Astroscale, a well-capitalized Japanese startup, is preparing a small satellite to do something that has never been done in space.
This new spacecraft, delivered into orbit Sunday by Rocket Lab, will approach a defunct upper stage from a Japanese H-IIA rocket that has been circling Earth for more than 15 years. Over the next few months, the satellite will try to move within arm’s reach of the rocket, taking pictures and performing complicated maneuvers to move around the bus-size H-IIA upper stage as it moves around the planet at nearly 5 miles per second (7.6 km/s).
These maneuvers are complex, but they’re nothing new for spacecraft visiting the International Space Station. Military satellites from the United States, Russia, and China also have capabilities for rendezvous and proximity operations (RPO), but as far as we know, these spacecraft have only maneuvered in ultra-close range around so-called “cooperative” objects designed to receive them.
The difference here is the H-IIA rocket is uncontrolled, likely spinning and in a slow tumble, and was never designed to accommodate any visitors. Japan left it in orbit in January 2009 following the launch of a climate monitoring satellite and didn’t look back.
That was the case, at least, until a few years ago, when the Japan Aerospace Exploration Agency (JAXA) partnered with Astroscale in a public-private partnership to demonstrate capabilities the private sector could use to eventually remove large pieces of space debris littering low-Earth orbit. The same robotic technologies could also apply to satellite servicing or refueling missions.
“We are putting this debris removal by robotic technology as one of our main technology development areas because safely approaching an object, and also observing the object and capturing the object, is basically a common technology for any on-orbit servicing,” said Eddie Kato, president and managing director of Astroscale Japan.
In hot pursuit
This mission is called ADRAS-J, short for Active Debris Removal by Astroscale-Japan. “This mission entails the first ever approach of actual space debris and will be a monumental step toward a more sustainable future in space,” Mike Lindsay, Astroscale’s chief technology officer, posted on X.
The ADRAS-J spacecraft, built in-house at Astroscale’s Tokyo headquarters, is about the size of a kitchen oven and weighs roughly 330 pounds (150 kilograms) fully fueled. The satellite launched from New Zealand at 9:52 am EST (1452 UTC) Sunday aboard an Electron rocket provided by Rocket Lab. About an hour after liftoff, ADRAS-J deployed from the Electron’s kick stage into an on-target polar orbit reaching an altitude of 370 miles (600 kilometers) at its highest point.
The liftoff from Rocket Lab’s spaceport in New Zealand was timed to allow ADRAS-J to launch into the same orbital plane as its objective—the H-IIA upper stage. Astroscale reported the spacecraft was healthy after Sunday’s launch. In a pre-launch interview, Kato said ADRAS-J will begin its pursuit of the spent H-IIA rocket in a couple of weeks, once ground teams complete initial checkouts of the spacecraft.
ADRAS-J will fire thrusters to match orbits with the H-IIA rocket, and as soon as next month, it could be flying within about 300 feet (100 meters) of the abandoned upper stage. Astroscale engineers will initially rely on ground-based tracking data to pinpoint the H-IIA’s location in space. Once in closer range, ADRAS-J will use visible and infrared cameras, along with laser ranging sensors, to transition to relative navigation mode. These sensors will measure the distance, closing rate, and orientation of the upper stage.
Astroscale officials view the switch from relying on ground tracking data to onboard relative navigation sensors as a crucial moment for the ADRAS-J mission. ADRAS-J will circle the rocket to assess its spin rate, spin axis, and the condition of its structure. This is the crux of the challenge for ADRAS-J because the rocket is unpowered and therefore unable to hold position. The upper stage also lacks laser reflectors and targets that would aid an approaching spacecraft.
This will mark the conclusion of the JAXA-supported portion of the ADRAS-J mission. If everything is working as planned, the spacecraft could move closer to the rocket to further validate Astroscale’s sensor suite and automated navigation and guidance algorithms. This will allow the company’s engineers to gather data for a proposed follow-on mission to actually go up and grab onto the same H-IIA upper stage and remove it from orbit.
“We are targeting to go closer, maybe 1 to 2 meters away from the object. Why? Because the next mission will be to really capture the H-IIA launch vehicle,” Kato told Ars last week. “In order to safely approach to a range where a robotic arm is able to be extended, it’s probably like 1.5 to 2 meters away from the object. We want to demonstrate up to that point through this ADRAS-J mission. Then on the next mission, called ADRAS-J2, we are actually equipping the robotic arm and capturing the H-IIA launch vehicle.”
JAXA is supporting ADRAS-J through the agency’s Commercial Removal of Debris Demonstration (CRD2) program. ADRAS-J is carrying out Phase 1 of this program, while Japan’s space agency has not yet selected who will win the Phase 2 contract to deorbit the H-IIA rocket.
Kato said the ADRAS-J mission will likely last “two to three months” before completing the demonstrations around the upper stage. Top of mind among Astroscale officials is to avoid colliding with the rocket.
“We can’t become debris. We can’t create debris,” Kato said. “So we have to very safely and carefully perform this mission.”
An all-of-the-above strategy
US Space Command said in December that the population of space debris in orbit has increased by 76 percent since 2019 to 44,600 objects. The uptick in space junk is primarily due to debris-generating events, such as anti-satellite tests or occasional explosions. The number of active satellites has also increased to more than 7,000, driven by launches of megaconstellations like SpaceX’s Starlink Internet network.
SpaceX and other commercial operators flying satellites in low-Earth orbit have committed to driving their spacecraft back into the atmosphere at the end of their missions, or at least low enough to naturally reenter after a few years. It’s also becoming more common for launch companies to deorbit the upper stages of their rockets after releasing their payloads in space.
So there’s growing awareness of the space debris problem. Risks from space junk pose a problem for all nations who operate in orbit, and national space agencies have stated an interest in remediating the largest pieces of debris. This has led entrepreneurs to establish startups, like Astroscale, to develop technologies to address this challenge, known as Active Debris Removal (ADR).
But as is often the case, there’s the question of who pays. Is there a viable market for space debris cleanup services? JAXA and the European Space Agency have invested relatively small amounts of funding to debris removal initiatives. The Japanese space agency’s partnership with Astroscale appears to be the furthest along, as evidenced by the launch of the ADRAS-J mission Sunday.
But Astroscale sees debris removal as just one segment of a larger business opportunity. “We are also looking at future services like on-orbit repair, assembly type things,” Kato told Ars. “Those are the whole variety of what we are trying to do right now. We identify ourselves as an orbit servicing company, not a debris removal company.”
This is a shrewd, all-of-the-above strategy for Astroscale. There’s more money, at least for now, in servicing and satellite refueling.
Founded in 2013, Astroscale is headquartered in Tokyo, with subsidiaries based in the United States, the United Kingdom, France, Israel, and Singapore. As of late last year, Astroscale has raised more than $383 million in capital from government and private sources.
In 2021, Astroscale launched a small-scale demonstration mission called ELSA-d, consisting of two tandem spacecraft that launched together, then separated in orbit for rendezvous and docking trials. ELSA-d successfully tested a magnetic docking mechanism that allowed the two spacecraft to link up again in orbit, but a propulsion problem cut short the mission’s final demonstrations.
Astroscale is developing a follow-up mission called ELSA-m for launch as soon as 2025. ELSA-m is a public-private partnership with the European Space Agency and will attempt to dock with and deorbit a OneWeb communications satellite. In the United States, Astroscale won a Space Force contract last year for an in-orbit refueling demonstration. The Pentagon is interested in refueling to enable its satellites to perform more sustained maneuvers and respond to threats the military sees in space.
ADRAS-J’s ability to rendezvous and operate in proximity to another spacecraft is foundational to all of these longer-term goals. “That’s actually common and an important technology base for any on-orbit servicing,” Kato said. “That’s how we view ADRAS-J.”