Radio silence as Russia tries to contact space cargo
The Progress capsule is circling the Earth in radio silence, carrying three tons of food and supplies for the astronauts living at the orbiting outpost.
None of the equipment on board was critical for the US segment of the ISS, and the astronauts have plenty of provisions, enough to last for months, officials at NASA said.
But if contact cannot be made, it could be just days before the spaceship runs out of fuel and starts an uncontrolled descent back into the atmosphere.
"Russian flight controllers plan for another attempt to communicate with a cargo resupply spacecraft bound for the station. The next attempt to link with the spacecraft comes at 8:50 pm EDT Tuesday (0050 GMT Wednesday)," said the US space agency.
During the spacecraft's first four orbits, Russian flight control teams tried to make contact but were unsuccessful.
The nature of the technical glitch is unclear, but NASA said a problem became apparent not long after the Progress 59 cargo craft separated from the third stage of the Soyuz rocket.
"An unspecified problem prevented Russian flight controllers from determining whether navigational antennas had deployed and whether fuel system manifolds had pressurized as planned," said NASA.
"When flight controllers initially could not confirm deployment of the antennas in the minutes following its launch, they selected the backup rendezvous plan of two days and 34 orbits instead of the planned four-orbit, six-hour rendezvous."
A spokesman at Russian mission control told AFP that the Progress "reached orbit but the full volume of telemetry (data transmissions) is not being received."
Russia's mission control website said that the ship would dock with the ISS, where the international crew of six people awaits the cargo, on April 30.
The Progress was carrying "1,940 pounds of propellant, 110 pounds of oxygen, 926 pounds of water, and 3,128 pounds of spare parts, supplies and scientific experiment hardware," NASA said.
"Among the US supplies on board are spare parts for the station's environmental control and life support system, backup spacewalk hardware, and crew clothing, all of which are replaceable."
Roscosmos space agency said earlier this month that the ship would also carry a copy of the Soviet Victory Banner: the red flag three Red Army soldiers raised over the Reichstag building in Berlin on May 1, 1945.
The flag, which is the official symbol of Soviet victory over Nazi Germany that Russia will commemorate on May 9, was to be used by Russian cosmonauts to send their greetings to the nation on that day.
The next delivery to the ISS is planned by SpaceX's Dragon cargo ship on June 19.
"Both the Russian and USOS segments of the station continue to operate normally and are adequately supplied well beyond the next planned resupply flight," the US space agency said.
An engine mishap on a similar Progress flight in 2011 led to complete loss of communication and failure to reach the target orbit.
Shortly after launch, it crashed into Siberia, marking one of Russia's biggest space setbacks.
Three or four Progress cargo ships are launched every year bringing necessities like oxygen, fuel and food supplies to the orbiting laboratory. After completing their mission they usually fall into the Pacific Ocean.
© 2015 AFP