time, the Navy was developing the submarine-launched Polaris missile, which required them to know the submarine's location. This led them and APL to develop the TRANSIT system, a forerunner of modern Global Positioning System (GPS) satellites. Backup units and replicas At least two vintage duplicates of Sputnik 1 exist, built apparently as backup units. One resides just outside Moscow in the corporate museum of Energia, the modern descendant of Korolev's design bureau, where it is on display by appointment only. Another is in the Museum of Flight in Seattle, Washington. Unlike Energia's unit, it has no internal components, but it does have casings and molded fittings inside (as well as evidence of battery wear), which suggests it was built as more than just a model. Authenticated by the Memorial Museum of Cosmonautics in Moscow, the unit was auctioned in 2001 and purchased by an anonymous private buyer, who donated it to the museum. Two more Sputnik backups are said to be in the personal collections of American entrepreneurs Richard Garriott and Jay S. Walker. In 1959, the Soviet Union donated a replica of Sputnik to the United Nations. There are other full-size Sputnik replicas (with varying degrees of accuracy) on display in locations around the world, including the National Air and Space Museum in the United States, the Science Museum in the United Kingdom, the Powerhouse Museum in Australia, and outside the Russian embassy in Spain. Three one-third scale student-built replicas of Sputnik 1 were deployed from the Mir space station between 1997 and 1999. The first, named Sputnik 40 to commemorate the fortieth anniversary of the launch of Sputnik 1, was deployed in November 1997. Sputnik 41 was launched a year later, and Sputnik 99 was deployed in February 1999. A fourth replica was launched, but never deployed, and was destroyed when Mir was deorbited. The Sputnik 1 EMC/EMI is a class of full-scale laboratory models of the satellite. The models, manufactured by OKB-1 and NII-885 (headed by Mikhail Ryazansky), were introduced on February 15, 1957. They were made to test ground electromagnetic compatibility (EMC) and electromagnetic interference (EMI). See also Yuri Gagarin — Soviet cosmonaut and first human to journey into outer space Donald B. Gillies — one of the first to calculate the Sputnik 1 orbit Kerim Kerimov — one of the lead architects behind Sputnik 1 Valentina Tereshkova — first woman in space ILLIAC I —