President Trump is signing a policy document Monday seeking to improve the tracking of space junk and limit future debris, but experts say the idea will be difficult to carry out.
The new policy, known as Space Policy Directive-3, orders the Commerce Department to create a public database of space objects, a vision first outlined in April by Vice President Mike Pence.
Experts cite severe technical limitations, including an inability to track small objects, large coverage gaps over nations such as Russia, and data-association challenges that make trajectory maps nearly impossible.
“There absolutely are limitations,” said Scott Pace, executive secretary of the National Space Council, during a Monday morning conference call. “It’s a big challenge, but we see some help coming from the commercial and international sides.”
The military will continue to maintain an “authoritative catalog” of space objects, Pace said, but the Commerce Department will be charged with combining that data with supplemental international and business data for public release.
Objects in low-Earth orbit, which is under 2,000 kilometers, are tracked using land- or sea-based radar. In the higher geosynchronous orbit, telescopes are required.
It’s unclear how much data the Defense Department, which maintains secretive satellites to track objects, will be willing to share with the Commerce Department for public release.
“I think the biggest drawback of this approach is that they will still be hamstrung by the national security restrictions on sharing the data and on the capability limitations of the DOD systems,” Brian Weeden, director of program planning at the Secure World Foundation, told the Washington Examiner this spring.
“A lot of the tracking data comes from radars that have other missions such as missile warning or missile defense, so there are restrictions on how much data can be shared,” Weeden said. “And the U.S. Air Force has struggled for more than a decade to upgrade its software and computer systems to be able to handle the increased workload.”
According to Weeden, about 23,000 space objects larger than 10 centimeters are tracked to some degree, including about 1,800 operational satellites. He estimated there are another 500,000 or so smaller pieces of space debris larger than 1 cm.
Determining the path of objects is difficult, since knowing the speed and direction depends on details such as shape that are not readily available, John Crassidis, director of the Center for Multisource Information Fusion at the State University of New York at Buffalo, told the Washington Examiner after Pence announced the policy.
“Even if you did have persistent surveillance … that becomes a huge data association nightmare. That’s solving one problem and creating another,” Crassidis said.
Space junk in low-Earth orbit consists of items such as rocket bodies and debris from collisions, and will eventually come down. Junk in geosynchronous orbit, meanwhile, is there permanently.
In 2010, the U.S. military added tracking capabilities with the SBSS Block 10 satellite for geosynchronous orbits. In 2014 and in August 2017, the Air Force launched four satellites to monitor outer-orbit items as part of its Geosynchronous Space Situational Awareness Program.
Since 2010, the military has provided close approach warnings to satellite operators, Weeden said, following the 2009 collision between the US Iridium 33 and Russian Cosmos 2251 satellites.
Pace, the National Space Council official, said Monday that the Commerce Department’s “open data repository” is only part of a larger picture. The new directive also orders NASA to update orbital debris mitigation standards and establish new rules for satellite design.
“We have had two administrations that tried very hard to make this happen,” Pace said, citing the expansion of private-sector space launches as a major reason for the directive, including the emerging concept of “mega-constellations” of corporate satellites to support services such as broadband Internet.
“Looking at the rapid launch rates that would be necessary to support some of the mega-constellations I think really crystallized everyone’s attention,” Pace said. “And we realized that if this is going to be successful and we’re going to expand the economy in space, it has to be done in a sustainable way.”
Trump’s previous space policy statements include Space Policy Directive-1, which outlines a plan to return astronauts to the moon and ultimately send them to Mars, and Space Policy Directive-2, which established the Commerce Department as the primary agency for managing private-sector space activity.
