VIIRS Thermal Vacuum Tests Among Advances

NASA Gives Northrop CERES Sensor Contract

Northrop Grumman Corp. [NOC] completed the initial step toward the critical design review (CDR) for the National Polar-orbiting Operational Environmental Satellite System (NPOESS), a company official said.

The CDR program milestone is expected to be completed in August, when the last action items are closed out.

That met the existing updated schedule baseline, a Northrop official said.

NPOESS is run by NASA, NOAA and the Department of Defense.

Officials from those agencies, Northrop and independent auditors reviewed the NPOESS system-level design in relation to performance requirements, interfaces to external systems and the concept of operations.

NPOESS consists of four major segments, including the space, command-control-and-communications, and integrated data processing and field terminal segments.

The program, overcoming earlier difficulties, is making advances, such as an NPOESS sensor heading into thermal vacuum chamber testing.

The Visible Infrared Imager Radiometer Suite (VIIRS) flight unit is being subjected to the extreme hot and cold cycles typical of the space environment to determine its flight worthiness. Thermal vacuum testing will be conducted over nearly 100 days to ensure the sensor will operate in space as designed. Raytheon Co. [RTN], the subcontractor to Northrop, is conducting the VIIRS testing.

"Getting VIIRS done and that sensor making it into thermal vac now is a very large event for the program, in turning the corner," Bob Burke, Northrop vice president for civil systems in the Space Systems Division, said in an interview, responding to questions from Space & Missile Defense Report.

"We are on the cusp here of having all of the NPP (NPOESS Preparatory Project) sensors delivered this year, which is going to enable the NPP satellite to fulfill its preparatory mission," Burke said.

Although VIIRS is late when judged by an earlier schedule, it is tracking to its replanned schedule, he said, "which calls for delivery no later than November of this year." The key point is that "the sensor is making good progress towards that delivery," he added, with about five or six weeks of margin to work with toward that date.

Further, he continued, the ground system deployment is proceeding well, along with the integrated data processing segment development has proceeded on schedule and on cost.

In years past, NPOESS has struggled with rising costs and schedule delays, and some sensors being omitted from the system. In congressional hearings, some lawmakers have expressed concerns that removal of sensors could leave gaps in U.S. data on crucial environmental/climate issues, as existing satellites reach end-of-life. But the NPOESS program since has rallied, with some lost ground regained, such as the full Ozone Mapping and Profiler Suite (OMPS) being restored to NPOESS, so it can trace harm to the ozone layer caused by chlorofluorocarbons.

In the interview, Burke said that NPOESS today is achieving a far greater level of success. While the company has "struggled with the sensors" issue, he said, "we have worked around the issue," and made advances to improve the satellite system.

Further, the proposed Obama administration budget for the fiscal year ending Sept. 30, 2010, supports the NPOESS program, he said.

"We’ve got a plan against [the 2010 budget] that meets the replan," meaning the restructured NPOESS program, Burke said. Thus he is "comfortable with the funding" that the Obama administration lays out for fiscal 2010, as far as the contractor portion of the funding is concerned.

At the same time, he said the program funding reserves have little room for the unexpected. As far as the correct funding reserve positions for the NPOESS program, "today, the program is tight against the funding needed to complete it, not because we haven’t turned the corner, but because any program like this needs to have some reserves that can be used to deal with development issues that crop up."

But help may be on the way for NPOESS, financially. "I think the government’s taking solid action to try to find the right reserve levels, working that through the budgeting process."

Northrop progress in the space area is evident in many areas, he said.

For example, Northrop won a contract for an NPOESS sensor that detects solar activity and effects.

NASA Langley Research Center, near Hampton, Va., gave Northrop a contract to build a sensor that measures the time and space distributions of incoming energy from the sun and outgoing thermal and reflected energy from Earth.

This is known as the Earth radiation budget. The sensor will be integrated onto the first NPOESS spacecraft.

The Clouds and the Earth’s Radiant Energy System (CERES) sensor is the seventh in the line built by Northrop at its Redondo Beach, Calif., space systems manufacturing facility. The unit will be developed using many existing parts, creating a cost effective and low risk solution to extending these important climate measurements.

CERES will measure the Earth’s radiation balance, which is a critical part of the climate system and is directly influenced by changes in greenhouse gases and aerosols, cloud properties, and surface and atmospheric temperature. CERES sensors are broadly acknowledged as the most accurate broadband climate sensors ever flown in space.

This sensor and an earlier generation of similar sensors also built by Northrop Grumman, called the Earth Radiation Budget Experiment, have been capturing measurements of the reflected solar radiation and emitted thermal radiation over the Earth’s surface since 1984.

Four CERES sensors are currently operational on NASA’s Terra and Aqua Earth Observing Systems. Another unit has been delivered and integrated onto the NPOESS Preparatory Project and one unit completed its mission aboard the Tropical Rainfall Measuring Mission.

Burke was asked in the interview about comments by lawmakers in hearings that having three separate agencies — NASA, NOAA and DOD — run the program has created confusion and delays. Some lawmakers have said it might be better to split the program up and have separate parts run by individual or paired agencies, hoping to cut costs and accelerate the program.

Asked about that, Burke responded that that would be "a significant disruption to the ongoing program" that at a minimum would "need to be carefully considered, evaluated, and in fact studied," especially coming in the midst of a program that in recent times "has made a lot of progress." He predicted it would mean delays and rework that ultimately would end up with higher costs and more time than continuing the NPOESS program with its current structure and completing the system.

It is urgent to move NPOESS ahead to ensure continuity of climate data, he said, because NPOESS needs to move to completion, head to orbit and begin functioning to ensure an overlap of data now being gathered by existing space systems, before they reach their retirement limits, Burke said, a view frequently voiced by lawmakers, NASA and NOAA officials, and others.

"If we disrupted our way forward… that gap would be of significant concern to the scientific community," he noted.