After much tinkering, Northrop Grumman Aerospace Systems has at last finished the cryogenic cooler that will keep JWST's Mid-Infrared Instrument at its frosty-cool operating temperature of minus 270 Celsius. Credit: NASA artist's concept

WASHINGTON — Northrop Grumman Aerospace Systems has apparently solved technical problems plaguing the James Webb Space Telescope’s cryogenic cooler and is ready to ship the hardware to NASA for environmental testing, the U.S. space agency said.

“The planned delivery date for the cryocooler compressor assembly from Northrop Grumman Aerospace Systems to the Jet Propulsion Laboratory is officially July 28,” NASA spokeswoman Felicia Chou wrote in a July 22 email.

That was apparently news to Paul Hertz, director of NASA’s Astrophysics Division, who told members of the NASA Advisory Council’s astrophysics subcommittee a day earlier the Mid-Infrared Instrument’s (MIRI) cryocooler had already made the 50 kilometer journey north to Pasadena, California, from Northrop’s Redondo Beach facility.

“The cryocooler for MIRI has been completed and we heard today that it has been shipped and that it’s arrived at JPL,” Hertz said, evidently in error.

“There has been some slight miscommunication here in headquarters that has been cleared up since Paul’s comments,” Chou said.

Northrop Grumman workers in Redondo Beach, California, pose with the finished MIRI cryocooler. Credit: NASA

Northrop Grumman spokeswoman Constance Reese declined to comment about how the company solved the technical problems that have bedeviled the cryocooler and caused Northrop’s contract for the hardware, worth $22 million when it was awarded in 2006, to balloon in value to $150 million through 2016.

Northrop’s MIRI cryocooler contract with JPL is separate from the company’s $3.5 billion JWST prime contract.

NASA completed an overhaul of JWST’s schedule in 2012, concluding in the process the flagship astronomy mission would cost some $8.8 billion to build, launch and operate in space for a five-year primary mission. As recently as 2013, Northrop and NASA expected the MIRI cryocooler would be delivered to JPL by January 2014.

Northrop inherited the design on which it based the MIRI cryocooler from TRW, which Northrop acquired in 2002. TRW came up with its design under the NASA-funded Advanced Cryocooler Technology Development Program, which the agency initiated in 2001 to develop more durable, colder-operating coolers for next-generation space-based observatories such as JWST.

But Northrop ran into trouble adapting the TRW design into a unit capable of keeping MIRI’s infrared detectors chilled to their operational temperature of roughly minus 270 degrees Celsius. The U.S. Government Accountability Office warned in December that Northrop might not get the cryocooler to JPL until this November.

Now it appears Northrop has averted that worst-case scenario.

Chou said Cryocooler tests in Pasadena will run for about a year, after which the unit will be shipped back to Redondo Beach for integration with the Northrop-built JWST spacecraft.

The spacecraft structure “is complete and in testing,” Hertz said July 21.

The JWST project as a whole, Hertz told the NASA Advisory Council’s astrophysics subcommittee, still has nine months of funded schedule reserve available. That is down from 11 months in March, when the Government Accountability Office last checked in with the flagship observatory.

Nine months, Hertz said, “is way in excess of what our golden rules say it should be, and well in excess of our planned burn-down rate for reserves when we replanned JWST.”

Still, the MIRI cryocooler remains on JWST’s critical path, Hertz said, meaning any further delays with that component will immediately eat into the entire program’s nine-month reserve.

Dan Leone is a SpaceNews staff writer, covering NASA, NOAA and a growing number of entrepreneurial space companies. He earned a bachelor’s degree in public communications from the American University in Washington.