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The main mirror of NASA’s James Webb Space Telescope being tested at Goddard Space Flight Center in Greenbelt, Maryland, in 2017.

NASA/Desiree Stover/Flickr (CC BY-NC-ND 2.0)

Flagship U.S. space telescope facing further delays

NASA’s troubled James Webb Space Telescope (JWST) is heading for more choppy water, says a report from the U.S. Government Accountability Office (GAO) released yesterday. Problems in testing the orbiting telescope’s components and integrating them together means further launch delays are likely, GAO found. And the slips could mean the project will breach the $8 billion cost ceiling imposed by Congress in 2011.

The JWST is a successor to the Hubble Space Telescope, but with a mirror more than three times as wide and focusing on slightly longer, infrared wavelengths. It is expected to revolutionize our knowledge of the early universe, planets around other stars, and much else in between.

It is also the most complex and costly science mission NASA (and its European and Canadian partners) have ever built. Its early development was plagued by cost overruns and schedule slips, but after a crisis in 2011 that nearly saw it canceled, Congress set its budget in stone. Since then, building and testing the spacecraft have mostly stayed on track, but last September NASA did push back the JWST’s planned launch from October 2018 to a date between March and June 2019.

Recently, the telescope and instruments completed a 100-day test in a giant vacuum chamber at Johnson Space Center in Houston, Texas. The components were then shipped to prime contractor Northrop Grumman’s facility in Redondo Beach, California, where they will be finally attached to the spacecraft bus and its tennis court–size deployable sunshield.

The project had been managing to keep healthy reserves in both budget and schedule, but in recent months those have begun to erode. Last year, the GAO report says, vibration testing of the telescope at Goddard Space Flight Center in Greenbelt, Maryland, threw up some unexpected results. Resolving those ate up all the remaining schedule reserve, which led to pushing back the launch to 2019, giving the team an additional 4 months of reserve. But then in October 2017, the first unfurling test of the sunshield also got behind schedule. The sunshield, made of five extremely thin and separated layers of metal-coated plastic, must be folded up for launch and then deployed in space. Northrop Grumman engineers practiced this with the delicate flight hardware four times. “It took longer than predicted, but it’s about getting it right,” says Northrop Grumman’s JWST program manager Scott Willoughby. The process requires “an overabundance of caution,” he says.

The mating of the telescope and bus will likely throw up more challenges and with only 1.5 months of reserve remaining, GAO deemed it likely that there will be another launch delay. Resolving these unexpected problems has also meant holding onto staff longer than expected, and GAO says this has eaten away at the project’s cash reserves. If there are any more problems, and further delays, the JWST will likely exceed Congress’s budget cap. How lawmakers would respond to that scenario isn’t clear.

NASA said in a statement released today: “As we enter this critical and challenging period, the Webb project is carefully reviewing its plans for the remaining tasks. The mission’s Standing Review Board will begin an independent assessment of the project plans in mid-March with an expected report out in early April.”