By Brian Swinburne, Standard Member Director, Space Data Association
Regardless of the mission, the military relies on intel. Clear uninterrupted communication with troops on the ground is vital and can be especially challenging when operating in remote terrain. Situations can change minute by minute, and ISR satellite data ensures well informed and strategic decision-making during operations.
Accurate Positioning, Navigation and Timing (PNT) depends on GPS data from satellites. Advanced GPS technology enables intelligence services to monitor their troops movements effectively and warn against threats. SpaceX are currently supporting upgrades to the Department of Defense’s GPS constellation. Providing “three times better accuracy and up to eight times improved anti-jamming capabilities” with the GPS III SV03 – part of the GPS III block, designed and built by Lockheed Martin.
These improvements to GPS comms will certainly be welcomed. However, it is the LEO projects which SpaceX and others are currently pursuing, that could end up having the opposite effect if debris is not carefully managed.
Risks in the LEO Environment
Orbital debris has become a hot topic in recent years, with the public’s awareness of Kessler syndrome increasing alongside LEO expansion. Of course, there have been inoperative satellites and fragments of debris in orbit for years, so space junk is not a new issue for those of us within the industry. However the volume of debris is increasing, it is estimated that on January 1st 2020 the amount of material orbiting the Earth exceeded 8,000 metric tons.
LEO debris orbits the Earth at speeds of around 8km/s, and the average impact speed with another object is approximately 10 km/s. As a result, any collision even with a tiny fragment of debris will result in serious damage upon impact. The recent expansion of the SpaceX LEO operation has been watched with interest but has also concerned many in the industry. With the ITU and the FCC approving tens of thousands of small sats, the risk of collisions within LEO increases with every launch.
End of life protocol is a key factor when it comes to managing LEO effectively. Unlike Geo-stationary satellites which are re-orbited to a graveyard orbit 235km+ (1000 x Cr x Area/mass) above the geosynchronous orbit, small satellites in LEO must de-orbit. LEO satellites need to use atmospheric drag to re-enter Earth’s atmosphere and burn-up. IADC regulations mean that all LEO operators will need to comply with disposal orbit guidelines within 25 years. However, the sheer volume of satellites proposed for LEO increases the margin for error significantly. Add to this, the fact that 10-15% of small satellites become inoperable before completing missions and it’s a risky proposition for all of us – particularly those working in the military sector.
Collective Data Sharing
Tracking the current collision threats is a challenge in itself, made all the more difficult once you factor in the commercial expansion of Low Earth Orbit constellations, as well as hundreds of independent and educational launches over the coming years. The only way to manage these changes is to work on them collaboratively, information sharing needs to become a high priority. In fact, the future of all operations depends on it.
Fortunately, by sharing TLE data to assist with the monitoring of satellite constellation trajectories we can mitigate some of the risks. Sharing TLE information ensures collision avoidance maneuvering can be conducted and helps with analysis. With a collective threat on this scale, collaboration is key and will benefit all operators.
Understandably the military is extremely guarded when it comes to sharing its mission intelligence but by working with the SDA data can be kept secure. Members have access to accurate information from the SDA which will improve conjunction assessment without having to make TLE information publicly available. The SDA works across all sectors including military, commercial and not for profit. Consolidating technical support and shared resources at its Space Data Center, where approximately 2,000 conjunction reports are generated over a 4 day period. The SDA then provides authoritative contact information to the operator affected by potentially hazardous debris.
Communication is not only crucial for military operations on the ground it is also vital in space. Keeping Low Earth Orbit usable is a particularly important focus and with an increasing number of players, data sharing will be essential over the next few years. The SDA can facilitate collaborative efforts around space situational awareness. Safe-guarding sensitive information and connecting operators in different sectors, in order to manage the debris issue as well as the future of space more effectively.