Small Satellites and Space Debris Mitigation

chapter 11 Small Satellites and Space Debris Mitigation

Cordula Steinkogler* i Introduction

Almost six decades of spaceflight have left a large quantity of debris in outer space. Due to the continuous increase in space activities, the amount of space debris is constantly growing. While in 2005 the total mass of catalogued objects in Earth orbit was an estimated 5,000 tons, this number had risen to approximately 6,000 tons by 2010 and amounts to over 6,600 tons today.1 At present, approximately 17,000 space objects with sizes ranging from a few centimetres to several meters are officially catalogued.2 Of these, however, only approximately

* The author would like to thank Prof Otto Koudelka (Graz University of Technology), Dr Manuel Metz (German Aerospace Center), Attila Matas (ITU) and Vladimir Agapov (Russian Academy of Sciences) for the valuable advice and useful material they provided on technical matters. 1 National Aeronautics and Space Administration, ‘Monthly Effective Mass of Objects in Earth Orbit by Region’ (Orbital Debris Quarterly News, January 2015) . 2 National Aeronautics and Space Administration, ‘Satellite Box Score’ (Orbital Debris Quarterly News, January 2015) . See also United States Strategic Command, ‘Satellite Situation Report’ (as of 6 June 2015). Note that according to the esa space debris risk assessment model esa MASTER 2009 the current number of space objects larger than 10 cm is approximately 29,000. See Institute of Aerospace Systems – Technische Universität Braunschweig, Maintenance of the esa MASTER Model – Final Report (European Space Agency 2011) 336. The difference is due to the fact that the United States Space Surveillance Network can track objects larger than 5–10 cm in Low Earth Orbit, but in higher altitudes it is only possible to track objects larger than 0,3-1 m. See Ram Jakhu and Joseph Pelton, Small Satellites and Their Regulation (Springer 2014) 7. Furthermore, data relating to debris that cannot be attributed to a specific source as well as data of military spacecraft are not published in the us Space Surveillance Network’s publicly available catalogue. See National Research Council, Limiting Future Collision Risk to Spacecraft: An Assessment of nasa’s Meteoroid and Orbital Debris Programs (National Academies Press 2011) 9. Also note that the number of objects of a size between 1 and 10 cm is estimated to be in the order of 720,000. See Technische Universität Braunschweig Institute of Aerospace Systems, Maintenance of the esa MASTER Model – Final Report (European Space Agency 2011) 336. Due to their small size these objects cannot be tracked continuously, which makes it difficult to predict collisions. Yet, even the collision with an object of this size can lead to the loss of a satellite mission. See Carsten Wiedemann, ‘Space Debris Mitigation’ in Irmgard Marboe (ed), Soft Law in Outer Space (Böhlau 2012) 316.

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1,100 are operational satellites.3 With the growing number of functional and non-functional objects in Earth orbit, the probability of in-orbit collisions is ris- ing. In the long term this could lead to a situation where the increase in space debris will be sustained only by collisions between collision fragments.4 This collision cascading effect, described as ‘Kessler Syndrome’, could render the use of outer space more and more difficult in the future. Space debris is therefore regarded as a serious hazard for the safety and sus- tainability of outer space activities. Yet, this issue is not explicitly addressed in the five United Nations space treaties. To fill this gap, a number of non-binding guidelines and standards on space debris mitigation have been developed on the international level over the past years. In addition, many states have adopted national legislation and procedures on space debris, making the international mitigation standards and guidelines applicable to national space operations. Small satellites have become increasingly popular in recent years and their advantages are manifold.5 However, the technical and operational particulari- ties that allow for their cost-effective development and use, pose specific technical and legal challenges related to the mitigation of space debris. At the same time, small satellites can play an important role in the development of new technologies in the area of space debris mitigation and can thus offer innova- tive solutions to the risks posed by space debris. Against the background of a predicted increase in small satellite activities in the future, the chances and challenges that small satellites present with regard to the issue of space debris merit particular attention.

3 United States Department of Defense, ‘Officials Expand Space-tracking Website’ (Department of Defense News, 25 August 2014) . 4 Donald Kessler, ‘Collisional cascading: The limits of population growth in low earth orbit’ (1991) 11 Advances in Space Research 63. 5 In this chapter, the term ‘small satellite’ refers to all subcategories of small satellites as pro- posed by the International Academy of Astronautics (iaa) Study Group on Small Satellite Missions for Earth Observation. See Rainer Sandau (ed), International Study on Cost- Effective Earth Observation Missions (Taylor & Francis 2006). Note however, that there is no universally accepted definition of a small satellite. For a detailed discussion of the definition of small satellites see the chapter of Otto Koudelka in this book. See also Ram Jakhu and Joseph Pelton, Small Satellites and Their Regulation (Springer 2014) 3; International Telecommunication Union and United Nations Office for Outer Space Affairs, ‘Guidance on Space Object Registration and Frequency Management for Small and Very Small Satellites’ (A/AC.105/C.2/2015/CRP.17, 2015) 2. For a general discussion of the characteristics of small satellites see the chapters of Otto Koudelka, Werner Balogh, Neta Palkovitz, Michael Dornik and Milton Smith in this book.