What would a sustainable space environment look?

October 4, 2022, is a day of great luck as humanity marks the 65th anniversary since the Space Age began. It all began in 1957 when the Soviet satellite Sputnik-1 was launched. This was the first artificial satellite ever sent into orbit. Over 40 countries have launched more than 8,900 satellites since that time. This has raised concerns about space debris, the danger it poses to future constellations, spacecraft, habitats in low Earth orbit (LEO), and other spacecraft.

This has led to many proposals for cleaning up “space trash” as well as satellite designs that would allow these satellites to deorbite and burn up. However, it is still uncertain whether a planet surrounded mega-constellations will be sustainable in the long term. James A. Blake (a University of Warwick research fellow) recently studied the evolution of LEO’s space debris environment and determined if future space operations are possible.

Blake’s Ph.D. research focused on the imaging of space debris in geosynchronous Earth orbits, or GEOs, at 36,000 km (22.370 mi) above Earth’s Equator. Satellites orbit the Earth in this area of space and have the same orbital time as the Earth. This makes them highly sought-after for telecommunications. Space in this area is limited, which could lead telecommunications problems and overcrowding.

Blake’s primary work was a survey on faint geosynchronous debris that was performed using the Isaac Newton Telescope at Roque de Los Muchachos Observatory, La Palma. His work was summarized in a study entitled “DebrisWatch I”: A survey of faint geosynchronous particles, which was published in the journal Advances in Space Research in January 2021. He stated in this study that the GEO debris population is growing and cannot be controlled.

A historic problem

According to the ESA’s Space Debris Office, (SDO), approximately 12,720 satellites had been launched to Earth orbit in the 12 years since Sputnik-1. An estimated 7,810 satellites are still in orbit, with approximately 5,200 remaining operational. All in all, approximately 29,860 debris objects are tracked regularly by Earth-based observation network and are kept in their catalog.

Previous thinking was that there would be very little debris in GEO due to the strict spacing regulations that are enforced to prevent satellites colliding. However, recent destructions of communications satellitesAMC-9 by Luxembourg-based telecoms, SES S.A. and Lockheed Martin’s Telkom-1have provided clear evidence of a debris pool in GEO. This has new implications for future GEO constellations.

Blake explained via email to Universe Today that charting the evolution and fate of space debris is crucial for the future of debris mitigation.

“Sputnik 1 was among thousands of satellites launched into Earth orbit over six decades. This number is growing rapidly. Some satellites have re-entered Earth’s atmosphere while others are still in orbit and pose a threat to active satellites that we rely on.

“Over time, orbital debris has increased due to accidental explosions and collidings, as well as intentional anti-satellite testing. The vast majority, though too small to detect by our current generation, of satellite surveillance networks, is still visible and could cause severe damage to spacecraft.

Blake believes there’s a lesson in humanity’s use of the near Earth environment. This lesson is applicable equally to humanity’s ground activities, in keeping with the interconnectedness of space exploration and human life on Earth. Humanity must act sustainably to preserve the freedoms enjoyed by future generations since the dawning of the Space Age. Blake says collision avoidance is essential to achieve this goal.

“Effective collision prevention requires accurate and timely information. As satellite and debris catalogues grow in size, surveillance networks are being asked to monitor more objects in order to provide enough warning to operators. They can then choose to maneuver their craft safely out of harm’s path.

Monitoring and mitigation

The current strategy to stop an uncontrollable environment of debris in orbit is a two-pronged one: tracking and “passivating”. Multiple space agencies and government offices across the globe are responsible for tracking satellites, and other debris. For example, the Joint Space Operation Center (JSpOC) at Vanderburg Air Force Base (California) uses the Space Surveillance Networks to monitor satellites and debris in orbit.

NASA Orbital Debris Program Office is located at Johnson Space Center. It measures the orbital debris environment and develops measures to stop it growing. NASA Headquarters in Washington D.C. is home to the Office of Safety and Mission Assurance, which is responsible for developing and implementing agency-wide policies and procedures to guarantee safety, reliability, and sustainability of space environments.

The ESA’s Space Debris Office, (ESO) is also located at the European Space Operations Center(ESOC) in Darmstadt. It is responsible to measure and model the orbital debris environment as well as develop mitigation and protection strategies. It coordinates activities and research with the ESA’s constituent agency agencies, which make up the European Network of Competences on Space Debris.

The Inter-Agency Space Debris Coordination Committee is an international forum that includes 13 national space agencies (including NASA and Roscosmos), the ESA and the Indian and Chinese satellite agencies. This body was established in 2001 and has been revised several times, the most recent being in 2020.

On the other side of the coin, there’s the “25-year rule”, which encourages operators to dispose of satellites within 25-years of their mission completion via atmospheric entry. Low-altitude satellites might already be naturally capable. However, satellites that are not compliant can be outfitted to use thrusters, drag sails and other instruments to accelerate deorbiting. Blake explained:

“Operators are encouraged at the end to ‘passivate’ spacecraft by depleting or saving any remaining sources of energy onboard the satellites or rocket bodies, thus reducing the chance of an explosion.” The ’25-year rule for deorbiting spacecraft in low earth orbit is still a concern. It will be crucial to increase international cooperation to tackle the debris problem.

Policy problems

Blake concluded that space policy is one of the greatest obstacles to sustainability. UNCOUPOUS adopted the IADC guidelines over the past decades as the basis for standard mitigation techniques on the international stage. These guidelines are voluntary, meaning they are not legally binding, and some space-faring states have chosen to not include them in their national regulatory structures.

LEO is still very strict with the “25 years rule”, and re-entry for objects in the high altitude GSO region is not possible. Operators will often attempt to lift decommissioned satellites into “graveyard” orbits that are much higher than GSO or what is known as a Supersynchronous Orbit (SSO). While this clears the orbit operational zone for future satellites, the debris can still pose danger to spacecraft destined to the Moon or deep-space.

Blake believes that active debris removal (ADR), in conjunction with stricter debris mitigation regulations, is what is required.

“Ultimately, however, we will need to conduct regular missions to actively dispose dead spacecraft or debris. However, a few technological hurdles remain. As the Russian ASAT test of November 2021 has shown, there is a need for international recognized, legally binding regulations to punish reckless behavior.

ADR systems are being tested by NASA and the ESA as well as the China National Space Agency, CNSA, and other space agencies. There are many concepts, including Earth-based directed energy arrays (lasers), spacecraft equipped in plasma beams, nets and harpoons, as well as spacecraft equipped with magnetic space tugs. Blake says there have been attempts to develop a “space sustainability ranking” that would encourage operators to use safe practices and reduce debris. However, several questions remain unanswered.

With space access becoming more accessible, how can a regulatory framework compare University CubeSat experiments with commercial constellations of satellites? (a la Starlink?) What liability will lawmakers assign in the event that a collision involves uncontrolled debris? What mechanisms will be used to ensure equal playing fields between the emerging space agencies as well as those with a long history in space?

These questions are being debated and solutions are being sought. It has also led a rise in non-profit organizations such as the Space Court Foundation (SCF), and the Space Generation Advisory Council(SGAC). There are also the tried-and-true efforts to formulate and clarify policy by the Institute of Air & Space Law at McGill University (IASL), and the United Nations Office for Outer Space Affairs(UNOOSA).

As space expands, we can expect to see spirited debate, resolutions and innovative ideas in the years ahead. As usual, the driving force behind these developments is a simple matter of necessity. Accessibility and safety are essential for humanity’s future in space. This cannot be achieved with large debris fields in orbit.