An unmanned Russian cargo ship sailed past the International Space Station instead of docking on autopilot, as engineers on Earth struggle to determine what went wrong.
A telemetry lock between the Russian-made Progress module and the space station was lost and the module flew past at a safe distance. NASA said the crew was never in danger and that the supplies are not critical and will not affect station operations.
NASA said that it will not attempt another docking today. Russian flight controllers don't know yet what caused the failure in the unmanned modules automated docking system.
The robotic cargo ship Progress 38 was slated to dock at the space station at 12:58 p.m. ET (1658 GMT) but lost its navigational lock on the orbiting lab about 25 minutes before the rendezvous.
"The Progress literally flew past the station, but at a safe distance from the outpost," NASA commentator Rob Navias said. "The station crew reported seeing the Progress drift beyond their view, as they worked to reestablish telemetry with the spacecraft."
The Progress 38 spacecraft flew by the space station at a distance of several kilometers (a couple miles) away, posing no threat of impact. But because of its orbit, there may not be a second chance to dock the spacecraft by remote control today, Navias said.
Known in Russia as Progress M-06M, the new Progress 38 spacecraft is packed with nearly 2.5 tons of fresh food, clothes, equipment and other supplies for the space station's six-person crew. It launched Wednesday from Baikonur Cosmodrome in Kazakhstan.
Packed aboard the spacecraft are 1,918 pounds of propellant for the station, 110 pounds of oxygen, 220 pounds of water and 2,667 pounds of dry cargo — which includes spare parts, science equipment and other supplies.
Russia's disposable Progress spacecraft are similar in appearance to the three-module Soyuz space taxis that ferry crews to and from the space station.
Both vehicles have a propulsion and orbital module, however Progress vehicles do not have a crew-carrying module like the Soyuz ships. Instead, Progress vehicles are equipped with a propellant module to store fuel for the space station's maneuvering thrusters.
Pictured is the Progress M-55 spacecraft in 2006. A similar spacecraft was scheduled to dock at the space station today, but flew past due to a technical failure.

The unmanned   supply ship failed to dock with the International Space Station Friday due to an apparent critical communications failure. The spacecraft bypassed the station at a safe distance and NASA officials report that the six member American-Russian space station crew were never in any danger; however, flight controllers are struggling to determine what exactly went wrong.

It is believed that the abort was caused by a malfunction in the Progress spacecraft's automatic docking system, resulting in the loss of telemetry data. The malfunction occurred while the spacecraft was at a distance of several kilometers from the orbital outpost, and there was never any threat to the spacecraft or the station, report NASA officials. "The Progress literally flew past the station, but at a safe distance from the outpost," says NASA commentator Rob Navias, "The station crew reported seeing the Progress drift beyond their view, as they worked to reestablish telemetry with the spacecraft."

The Progress supply ship was intended to deliver food, water, fuel, and other supplies to the space station and was launched earlier this week. According to Russian officials, no additional docking attempts will be made today. Flight controllers in Moscow are analyzing the problem and are weighing the possibility of a second docking attempt within 48 hours, but this still remains to be determined.