Avoiding low-Earth orbit collisions -- the clock is ticking

There was a recent dispute between OneWeb and SpaceX regarding the possibility of a collision between two of their low-Earth orbit (LEO) satellites. OneWeb's satellite (OneWeb-1078) was launched on March 25 and headed for it's orbit at an altitude of 1,200 km when, in early April, it passed near a SpaceX satellite (Starlink-1546) in orbit at about 450 km.

There was no collision, but subsequently OneWeb's government affairs chief Chris McLaughlin said SpaceX had turned off their autonomous collision-avoidance system so OneWeb could maneuver around their satellite and SpaceX denied that they had switched the system off and said "there was never a risk of collision."

This sounds a little like a PR battle, but both sides may have been sincere because satellite tracking is imprecise. The satellites were being tracked by SpaceX, OneWeb, and two independent organizations, the Air Force 18th Space Control Squadron (18 SPCS) and LeoLabs which offers a commercial satellite tracking service. As we see in the plot shown here (source), their estimates of the probability of collision vary.

In addition to helping explain the dispute between SpaceX and OneWeb, the variance in these estimates illustrates the difficulty of accurately tracking and predicting the orbits of satellite. The incident also highlights the difficulty of communicating and cooperating in deciding on maneuvers to avoid collisions.

SpaceX and OneWeb began deploying their broadband Internet service constellations recently, but as of early 2020, LeoLabs was tracking about 14,000 objects in LEO that were 10 centimeters across and larger. About 1,700 were functional satellites working on other application and the rest were debris. We also had a debris-collision warning Last week when the astronauts en route to the International Space Station were instructed to put on their space suits due to the possiblity of a collision with a piece of space junk.

Fast forward five years

The SpaceX-OneWeb and astronaut-debris events provide an early warning. There are around 3,000 satellites in LEO today, but how about five years from now? As shown here, the five would-be broadband constellation operators have authorization to launch over 30,000 satellites and, if we add in pending requests for approval, the total increases to around 100,000. Furthermore, Russia and the European Union are working on broadband satellite plans as are the US and Chinese militaries and don't forget the forthcoming large non-broadband constellations, like Geely's Geespace constellation.

We've had a few scares recently and the number of close calls requiring an automated or manual maneuver to avoid a collision will increase dramatically in the future. Runaway debris in LEO would cost us more than just having to give up the goal of global broadband service. It would disrupt critical applications we already depend upon in climate science, emergency response, agriculture, etc. I am confident that LEO broadband providers can find solutions to the technical problems they face like low-cost antennas, inter-satellite laser links and spectrum sharing, but collision avoidance is tougher because in addition to technical innovation like improving the accuracy and resolution of terrestrial and space-based orbit tracking, it will take political action.

This map shows that 72 nations own and/or operate satellites, but last week, English-speaking engineers at SpaceX and OneWeb were unable to agree on the orbit data and communicate and cooperate when it appeared that a collision might be forthcoming. If SpaceX and OneWeb cannot agree, what will happen when, for example, military satellites from China and the US are involved?

Space, like the oceans, is a global commons and it is not in anyone's interest to spoil it. We need global regulations, standards and procedure and a means of enforcing compliance if we are to avoid collisions and mitigate debris. We are running out of time. We've been working on maritime law for centuries and the UN International Maritime Council has 174 member states -- have we begun talking about this issue with the Chinese?

It's time to act.

The European Space Agency (ESA) has produced a 12-minute video (with cool animations) that describes the debris problem and the current debris mitigation guidelines, which are neither universally followed nor adequate for the future. ESA projects for automating collision avoidance, refueling and repairing satellites in space, active debris removal and technology to hasten the deorbiting of defunct satellites are mentioned in this call for action. Indeed the title of the video is "Time to Act."

Update 5/2/2021

Several readers pointed out that the Chinese ratified the UN Outer Space Treaty and Registration Convention in the 1980s. If one takes my question "have we begun talking about this issue with the Chinese?" literally, the answer is "yes." But, clearly the situation has changed since the 1980s so a more relevant question would have been "are SpaceX and Guowang engineers talking with each other?" I don't know if we can wait for Outer Space Treaty-2.

Update 6/1/21

Ground segment market researhcr Alexandre Corral predicts that "over 2,100 Earth observation satellites will be launched as part of about 70 constellations during the next decade, driven by the operators' ambition to provide higher revisit with global coverage." That is nothing like what SpaceX and the other broadband constellations anticipate, but it will add to congestion in LEO.

Chinese space situational awareness and traffic management regulations and procedures

China's active (orange) and inactive (blue) satellites in low-
Earth orbit today (source). They plan to launch many more,
including a 12,992-satellite broadband Internet constellation.

In a recent issue of the Dongfang Hour Newsletter, Blaine Curcio pointed out that China's powerful State Administration of Science, Technology, and Industry for National Defence (SASTIND) had published a notice intended to promote the orderly development of microsatellites and strengthen safety management.

The notice defines microsatellites as being below 1,000 kilograms, which would include those making up China's planned GwoWang/SatNet broadband constellation. Since this is slated to be a very large (12,992 satellite), it will exacerbate the problem of potential collisions in low-Earth orbit.

The notice lists 24 requirements many of which have to do with space situational awareness and traffic management:

• Microsatellites should have mature and reliable de-orbit capability and avoid long-term occupation of common orbits. Satellites below 2,000 kilometers should de-orbit within 25 years of the end of the mission and those over 2,000 should rise to the graveyard orbit.
• Satellite operators should take necessary technical measures to avoid the generation of separate fragments in orbit, including falling off, discarding, throwing, etc., and avoid explosions of energy storage components such as fuel tanks and batteries.
• A  debris-mitigation plan should accompany the application for a license to launch. It shall include theoretical analysis, technical measures to be taken, effect prediction, etc, and meet the requirements mentioned above.
• When a microsatellite is launched into orbit or its status in orbit changes, the owner shall inform the National Defense Science and Industry Bureau.
• Thirty days before microsatellites carry out operations such as orbit transfer, rendezvous and docking, debris removal, and on-orbit maintenance, the operator shall notify the relevant national authorities. If a major security risk occurs during operation, it shall be terminated or immediately adjusted.
• Relevant national departments will announce early warnings of possible microsatellite collisions, review evasion strategies, research risk, and recommend mitigation action.
• Microsatellite operators should carry out collision avoidance maneuvers when discovering the risk of collision and report the situation and action taken to the relevant national authorities within one hour of the discovery of the risk.
• Microsatellite operators should report collisions to the relevant national authorities within one hour.
• In the event of a major emergency or emergency response event, the microsatellite operator should obey the overall management policies of the relevant state departments.
• State departments are responsible for the daily monitoring and evaluation of the orbit status of microsatellites and de-orbit activities. When the orbit or status of microsatellite changes, the operator shall promptly inform the relevant state departments. 
• For those who fail to report relevant information as required, the state department may take appropriate measures.
• Microsatellites with mission objectives such as technology verification and scientific experiments have a relatively short business cycle and are encouraged to operate in orbits below 350 kilometers in order to facilitate rapid de-orbit after completion of the mission.

Disclaimer: The above is an edited version of a Google translation of the SASTIND notice and I welcome corrections, but the main point is that China acknowledges the importance of space safety. That's good news, but preserving the space commons will require agreement on regulations and procedures among all governments and companies that operate satellites and track orbiting objects.

SpaceX will soon have reusable rockets that can launch hundreds of satellites at a time and sometime after that China will be capable of the same. Chinese state-owned enterprises and at least one private company are working on reusability and they have the opportunity to learn from videos of SpaceX's soft-landing failures and publically available analysis from SpaceX and journalists like the Everyday Astronaut. The clock is ticking.

Update 6/14/2021

Andrew Jones has reported that the development plans for the 14th five-year plan period (2021-25) of the China National Space Administration includes a section on "expanding space cooperation and enhancing the common well-being of humankind".

The G7 and EU join China in call for space debris and collision regulation

Last month, the Chinese government published space situational awareness and traffic management regulations and procedures designed to guard against collisions in orbit and mitigate space debris, and this month, at the G7 summit, delegates from Canada, France, Germany, Italy, Japan, the USA, the UK, and the EU pledged to take action to tackle the growing hazard of space debris as our planet’s orbit becomes increasingly crowded.

They stated their commitment to "safe and sustainable use of space to support humanity’s ambitions now and in the future,” acknowledged the “the growing hazard of space debris and increasing congestion in Earth’s orbit" and agreed "to strengthen our efforts to ensure the sustainable use of space for the benefit and in the interests of all countries."

They called upon all nations to work together, through groups like the United Nations Committee on the Peaceful Uses of Outer Space, the International Organization for Standardization, and the Inter-Agency Space Debris Coordination Committee, to preserve the space environment for future generations. 

Even Russia is talking about cooperation in space. In a recent interview, Vladamir Putin said they were not splitting off from the U.S. and moving forward with China. He denied reports that Russia was preparing to give or to offer to Iran a satellite technology that will enable it to target military targets and said "We don't want space militarized, in the same manner, we don't want cyberspace militarized." (That's not very encouraging is it :-)?

These are positive steps that would seem to set the stage for cooperation, at least between the G7, EU, and China. The governments and agencies named above must collaborate on this issue, but they need input from the organizations that operate and monitor satellites like SpaceX, GuoWang, the US Space Force, NASA, LeoLabs, etc. Let's hope they act quickly because, with tens of thousands of low-Earth orbit satellites approved for launch, the clock is ticking.

We got a wake-up call on May 12th when an external camera discovered
that a piece of debris that was too small to track had hit the International
Space Station. Source