The proposal request sent out Friday asks satellite manufacturers to suggest designs for the data distribution system, ground element, and system configuration of the new National Polar-Orbiting Environmental Satellite System (NPOESS).

The new network will replace the existing Defense Meteorological Satellite Program (DMSP) and Polar-Orbiting Operational Satellites run by the National Oceanic and Atmospheric Administration (NOAA).

Some of the companies that are likely to submit proposals by the end of the year include Boeing, Lockheed Martin (the manufacturer of the existing defense weather satellite), Loral, Orbital Sciences, Spectrum Astro and TRW.

NPOESS has been delayed for restructuring and at one point in 1997 was on the verge of cancellation because of delays. Disagreements among the three agencies involved--the NOAA, the DoD, and NASA--have also been cited as reasons the project has been behind its initial schedules.

As currently planned, the NPOESS constellation would consist of three satellites lofted from Vandenberg Air Base in California atop medium versions of the Evolved Expendable Launch Vehicle (EELV) space booster.

In sun-synchronous orbit, the satellites would provide weather imagery and related environmental data products to civil and military users during each of the crafts 14 orbits per day.

The NPOESS program office is still designing the types of sensors that will fly on the spacecraft bus. Candidates listed last year include a Multispectral Imaging Sensor, and a sensor to detect changes in the Earths magnetic field.

The military ground facilities to acquire NPOESS data will also be capable of merging that information with other sensor data and infrared imagery to give commanders a complete environmental picture of potential battlespaces.

Although it is primarily a domestic project, the constellation with also include a European satellite. That spacecraft, called METOP, will be built by a European contractor but will carry imagers and sensors made in the U.S.