A weather satellite to fill a widening gap between old and new observatory fleets will be delayed several months because of problems with components in an infrared sounder, according to NASA.

The NPOESS Preparatory Project spacecraft. Credit: Ball Aerospace

Two troublesome instruments have been the cause of the most recent delays in the NPOESS Preparatory Project, a NASA-led research mission that will also be thrust into another role as an operational resource for weather forecasters.

One of the payloads, the Visible Infrared Imaging Radiometer Suite, finished testing at Raytheon Co. and will soon be delivered for integration on the NPP spacecraft at Ball Aerospace and Technologies Corp. in Boulder, Colo.

But another sensor has encountered problems threatening to push the NPP mission's launch until at least the middle of 2011. NPP's official launch date has been set for January 2011 on a Delta 2 rocket from Vandenberg Air Force Base, Calif.

The Cross-track Infrared Sounder, built by ITT Corp., is now in the critical path to NPP's launch, according to Michael Freilich, director of the Earth Science division at NASA Headquarters.

"While they are evaluating the latest challenges for CrIS, we're not stating a new launch date, but there is a likelihood that it will be delayed a number of months from January 2011," Freilich said.

CrIS and VIIRS are both provided as part of the National Oceanic and Atmospheric Administration's contribution to the mission. CrIS will measure vertical profiles of temperature and water vapor, and VIIRS will collect imagery and data on the atmosphere, clouds, Earth's radiation budget, oceans and land surfaces.

"During a final detailed evaluation of the CrIS instrument design, the Northrop Grumman/ITT team found some electronic components that did not fully meet voltage requirements for space applications," a Northrop Grumman spokesperson said in a written statement.

The suspect parts were replaced and the CrIS instrument will go through thermal vacuum testing again before shipping to Colorado next summer for attachment to the NPP spacecraft, according to Northrop Grumman.

NPP will have dual missions because the National Polar-Orbiting Operational Environmental Satellite System, or NPOESS, is running behind schedule and over-budget. Projected cost growth could make the program's life-cycle cost soar above $15 billion, according to appropriators.

Northrop Grumman is the prime contractor for the NPOESS fleet, which is now scheduled to begin launching in December 2014. That is six months later than NOAA's previously disclosed launch date, and a year later than the target date announced early this year.

Artist's concept of an NPOESS satellite in orbit. Credit: Northrop Grumman

The satellites will take over for polar-orbiting spacecraft for NOAA and the U.S. Air Force that have provided constant weather coverage for nearly 50 years.

VIIRS and CrIS are early copies of instruments designed to fly NPOESS satellites. NPP also carries an ozone mapper, microwave sounder and radiant energy sensor to continue scientific measurements from other aging satellites, including the Earth Observing System flagship missions Terra, Aqua and Aura.

Although NPP was originally conceived as a technology risk reduction and research mission, mounting delays to the NPOESS constellation will mean meteorologists will use the satellite's data for operational weather forecasts.

NOAA and EUMETSAT, the European weather satellite organization, are joining their satellite groups to reduce the odds of a coverage gap. Europe's MetOp satellites will collect imagery in "morning" orbits and NOAA platforms will cover "afternoon" orbits.

"NOAA and EUMETSAT have shared a strong and successful partnership for over 20 years," said John Leslie, a NOAA spokesperson. "EUMETSAT's MetOp satellite provides coverage in the mid-morning orbit, contributing important observations and data for weather forecasts, hurricane tracking, winter storms and space situational awareness."

But the troubled NPOESS program has left Congress concerned about the health of the next-generation system.

In a report attached to NOAA's fiscal year 2010 budget bill, the Senate and House of Representatives conference committee said the budget and delay issues "portend an unacceptably high risk of weather and climate satellite observation gaps."

The committee is recommending based funding the NPOESS program based on the Obama administration's budget request, but the funding level "does not reflect the true need and the program's long-term projections for success remain in doubt."

"In fact, to date this experiment in combining disparate elements has been a horrendous and costly failure," the committee report said. Appropriators cited a dysfunctional relationship among NOAA, NASA and the Pentagon, the three partners in the NPOESS program, and encouraged NOAA to study contingency options to ensure there is no data gap from polar satellites.