ner_tags: O B-Person O O B-Location B-Organization I-Organization I-Organization I-Organization I-Organization B-Organization O O O O O O B-Grant I-Grant I-Grant B-Person O O B-Grant I-Grant I-Grant I-Grant I-Grant O O O O O O O B-Grant I-Grant O O O O O O O B-Person I-Person O O O O B-Person I-Person O O B-Organization I-Organization I-Organization I-Organization O O O O O O O
tokens: Acknowledgements D.H. acknowledges the Spanish Ministry of Economy and Competitiveness (MINECO) for the financial support under the FPI programme BES-2015-075200, R.A. under the Ramón y Cajal program RYC-2010-06519, and the three authors under the programme RETOS ESP2014-57495-C2-R. We are grateful for the hospitality of J. Cabrera and the group of H. Rauer at the DLR Institute of Planetology, where part of this work was performed.