Author: Space Economy Academy. In this article, we will explore various measures against the space debris problem that poses a threat to our satellites and space missions.
Measures against the Space Debris. The growing amount of space debris is one of the biggest dangers to our satellites and spacecraft. If this growth continues, the higher risk and thus cost of sending expensive equipment as well as human life to space will seriously affect the frequency of successful space missions. It is therefore a priority to try to curb this development by reducing the number of debris orbiting the Earth and taking measures against the space debris to reduce the risk posed by space debris.
Space debris is defined as defunct human-made objects in space which no longer serve a useful function, particularly those being in Earth orbit. These objects span from the tiniest fragments – solidified liquids expelled from spacecraft, unburned particles from solid rocket motors, and even paint flecks – to large spacecraft and launch vehicle stages, and a vast amount of fragmentation debris from the breakup of such bodies and satellites.
Debris can be caused by a variety of reasons. Small parts accidentally being released during deployment of a satellite, or upper parts of rockets from orbital insertion maneuvers. It could be satellites that fail to deploy properly, or satellites that reach their end-of-life and are no longer in operation. It can be parts of a debris-on-debris collision, from debris colliding with spacecraft, or from an explosion on a spacecraft (like a battery exploding). Several spacecraft, both crewed and uncrewed, have been damaged or destroyed by space debris.
Space debris. As of September 2024, the number of space objects regularly tracked by Space Surveillance Networks is about 36,860, including 10,200 active satellites. However, these are just the objects large enough to be tracked and in an orbit that makes tracking possible. ESA’s Space Debris Office estimates there to be more than 40,000 space debris objects greater than 10 cm, more than a million objects between 1 to 10 cm, and 130 million space debris objects between 1 mm to 1 cm. In Low Earth Orbit, objects in space have a velocity of 7 km per second. The energy of an impact is directly proportional to the square of the speed, and at such high velocities even small debris can cause large damage to spacecraft they hit, render expensive equipment useless, and create life threatening situations.
Also, the explosion when debris hits other debris or spacecraft generates even more debris that increases the risk for impact exponentially. With higher risks for equipment sent to space, the cost of space operations and satellite launches would increase. Also, existing spacecraft may need to do maneuvers to avoid collision, reducing their fuel level each time, hence shortening their expected lifetime. In the long term, if the risk for operations in space becomes too high, humans could be precluded from space for a few decades.
So how can the space industry reduce the risk posed by space debris?
Furthermore, to minimize the risk of explosions when old satellites are being hit by debris, one could make sure all pressurized gas is being released from the satellite after its mission is done. However, the gas itself is also a form of debris, so this is not the best solution. There are regulations being made on higher levels, like demanding that all small satellites in Low Earth Orbit must be de orbited within a certain time limit, as well as discouraging use of the kind of deployers that would generate more debris. Efforts to reduce space debris have seen some progress, but not enough to stop the increase in debris growth. The three broad methods of reducing the risks posed by orbital debris are:
Avoiding debris from being formed in the first place (mitigation), better tracking and characterization of debris, and finding ways to remove existing debris (remediation). NASA’s Office of Technology, Policy, and Strategy (OTPS) has through two recent reports (released in 2023 and 2024) put focus on cost-effective ways to remediate and mitigate debris. These measures against the space debris problem are critical for the future of space exploration.
The first report, “Cost and Benefit Analysis of Orbital Debris Remediation,” provided cost-benefit analyses of remediation measures for orbital debris, including moving, removing or reusing objects. Contrary to previous concerns about remediation having huge deployment costs and a long time span before achieving benefits, the report found that some remediation approaches may achieve net benefits in under a decade. Methods for removing debris measuring 1-10 cm appear to produce net benefits quickly. Similarly, methods for nudging larger debris to avoid collisions could also produce net benefits almost immediately. Using reusable spacecraft for forcing the largest debris down to the ground in a controlled way might provide net benefits within 30 years. Such measures against the space debris will ensure safer missions.
Using similar methods for forcing smaller debris to fall to the ground in uncontrolled ways are potentially cheaper than using drag sails. Recycling space debris into propellant would remove the need for launches of propellant from the ground, but the costs of research & development needed until a system like this could work makes this option just as expensive as conventional remediation systems.
The follow-up report, Cost and Benefit Analysis of Mitigating, Tracking, and Remediating Orbital Debris provided improved estimates of the risks posed to spacecraft, from the smallest to the largest objects. It also addressed effectiveness relative to mitigating, tracking, and characterizing debris. The two biggest insights from this study were:
1. Debris Remediation can be as cost-effective as Tracking and Mitigation. The most effective form of remediation is just-in-time collision avoidance, nudging large debris away from possible collisions. The next-most-effective remediation action is to remove centimeter-size debris with a laser system.
2. Rapidly deorbiting defunct spacecraft is highly cost-effective: A spacecraft in low Earth orbit should be deorbited within 25 years after its mission ends. The analysis indicates that reducing this timeline into a 5-year rule is a cost-effective way to reduce debris risks. Even more net benefits could be gained by reducing the deorbit timeline further. Implementing these measures against the space debris will significantly enhance global space safety.
By presenting detailed cost-benefit analyses, these studies aim to help governments and the space industry in making informed decisions about which strategies and technologies to invest in and promote long-term sustainability for operating in space.
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