Moons of Mars attention when Houston's claim was repeated in earnest by a Soviet scientist, Iosif Shklovsky, who, based on a later-disproven density estimate, suggested Phobos was a hollow metal shell. Searches have been conducted for additional satellites. In 2003, Scott S. Sheppard and David C. Jewitt surveyed nearly the entire Hill sphere of Mars for irregular satellites. However scattered light from Mars prevented them from searching the inner few arcminutes where the satellites Phobos and Deimos reside. No new satellites were found to an apparent limiting red magnitude of 23.5, which corresponds to radii of about 0.09 km using an albedo of
Mars One but that accommodating Mars One requirements would require some additional work and that such action was not a part of the current focus of SpaceX. SpaceX has no ongoing contracts with Mars One. The first Mars One cargo mission to Mars is proposed to launch by 2022, followed by a crewed mission in 2024, but without funds, hardware, and without a launcher it is seen as unlikely to happen. A hypothetical crewed interplanetary spacecraft, for which there are no concept design studies, would be assembled in low Earth orbit and comprise two propellant modules: a Transit Living Module (discarded just