Dr Bertolami from the University of Porto was speaking to MailOnline . He studied different types of propulsion that could get humans to Mars . In total a manned mission would the 2030s , which poses major problems , such as exposure to radiation . He thinks Nasa 's plan to land humans there in last three to four years is not feasible . ‘ I would like to be a bit more optimistic , but I ’ m afraid this is how it is ’
Dr Bertolami from the University of Porto was speaking to MailOnline . He studied different types of propulsion that could get humans to Mars . In total a manned mission would last three to four years , which poses major problems , such as exposure to radiation . He thinks Nasa 's plan to land humans there in the 2030s is not feasible . ‘ I would like to be a bit more optimistic , but I ’ m afraid this is how it is ’