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 (orbiter). On 3 March 2014 Mars One announced a working agreement with Uwingu, stating that the program would use Uwingu's map of Mars in all of their missions. Since the official announcement of their conversion to a "Stichting" foundation, Mars One has been accepting donations through their website. As of 4 July 2016, Mars One had received $928,888 in donations and merchandise sales. The 2016 donation update adds the Indiegogo campaign ($313,744) to the private donation and merchandise total. On 10 December 2013, Mars One set up a crowdfunding campaign on Indiegogo to help fund a 2018 demonstration robotic mission