One of the most important challenges to be addressed by the space sector during the next decades is the proliferation of space debris; these are dead satellites, spent upper stages, and fragments created during accidental break-ups and collisions. After around 60 years of space activity, the total mass is more than 7500 tonnes. Collaborative studies of the space agencies showed that the space debris population is undergoing the Kessler syndrome: space debris density is already above the threshold that triggers a cascade of collisions and the uncontrolled growth of the number of objects in orbit. An example happened in February 2009, when the communication satellite Iridium-33 and a Russian military satellite, Kosmos2251, collided at 776 km altitude with a relative velocity of 11.7 km/s and generated more than 2300 trackable fragments. Catastrophic collisions will continue to occur every 5 to 9 years [Liou, J. C., et al, IADC 12-08, Rev. 1, 2013].
Pushed by the increasing social needs for communication, information, and Earth observation, the sector has planned the launch of mega-constellations that will deteriorate even more the space environment. Space Debris Mitigation Guidelines by the Inter-Agency Space Debris Coordinating Committee in 2002, adopted in 2007 by United Nations, established that spacecraft should re-enter the atmosphere (de-orbited) within 25 years of retirement. Except specific space-agency-funded projects, this guideline is not satisfied by space companies because de-orbiting manoeuvres using conventional technologies are very expensive. For instance, de-orbiting a 1-ton spacecraft from LEO by using chemical thrusters requires about 150 kg of propellant. Just the launch cost of this mass is more than 1.5 M€. This creates a vicious cycle: spacecraft are not deorbited at the end-of-life because there is not a cheap technology, and governments, although aware about the seriousness of the problem, do not create a tough legal framework that would deteriorate the competitiveness of their own industry. Similarly to global warming, international cooperation and global agreement are necessary.
The LWT can be the game-changing technology needed by the sector to break the previous mentioned vicious cycle. Since the operation of a LWT in generator mode does not need propellant nor power, and it is fully passive, a deorbit kit based on LWT would be effective and competitive with respect to other alternatives. Theoretical analysis has shown that a LWT with a mass of about 16 kg can deorbit passively a half-ton spacecraft from Geostationary Transfer Orbit in less than 6 months [Sanchez-Arriaga, et al, J. Propulsion and Power, 2017]. Legislative authorities could change the deorbit guidelines to being mandatory without eroding the competitiveness of their own industry, thus opening a new market for deorbit technologies.
E.T.PACK 