HUMAN BEINGS are messy. They tend to leave rubbish behind wherever they go – and to expect someone else to clean up the rubbish. This is true even in outer space. The problem of debris upheaval and the associated risk of colliding and damaging it with an active and probably expensive satellite has been around for a while. But it is getting worse fast. In the last three years, the number of times such junk has had almost satellites has approximately doubled.
This is at least the calculation made by Daniel Oltrogge, an expert whose conclusion is drawn from his two posts. Mr. Oltrogge is an advisor to the Space Data Association, an industry body that feeds orbit information from many satellite operators into a computer model that predicts possible collisions so that spacecraft, or at least those with appropriate propellers, can be moved out of harm’s way. manner. Mr. Oltrogge is also the director of the Center for Space Standards and Innovation at AGI, a U.S. firm that develops orbital mechanics development software that also helps satellite operators circumvent collisions.
Part of the problem is the growing number of launches that are taking place. On January 13, Virgin Orbit, a firm in Richard Branson’s Virgin Group, which is yet another new entrant to the market, plans to elevate ten satellites in orbit with a rocket released from a custom Boeing 747-400. Another part, however, is that every year a dozen or so large pieces of rubbish break around the earth. About half of these explosions are caused by things like the ignition of residual rocket fuel and the bursting of old batteries and tanks under pressure. The rest is the result of collisions.
The result is a chain reaction of impact in a trajectory. Contrary to the fictional version of such a chain reaction, which disturbs Sandra Bullock’s character in “Gravity”, a film released in 2013, this real one accelerates only slowly, so there is still time to shorten it . But if action is not taken soon, satellite insurance premiums will rise, spending on detection and collision systems will have to increase, and certain orbits may become unusable. If things get really bad, the authorities will even have to step in to limit the number of launches.
Valskote
If you stop this chain reaction around the orbital jamming stop, it means that you are throwing a portion of the excess amount into space into the earth’s atmosphere, where the frictional heat of reintroduction will burn it. Cleaning is not necessary. It is enough to remove a handful of the larger abandoned persons each year. Exactly how much is being debated about it. Yamamoto Toru of the Japanese space agency, JAXA, estimates between three and seven. Ted Muelhaupt of the American Aerospace Corporation, a tax-funded research center, counts a dozen. But even that sounds feasible. Except that no one knows how to do it.
However, people plan to exercise. One practice mission, scheduled for March, is led by Astroscale, a Tokyo-based company. Astroscale proposes to launch a mission called ELSA-d from Baikonur Cosmodrome in Kazakhstan. It consists of a 175 kg mothership called a servicer, and a 17 kg pod equipped with an iron plate that serves as a dummy target. If all goes well, the server will shoot out the pod three times and reclaim in successive difficult test runs before the propellers push the entire kaboodle into the atmosphere below to a fiery downfall.
In the first test, the maintenance springs will use the springs to push the pod out, and as soon as it is ten meters further, it will come closer again, lock onto the clutch plate with an arm with a magnetic head, pull the arm back and pull it back to the server. For the second test, it will push the pod at least 100 meters further before it starts approaching. A reaction wheel and a set of magnetic torque generators then place the pod in a tumbler that involves all three axes of motion, at a speed of half a degree per second.
This is, as it were, an important twist – because pieces of rotating debris usually spin this way. A real disruption mission will therefore have to deal with such rotating objects. Marks on the pod will help the server work out the prey of his prey. Using eight thrusters, it will maneuver itself until these marks are stationary for its sensors. This will mean that the motion exactly matches that of the tumbling pod, and that the magnetic head can therefore be extended to do its job.
For the third capture test, the maintenance workers will first use its thrusters to move a few miles away from the pod, placing the pod outside the sensor range. Then it will search for it, as it would if it were looking for a real abandoned spacecraft.
Despite all the technological skills required by these tests, however, there is a greater challenge to actual abandonment than dummy. First, unlike Astroscale’s pod, few spacecraft are designed to accelerate their own removal. Also, the objects that need to be removed the most are dangerously heavy. A spacecraft that calculates incorrectly while trying to capture such a piece of tumbling debris can be broken into pieces, thus contributing to the problem it had to solve.
Understand the matter
The commercial removal of rubble demonstration, a plan by JAXA to weaken a discarded Japanese rocket stage, highlights these problems. Before a spacecraft can be designed to capture which decaying Japanese space agency chooses as the target of the experiment, a reconnaissance mission must first be launched to study it more closely. JAXA awarded the contract for this part of the demonstration to Astroscale, which plans to do so using a vessel called ADRAS-J, which will be launched in two years. To measure the movement and characteristics of a rocket part that can weigh tons, ADRAS-J will approach within a few meters. Once the necessary data is collected, another spacecraft can be designed to grab the debris on a subsequent mission.
In this case, magnets will not be used to wrestle with the target, as normal spacecraft contain no iron. However, it may be possible to use a harpoon to capture such an object. In a test conducted in 2019, Airbus, a European aviation giant, successfully fired a harpoon from a satellite into a piece of panel work 1 meter away. However, the panel work was coupled to a tree that stretched off the satellite, and so it was the most preliminary experiment. A harpoon can also miss, ricochet or – even worse – break down parts of the target which will then add more objects to the heavenly clutter.
Another option is to shoot a net. Airbus tested this idea in 2018. The test successfully encased a small “cubesat” that was pushed seven meters away from the networking vessel – although this just was not tied to the mother ship, which would therefore not be able to reach the target. Tethers are indeed difficult to manage in the weightlessness of the runway, which is why Airbus chose not to use one in this preliminary experiment with a net throw. And some doubt that such cosmic retiarii is a sensible idea. Chris Blackerby, chief operating officer of Astroscale, expects that the best approach would be to design robotic weapons to clamp the target ring of the target vehicle (the shallow cylinder that connected it to the downstream launch stage that lifted it off the ground), if it still intact.
If all this works, the JAXA demonstration for debris removal will face a final challenge. This is to perform a safe re-entry. Many pieces of the entrance complex of Captain and Prisoner will survive friction melting and quickly strike the earth’s surface. If the entry were to take place in a random place, the probability of a human accident would now exceed the threshold of one in 10,000 that NASA, the US space agency, set in 1995 as an acceptable level of risk, and which was set by Japan and other countries thereafter. The complex will therefore have to be placed in a steep turn-off facing an uninhabited area – probably part of the Pacific Ocean.
As for the first approval of actual orbital residues, it is likely to be a European matter, as in 2019 the European Space Agency awarded a contract to ClearSpace, a Swiss firm, to seize a 100kg piece of rocket debris that has been running Earth since 2013. This mission is scheduled for 2025.
ClearSpace plans to use a capture vessel with four robotic arms. Unlike harpoons or networks, this strategy can make repeated attempts at recovery. Nevertheless, ClearSpace boss Luc Piguet expects his spacecraft to spend at least nine months in trials near the target before securing the deserted and slowing down enough to land.
Pay!
A period of serious clean-up in space is still far away. In addition to the technological barriers, garbage removal will be expensive. In addition to the cost of luring something into a lane, controlled entry of an object requires fuel, large thrusters, and careful attention from a ground controller. These things can fetch millions of dollars, perhaps more than $ 20 million, at the cost of a disruptive operation. ClearSpace’s mission, for example, could cost up to € 100 million ($ 122 million), although Piguet hopes the next jobs will be cheaper.
Cheaper or not, but the question remains: “who will pay”? The littering of space is an example of the tragedy of the community, in which it is in everyone’s interest to solve a problem, but no one is the only individual taking the burden on him.
The solutions to the common tragedies must therefore usually be imposed from the outside, often by governments. One idea is a special launch tax, with the proceeds supposed to pay for clean-up operations. A more creative proposal is what Mr. Muelhaupt calls it a “bottle dumping system”. Astronauts would pay a deposit for each vessel they charged in orbit. If owners fail to repair their equipment after the mission is over, the work can be done by someone else, who would then recover the deposit. This will encourage people to build up disruptive capabilities in satellites from the start so that the heavenly dustmen will eventually no longer be needed. A third proposal, proposed by Akhil Rao of Middlebury College, Vermont, is to charge rent, known as revolutions, for each commercial satellite in orbit. This will have the same effect.
Support for such schemes is increasing, although it requires both international agreements between countries with launch facilities and a enforcement mechanism to prevent outsiders with diaper rules from suppressing the arrangement.
There is another point. As Jean-Daniel Testé, once head of the French Air Force’s Joint Space Command, noted, equipment designed to orbit the orbit could also be used to eliminate satellites. Mr. Testé says the progress in orbital robotics made by France’s opponents, not to mention the lack of international “space gendarmerie”, is leading his country to plan spacecraft to defend its military and intelligence satellites.
Mr. Testé is kind about the details. But France’s minister of armed forces, Florence Parly, has revealed more about her country’s plans than her equivalents in other powers, including the United States. She predicts that France will launch a special “lookout” and “active defense” spacecraft to protect its assets in space. The latter is probably armed with powerful lasers. As Ms Parly put it: ‘we intend to blind threatening spacecraft’. Preferably without disintegrating it.