Dear colleagues, the Scientific Committee invites all authors to submit abstracts for consideration and inclusion in the scientific programme of the 20th IAA Humans in Space Symposium (HIS) which will be held from June 29 to July 3, 2015 in Prague. Due to a high level of interest from participants, we are pleased to announce that the abstract submission deadline has been extended to March 20, 2015. We are looking forward to welcoming you to Prague. Best regards, HIS 2015 Secretariat & LOC Symposium Secretariat Guarant International spol. s. r. o. Na Pankráci 17, 140 21 Praha 4, Czech Republic tel: +420 284 001 444, fax: +420 284 001 448 e-mail: his2015@guarant.cz Local Organizing Committee Czech Space Office Prvního pluku 17, 186 00 Praha 8, Czech Republic tel: +420 224 918 288 e-mail: vaclavik@czechspace.cz