Unexplained Short Burn On Engines Baffles Engineers

Russian engineers are trying to determine why the engines of a Progress M-58 cargo ship docked with the ISS shut down early on Thursday.

Engineers use the engines on the Progress to maneuver the ISS. Thursday's planned 17-minute burn was to push the ISS to a higher orbit in preparation for a planned rendezvous with the US space shuttle Discovery.

The early shut down of the engines left the ISS three miles short of a planned four mile orbital correction.

Engineers from Engergia, the company that makes the engines for the Progress cargo ships, haven't yet determined the cause of the abbreviated burn, but Interfax news quoted a company rep as saying they may fire the engines again as early as Saturday.

Russian and US engineers are discussing today whether the lower orbit might interfere with the upcoming rendezvous maneuver.

Russian space official Igor Paninin told Interfax, "In principle, this docking is possible at this height of the orbit. However, there are additional nuances that should be taken into consideration."

The ISS orbits approximately 220 miles above earth. Like all objects in orbit, its ever so slow fall back to earth requires periodic corrections to maintain altitude. Typically those corrections come just before rendezvous launches.

The shuttle Discovery is on-track for December 7 launch. This will mark its first night launch in four years. NASA is satisfied cameras designed to monitor the launch and watch for falling foam from the main fuel tank will have enough light from the firing engines and boosters.

FMI: www.nasa.gov