At this very moment, there are over 10,000 operational satellites in low Earth orbit, along with 3,500 decommissioned (or defunct) satellites, tens of thousands of pieces of debris 10 centimeters or larger, and more than 100 million smaller debris pieces — and the risks of conjunctions are increasing. These numbers will only multiply as the cadence of commercial and government launches rapidly increases. While there are varying forecasts for how many new satellites will enter orbit by 2030 that range from 20,000 to 58,000, there is no question that low Earth orbit (LEO) congestion is set to increase substantially.
With the growing traffic in space and the increasing number of alerts, conventional methods of risk assessment and collision avoidance that rely on manual processes and limited disclosure are no longer sufficient. For example, my company tracks, on average, more than 60,000 alerts per week for a constellation of around 100 satellites in a busy orbital environment. Or, consider that SpaceX’s Starlink constellation performed nearly 50,000 collision avoidance maneuvers in just the first half of 2024. That amounted to 275 maneuvers per day.
As LEO traffic rises and orbits become more challenging, the satellite industry needs to prioritize closer cooperation to enhance safeguards and improve real-time information sharing. Responsible stewardship is essential for avoiding a disaster, and yet we are missing the mark in several key areas. Real-time information sharing, active propulsion systems and well-resourced mission operations are three crucial steps that must be taken to reduce the risk of collisions.
Ephemeris
The most important means for reducing conjunction risks is to have accurate, real-time data on a satellite’s precise location and maneuver plans both now and in the future.
This data, known as ephemeris, is critical for ensuring a safe operating environment in orbit. However, many private companies are not sharing this information as much as they should be.
While the U.S. Space Force tracks orbital assets through the Space Surveillance Network, there are limits to its effectiveness in preventing conjunctions. For example, the Space Force’s two-line element sets — datasets used to track orbits — are only accurate within a few kilometers for LEO satellites. Additionally, the USSF’s Special Perturbations catalog, which is more accurate than the two-line element sets, does not account for precise corrections or maneuvers planned by satellite operators. Commercial solutions offer greater accuracy, but they don’t always have access to insider data such as satellite maneuver plans.
This is why collaboration is so important. The most precise, real-time information on a satellite’s location is only known by the satellite operator. They have exclusive access to key information such as the satellite’s global navigation data, onboard sensors, maneuver plans, satellite design and health, and other critical data. This information is essential for establishing precise ephemeris and ensuring safe operations in space. However, we have found that only 3% to 4% of global satellite operators currently share this information with the industry.
While it is understandable that operators want to protect their proprietary information, precise, near-real-time ephemeris is critical to ensuring a safe orbital environment for all. We need to change the mindset about this and start thinking of ephemeris as vital information that must be widely shared within the industry.
Maneuverability
Congestion is increasing the rate of conjunctions. But the lack of active propulsion systems is making it worse.
The number of commercial satellites in orbit has increased significantly since early 2020, but many of them, especially smallsats, are not equipped with active propulsion systems. The lack of maneuverability makes it more challenging to adjust the satellite’s flight path to avoid potential collisions.
Earlier this year, we worked with two commercial operators who faced a critical situation. Their satellites faced a high-risk conjunction event, predicted to pass within one kilometer of one another within 12 hours of when the event was detected. Unfortunately, neither satellite had an active propulsion system, so they could not be easily maneuvered. As a result, the only option was to use a maneuver option known as differential drag, which involves adjusting the satellite’s attitude and solar array angles to increase or decrease atmospheric resistance to change its trajectory. However, differential drag has limited capabilities and takes longer to produce a significant change in trajectory, so it is best reserved for routine operations like maintaining constellation formations where safety isn’t at risk. It is not an ideal solution for emergency maneuvers. But, in this case, there was no other option due to the urgency of the situation. Using our space traffic coordination platform, the two operators designed and performed the first-ever simultaneous differential drag collision avoidance maneuvers in LEO to change their satellites’ trajectories just enough to meaningfully reduce the risk.
Fortunately, these maneuvers worked and the two satellites were unharmed. However, this near-miss is a clear warning about the urgent need for active propulsion systems. While altering a satellite’s drag profile can be a useful way to save thruster fuel while performing basic maneuvers, it is not a reliable means for preventing orbital collisions — especially with short notice. LEO is becoming too crowded to rely on improvised solutions during high-risk situations. With new advances in smallsat propulsion systems, operators need to take a closer look at how they can integrate these technologies across all of their spacecraft.
Mission operations
With more companies and nations launching more rockets and satellites than ever before, the dynamics of LEO are changing dramatically, and mission operations teams are more important than ever.
It is critical for satellite operators to have adequately sized operations teams that can handle both routine issues and emergencies. Companies need to make sure their budgets are sufficient to support the proper level of staffing and to retain highly experienced personnel. With so many new payloads entering orbit (many of which are non-maneuverable), a growing number of defunct satellites, and the anticipated increase in fragmentation events, these teams will be responsible for managing a higher number of conjunction warnings in a shorter amount of time.
Automation is also increasingly critical. There is a growing number of automated space traffic coordination and space traffic management systems that can substantially improve space situational awareness, conjunction analysis, autonomous maneuver generation and, in some cases, coordinated maneuvers between two satellites. Automation will be a critical capability for ops teams as conjunction events increase and the time available to manage them decreases.
Conjunction risks are increasing across all orbital regimes, but the risk is particularly acute in LEO. As the launch cadence increases and more payloads are delivered into orbit, we will see more collisions unless key changes are made.
Our industry needs to improve cooperation between operators and take all steps possible to proactively manage conjunction risks so that we as an industry can take the appropriate measures to avoid them.
Siamak Hesar is the co-founder and CEO of Kayhan Space. He holds a Ph.D. in Aerospace Engineering Sciences from the University of Colorado, Boulder. He has supported NASA missions in the past as a flight dynamics engineer and space situational awareness specialist. Prior to Kayhan Space, Siamak led several software development efforts focused on collision risk assessment and mitigation, and autonomous onboard navigation. He is passionate about space and wants to do his part to ensure a sustainable Earth orbital environment for future generations.
