Russian and European authorities searched for an experimental mini-spacecraft on the eastern peninsula of Kamchatka on Saturday, a day after the prototype was test launched from a nuclear submarine thousands of kilometres away, news reports said.
The Demonstrator spacecraft - designed to carry cargo and passengers from the international space station to Earth - was launched from the submarine Borisoglebsk in the Barents Sea on Friday and was reported to have descended toward its target on time.
Russian news agencies and television, however, later reported that engineers had no communication with the craft and had to call off the search at nightfall.
Officials were not immediately available for comment.
The Borisoglebsk also launched a successful ballistic missile test on Saturday, hitting a target on Kamchatka, the Defence Ministry said.
The Demonstrator is to be folded up and transported to the space station on a Russian Progress cargo ship and will be
used to bring payloads back to Earth, designers say.
The ship's collapsible, cone-shaped body is made of light material that can withstand high temperatures and it can fly on a predictable trajectory without engines - making it a cheap alternative to the Soyuz spacecraft currently in use.
It was built on contract for the European Space Agency and the European Aeronautic Defence & Space Co, Interfax said.