This article by Kuniaki Otsuka, Yutaka Kubo, Mitsutoshi Hayashi, Naomune Yamamoto and Koichi Shibata (Tokyo Women’s Medical University, Tokyo, Japan), Germaine Cornelissen (University of Minnesota, Minneapolis, MN, USA), Tatsuya Aiba, Satoshi Furukawa, Hiroshi Ohshima and Chiaki Mukai (Japan Aerospace Exploration Agency, Tokyo, Japan) was published online by npj Microgravity on November 30, 2015.