A scenario in which the high density of debris in low Earth orbit (LEO) causes a continual chain reaction of collisions, known as the Kessler syndrome, could put a halt to space services.
But how urgent is the risk?
The risk is measurable, Mark Dankberg, Viasat (NASDAQ:VSAT) chairman and chief executive, told Connectivity Business News. Dankberg co-founded Viasat in 1986, and recently resumed the chairman and CEO roles at the satellite company.
“There are consultants, academics and space agencies,” Dankberg said. “Instead of just saying, ‘space is big and satellites are tiny,’ we’re saying that they can measure the risk.”
It’s a message that Dankberg has conveyed repeatedly in the past year, in keynotes at the Connect (X) 2022 conference in May, at SmallSat Symposium 2022 in February and at Satellite Innovation 2021 in October of last year.
Viasat issued a statement on space sustainability in its 2021 annual report, and there will be a similar statement in this year’s report, Dankberg said.
“Space investors should be mindful that there will be no new space — or old space, for that matter — opportunity, unless there is safe, sustainable access to space,” Viasat’s 2021 annual report said. “Access to space cannot be taken for granted, and threats and risks have come sharply into focus over the past year.”
Regulators take notice
Some regulators, including the Federal Communications Commission (FCC), have been aware of space collision risks for years. Earth’s orbital region is “a resource that is ‘non-excludable’ in consumption (use of space is available to all countries), but ‘rivalrous’ (each country’s use of space reduces the amount available to others),” the FCC noted in 2018 in a notice of proposed rulemaking titled “Mitigation of Orbital Debris in the New Space Age.”
The nonprofit MITRE Corporation, a federally funded research and development organization, has also expressed concern regarding space debris collisions.
“[T]here has been relatively little analysis of the collision and debris threats posed by the recently announced large constellations,” according to 2020 report “The Impacts of Large Constellations of Satellites” by the MITRE Corporation written for the National Science Foundation. “The most recent NASA studies from 2018 included 8,000 satellites at 1,200 km and showed significant dangers unless nearly all satellites are successfully de-orbited at end of life.”
There were about 20,000 trackable objects of at least 10 cm (4 inches) in size, of which about 3,000 were operational satellites, according to the MITRE report. “A ‘trackable’ piece of space debris is about 10 cm and 1 kg, the size required to catastrophically destroy a satellite of mass 1,000 kg,” according to the report.
Debris in LEO
A single space collision generates a high volume of debris.
An example is the 2009 collision between Iridium-33 and COSMOS-2251 at the 800 km orbit, which generated 1,439 trackable objects with apogees between 400 km and 1,600 km, according to “Design Trades for Environmentally Friendly Broadband LEO Satellite Systems,” a paper co-authored by Mark Sturza, president of consulting firm 3C Systems Company, and Gemma Saura Carretero, senior mission systems design lead at on-orbit services provider D-Orbit. Carretero previously served as a senior systems design engineer at Viasat.
Modern satellites can maneuver to avoid debris and have access to debris data from space situational awareness systems. At the recent Space Sustainability Conference, one attendee recommended forbidding the launch of non-maneuverable satellites, according to Dankberg. “But if I launch 4,000 satellites and I know that 2% will fail, then I’ve just launched 80 non-maneuverable satellites,” Dankberg noted.
The challenge for operators is predicting the number of collisions — even as the number of satellites grows to around 33,000 by 2031 from 3,000 a few years ago.
“If an on-orbit collision avoidance rule of thumb is desired, there is an emerging industry consensus, although it is not grounded in any specific analysis,” that operators should take action to lower the probability of collision to less than 1:10,000 for any satellite, NASA wrote in a 2019 letter to the FCC.
Rather than attempt to calculate the overall collision risk of a constellation, NASA recommended the FCC focus on the collision risk of each satellite in the constellation. In its 2020 rules “Mitigation of Orbital Debris in the New Space Age,” the FCC asked operators to calculate both numbers.
The rules state that operators applying to deploy satellites in non-geostationary orbits must indicate whether they have calculated the probability of a collision with trackable debris is less than 1/1,000 during the lifetime of a satellite. They must also specify whether they have calculated the collision probability of the constellation as a whole, which the FCC requests be calculated as the sum of the collision probabilities of each satellite. In order to calculate these collision probabilities, the FCC requires “the use of the NASA Debris Assessment Software or a higher fidelity assessment tool.”
“Once you know that space is a limited resource, it’s important to know what those limits are,” Dankberg told Connectivity Business News. “If it’s a box with a limit, why are we trying to fill up the box as fast as we can? Why don’t we leave room in the box for future innovation?”
‘Time to act now’
A system for which the mean time between orbital collisions is zero is one possible mathematical definition of the Kessler syndrome, according to Dankberg. The syndrome was named after NASA scientist Donald J. Kessler who proposed the theory in 1978.
“Anyone can find what that number was a few years ago, what it is now, and project what it will be in the future,” Dankberg said. “If the Kessler syndrome is 50 years away, there’s relatively little urgency, but if it’s five years away, it’s time to act now.”
A Viasat spokesperson clarified to Connectivity Business News after publication that the company wants to keep Kessler syndrome more than 100 years away, and therefore it’s time to act when the syndrome is 25 or 50 years away.
After publication, Dankberg further clarified Viasat’s position. “We need to act in advance of allowing the environment to get within, say, less than about 100 years of a Kessler Syndrome – by managing the conditions on what and how much is launched,” he told Connectivity Business News. “It will be difficult, or even impossible, to remediate when we over-populate LEO to the point where it is much more imminent than that.”
While insurance can provide market solutions to other environmental risks, insurers will not save LEO. Only $2.8 billion of $35 billion in assets in LEO are insured, Chris Kunstadter, global head of space at insurer AXA XL told Connectivity Business News earlier this year.
To that end, Viasat is working with regulators worldwide, Dankberg previously told Connectivity Business News. Since satellite operators must obtain landing rights in a nation to use services there, one way for nations to control access to space is by asserting their power over landing rights, he added.
If a sufficient number of nations have rules in place by the time of the International Telecommunication Union’s (ITU) 2023 World Radiocommunication Conference, the satellite industry will have achieved something that was previously accomplished in the mobile industry. “The FCC deviated from the ITU regarding 5G rules for 28 MHz spectrum and said, ‘we’re doing this for good reason, and other countries can join us,’” Dankberg told Connectivity Business News.
While some national regulators would prefer the ITU make the tough decisions, Dankberg said, governments may instead prefer a network of multilateral agreements to the decision of a United Nations organization.
Editor’s Note: This story has been changed to reflect clarifications from Viasat regarding how to mitigate the Kessler syndrome.