The Orbital Debris Problem
The problem of orbital debris has been a priority for government agencies and commercial entities in recent years. While it may seem distant and irrelevant, detecting and tracking space debris is crucial for the danger it poses to humans and technology in space that supports our public way-of-life (e.g. banking, navigation, communication, etc.) and national security. The space around the Earth is crowded with space debris, and the numbers are astonishing. According to the Inter-Agency Space Debris Coordination Committee, statistical models estimate more than 30,000 space debris objects larger than 10 cm, and around 900,000 objects larger than 1 cm. This debris includes non-functioning spacecraft, launch vehicles, pieces from satellite breakups, paint flecks, etc. A current estimate states that there are 128 million objects between the sizes of 1 mm and 1 cm. Figure 1, from the IADC, shows that there are huge, estimated numbers of small objects in low earth orbit, without the actual numbers known.
It is not about the size but the energy that even the smallest objects carry. These debris objects are traveling at speeds between 15,000 – 20,000 mph. Even the smallest object, the size of a grain of rice, carries enough energy (equivalent to a truck traveling at about 70 mph) and an impact can render spacecraft inoperable or destroy sensitive spacecraft component. Worse yet, it can result in fatality in case of human astronauts.
National Security and the Space Debris Problem
The Department of Defense has a vested interest in detecting and tracking and possibly removing space debris due to its implications for national security: Space debris represents threats to Space Assets, Space Situational Awareness, Defensive Measures and Warfighter Communications.
Threat to Space Assets
Space plays a critical role in the military's operations, including communication, reconnaissance, mapping, intelligence gathering, and navigation. The presence of space debris poses a direct threat to space-based assets that support these missions. Collisions between operational satellites and space debris can lead to damage or destruction of military space systems, disrupting vital communication networks, surveillance capabilities, and other military functions.
Space Situational Awareness
To ensure effective military operations, the DoD requires accurate and up-to-date information about the space environment. This includes knowledge of the location, trajectory, and characteristics of both friendly and potential adversary satellites. Space debris complicates this situational awareness by cluttering Earth's orbit and introducing uncertainties in satellite tracking and identification. The DoD needs to account for space debris to maintain a clear picture of the space domain and protect its own assets.
Defensive Measures
As space becomes increasingly contested, the DoD needs to be prepared to defend its satellites and space-based capabilities. This includes the ability to detect and track potential threats, such as anti-satellite weapons or hostile activities in space. However, the presence of a large amount of space debris can make it challenging to distinguish between natural debris and intentional threats. Accurate monitoring of space debris helps the DoD differentiate between normal orbital objects and potential hostile objects.
Ensuring Space-Based Warfighter Command-Control Communications
Warfighters depend on space-based technologies to provide command and control communications, employ high-technology sensors and weapon systems, and access the vast array of real-time intelligence and information that gives them a decisive advantage for mission success. Military and commercial satellite communications systems, tied seamlessly into the terrestrial infrastructure, must provide assured and survivable communications on demand, on the move, and around the globe. Superior satellite communications are essential to fight and win on the modem day battlefield. Space debris, as small as 1 mm, can affect military ground communications by disrupting on orbit satellites and making positioning new satellites impossible, leaving the warfighter on the ground vulnerable to attack and unable to coordinate its forces.