Phobos (moon) tidal forces. Phobos could be a second-generation Solar System object that coalesced in orbit after Mars formed, rather than forming concurrently out of the same birth cloud as Mars. Another hypothesis is that Mars was once surrounded by many Phobos- and Deimos-sized bodies, perhaps ejected into orbit around it by a collision with a large planetesimal. The high porosity of the interior of Phobos (based on the density of 1.88 g/cm, voids are estimated to comprise 25 to 35 percent of Phobos's volume) is inconsistent with an asteroidal origin. Observations of Phobos in the thermal infrared suggest a composition containing
Mars One for public viewing. Mars One initially estimated a one-way trip, excluding the cost of maintaining four astronauts on Mars until they die, at 6 billion USD. Lansdorp has declined questions regarding the cost estimate. A proposed global reality-TV show was intended to provide funds to finance the expedition, however, no such television show has emerged and no contracts have been signed. The astronaut selection process (with some public participation) was to be televised and continue on through the first years of living on Mars. Discussions between Endemol started in June 2014, producers of the "Big Brother" series, and Mars One