Active space debris removal—A preliminary mission analysis and design Marco M. Castronuovo n ASI – Agenzia Spaziale Italiana, Viale Liegi 26, 00198 Roma, Italy article info Article history: Received 6 October 2010 Received in revised form 29 April 2011 Accepted 30 April 2011 Available online 20 July 2011 Keywords: Space debris Removal Capture Low Earth orbit (LEO) abstract The active removal of five to ten large objects per year from the low Earth orbit (LEO) region is the only way to prevent the debris collisions from cascading. Among the three orbital regions near the Earth where most catastrophic collisions are predicted to occur, the one corresponding to a sun-synchronous condition is considered the most relevant. Forty-one large rocket bodies orbiting in this belt have been identified as the priority targets for removal. As part of a more comprehensive system engineering solution, a space mission dedicated to the de-orbiting of five rocket bodies per year from this orbital regime has been designed. The selected concept of operations envisages the launch of a satellite carrying a number of de-orbiting devices, such as solid propellant kits. The satellite performs a rendezvous with an identified object and mates with it by means of a robotic arm. A de-orbiting device is attached to the object by means of a second robotic arm, the object is released and the device is activated. The spacecraft travels then to the next target. The present paper shows that an active debris removal mission capable of de-orbiting 35 large objects in 7 years is technically feasible, and the resulting propellant mass budget is compatible with many existing platforms. & 2011 Elsevier Ltd. All rights reserved. 1. Introduction Since the launch of Sputnik-1 in 1957 the number of man-made objects in space has been constantly increas- ing. More than 15,000 objects that can be tracked by radar and telescopes from the ground are currently in orbit around the Earth. Of these only approximately 6% are active satellites. The rest can be classified as space debris, i.e. non-operational satellites, derelict launch vehicle stages, mission-related hardware and fragments resulting from explosions or collisions. The Chinese anti-satellite demonstration in 2007 and the impact between an active U.S. Iridium satellite and a defunct Russian Cosmos spacecraft in 2009 have greatly worsen the situation, increasing dramatically the number of fragments. While space seemed limitless 50 years ago, the space age has demonstrated how quickly the orbits around the Earth can be filled. Space debris has evolved from an environ- mental nuisance to a critical hazard to functioning satel- lites, as well as to human space activity. In fact, the International Space Station, the Space Shuttle and many satellites have often to carry out orbital maneuvers to avoid collisions with space junk. Given the high relative velocities involved (up to approximately 15 km/s), it is obviously also a major concern for astronauts performing extra-vehicular activity protected only by their space suits. At altitudes above the levels where atmospheric drag is significant, the time required for orbital decay is Contents lists available at ScienceDirect journal homepage: www.elsevier.com/locate/actaastro Acta Astronautica 0094-5765/$ - see front matter & 2011 Elsevier Ltd. All rights reserved. doi:10.1016/j.actaastro.2011.04.017 Abbreviations: AOCS, Attitude and Orbit Control System; CFI, customer furnished item; COPUOS, Committee on Peaceful Uses of Outer Space (UN); DEOS, Deutsche Orbitale Servicing Mission; DISCOS, Database and Information System Characterising Objects in Space; DLR, Deutsches Zentrum f ¨ ur Luft- und Raumfahrt e.V.; IADC, Inter-Agency Space Debris Coordination Committee; LCS, laser camera system; LEO, low Earth orbit; LIDAR, light detection and ranging; NORAD, North American Aerospace Defense Command; R/B, rocket body; SSO, Sun-synchronous orbit; STK, Satellite Tool Kit s ; TDK, Thruster De-orbiting Kit; TLE, Two- line elements n Tel.: þ39 068567395; fax: þ39 068567428. E-mail address: marco.castronuovo@asi.it Acta Astronautica 69 (2011) 848–859