tokens: Acknowledgments The authors thank Clive Dickinson and Patrick Leahy for useful discussions and comments on the manuscript. We also acknowledge useful discussions with Pascal Rideau and Joel Michaud concerning practical constraints related to data transfer and to attitude and orbit control. CGRW acknowledges the award of an STFC quota studentship the support of the Engineering and Physical Sciences Research Council (grant no. EP/M011852/1). MLB acknowledges the European Research Council for support through the award of an ERC Starting Independent Researcher Grant (EC FP7 grant no. 280127). MLB also thanks the STFC for the award of Advanced and Halliday fellowships (grant no. ST/I005129/1). Some of the results in this paper have been derived using the healpix (Grski etal. 2005 ) package.
ner_tags: O O O O B-Person I-Person O B-Person I-Person O O O O O O O O O O O O O O B-Person I-Person O B-Person I-Person O O O O O O O O O O O O O B-Person O O O O O B-Organization B-Fellowship I-Fellowship O O O O B-Organization I-Organization I-Organization I-Organization I-Organization I-Organization B-Grant I-Grant I-Grant B-Person O O B-Organization I-Organization I-Organization O O O O O O O B-Organization B-Grant I-Grant I-Grant I-Grant B-Organization B-Grant I-Grant I-Grant I-Grant B-Person O O O B-Organization O O O O B-Fellowship I-Fellowship I-Fellowship I-Fellowship B-Fellowship I-Fellowship I-Fellowship O O O O O O O O O O O O B-Software B-Citation I-Citation I-Citation O O