JWST. Credit: Northrop Grumman

Not counting the massively overbudget James Webb Space Telescope (JWST), NASA has done a better job during the last several years keeping its major projects on time and within budget, according to the latest annual assessment of civil space activities prepared by the investigative arm of Congress.

The U.S. Government Accountability Office (GAO) looked at 17 NASA projects costing at least $250 million — not counting JWST — and found that, on average, cost growth and schedule delays have fallen by two-thirds since 2009, the first year the report was prepared.

The report praises NASA for better management practices and reduced reliance on immature technologies. But the report also attributes some of the apparent improvement to the fact that some of the worst offenders have finally launched.

The biggest exception is JWST, whose estimated price tag has risen 140 percent since the GAO’s 2009 assessment.

“Including the JWST in the calculation would increase the 2013 portfolio’s average development cost growth from 3.9 percent to 46.4 percent and would double the average launch delay, from 4 to 8 months, and obscure the progress the rest of the portfolio has made toward maintaining cost and schedule baselines,” the GAO wrote in its April 17 report, “NASA: Assessment of Selected Large-Scale Projects.”

JWST’s total projected cost has risen to $8.8 billion since 2009, when NASA estimated that it could build and operate the infrared telescope for less than $5 billion. The GAO, echoing an in-depth JWST report it issued in December, raised questions about the processes NASA used to come up with the new price tag. “For example, the credibility of the estimate was lessened because a sensitivity analysis was not performed that would have identified key drivers of costs, such as workforce size,” the report said.

The GAO noted that NASA is still having technical issues on both the JWST spacecraft and integrated science instrument module that have impacted test schedules and threaten to leave the project with insufficient cost and schedule reserves as it enters the home stretch.

“GAO’s prior work shows that it is during integration and test where problems are commonly found and schedules tend to slip. Given that JWST has a challenging integration and test schedule, this could particularly be the case,” the GAO wrote.

Among the issues currently putting pressure on JWST’s budget are: late delivery of instruments; difficulties with the instrument module’s cryogenic cooler; and spacecraft weight growth due to unexpected increases in the estimated weight of electrical wiring harnesses and other structures.