Russia was forced to postpone the docking of an unmanned cargo ship with the International Space Station on Tuesday because of a problem receiving data from the supply craft.
The Progress M-27M should have docked with the orbiting station about six hours after its launch from the Baikonur Cosmodrome in Kazakhstan early on Tuesday but the Roscosmos space agency said it now expected a delay of at least two days.
"There are some problems with the data telemetry. They are being worked on by Roscosmos specialists," it said in a statement that gave few details.
The TASS news agency quoted an unnamed space official as saying the Progress, carrying supplies such as food and fuel, had missed its intended orbit and could be lost if it is not corrected. Other officials told Russian news agencies there had been a problem opening two antennae on the craft.
Space exploration is a subject of national pride in Russia, rooted in the Cold War "space race" with the United States, but the collapse of the Soviet Union starved the space program of funds and it has been beset by problems in recent years.
The current crew on the International Space Station is made up of Americans Terry Virts and Scott Kelly, Russians Anton Shkaplerov, Gennady Padalka and Mikhail Korniyenko and Italian Samantha Cristoforetti.