A test of new spacecraft docking gear for Russian flights to the International Space Station failed, the U.S. and Russian space agencies said on Tuesday, casting doubt on the automated system meant to simplify missions to the orbiting outpost.
The space agencies said a new docking attempt would likely take place on Sunday, after an unmanned Japanese spacecraft, the HTV-3, reaches the station and is manually berthed by astronauts later this week.
Russia's single-use Progress cargo ship had already delivered fuel and other supplies to six astronauts aboard the International Space Station and was due to burn up on re-entry, laden with trash, on July 30, after the next test.
The craft is now orbiting at a safe distance from the outpost while Russian engineers study why the Kurs-NA rendezvous system automatically aborted during the linkup attempt.
"The test was proceeding normally until about the time that the new Kurs-NA rendezvous system was to be engaged," NASA said in a statement on its website.
"As commands were being issued to activate the Kurs system, a failure was announced, triggering a passive abort."
Kurs-NA is an upgrade of the Kurs docking gear used for years on Russia's manned Soyuz and robotic Progress spacecrafts. The system features updated electronics and is designed to improve safety and use less power, according to NASA.
Since the retirement of the U.S. space shuttles last year, the United States has been dependent on Russia and is paying $60 million per person to fly astronauts to the ISS, a $100 billion research complex orbiting 240 miles (385 km) above Earth.
Moscow is struggling to restore the prestige of its once-pioneering space programme after a string of launch mishaps last year, including the failure of a mission to return samples from the Martian moon Phobos.