condense the gases into liquid hydrogen and liquid oxygen and also process them into hydrogen peroxide, all of which could be used as rocket fuels." Mars exploration In June 2012, private Dutch non-profit, Mars One, announced a private one-way (no return) human mission to Mars with the aim to establish a permanent human colony on Mars. The plan was to send a communication satellite and pathfinder lander to the planet by 2016 and, after several stages, land four humans on the Martian surface for permanent settlement in 2023. A new set of four astronauts would then arrive every two years. Mars One has received a variety of criticism, mostly relating to medical, technical and financial feasibility. There are also unverified claims that Mars One is a scam designed to take as much money as possible from donors, including reality show contestants. Many have criticized the project's US$6 billion budget as being too low to successfully transport humans to Mars, to the point of being delusional. A similar project study by NASA estimated the cost of such a feat at US$100 billion, although that included transporting the astronauts back to Earth. Objections have also been raised regarding the reality TV project associated with the expedition. Given the transient nature of most reality TV ventures, many believe that as viewership declines, funding could significantly decrease, thereby harming the entire expedition. Further, contestants have reported that they were ranked based on their donations and funds raised. In February 2013, the US nonprofit Inspiration Mars Foundation announced a plan to send a married couple on a 2018 mission to travel to Mars and back to Earth on a 501-day round trip, with no landing planned on Mars. The mission would have taken advantage of an infrequently occurring free return trajectory—a unique orbit opportunity which occurs only once every fifteen years—and will allow the space capsule to use the smallest possible amount of fuel to get it to Mars and back to Earth. The two-person American crew – a man and a woman – will orbit around Mars at a distance of of the surface. "If anything goes wrong, the spacecraft should make its own way back to Earth — but with no possibility of any shortcuts home." On September 27, 2016, at the 67th annual meeting of the International Astronautical Congress, Elon Musk unveiled substantial details of the Interplanetary Transport System (ITS) design for