave much in the atmosphere if it does de-orbit and burn up. Most other hardware will vaporize into a gas of aluminum and various other metals, perhaps oxidized. Again, having a wood housing won’t eliminate these metals, given that many of them come from the satellites components and the rocket that put them in place. And, at least for the foreseeable future, this material won’t be present in the atmosphere at high enough levels to be meaningful.

Given all this, it’s completely unclear what problem wooden satellites are meant to solve. Still, the idea of figuring out how to process wood so that it would function in this context is an intriguing materials science problem, and might have some very down-to-earth applications. So, here’s to hoping that the project goes ahead regardless.

Shooting Space Debris Down with Lasers

SatelliteThe collision earlier this year between an inoperative Russian military satellite and an Iridium communication satellite led to a lot of speculation about the future of satellites and dealing with such collisions and the debris created in their aftermath. The February 2009 collision apparently created upwards of 500 individual pieces of debris which can potentially threaten other satellites.

Moreover, there is a small chance of a cascading debris failure called the Kessler Syndrome in which debris from one collision causes other collisions which in turn cause other collisions until it is all but impossible to orbit satellites around the Earth.

Fortunately, NASA has a plan — we could always shoot down space debris ranging from 1 to 10cm in size with ground-based lasers. SpaceFuture.com posted a summary of the status of such research published back in 1997,

A recent NASA study sought to determine the feasibility of removing the threat to low-altitude spacecraft by deorbiting nearly all debris objects of primary concern. This would be accomplished by irradiating the objects with a ground laser, which would ablate a thin surface layer of the debris and cause plasma blowoff. The resulting dynamic reaction would change the object’s orbit, decreasing its perigee and causing its rapid reentry. The study, called Orion after the mythological archer, was cosponsored by the USAF Space Command, directed by the author (then at NASA Headquarters), and managed by John Campbell of Marshall.

. . .

Several Orion systems were defined by the team, as were the characteristics and performance of two representative systems. The nearer term system would be able to remove from orbit essentially all of the 30,000 110-cm debris objects at or below about 800-km altitude within three years, for an estimated total cost of $60 million-$80 million, including R&D and operations. The longer term system would be able to remove essentially all of the 125,000 1-10-cm debris objects at or below 1.500-km altitude within two years, for an estimated total cost of $150 million-$180 million.

NASA would focus primarily on the smallest debris which can be hard to detect, opting to simply maneuver around debris larger than 10cm since it is easier to detect and, also, avoid. However, debris less than 1cm still poses a risk but is not reliably detect and would not be targeted by this system.

The article notes this system could not be used as a method of destroying satellites — you’d have to point the laser at a satellite continuously for months to effect its perigree enough to notice, and literally for years before causing major structural damage to a satellite.