NASA has 10 months of funded schedule reserve on James Webb Space Telescope (JWST) as the program enters a challenging phase, key stakeholders testified Tuesday.

NASA Associate Administrator for Science Mission Directorate John Grunsfeld told the House Science, Space and Technology (SST) space subcommittee said the civil space agency added 13 months of funded schedule reserve when the program was rebaselined in 2011. Grunsfeld also said, four years into the rebaseline, the program remains within budget and on schedule for its launch goal, which is October 2018.

Photo: NASA.
Photo: NASA.

JWST is one of NASA’s most complex and expensive projects, with the Government Accountability Office (GAO) estimating the program’s cost at $8.8 billion. GAO Director of Acquisition and Sourcing Management Cristina Chaplain said Tuesday the program is entering its most challenging phase, integration and testing, which she expects to take another 3.5 years to complete. Integration and testing, Chaplain said, is where problems are likely to be found and, as a result, schedules slip.

“Maintaining as much schedule reserve as possible is critical during this phase to resolve known risks and unknown problems that may be discovered,” Chaplain said in her prepared testimony.

According to GAO, JWST is defined by three elements: The integrated science instrument module (ISIM), the optical telescope element (OTE), the spacecraft and two of its major subsystems, the cryo cooler and the sunshield.

Chaplain said only two elements and major subsystems, ISIM and OTE, have entered integration and testing. Integration and testing, Chaplain said, for the spacecraft and sunshield, and for the ISIM and OTE when they are integrated together, begins in 2016. She said the entire observatory will begin integration in late 2017.

Grunsfeld said NASA this year will complete all of its planned work on ISIM. The 18 mirror segments, he said, will be mounted to their support structure, the five sunshield membranes will be manufactured and NASA will continue the acquisition of parts and spacecraft bus integration. After 2015, he said, almost all of the manufacturing will be complete.

Grunsfeld said the cryo cooler has the specific attention of NASA management and that two-thirds of the hardware has been delivered. Grunsfeld said the remaining third of the cryo cooler hardware is undergoing final assembly and testing with a planned delivery in three months. The cryo cooler, formally called the mid-infrared instrument, cools JWST detectors to roughly -449 degrees Fahrenheit.

“The design and development of this cryo cooler has proved to be quite challenging,” Grunsfeld said.

GAO said since entering development in 1999, JWST has experienced cost and schedule delays. Cost estimates of the program ranged from $1 billion to $3.5 billion and expected launch dates from 2007 to 2011.

Northrop Grumman [NOC] is the prime contractor for JWST while Ball Aerospace [BLL] provides the telescope’s optical design and mirrors, the wavefront sensing, control design and algorithms. Exelis [XLS] integrates and tests the optical telescope while Orbital ATK [OA] provides the telescope’s composite structures. Northrop Grumman was unable to respond to a request for comment by press time.