The “Zombie Rocket” and the Era of In-Orbit Servicing

The Japanese company Astroscale has photographed space debris in low Earth orbit, which will soon be the subject of an active debris removal mission. Various missions have already been conducted or are about to launch to address different needs: from de-orbiting to refueling and repairing.

BY EMILIO COZZI

The Silent Solitary.

This could be the title of an image that, if not iconic, will still represent an important precedent, a sort of watershed for a seemingly small but substantial revolution. We have entered the era of in-orbit servicing (or on-orbit servicing, or simply satellite servicing), as suggested by the photo of a defunct and unusable Japanese rocket standing out against the black of the extra-atmospheric void, captured by the Adras-J vehicle of the Japanese company Astroscale, one of the pioneers in this field.

In itself, the photo is not the sharpest of icons. However, it is the first image of space debris, in other words, space junk, captured in orbit by a mission dedicated to characterizing it as part of a cleanup program around Earth.

The so-called “low orbit,” or LEO in jargon, is the most exploited portion beyond the atmosphere, progressively populated with satellites of various sizes and functions, as well as carcasses of devices that have reached the end of their operational life, or rocket parts, like the Japanese one targeted by Astroscale, drifting after completing their duty. There are millions of fragments of different sizes and masses traveling thousands of kilometers per hour along the low orbit. From there, from the orbits closest to Earth, activities will soon commence not only for removal but also for refueling and maintenance. This will fuel one of the sectors promising one of the most significant expansions in the space economy.

From Humans to Robots

The concept of in-orbit maintenance service is not new: the first in-orbit servicing missions date back to the 1980s and 1990s. However, they were conducted by astronauts, specifically NASA astronauts on Space Shuttles. The first example involved the Solar Maximum Mission (SMM), a satellite dedicated to observing solar events, approached, captured, and repaired in 1984. The five missions involving the Hubble Space Telescope as the “patient” are well-known. Their cost was exorbitant due to the use of expensive shuttles and the involvement of human personnel, with stringent and demanding safety requirements.

The first successful attempt with a robotic demonstrator for such missions was completed in 2007 by DARPA, a government agency of the U.S. Department of Defense responsible for developing new technologies for military use, with a pair of satellites (a target to service and a servicer) in the Orbital Express program.

Nowadays, the need is increasingly felt. For different reasons depending on the orbits involved. However, costs must be reduced, a goal achievable because there will no longer be a need to send a crew of seven with a $1.5 billion flight, as was the case with the Shuttle.

From now on, the focus will be on robotization, as Astroscale and others demonstrate.

GEO and LEO, Different Needs

In low Earth orbit, space debris constitutes a non-negligible mass. Efforts are concentrated there, just outside the atmosphere, particularly for removal, starting with the “largest pieces.”

Defunct satellites (about 2,500), perhaps for decades, without fuel or command-receiving capacity due to malfunction, or, as in the case of the object photographed by Astroscale, rocket parts not designed to be maneuvered once their task is completed.

Until a few years ago, there was no awareness to predict an immediate reentry into the atmosphere. Therefore, some debris has been wandering for decades (the H-2A rocket stage photographed by Astroscale has been up there since 2009) and poses a risk to other assets flying at the same altitude on intersecting orbits. The most pressing issue at altitudes between 300 and 2,000 kilometers is precisely this. The simplest and most effective solution is to send tow trucks to clean up the useless items, dragging them down to burn up in the atmosphere.

At the same time, low Earth orbit is also the space to test other approach and docking maneuvers useful for re-orbiting and refueling operations. Maintenance will be possible in the future with satellites designed and built to be repaired and refueled.

In-Orbit Maintenance and Re-orbiting as a Business

In contrast, in-orbit maintenance and re-orbiting constitute a necessary business where there are substantial investments for individual satellites, mainly in geostationary orbit. At 36,000 kilometers from Earth, the possibility of satellite collisions is not a concern (at that altitude, the relative velocity approaches zero because each satellite remains vertically above a point on the surface), but any problem, perhaps with the propulsion system, risks wasting tens of millions in investments. A vehicle capable of returning the client to its operational orbit, refueling a satellite, or moving it to a graveyard orbit, freeing up slots for a replacement, would be needed.

For the record, Astroscale has not done something truly unprecedented: in 2020, Northrop Grumman’s Mission Extension Vehicle 1 (MEV-1) approached, photographed, and then moved a nearly fuel-depleted geostationary Intelsat satellite back to an operational orbit. Attached to the client satellite, MEV-1 guaranteed an additional five years of operational life to an asset costing hundreds of millions of dollars. A similar operation was completed by MEV-2, again on an Intelsat, this time directly docked in an operational, geostationary orbit.

Astroscale Missions

Even though Adras-J demonstrated its target, it will not dock with the rocket drifting like a zombie in space. These are general tests for future missions. Adras-J has been selected by the Japanese space agency, JAXA, for the first phase of the “Commercial Removal of Space Debris Demonstration” program. During its mission, the satellite conducted multiple maneuvers in a progressive approach from about 200 kilometers to a few hundred meters, thanks to a navigation algorithm capable of processing images from the onboard camera.

Recently, JAXA selected Astroscale for the second part of the program. Another similar satellite, Adras-J2, is expected to approach the same piece of debris, capture it, and deorbit it. This would be the first attempt to actively remove such a large (comparable to a four-meter-diameter silo, as tall as a three-story building) and non-cooperative object, meaning it cannot be controlled or was not designed to be handled.

Previously, with the Elsa-d mission, Astroscale launched two small satellites into orbit as demonstrators for rendezvous and docking operations.

The company’s success is now global: Astroscale has been operating outside Japan for some time, particularly in the United Kingdom, where it is developing the Cosmic (Cleaning up Outer Space Mission through Innovative Capture) orbital debris removal for the country’s space agency and Elsa-M with Oneweb for ESA (which invested 15 million euros).

The French space agency CNES has also signed a contract with the Japanese company to study a mission of this type. There is also APS-R (Astroscale Prototype Servicer for Refueling), conducted by Astroscale’s American branch in collaboration with Orbit Fab. This activity includes refueling in the region populated by the most expensive satellites: in geostationary orbit. It involves a tank, built by Orbit Fab, to be parked just above the orbit and a satellite shuttle to fill its “tank” and refuel client assets with hydrazine (the typical fuel used for orbital maneuvers). The US Space Force has reportedly invested $25.5 million in the project.

New Players and the Economy of the Future

Astroscale was founded in 2015 and has so far raised just under $400 million in funding. ClearSpace, a Swiss company with a branch in the UK, has attracted about a tenth of the funds but already plans at least two technology demonstration missions for active debris removal, the first commissioned by the European Space Agency and the other by the UK Space Agency.

These are new entities that will have to compete with giants like the already mentioned Northrop Grumman and DARPA. The latter, with a mission planned for 2025, will target the US Space Force’s Delta 11 military satellite for the most refined approach ever attempted in this type of mission. The mission will apply an electro-optical image sensor to the satellite. It will involve delicate and complex approach and docking maneuvers using robotic arms developed by DARPA and the Naval Research Laboratory.

In Italy, in 2023, the Italian Space Agency signed a contract with Thales Alenia Space, the lead company of a temporary consortium including Leonardo, Telespazio, Avio, and D-Orbit, for a 235-million-euro in-orbit servicing demonstration mission funded by the PNRR. The technologies to be validated will include refueling, repair or replacement of components, orbital transfer, and atmospheric reentry.

In this case, public support will also open the door to the future market, which in this sector promises to be worth between 2.5 and 5 billion dollars over the next decade.

For this reason, that “silent solitary” image says a lot.