One of the top priorities for NASA is regulating the increase of orbital debris in near-Earth space. Orbital debris includes man-made objects orbiting about the Earth with no useful purpose and also naturally occurring primitive materials such as meteoroid particles. Primitive materials are those that are least modified by the processes where the initial solar nebula evolved into our present solar system. As surviving remnants of the nebula, they include chondritic meteorites, cosmic and interplanetary dust particles, and cometary material sampled both in Earth’s stratosphere and by the Stardust sample return mission. Some examples of man-made orbital debris include carriers for multiple payloads, debris intentionally released during from a launch vehicle or during mission operations, debris resulting from spacecraft or upper stage explosions or collisions, spacecraft and upper stages of launch vehicles, solid rocket motor effluents, and small paint chips released by thermal stress or particle impacts.

The U.S. Government has put programs and projects into place that will assess and limit the amount of debris that is released in a planned manner by writing into law mitigation standard practices. In all operational orbit regimes, spacecraft must be designed to minimize or eradicate debris released in normal operation. Debris larger than 5mm remaining in orbit for longer than 25 years must be analyzed and vindicated regarding cost effectiveness and mission necessity. Programs are also in place to address accidental explosions and the mitigation of debris limiting the risk to other space systems during mission and after completion of mission, post-mission disposal of space structures, and selection of safe flight profiles and operational configuration.

Mitigation measures include prevention of new debris, analyzing tether systems, designing satellites to withstand impacts by small debris, designing spacecraft or upper stage to limit the probability of collision with known objects during orbital lifetime, implementing operational procedures such as using orbital regimes with less debris, adopting specific spacecraft attitudes, and atmospheric reentry options. NASA was the first space agency in the world to issue a comprehensive set of orbital debris mitigation guidelines taking place in 1995. The U.S. Government shortly after developed a set of Orbital Debris Mitigation Standard Practices. The Inter-Agency Space Debris Coordination Committee then adopted a consensus set of guidelines designed to mitigate the growth of the orbital debris in 2002. The Scientific and Technical Subcommittee of the United Nations’ Committee on the Peaceful Uses of Outer Space adopted a set of space debris mitigation guidelines very similar to the IADC guidelines in 2007. The guidelines were later endorsed by the United Nations in 2008.

Currently, more than 22,000 orbital debris are being tracked by the U.S. Space Surveillance Network traveling between 4 and 5 miles per second.  Many ways to eliminate orbital debris are currently being discussed. The e.DeOrbit mission was proposed publicly in 2014 by the European Space Agency. The mission would seek out satellite debris at an altitude between 500 and 620 miles. The European Space Agency is considering several kinds of “capture mechanisms” to pick up the debris, such as nets, harpoons, robotic arms and tentacles. CleanSpace One is a technology demonstration spacecraft that is expected to launch this year from the back of a modified Airbus A300 jumbo jet. The Swiss Space Systems satellite would then meet up with a decommissioned SwissCube nanosatellite to move it out of orbit. This would be a method of pushing the debris out of space.

The Japanese Aerospace Exploration Agency proposes to use an electrodynamic tether where current would slow down the speed of satellites or space debris. Slowing the satellite speed would make it gradually fall closer to Earth where it would burn and turn to ash. This would be a method where the power of electricity would be used. Texas A&M University’s Sling-Sat Space Sweeper proposes swing capturing an object, swinging it towards Earth’s atmosphere, and then using the momentum to sail on to the next piece of space debris for removal. CubeSail, a British proposal, would use the drag of a solar sail to push orbiting space debris down to lower orbits.

Space Debris Elimination, or SpaDE, would push satellites into a lower orbit by using air bursts within the atmosphere. A design proposal from Daniel Gregory of Raytheon BBN Technologies in Virginia would use a balloon or high-altitude plain to send the bursts out. This method is referred to as huffing and puffing. Another method is where a network of nanosatellites, connected with a piece of electrically conducting tape that could be as long as 2 miles, could knock satellites down as it passes through Earth’s magnetic field and produces voltage. The solar-powered ElectroDynamic Debris Eliminator (proposed by Star Technology and Research, Inc.) would get rid of all large pieces of satellite debris in low-Earth orbit within a dozen years. The Kessler syndrome is a chain reaction of collisions dramtically increasing the amount of debris. This could affect useful polar-orbiting bands, increase the cost of protection for spacecraft missions, and could potentially destroy live satellites. The measurement, mitigation, and potential removal of debris is critical for the future of space.

A current event that you would think had no impact on space debris is having an impact. An unexpected effect of a no-deal Brexit would be the UK potentially getting less warning about space debris plummeting towards Earth. EU space surveillance and tracking (EUSST) program set up in 2014 tracks orbiting debris that could pose a risk to satellites and issues “re-entry warnings”. If the UK leaves the EU without making a deal, it may no longer be part of the program in terms of operation and further development. However, as well as the UK’s tracking capabilities, which form part of the EUSST system, the UK will continue to receive space, surveillance and tracking data from the US.