The scramjet technology of hypersonic flight has been started by the Soviets as the Kholod. The cryogenic liquid hydrogen engine placed on the head of the missile is fired during approximately one minute after the system reaches a supersonic speed. This effect propels the non maneuverable vehicle to an altitude of 35 km with a top speed in excess of Mach 6.
The first successful test of the Kholod was made in November 1991. The fall of the USSR in December of the same year did not stop the project but allowed the French engineers of ONERA to participate. The second successful test is executed in November 1992.
NASA participates from 1994. Two trials fail, although the missile reaches Mach 5.8 and 6.2 respectively. The last launch, on February 12, 1998, is a great success. The Kholod reaches Mach 6.4 and an altitude of 27 km after a firing of 77 seconds. In 2001, the USA develop the X-43 project which is a logical continuation of the Kholod.
On September 8 in London, RM Auctions sells a Kholod, lot 101. This set which is not in flight configuration is announced as a joint system of Russian CIAM and of NASA. It was probably assembled in the final phase of the project as a full size model or as a spare, or for preparing a flight that has not been made.