Courcy's Future Threats - December 2013

The dangers posed by space debris are now well recognised, but mitigation strategies are still at an early stage. Nevertheless, new technologies are being planned, and a new solution is pegged for testing by 2018.

In our April 2013 issue of Courcy’s Future Threats we discussed a report commissioned by the Inter-Agency Space Debris Coordination Committee (IADC), an international governmental forum for the worldwide coordination of activities related to the issues of man-made and natural debris in space. The report was entitled Stability of the Future LEO Environment and was the culmination of two years’ work conducted by six separate agencies: the Italian Space Agency (ASI); the European Space Agency (ESA); the Indian Space Research Organisation (ISRO); the Japan Aerospace Exploration Agency (JAXA); the US National Aeronautics and Space Administration (NASA); and the United Kingdom Space Agency (UKSA).

The results from the six agencies’ work were collated to form the final report, and despite the fact that all agencies based their work on favourable assumptions, the conclusions were worrying.

Each agency used a different model to assess the state of the Low Earth Orbit (LEO), and the most disturbing element was that each of the different models painted the same picture; the amount of debris in orbit is projected to increase, and with it the number of collisions (see graphs).

Source: Astrium UK

• Kessler Syndrome

A model known as the Kessler Syndrome has been used to predict that eventually there will be enough space debris that it will become self-promulgating, causing a never ending spiral of debris as it collides with itself and is slowly reduced into smaller and smaller pieces. Many researchers believe that this may already be occurring, and if the amount of debris continues to increase unchecked it could be an irreversible trend – hence the urgent need for remediation strategies. Tracking the debris is a daunting task, and the statistics are complicated. The quantity is not merely physically increasing, but also tracking technology is constantly improving and augmenting the amount of known debris.

The IADC report, with input from the participating agencies, made two key recommendations: the first was that there needs to be greater compliance with the 25-year rule (under which a nation or company launching a new object into space commits to de-orbiting it within 25 years of the end of its operational life); the second was that greater efforts be made to develop technologies to clean up the LEO.

With regard to the second recommendation, various options are being explored. Some groups are working on satellites that will fire harpoons or grapples at the object that needs removing from orbit and drag it down into the atmosphere to burn up. Examples of this are CleanSpace One (discussed in detail below) and UK firm Astrium’s ongoing harpoon based research. Other groups are focussing on ground based technologies, such as highly focussed lasers that will decelerate objects and cause them to fall back to Earth.

CleanSpace One

The next remediation option to be fully tested in space will be the Swiss project CleanSpace One. The project was launched by École Polytechnique Fédérale de Lausanne (EPFL), and is now a joint venture with a private company, Swiss Space Systems (S3). The plan is to launch the new CleanSpace One satellite using the European Suborbital Reusable Shuttle (SOAR), a small space plane developed by EPFL for low-cost launches off the back of a modified Airbus A300 jumbo jet. SOAR is designed to launch payloads of up to 250kg (551 pounds) into LEO.

EPFL and S3 are in advanced talks with Canada over a potential launch site, with the first launch planned for 2018. Other potential launch sites include the US and Spain.

CleanSpace One’s is a 30kg (66-pound) spacecraft designed to latch onto a target object with a grapple and de-orbit it (see diagram). The first mission will be a demonstration of the concept. It will link up with Switzerland’s now defunct SwissCube nanosatellite – a small cube that measures 10cm (3.93 inches) on each side – and drag it into the atmosphere where it will burn up harmlessly. The purpose of the first mission is to demonstrate orbital identification and rendezvous with an uncooperative target, and has an estimated cost of about 15 million Swiss Francs ($16 million).

S3 is CleanSpace One’s primary sponsor, and will pay $5.3 million for assembling and testing the satellite’s components and ground-based command operations. The company has also set aside $10.7 million for the development of its own version of a SOAR launch system.

“In 2018, [CleanSpace One] this will be one of our first launches, if not the first one,” Grégoire Lorétan, head of S3 communications, told the website SPACE.com in an email in October 2013. Lorétan added that S3 would have an announcement about a partnership with Canada in “a few weeks.”

In the sights

CleanSpace One’s first satellite target for a de-orbit demonstration is Switzerland’s SwissCube nanosat (also an EPFL craft). There are several reasons for the choice of target, some technical and others legal. SwissCube is small and regularly shaped, and does not have delicate gas canisters, fuel cells, or other delicate structures such as solar panels on the outside that could be ruptured or smashed in the de-orbit attempt. One of the challenges associated with removing an object from the LEO is to do so without turning a single piece of debris into several.

Another reason for choosing SwissCube as the demonstration target is that it could begin to interfere with other satellites in the future. The SwissCube satellite is known to have come within 75 metres [246 feet] of another piece of debris on 11 September 2013. Had there been a collision it could have generated a large number of smaller pieces of debris, each of which could have posed a threat to spacecraft.

Some of the thornier issues – certainly those that might present significant problems for LEO remediation strategies in the future – are legal. For the CleanSpace One demonstration a Swiss target had to be selected to avoid potential legal and diplomatic concerns surrounding the de-orbiting of a satellite owned by another country or foreign owned company. A satellite that can dock with and de-orbit a spacecraft has potential as an anti-satellite weapon.

The United Nations’ Committee for the Peaceful Uses of Outer Space expressed concerns about other people’s debris being de-orbited, and was keen for EPFL to only de-orbit its own spacecraft.

Alternatives

Some space debris must be removed, that much is clear. There are defunct satellites, and pieces of debris from previous collisions and explosions, that are simply in the way and cannot be turned to any useful purpose. However, there are other strategies that could help reduce the amount of debris being generated in the future.

Currently, when a satellite is launched it has a particular lifespan. When it has reached the end of its useful life, because it has broken down, run out of fuel, or been turned off before it can go offline by itself an cause a service outage (if it is a communications satellite, for example), it is dead in space. If the country or company launching it is a responsible actor there will be a plan for the satellite to be removed from orbit within 25 years. This could be by allowing the orbit to naturally deteriorate, or by using the remaining fuel on board to direct the satellite into a decaying orbit. However, if more satellites are being launched to replace those going offline, and the old satellites are still in the LEO for another 25 years, the region will continue to become more and more congested. And that is before considering that there is only limited compliance with the 25 year rule in any case.

What some organisations are beginning to consider are strategies to extend the lifespan of satellites, reducing the need to launch replacements.

Some of the same technologies that feed into projects like CleanSpace One can be employed in life extension projects; indeed, EPFL is also working on this type of strategy with other partners. EPFL is not the first European organisation to examine spacecraft life extension. In 2007 there were two European companies, the U.K.-based Orbital Satellite Services (OSS) and Greco-German company Kosmas Georing Services, promoting their life extension spacecraft and announcing customers.

OSS claimed to have identified 140 commercial satellites that by 2017 could have been serviced by its 1,000-pound (453 kg) spacecraft. Kosmas’ refuelling spacecraft, Hermes, had Middle Eastern satellite operator Arabsat as a client; Kosmas had priced its refuelling services at up to 10 million euros ($13.2 million) per 50kg (110 pounds) of propellant.

The US Department of Defense (DoD) has looked at similar technologies: both servicing and de-orbiting. From 2003 to 2008 the US military’s Defense Advanced Research Project Agency (DARPA) performed studies such as the Spacecraft for the Universal Modification of Orbits (SUMO) and Front-end Robotics Enabling Near-term Demonstration. DARPA’s SUMO website stated that, “SUMO can perform station-keeping and attitude control and modify the spacecraft’s orbit,” indicating the military’s interest in de-orbiting combatant’s uncooperative satellites.

In 2007 DARPA successfully carried out an in-orbit servicing demonstration mission with its Orbital Express vehicle. The agency is currently developing the Phoenix space debris cleanup and salvage satellite, which would use parts from dead satellites to fix other satellites or build new craft in space.

Viability

Many nations and companies are getting close to bringing viable LEO remediation projects on stream. It would be incorrect to view their efforts as a race, as no single method yet proposed would be effective against all types of object. De-orbiting objects using a grapple or harpoon will be effective against some satellites, but too high a risk to use against objects with vulnerable fuel cells and gas canisters. High-powered lasers could prove to be useful tools against small pieces of debris, but not practical to use against large objects. Some satellites, nearing the end of their useful life, could have their lifespan extended, but probably not indefinitely.

It is most likely that a successful overall strategy would have to include a raft of different measures, each of which must be tested for effectiveness over the coming years. Given our reliance on space-based technologies in our everyday live, for communications, navigation and (poignantly in parts of the UK and US at the time of writing) weather forecasting, it would be as well if these tools could be developed sooner rather than later.

• Space Work Programme

The EU’s next seven year Research and Innovation Programme has opened with the first call for proposals under the €1.5 billion budget allocated to space research. The Space Work Programme is an element of the EU’s emerging space policy, with ambitions to meet policy and societal challenges, and promote European space sector competitiveness. One of the key tenets of the programme is the protection of space and terrestrial assets from space-borne hazards. There is still time to submit proposals, but the deadline is tight – all proposals must be in by late March/early April.