Sweeping Up Space: The End-of-Life Solution

Posted July 6th, 2021 Posted in Blog

Kieran O’Brien – Senior Project Manager

Space sustainability has become a hot topic across the international space industry, and for good reason.

To date, governments and satellite operators have launched an estimated 11,670 satellites into space, many of which have been positioned in low-Earth orbit (LEO). According to the European Space Agency, only 4,300 of the remaining 7,200 orbiting satellites are still active, leaving nearly 3,000 non-maneuverable vehicles racing through space. Active space vehicles frequently perform “Collision Avoidance Maneuvers” (CAMs) to evade impact with other active objects and defunct space debris. Even the International Space Station (ISS) is not safe. Orbital debris presents one of the highest risks to the station, forcing up to 4+ Collision Avoidance Maneuvers a year. The paths of decaying objects frequently intersect that of the ISS, as they spiral towards the Earth’s impassable atmosphere and their fiery grave. And just recently in May, a piece of debris was found to have struck the station’s Canadarm2, leaving a sizeable hole.

The orbital environment is set to change further with the emergence of large satellite constellations. These large networks will grow the number of satellites in orbit, with tens of thousands of new satellites predicted to be launched by 2030, leading to an increasingly congested orbital environment. The sheer quantity alone should be enough to raise alarm bells for satellite operators, as well as any users of space-based infrastructure, the latter of which more or less covers every living person in the developed world.

Space is a notoriously harsh environment and satellite failures happen. The numbers involved in large constellations make in-orbit failures a significant issue for space sustainability. Take, for example, a hypothetical constellation of 1,000 satellites operating at a high-LEO altitude. A failure rate of 5% would result in around 50 dead spacecraft hurtling through the same orbital environment as the remaining live craft. As more satellites are launched to replenish the constellation, the number of failed satellites in orbit would only increase. This clearly poses a significant threat to any objects in the same or similar orbits, including the operator’s own constellation. It is one thing to pilot hundreds of controlled vehicles through their planned orbits in coordinated unison, but another thing entirely to add 50 malfunctioning rogues, each travelling at orbital speeds of over 17,000mph.

Not only does this risk the operator’s own constellation and other objects in the same orbital vicinity… it threatens the entire LEO environment, as each collision can potentially create tens of thousands of new pieces of debris. Over time, this could lead to a “Kessler Syndrome” runaway effect, where an increasing number of orbital objects leads to a growing number of collisions, and thus an ever-increasing volume of orbital debris.

So, with the exponential rise of constellations already underway and set to continue, what can we do to simultaneously benefit from revolutionary LEO-broadband networks whilst guaranteeing a sustainable space environment for future generations?

This is where End-of-Life (EOL) Servicing comes in. With a small amount of forethought and pre-emptive action, constellation operators can prepare their satellites with docking plates before launch, allowing compatible servicer satellites to rendezvous, dock with, and dispose of these clients at the end of their lives.

Imagine an entire fleet of highly advanced robotic servicers, ready and waiting to rendezvous with nearby satellites to actively de-orbit them at the end of their lives. Once complete, these robotic space sweepers could return to their parking orbits and lie patiently in wait for another call from their next satellite-in-need. This might sound like science fiction, but this is one of several visions that Astroscale are already well on their way to achieving. The recent launch of the ELSA-d (End-of-Life Services by Astroscale-demonstration) and the revolutionary multi-client servicer program, ELSA-M, are milestones on the path to bringing this vision into reality.

This ELSA-M program represents the global space industry’s next big step towards offering a commercial servicer capable of removing multiple pieces of debris in a single mission. Current activities include the development of key EOL technologies with our partners at the UK Space Agency, European Space Agency and OneWeb, under the recently signed Sunrise program. These technology developments will enable the first ever rendezvous and docking between an EOL servicer and a commercial client spacecraft, paving the way for the start of our commercial EOL service.

And this is just the beginning. By mastering the technologies required for on-orbit rendezvous and close proximity operations, along with robotic capture of uncontrolled space objects, this EOL technology will support the development of even more advanced forms of on-orbit servicing, including on-orbit refueling, on-orbit upgrades, and even on-orbit manufacturing and / or assembly.

But for now, the main objective remains simple, though far from easy… as Astroscale develops revolutionary EOL technology, we work in partnership towards preserving a clean, safe and sustainable orbital environment for humanity’s continued exploration and utilization of the cosmos.