A new era of space robotics, 36,000km above Earth
Image credit: Space Logistics
Space has been a straightforward business so far: launch it; turn it on; hope it works; avoid the stray piece of space junk; let it die. Now, a more complex space economy is on the horizon, with maintenance spacecraft, repair robots, garbage removal trucks and even orbital manufacturing depots.
This year is set to see history made with the first ever servicing operation on an in-orbit satellite. Robotic orbital trouble-shooters, which are expected to pave the way for a new era of space robotics, will one day shuttle malfunctioning spacecraft back and forth, refuel them, perform basic repairs or serve as temporary propulsion and steering units.
Satellites are a crucial component of 21st-century technology infrastructure. We depend on them for weather forecasting and climate monitoring, telecoms, navigation and a plethora of scientific and emerging applications. Satellites are often costly to build and launch, and once in orbit, little can be done to upgrade, inspect or fix them. If all goes well, operators can get up to 20 years’ service from their assets. If unexpected problems occur, the investment might go to waste.
The first ever in-orbit servicing spacecraft, the Mission Extension Vehicle 1 (MEV-1), built by Space Logistics, a wholly owned subsidiary of American aerospace giant Northrup Grumman, is set to perform the first automated docking between two commercial satellites. Upon completing this manoeuvre, it will commence the equally pioneering task of extending the life of an ageing telecommunications satellite of US operator Intelsat.
The demonstration will take place in the so-called graveyard orbit about 200km above the geostationary ring, an orbit at the altitude of 36,000km, where spacecraft appear suspended above a certain spot on Earth. Sought after by operators of meteorological and telecommunications satellites, the geostationary orbit is one of the busiest regions of space. To keep it tidy for future users, operators are obliged to move their spacecraft into the graveyard at the end of each mission.
“This mission represents many industry firsts,” Joe Anderson, vice president of business development and operations at Space Logistics, tells E&T. “We are using many new technologies and because there are some concerns, we decided to perform the demonstration in the graveyard orbit.”
MEV-1, which launched in mid-October 2019 from Russia’s cosmodrome Baikonur in Kazakhstan, raises itself into the geostationary graveyard orbit from the so-called geostationary transfer orbit, where it has been left by the launcher, using its electric thrusters. In the graveyard orbit, the service vehicle will meet its client, Intelsat’s IS901. Intelsat’s operators have moved the craft into the graveyard orbit using its onboard propulsion system ahead of the demonstration.
IS901 is an 18-year-old veteran. Under normal circumstances, the satellite would soon reach the end of its life, but Intelsat hopes that MEV-1 could add at least five years to its mission. The servicing spacecraft, which will autonomously approach and attach itself to IS901, will first move the satellite into a new slot in the geostationary orbit and then use its thrusters to maintain its position and attitude for the duration of the mission. At the end of the five-year period, MEV-1 will push IS901 back to the graveyard orbit before disconnecting and moving on to another client.
Space Logistics, previously part of Orbital ATK, acquired by Northrop Grumman in 2018, spent ten years developing technologies for the mission at the company’s Rendezvous, Proximity, Operations and Docking (RPOD) laboratory.
“In this laboratory, we have a number of very large industrial robots that we are using as puppeteers for the mock-up of the MEV,” says Anderson. “We used that laboratory to develop prototypes and test our software algorithms and sensors that are used to do the rendezvous and docking.”
Space Logistics reused some of the technologies developed by Orbital ATK originally for the Cygnus spacecraft, one of the cargo vehicles resupplying the International Space Station (ISS). Cygnus, however, doesn’t dock autonomously but is captured by the station’s robotic arm and berthed to the station’s Harmony module. While the ISS has dedicated docking and berthing ports, MEV-1 will have to be able to attach to satellites that were not designed with orbital docking in mind.
The MEV does that by taking advantage of two features that are, according to Anderson, on 80 per cent of geostationary satellites currently in orbit – the so-called liquid apogee engine and the launcher adapter ring.
“Before the start of the manoeuvre, MEV-1 circles around the target a few times and inspects it with its visible, infrared and lidar sensors,” Anderson explains. “It then positions itself 500m behind the target and waits for a command from the ground control team to start the approach, which is very slow.”
At the distance of one metre from the target, MEV-1 deploys a probe, which enters through the liquid apogee engine into the client satellite. Inside, the probe deploys its ‘fingers’ in order not to slip out. MEV-1 pulls the probe back and the two satellites are brought together, with the launcher adapter ring on the client satellite pressed against three stanchions on the MEV.
“We end up with a very simple push-pull tension where we are pulling at the centre of that liquid apogee engine and we are pushing against the launcher adaptor ring and that’s what clasps the two vehicles together,” says Anderson. “From that point onward, the MEV takes over the attitude and orbit control of the combined vehicle stack.”
As an idea, in-orbit servicing has been around for almost 20 years, according to Anderson. The technology, however, didn’t make economic sense before. The cost was too high and the risks considerable. On top of that, operators would prefer to replace their ageing systems with modern, more efficient ones. However, the tide has turned, space has become more cluttered and cost-cutting became more of an interest. The idea of prolonging the life of existing satellites instead of building and launching new ones came to the fore.
What’s next for space robots?
In-orbit servicing presents only the first step towards a future that resembles what once would have been science fiction. Robotic manufacturing in space and orbital assembly of spacecraft, too, is getting closer to reality. US company Made in Space is developing a space robot called Archinaut One that will enable manufacturing of large structures for space in space.
Made in Space received $73.7m of Nasa funding for the Archinaut pilot project, which is expected to fly to space in 2022.
Fitted with a cutting-edge space-qualified 3D printer and robotic manipulator arms, Archinaut will print, assemble and deploy its own operational solar array, which, the company says, will be five times more efficient than regular solar panels used on today’s spacecraft.
In the future, such orbital robots could build various components for existing satellites such as super-powerful antennas, radar booms, extra-large solar panels and others. The robots could also assemble entire telescopes larger than those that are possible to launch from Earth. Larger telescopes mean greater advances in scientific understanding. The ability to manufacture in space means considerably lower cost since the cost of launch from Earth represents a large portion of the overall cost of space exploration and utilisation.
“There have been lots of new activities behind space sustainability in the last few years and I think we will see more resources being put into resolving the potential risks in orbit,” says Daniel Campbell, managing director of Effective Space, a UK-based start-up developing what they call ‘space drones’, small satellites that would provide life-extension services similar to those offered by Space Logistics.
The company is part of the Consortium for Execution of Rendezvous and Servicing Operations (CONFERS), led by the US Defense Advanced Research Projects Agency (DARPA), which aims to develop operations standards for in-orbit servicing.
Effective Space, which hopes to launch its maiden mission in 2021, relies on a 1×1×1.5m platform, designed to extend the life of a satellite by up to 18 years. Space Logistics’ MEV-1, for comparison, based on a standard platform for geostationary satellites, comes in a larger 3.0×2.1×2.3m package.
Just like MEV-1, Effective Space’s drones will be able to detach and serve multiple satellites within their designed lifespan.
Campbell says that in addition to the growing sustainability concerns, in-orbit servicing would be handy as satellite operators await the arrival of low Earth orbit mega-constellations – a new and unproven technology for telecommunications.
“Many of the operators are waiting to see the impact of these deployments on the geo business,” Campbell says. “That incentivises them to hold off any replacement satellites and they see life extension as a potential gap filler.”
DARPA envisions that robotic in-orbit servicing technology could in the future reduce the cost of geostationary satellites, which currently need to be packed with back-up systems just to ensure the mission’s success. That obviously increases complexity, weight and cost. In the future, new payloads could be installed as and when required by the robotic service vehicles.
Campbell says Effective Space is also looking at the possibility of using in-orbit servicing in the low Earth orbit (LEO), the area closest to the Earth up to the altitude of 2,000km, which is the most congested and set to become even more cluttered with the arrival of mega-constellations. The business case in LEO, however, will be more difficult to prove. LEO satellites tend to be smaller, cheaper and usually designed with shorter lifespans in mind compared to the geostationary platforms.
“It’s part of the number-crunching that needs to make sense,” Campbell adds. “But perhaps the incentive to use these services will not be purely economic but part of licensing requirements that will oblige the operators to safely dispose of their satellites before deploying new ones to LEO.
Space industry consultancy Northern Sky Research predicts that the in-orbit servicing market will be worth $3bn (£2.3bn) by 2028 with life extension driving most of the revenue. Chris Brunskill, head of Access to Space at UK Satellite Applications Catapult, compares the current situation in space to the world’s procrastination around climate change and plastic pollution.
“At the moment, we are getting away with it,” he says. “Mostly, it won’t be a problem during our lives, but it will be something the next generation will have to worry about. The market is first going to grow very slowly, but as we start to see larger constellations, the need to manage those is going to increasingly grow the need for commercial debris mitigation and in-orbit servicing capabilities and companies.”
The UK hopes to carve a slice from the prospective in-orbit servicing pie and has recently launched what is to become the UK’s National In-orbit Servicing and Operations Centre in Harwell, Oxfordshire.
“There are about half a dozen companies in the UK exploring in-orbit servicing,” says Brunskill. “That includes start-ups but also some of the established businesses such as Airbus. We are trying to establish the UK as a global centre of excellence and capabilities for debris mitigation and in-orbit servicing. With this facility we want to remove some of the roadblocks for those companies to develop their services.”
The Space Applications Catapult has developed the facility in cooperation with the Japan-headquartered start-up Astroscale, which will conduct the world’s first commercial active space debris removal mission, the End-of-Life Service by Astroscale (ELSA) mission, from here in 2020.
Northrup Grumman, in the meantime, is already developing its next-generation in-orbit servicing vehicle, which will enable larger-scale operations and lower the cost of the service. The rendezvous operations will be carried out by the Mission Robotic Vehicle (MRV), essentially an upgraded MEV fitted with a robotic arm. The actual propulsion and attitude control function for the client satellite will be provided by the Mission Extension Pods (MEP), smaller and cheaper units that will be installed by the MRV.
The more complex and expensive MRV will be able to install multiple MEPs in a short period of time as well as other augmentation payloads. Northrop Grumman says the MRV will even be able to perform simple repairs and perform detail inspections of the client spacecraft. *
The big challenge
The biggest challenge for in-orbit servicing and robotic space operations is not in the engineering and technology field but rather in the legal and regulatory domain. A whole new set of regulations, licensing regimes and insurance policies will be needed for the technology to fully take off.
“The regulatory environment is not developed for this type of activity in space,” says Anderson. “There are regulatory and licensing regimes for the remote sensing of the Earth and for telecommunications, but to do a service like this is something completely new and different.”
Space insurers similarly struggle to fit this type of new commercial service into their existing schemes, Anderson adds.
“The space insurance market is accustomed to insuring things like geostationary communication satellites but now when we are going to rendezvous and dock in orbit and bring these two vehicles together, it has brought a new challenge,” he says. “If there was a problem in orbit, who would be liable? How would one calculate what the insurance claim would be?
Brunskill adds that in the UK work is under way to fill these regulatory gaps and update regulations to match the latest technology developments.
“I think that the regulatory infrastructure will probably lag behind the commercial need for this,” he says. “But companies operating mega-constellations will need these services to maintain their own spacecraft, otherwise they would be their own worst enemy.”
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