The European Space Agency is developing a new system, known by its acronym Collision Risk Assessment and Automated Mitigation (CREAM), to automate the labor-intensive process of monitoring, assessing and responding to possible space debris.
The area between the Earth and the Moon, especially in low Earth orbit, may need a thorough cleanup. It is estimated that there are more than 11,000 active satellites in orbit, as well as 3,300 out of service satellites, and a staggering 1.2 million pieces of debris larger than one centimeter in diameter. This does not include the tens of thousands of new satellites planned for launch in the future.
Due to the huge amount of communications, it has become routine for space agencies and major military powers to track the location and whereabouts of satellites. If a satellite appears to have passed another satellite within a kilometer (0.62 miles), or there is a one in 10,000 chance of collision, standard procedure is to temporarily alter the orbit of one of the objects to ensure safety.
The problem is, it's not as simple as it sounds. In addition to determining the likelihood of a collision, the precise trajectory of each object must be calculated, their activity and maneuvering status recorded, avoidance strategies formulated and approved, and instruments shut down, thrusters activated to change orbit, and thrusters activated again to return to the original orbit in preparation for the objects.
All of this takes a lot of time, money, and manpower—not to mention gathering everyone involved in the incident and getting their consent. ESA alone says its spacecraft must make up to four such call-ups each year, and that as the number of calls increases, so does the risk of collision.
Starting in 2020, the CREAM project will automate tasks such as collision risk assessment, maneuver planning and coordination between different spacecraft. Using algorithms, the system can evaluate potential close approaches, calculate the probability of collision, and predict accident parameters.
Once a potential collision is identified, CREAM automatically calculates the best strategy to avoid the hazard – a task that typically requires significant human input. It then communicates and negotiates with space operators, regulators and service providers associated with the relevant spacecraft, even reaching maneuvering agreements with minimal human intervention.
Currently, CREAM is moving from ground testing to on-orbit validation, which includes carrying the system as a digital payload on a satellite. The first validation will take place in 2027. The mission, called CREAM-IOD, will use a low-cost satellite capable of automatically calculating orbits, assessing encounters and calculating avoidance maneuvers.
In addition to immediate applications, ESA hopes CREAM will facilitate a feedback loop to develop the technology and the rules by which it operates.
Source: ESA