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 before arrival at Mars) and a lander (see "Human Lander" below). In 2012, Mars One speculated that the Transit Living Module could potentially be designed and built by Thales Alenia Space. A concept study was produced by Lockheed Martin for a demonstration lander based on the 2008 "Phoenix" lander. In December 2013 Mars One awarded a contract to Surrey Satellite Technology for a study of the satellite technology required to provide 24/7 communication between Earth and the Mars base. Mars One proposed at least two satellites, one in areostationary orbit above Mars and a second at the Earth – Sun