The James Webb Space Telescope, already in the running for the most expensive robotic mission in NASA's history, will need an extra $1.5 billion just to blast off more than a year later than currently planned, according to an independent review panel.

Artist's concept of JWST. Credit: NASA/ESA

The review board revised the observatory's life-cycle cost to $6.5 billion and concluded the earliest JWST could launch is September 2015. In April, NASA officially estimated the project's total cost to be $5.1 billion for liftoff in June 2014.

Heralded as the successor to the famed Hubble Space Telescope, JWST is a joint project between NASA, the European Space Agency and the Canadian Space Agency. Scientists expect JWST will provide results 100 times better than Hubble, which has set the gold standard in astronomy research.

NASA has spent about $3 billion on the project to date. When the agency named the telescope for former administrator James Webb in 2002, the observatory was supposed to launch in 2010.

Since then, its launch has slipped nearly one year later for every year on the calendar.

Chaired by longtime NASA project manager John Casani, the panel found the project requires another $250 million in both 2011 and 2012 to meet the September 2015 launch date.

It is not clear where NASA could find the extra money. NASA has added funding to JWST little-by-little over the past two years, both through budget transfers within the agency and the 2009 economic stimulus package.

Chris Scolese, NASA's associate administrator, said it will be a challenge to find $500 million over the next two years.

"We have to work with the administration and Congress to understand what flexibility we have," Scolese said. "I think it's fair to say I doubt we're going to find $250 million (in appropriations)."

With the urgency highlighted in the Casani report, NASA officials said they will be considering all options to route the necessary funding to JWST.

Asked where NASA could scrape up money to make up the shortfall, Scolese reiterated the agency's policy of first looking within the astrophysics division.

"First, as we always do, we'll look within the community that's affected, then look across the science mission directorate, then look across the agency," Scolese said.

This graph compares JWST's baseline $5.1 billion life-cycle budget (black line) with the independent cost assessment (purple line). Credit: NASA

JWST's budget already accounts for about 40 percent of NASA's astrophysics portfolio, and top division managers say previous cost overruns were already constraining work on other astronomy probes.

The panel also recommended shifting management and accountability for the observatory from the astrophysics division to a new unit solely responsible for JWST.

Streamlining tests of the JWST spacecraft and science module could also shave time and money from the mission's schedule and budget. The Test Assessment Team, another JWST review ordered this year, identified several areas in which integration and testing could be shortened without sacrificing a reasonable level of risk.

JWST's financial blunders stem from an unsound budget presented during the mission's confirmation review in 2008. The panel also laid blame on NASA Headquarters and Goddard Space Flight Center for not catching the flawed budget and schedule.

"The fundamental root cause of the problem is that at the time of confirmation, which goes back to July 2008, the budget that NASA was presented with by the project office was basically flawed," Casani said.

Because of the shortcomings in its original budget forecast, NASA did not allocate sufficient funding reserves for JWST to meet development snags in the years since the confirmation review, according to Casani, a former project manager of NASA's Mariner, Voyager, Galileo and Cassini missions.

"The bottom line is there was just not enough money in the budget to execute the work that was required," Casani said.

Formally called the Independent Comprehensive Review Panel, the board was formed after a request by Sen. Barbara Mikulski, D-Md., a lawmaker representing the Goddard Space Flight Center, home of the JWST project.

"We didn't find any way the project cost could be reduced in any way," Casani said.

But the report provides a blueprint for avoid further cost growth, according to Casani.

The agency is "taking this extremely seriously," Scolese said, and NASA is reorganizing the JWST management structure to report directly to the administrator's office.

A representation JWST's expected view in a deep field image of the distant universe. Credit: Space Telescope Science Institute

"No one is more concerned about the situation we find ourselves in than I am, and that is why I am reorganizing the JWST project at Headquarters and the Goddard Space Flight Center, and assigning a new senior manager at Headquarters to lead this important effort," NASA Administrator Charles Bolden said in a statement Wednesday.

Scolese announced Richard Howard, NASA's deputy chief technologist, will oversee the project's interaction with agency leadership.

"This will ensure more direct reporting to me and increase the project's visibility within the agency's management structure," Bolden said.

Officials said it was too early to settle on a strategy to deal with the pressing cost and schedule problems. Howard said he hoped to have a plan by early February.

"I am encouraged the ICRP verified our assessment that JWST is technically sound, and that the project continues to make progress and meet its milestones," Bolden said. "However, I am disappointed we have not maintained the level of cost control we strive to achieve -- something the American taxpayer deserves in all of our projects."

The observatory is designed to collect near- and mid-infrared light with a 21.3-foot beryllium primary mirror. JWST promises to search for the first galaxies or light-emitting objects after the Big Bang, chart the history of galaxy formation, track the evolution of stellar systems, and make chemical maps of planets, stars and galaxies.

Part of Europe's contribution to the project, an Ariane 5 rocket will launch the 14,300-pound spacecraft from South America and dispatch on a three-month journey toward a gravity-neutral Lagrange point about one million miles from Earth. It will observe the cosmos for at least five-and-a-half years, with an ultimate goal of operating for more than 10 years.

A sunshade the size of a tennis court will block sunlight from the telescope's four science instruments, which must be chilled to below 50 Kelvin, or -370 degrees Fahrenheit.