Industry officials overseeing the development of the U.S. government’s next generation of polar-orbiting weather satellites believe that they have solved the issues that caused damage on the frame for a key instrument during vibration testing last year.

Vibration testing conducted in August confirmed that the frame for the Cross Track Infrared Sounder can handle the stress of launch with margin to spare, according to Dave Ryan, vice president and program manager for the National Polar-orbiting Operational Environmental Satellite System (NPOESS) at Northrop Grumman Space Technology in Redondo Beach, Calif., the prime contractor for the satellites.

The Cross Track Infrared Sounder was built by ITT Space Systems of Rochester, N.Y., under subcontract to Northrop Grumman. The instrument is intended to measure temperature and moisture in the atmosphere for weather and climate research conditions.

The NPOESS satellites, jointly funded by the U.S. Air Force and the National Oceanic and Atmospheric Administration, are intended to replace the separate polar-orbiting constellations used by the two agencies today. NASA is a junior partner in the NPOESS program office.

“The modules in this sensor have been thoroughly tested and will be ready for flight,” said Frank Koester, vice president of Commercial and Space Science for ITT Space Systems Division, in a news release dated Sept. 6. “The [Cross Track Infrared Sounder] sensor and structural frame is now very robust and we’re confident it will meet the mission objectives.”

Completion of the vibration testing on the Cross Track Infrared Sounder frame clears the instrument to be reassembled and tested for potential electromagnetic interference issues, as well as thermal vacuum performance. The sensor is scheduled to be delivered by May 2008 for integration on the NPOESS Preparatory Project spacecraft, a precursor to the NPOESS constellation, which is scheduled to launch in 2009.

In a

Sept. 6

conference call with reporters, Ryan said that the tri-agency executive committee overseeing the NPOESS program will make a decision shortly on a course of action for dealing with problems on another sensor – the Visible Infrared Imager Radiometer Suite, which is built by Raytheon Space and Airborne Systems of El Segundo, Calif.

The Visible Infrared Imager Radiometer Suite caught much of the blame for technical difficulty that drove up the cost of the NPOESS satellites and delayed their first launch, resulting in a restructuring of the program last June. The satellites were initially expected to cost $6.8 billion. The latest estimate is more than $11 billion. The first launch was initially planned for 2008, but now is expected in 2013.

Ryan said that the Visible Infrared Imager Radiometer Suite has performed well in recent tests, despite a lingering issue with interference, or “cross talk,” between its different channels of light that are used to measure ocean color. Given the overall strong performance of the sensor, the executive committee could opt to launch it aboard the NPOESS Preparatory Project in its current condition, or have the contractors retrofit the instrument with a new filter that could address the interference issue, Ryan said.

Modifying the instrument to use the replacement filter is not likely to be expensive, but could delay the launch of the NPOESS Preparatory Project by a few months, Ryan said. The executive committee also would have to decide whether to accept the risk inherent with opening up the sensor to add the new filter, he said.

Installation of new filters is considered likely for the Visible Infrared Imager Radiometer Suites that will go on the NPOESS satellites, as program officials have more time to work on the instrument in advance of the planned 2011 delivery date, Ryan said.

Meanwhile, the government is close to naming a new program executive officer for the NPOESS effort, Ryan said. Air Force Brig. Gen. Susan Mashiko was the first to serve as NPOESS program executive officer, a position created in response to the problems encountered with the program, but left in July to serve as commander of the military satellite communications wing at the Air Force Space and Missile Systems Center in Los Angeles.

Mashiko’s departure came to the disappointment of members of Congress and the Government Accountability Office, who expressed concern that her departure would lead to instability on the NPOESS effort. Gary Davis, director of the office of systems development under the National Oceanic and Atmospheric Administration’s satellite division, has been serving as the acting program executive officer since Mashiko left; a full-time replacement is expected to be named “imminently,” Ryan said.