Work on the James Webb Space Telescope (JWST) is on track to stay within its latest cost and schedule plan, NASA told Congress Dec. 6, now that the agency has implemented recommendations from the outside panel that found the 6.5-meter segmented infrared telescope’s cost had jumped by $3.6 billion over its earlier estimate.

NASA now has a robust new baseline cost and schedule for JWST,” Rick Howard, JWST program director, told the House Science Committee. “This new baseline provides high confidence that NASA can implement JWST within the resources available in a constrained budget environment and achieve a launch readiness date of October 2018.”

Congress added $156 million to NASA’s fiscal 2012 budget request for the Webb telescope, and capped overall development cost at $8 billion. For the fiscal year that ends next September, the agency has $530 million to spend on the project.

Among reforms Howard said the agency has taken are replacing its management structure — and managers — with him as the new program chief running an agency-level program at NASA headquarters, and a top-priority rating from Administrator Charles Bolden. The confidence level required for cost estimates has been raised from 70% to 80%, signifying more careful analysis of cost factors, and the program has added 13 months of funded schedule reserve to meet unexpected problems. The primary challenges remaining in the program are building the spacecraft and the sunshield that will allow it to operate chilled to a temperature of 40K at the Sun-Earth L2 Lagrange point, and integrating and testing the outsized elements in a large thermal vacuum chamber at Johnson Space Center in Houston.

Near term, Howard told Rep. Donna Edwards (D-Md.) Congress can gauge progress on the telescope’s development by whether all four of its instruments are delivered in the coming year, whether testing of the 18 beryllium mirror segments is finished, and whether the center section of the primary backup structure that supports the mirrors is finished.

In fiscal 2011, he said, the program met 19 milestones on or ahead of schedule; missed one deadline by a month and deferred another for a redesign.

“NASA thoroughly understands how to execute this program and has a solid plan to do so,” Howard told the panel.

Not all of its members were convinced, however, particularly fiscal conservatives who pointed out that the original estimated cost of the telescope was $1 billion, with launch in 2007.

“While I recognize that you’ve only come on board the Titanic in 2010, after it hit the iceberg, here we’re talking about a project that has a $7 billion cost overrun from the initial proposal that we had in 2001, and an 11-year delay to completion since the original Webb telescope was slated to be launched in 2007,” said Rep. James Sensenbrenner (R-Wis.), a former Science Committee chairman. “Now how can we justify this to our constituents?”

“We have to realize that early estimates on the cost of James Webb going back to ’97 were just that, estimates,” Howard replied. “The first time that the agency was ready to commit to a price for the Webb was in 2008, and that’s the $5 billion figure.”