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Astroscale will use the ELSA-d spacecraft, launched March 22, to demonstrate technologies needed for active debris removal. (credit: Astroscale)

The growing case for active debris removal

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There are, unfortunately, plenty of reminders of the growing problem of orbital debris. On March 18, the Space Force’s 18th Space Control Squadron (18 SPCS), responsible for tracking objects in Earth orbit, announced that the retired NOAA-17 polar-orbiting weather satellite had broken up eight days earlier, creating 16 pieces being tracked (and likely more too small to be tracked.) On March 22, 18 SPCS reported that a Chinese satellite, Yunhai 1-02, had broken up four days earlier, creating 21 pieces being tracked.

“To effectively address the orbital debris issue, global mitigation and strategic remediation efforts are necessary,” NASA’s Office of Inspector General concluded.

What happened to Yunhai 1-02, a Chinese environmental monitoring satellite launched a year and a half ago, is not yet known. The 18 SPCS said only that “analysis is ongoing” regarding that breakup. (Yunhai 1-02, like NOAA-17, was also in a polar orbit, but there’s no evidence that two events are related.) In the case of NOAA-17, the 18 SPCS said there was “no indication” the breakup was caused by collision with another object.

It’s more likely that NOAA-17 broke up on its own. Such a breakup would not be unprecedented: a similar satellite, NOAA-16, broke up in November 2015 a year and a half after suffering a mission-ending “critical anomaly.” Two US Air Force weather satellites, which, like the NOAA satellites, were built by Lockheed Martin, broke up in orbit in 2015 and 2016.

NOAA-17, launched in 2002, had been retired nearly eight years ago. In an April 2013 statement about its decommissioning, NOAA said it completed a “deactivation process” intended to remove energy sources that could cause a breakup. After the breakup, NOAA confirmed it completed that process, which included discharging the satellite’s batteries and venting its propellant tanks. “These steps were taken to ensure the satellite was as inert as possible,” NOAA said.

Those efforts followed US government guidelines for mitigating the creation of orbital debris, but clearly were not sufficient. “I don’t doubt NOAA did what they could, and think this is more a case of a legacy satellite that was designed in an era before we really cared much about debris mitigation,” said Brian Weeden, director of program planning at the Secure World Foundation.

Many in the space industry are raising alarms about the growing population of debris, including defunct satellites and upper stages that are unable to comply with orbital debris mitigation guidelines such as deorbiting within 25 years of the end of their mission—or whose operators, for whatever reason, are unwilling to comply. Simply trying to limit the growth of orbital debris is no longer enough.

“Given the rapid increase of space activity worldwide and the current state of orbital debris in LEO, international space agencies and the scientific community agree that mitigation-only activities focused solely on prevention are not sufficient to stabilize the orbital debris environment,” NASA’s Office of Inspector General concluded in a January report on orbital debris risks. “Rather, to effectively address the orbital debris issue, global mitigation and strategic remediation efforts are necessary.”

Remediation, or the removal of debris, is starting to move to the forefront of discussions about dealing with orbital debris thanks to both the heightened concerns about debris as well as technical demonstrations of the feasibility of removing debris.

“Active debris removal is perhaps the most demanding form of on-orbit servicing,” said Astroscale’s Lindsay.

The latest development in that latter category is the launch March 22 of the End-of-Life Services by Astroscale demonstration, or ELSA-d, spacecraft by Astroscale, a Japanese company developing technologies for active debris removal (ADR). ELSA-d was one of about three dozen rideshare payloads on a Soyuz rocket launching from the Baikonur Cosmodrome, a mission brokered by GK Launch Services.

Once ELSA-d completes its initial checkouts in orbit this spring, it will conduct a series of tests using a small client spacecraft launched attached to the main servicer spacecraft. ELSA-d will release and then capture the client spacecraft, repeating the tests with the client spacecraft tumbling, as a defunct satellite or piece of debris might be. The servicer will also test the ability to fly around and inspect the client spacecraft. Once those tests are complete, the servicer will capture the client and lower its orbit to speed up its destructive reentry.

“Active debris removal is perhaps the most demanding form of on-orbit servicing,” said Mike Lindsay, chief technology officer of Astroscale, during a presentation in early March at a workshop on orbital debris held by the LRA Institute. That’s because of the large number of unknowns about the size, mass, and orientation of the debris that can make it difficult to approach, grapple, and move the object.

ELSA-d, he said, will test ways to deal with those uncertainties, like grappling tumbling objects. “This is a very big challenge for ADR,” he said. “That’s the main goal of ELSA-d.”

Astroscale is working on a second demonstration mission, called ADRAS-J, for the Japanese space agency JAXA. That spacecraft will approach an upper stage left in orbit by a Japanese launch, inspecting the stage in preparation for a later effort to deorbit it.

“This is taking it from a known client, a pre-defined client, and going to the next step, which is a client that has a lot of unknown parameters,” Lindsay said. “We have to pinpoint its location, its orbit, its tumble conditions, and look at the structural integrity of this object.”

Astroscale calls itself the only company “solely dedicated to on-orbit servicing across all orbits,” including work to extend the life of active satellites. It is not the only company, though, that has been working on ADR or related technologies to address the orbital debris problem.

Surrey Satellite Technology Ltd. (SSTL), a smallsat pioneer, demonstrated its own technologies to remove orbital debris with a smallsat aptly called RemoveDEBRIS. The smallsat, developed by SSTL with funding from the European Commission, launched from the ISS in 2018, and over the course of several months, tested technologies to remove orbital debris.

Some of those technologies were modern versions of very old concepts, such as a net. “It’s like a gladiator’s net from Roman times,” said Alex da Silva Curiel, business development manager at SSTL, at the LRA Institute meeting. It demonstrated the ability to capture small objects, which can then be reeled back into to the servicer spacecraft by a tether.

Another was a harpoon, which in the RemoveDEBRIS test was successfully fired at a target at the end of a boom extended from the servicer. In the test, the harpoon successfully hit the target, but with enough force to snap the boom. The harpoon, target, and boom tangled together, fortunately without damaging the main spacecraft.

“I believe the challenges we face in orbit are opportunities for innovation and entrepreneurism. With government and industry working together, we can support technologies that can remove debris,” said Jurczyk.

“Essentially, the harpoon element worked very well, and proves that this kind of method can be used in space,” he said. But, he added, “you need to do quite a bit of research on what you are actually removing” to avoid doing something like puncturing a fuel tank.

Other demonstrations of debris removal technologies are in the works. That includes ClearSpace-1, a Swiss spacecraft scheduled for launch in the mid-2020s and backed by ESA. It will capture a payload adapter left in orbit from a Vega launch in 2013 and deorbit it.

What’s missing, many in the industry argue, is any coordinated effort to develop orbital debris removal technologies and systems, as well as put them into use. The expectation is that governments will take the lead, in both supporting technology development and funding demonstrations and later disposal missions. However, there’s been little concrete action on the issue.

The NASA inspector general’s report specifically recommended several steps for the agency to pursue on debris remediation. Those recommendations including leading efforts at the national and international level to support “activities to encourage active debris removal” and collaborate with industry and other government agencies “to adopt national and international guidelines on active debris removal.” The report also recommended NASA invest in technologies related to orbital debris removal.

NASA partially concurred with those recommendations in a response in the report, suggesting its efforts were limited by national space policy. “At present, there is no Administration direction to NASA for leading national and international collaborative efforts to encourage active debris removal,” it stated.

At a March 23 meeting of the FAA’s Commercial Space Transportation Advisory Committee (COMSTAC), NASA acting administrator Steve Jurczyk noted the cooperation between the two agencies on topics such as work to “preserve and protect the orbital environment.” He also mentioned NASA’s publication of a handbook on best practices for collision avoidance, with an industry day planned to get input from the private sector on those best practices.

In a similar vein, NASA announced March 18 the signing of an agreement with SpaceX regarding spaceflight safety. Under that agreement, SpaceX will be responsible for maneuvering its Starlink satellites should any come close to the International Space Station or other NASA spacecraft in low Earth orbit.

“It’s critical that we all work together to preserve the low Earth orbit environment,” Jurczyk said at the COMSTAC meeting. “At the same time, I believe the challenges we face in orbit are opportunities for innovation and entrepreneurism. With government and industry working together, we can support technologies that can remove debris, and perhaps even convert such debris into useful construction materials.”

However, the path from the current situation, with NASA lacking “administration direction” to take the lead on active debris removal, to a future state where NASA partners with industry on turning debris into construction materials, is not clear. Nor is it clear how much of a priority it will be for the new administration, along with efforts such as handing over responsibility for civil space traffic management to the Commerce Department’s Office of Space Commerce, as the Trump Administration planned under Space Policy Directive 3 in 2018.

“I would hope this serves as yet another example why the US and other governments need to invest in active debris removal capabilities to take legacy satellites that were never designed to comply with the debris mitigation guidelines and remove them from orbit,” Weeden said of the NOAA-17 breakup.

Pursing active debris removal, though, is not a replacement for preventing debris in the first place. “The better we are at mitigation, the less need there is for remediation,” said Ted Muelhaupt, principal director at the Aerospace Corporation’s Center for Orbital and Reentry Debris Studies, at the LRA Institute workshop.

“We should get started on active debris removal,” he added, but only through careful cost-benefit analyses to keep a bad problem from getting worse. “Don’t make any more debris while you’re cleaning up old debris.”

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