Space  travel  has   always  been a   dream  of  mankind  and   Johannes  Kepler,  a  leading  figure  of  the  17th century  scientific   revolution,   anticipated   its   realization   already  on   the  basis   of   his  astronomical observations: In  his »Dissertatio cum Nuncio Sidereo« (1610)  he wrote to Galileo Galilei:

»(.) Given  ships  or  sails  adapted  to  the  winds of   heaven, there  will  be  men  who  will  not  shrink  from even  that  vast  expanse.  So,  for  the  sake  of   those who will  be  ready  to  undertake  such  voyage, let  us conduct  the astronomy – I  for  the Moon and you, Galileo, for Jupiter.«