European Space Agency Targets Orbital Debris, Solar Storms

The European Space Agency (ESA) received a sizable budget boost in late 2019 and committed to joining NASA's Artemis program, expanding Earth observation, returning a sample from Mars, and developing new rockets. Meanwhile, less glamorous projects will seek to safeguard and maintain the use of critical infrastructure in space and on Earth.

Space Debris Removal

ESA's ClearSpace-1 mission, having just received funding in November, is designed to address the growing danger of space debris, which threatens the use of low Earth orbit. Thirty-four thousand pieces of space junk larger than 10 centimeters (cm) are now in orbit around Earth, along with 900,000 pieces larger than 1 cm. They stem from hundreds of space missions launched since Sputnik-1 heralded the beginning of the Space Age in 1957. Traveling at the equivalent of Mach 25, even the tiniest piece of debris can threaten, for example, the International Space Station and its inhabitants, and create more debris when it collides.

The ClearSpace-1 Active Debris Removal (ADR) mission will be carried out by a commercial consortium led by Swiss startup ClearSpace. Planned for launch in 2025, the mission will target a spent upper stage from an ESA Vega rocket orbiting at 720 kilometers above the Earth. Atmospheric drag is very low at this altitude, meaning objects remain in orbit for decades before reentry.

There, ClearSpace-1 will rendezvous with a target, which will be traveling at close to 8 kilometers per second. After making its approach, the spacecraft will employ 'tentacles' to reach beyond and around the object.

"It's like tentacles that embrace the object because you can capture the object before you touch it. Dynamics in space are very interesting because if you touch the object on one side, it will immediately drift away," says Holger Krag of ESA's Space Safety department and head of the Space Debris Office in Darmstadt, Germany.

During the first mission, once ClearSpace-1 secures its target, the satellite will use its own propulsion to reenter Earth's atmosphere, burning up in the process and destroying the piece it embraced. In future missions, ClearSpace hopes to build spacecraft that can remove multiple pieces of debris before the satellite burns up with all the debris onboard.

Collisions involving such objects create more debris and increase the odds of future impacts. This cascade effect is known as the Kessler Syndrome for the NASA scientist who first described it. The 2009 collision of the active U.S. commercial Iridium 33 and defunct Russian military Kosmos-2251 satellites created a cloud of thousands of pieces of debris.

With SpaceX, OneWeb, and other firms planning so-called megaconstellations of hundreds or even thousands of satellites, getting ahead of the situation is crucial to prevent low Earth orbit from becoming a graveyard.

Eventually, ClearSpace-1 is intended to be a cost-efficient, repeatable approach to reducing debris available at a low price for customers, says Krag. ESA backing for the project comes with the aim of helping to establish a new market for debris removal and in-orbit servicing. Northern Sky Research projects that revenues from such services could reach US $4.5 billion by 2028.

Other debris removal and servicing initiatives are being devised by companies including Astroscale in Japan and Northrop Grumman in the United States. The U.K.-based Surrey Satellite is also working on net and harpoon concepts to tackle space junk.

Solar Storm Early Warning

ESA is also looking to protect Earth from potential catastrophe with a mission to provide early warning of solar activity. The Carrington event, as the largest solar storm on record is known, was powerful enough to send aurora activity to as low as 20 degrees latitude and interfered with telegraph operators in North America. That was in 1859, with little vulnerable electrical infrastructure in place. A similar event today would disrupt GPS and communications satellites, cause power outages, affect oil drilling (which uses magnetic fields to navigate), and generally cause turmoil.

The L5 'Lagrange' mission will head to the Sun-Earth Lagrange point 5, one of a number of stable positions created by gravitational forces of the two large bodies. From there, it will monitor the Sun for major events and warn of coronal mass ejections (CMEs) including estimates of their speed and direction.

These measurements would be used to provide space weather alerts and help mitigate against catastrophic damage to both orbital and terrestrial electronics. Krag, in an interview at a European Space Week meeting last month, states that these alerts could reduce potential harm and loss of life if used to postpone surgeries, divert flights over and near the poles, and stop trains during the peak of predicted activity from moderate-to-large solar storms.

"Estimates over the next 15 years are that damages with no pre-warning can be in the order of billions to the sensitive infrastructure we have," Krag states. Developments like autonomous driving, which rely on wireless communications, would be another concern, as would crewed space missions, especially those traveling beyond low Earth orbit, such as NASA's Artemis program to return astronauts to the moon.

Despite an overall budget boost, ESA's request for 600 million euros from its member states for 'space safety' missions was not fully met. The L5 mission was not funded in its entirety so the team will concentrate first on developing the spacecraft's instruments over the next three-year budget cycle, and hope for more funding in the future. Instruments currently under assessment include a coronagraph to help predict CME arrival times, a wide-angle, visible-light imaging system, a magnetograph to scan spectral absorption lines, and an X-ray flux monitor to quantify flare energy.