It will soon be possible to send a satellite to repair another

news image

JET PACKS for satellites. According to Daniel Campbell, the boss of Effective Space, the British and Israeli firm which is building them, that is the way to think of the robotic spacecraft his company plans to start launching in 2020. The purpose of Effective Space’s devices, which it calls SPACE DRONEs, is to prolong the lives of communications satellites (com-sats) that would otherwise be decommissioned for lack of fuel for station-keeping—in other words, for maintaining their proper orbits.

At the moment, about two dozen big geosynchronous com-sats (those with orbits exactly 24 hours long, which thus hover continuously over the same spot on Earth) are retired each year, most commonly because of fuel exhaustion. Mr Campbell proposes to do something about that. In partnership with Israel Aerospace Industries, a government-owned firm, he plans to build the first two SPACE DRONEs in Tel Aviv, for launch in 2020. Once itself in geosynchronous orbit, at an altitude of 36,000km, each drone will slowly approach and clamp onto such an exhausted com-sat, giving it a new set of thrusters with which to manoeuvre—and thus, since the thrusters should last 15 years, a new lease of life. If this works, dozens more drones should follow. According to Mr Campbell, Effective Space already has one contract, worth $100m, for such repositioning work.

Nor is Effective Space alone in its endeavours. Next year SpaceLogistics, a subsidiary of Northrop Grumman, an American engineering giant, will launch its first such “mission extension” spacecraft. MEV-1, as it is named, will handle station-keeping for Intelsat-901, a big com-sat that is currently low on fuel. SpaceLogistics reckons its docking system can clamp onto 80% of today’s geosynchronous satellites. And NASA, America’s space agency, is planning something similar for launch in 2020. This has two robotic arms and is intended to refuel Landsat-7, an Earth-observation satellite that was launched in 1999.

These projects are no small undertakings. But even more sophisticated ideas are in the pipeline. For an inkling, consider a programme called Robotic Servicing of Geosynchronous Satellites (RSGS) that is being run by DARPA, a research arm of America’s defence department.

In April 2021 DARPA plans, in collaboration with Space Systems Loral (SSL), a firm in Silicon Valley, to launch an RSGS spacecraft that has two dexterous robotic arms and thrusters sensitive enough to accelerate or slow orbital velocities by as little as a centimetre per second. Over a lifetime of 15 years or so this craft could inspect and service as many as 30 satellites. Besides refuelling them, it could do such things as plugging in electronics upgrades, extending jammed telescopic antennae and unfolding arrays of solar panels that had not deployed properly.

That last fix would, for example, solve a predicament that has halved the transmission capacity of Estrela do Sul-2, a geosynchronous satellite built by SSL that has been in orbit since 2011. Moreover, according to Richard White, the firm’s government-liaison officer, if a close-up inspection reveals the need for a tool not carried on the servicing spacecraft, it could be sent up via a small-payload “orbital delivery system” which SSL successfully tested for the first time this year.

Advances in space robotics have also led to efforts to develop kit that might be used to capture pieces of defunct spacecraft zipping around Earth. Such junk is abundant in low orbits (those with an altitude of less than 2,000km), and is threatening not only because of the damage it can do to individual satellites, but also because such collisions themselves beget debris, creating the risk of a chain reaction of impacts.

In 2016 China launched a small spacecraft named Aolong (“Roaming Dragon”), reportedly to test a robotic arm designed to capture debris. Chinese officials have suggested that more such vehicles are in the pipeline. Earlier this year, a European consortium also launched a spacecraft designed to test ways of capturing junk. RemoveDEBRIS, as it is called, fired a net on September 16th and successfully caught an object it had released to simulate space junk. This was a world first. In February it will attempt another, by firing a harpoon designed to skewer a chunk of composite material brought along for the test.

Dark stars

These advances in what engineers call “rendezvous and proximity operations” have elated many. But they have a dark side. Something that can grab or dock with objects in space might also be used to destroy them. As William Shelton, a former head of the American air force’s space command, puts it, the difference between a service spacecraft and a weapon is merely “a change of intent”. According to Mr Shelton, in the past decade China and Russia have made “stunning” progress with such systems. At least one Chinese satellite has bumped into another one, perhaps in a test of the feasibility of such attacks.

Attack by service spacecraft is certainly not the only threat to orbiting satellites. Cyber-invasion of their software is an obvious way to try to neutralise them. They might also be blasted by powerful lasers. And they can surely be knocked out by interceptors launched from the ground. But such “kinetic” attacks generate debris, as a test conducted by China in 2007 showed. Since that debris would threaten other satellites indiscriminately, it would put the attacker’s assets at risk as well as those of its opponent. A service-spacecraft attack could avoid that by emptying a rival’s satellite of fuel, severing its antennae or spray-painting its lenses and solar panels.

At least five Russian spacecraft, called “space-apparatus inspectors” by the country’s defence ministry, have already conducted rendezvous and proximity operations in both geosynchronous orbits and orbits close to Earth. Speaking in September, France’s defence minister, Florence Parly, pointed to the troublingly close approach of a Russian military spacecraft named Olimp-K to a French and Italian military satellite as evidence that satellites “are becoming prey, targets”. France recently decided to equip its future Syracuse military satellites with surveillance systems that will monitor approaching spacecraft.

Other countries, too, are adapting to the threat. President Donald Trump’s space strategy, unveiled in March, states specifically that America will “counter threats” to its assets in space. American satellites are now being fitted with special thrusters designed for evasive manoeuvres, says Omar Lamrani, a military analyst at Stratfor, a geopolitical consultancy in Austin, Texas. Spacefaring states, America included, are dividing their assets between larger numbers of smaller satellites and also building more redundancy into their systems. Erwin Duhamel, who was until earlier this month head of security strategy at the European Space Agency (ESA), observes that officials in several places are now studying the idea of defending important satellites with “bodyguard” spacecraft. Mr Duhamel reckons ten or so satellites crucial to Europe’s security are in particular need of such protection.

How such sentinels should defend their charges is debated. They might block the approach of an attacking satellite, or serve as a shield against a laser strike. They could also be armed themselves, with lasers or small “kinetic kill” missiles—basically, sophisticated bullets. Fighting fire with fire in this way does run into the orbital-shrapnel problem, but according to Roy Lindelauf, an expert on satellite protection at the Dutch defence ministry, there is a way around that, at least for attacks on satellites in orbit close to Earth. Blast a hostile spacecraft from above, he says, and the wreckage will be forced downward to fiery doom in the atmosphere below.

For itself, ESA plans to launch, in 2023, a mission dubbed e.Deorbit. This craft’s first job will be to push into the atmosphere a derelict Earth-observation satellite called Envisat. ESA has yet to settle on the best way for e.Deorbit to capture such a “non-co-operative” object (Envisat weighs nearly eight tonnes, and is tumbling as it travels), but reckons that grabbing it with robotic arms or catching it in a tethered net are the most likely options. Either would be a classic piece of dual-use technology that could also be deployed to “neutralise” an inconvenient military satellite belonging to a hostile power.

America may be planning something yet more effective—capturing enemy satellites for inspection rather than destroying them. Two unmanned American air force space planes, OTV-1 and OTV-2, have spent years in and out of orbit since 2010. The programme is classified but a former adviser to Barack Obama, who prefers to remain nameless, says the space planes’ cargo bays could be used to remove seized satellites from orbit.

One consequence of all these developments is that a proposed ban on weapons in space that has long been pushed by Russia and China makes no sense, says Brian Chow, a space-policy expert who recently retired from Rand, a Californian think-tank. Potential weapons are already arriving in space, even if they are not officially labelled as such. A better approach, Mr Chow says, would be to prohibit unauthorised approaches, by declaring sensitive satellites to be surrounded by appropriately sized “no go” bubbles.

Some people reckon this would be illegal. The Outer Space Treaty of 1967, of which America is a signatory nation, states that space is not subject to national appropriation. But, half a century on, that treaty may be in need of revision.

Read More

Leave a Reply

Your email address will not be published. Required fields are marked *