As NASA prepares to wrap up its shuttle program, leaving open questions about what comes next for U.S. human spaceflight, the next big thing in NASA's astronomy program has been dealt a blow. The James Webb Space Telescope, a tennis court–size spacecraft that would take up a position in deep space to peer farther than ever into the cosmos, has been in development as a replacement for and successor to the Hubble Space Telescope, which has already logged 21 years in orbit. But the House Appropriations Committee, in a bill announced July 6, proposed axing the project entirely this week, citing mismanagement and bad budgeting.

The bill, which would cut $1.6 billion, or about 9 percent, from NASA's overall budget, would have to clear the full House and gain Senate approval before becoming law. But the specter of JWST cancellation looms large over a field already facing diminished resources. "Obviously, this upsetting," American Astronomical Society (AAS) Executive Officer Kevin Marvel wrote on his organization's blog. "The astronomy community knows the value of the JWST, recognizes that nearly all technical hurdles have been overcome and that a review of the program's management, budget and completion plan is nearly complete."

The House committee's concerns have some grounds; in November 2010, a review convened by Sen. Barbara Mikulski (D–Md.) found JWST was well behind schedule and $1.4 billion over budget, bringing the total estimate for the observatory to $6.5 billion. (NASA has already spent roughly half that amount.) The telescope, which had been targeted for a 2014 launch, would launch no sooner than 2015, the report concluded. In recent months much later launch dates of 2018 or beyond have been rumored.

But delays and cost overruns are nothing new for projects of unprecedented scale. Take the launch of the Hubble Space Telescope, which is a much smaller observatory than JWST, orbiting far closer to Earth, and whose deployment was a much simpler affair than the elaborate de-cocooning JWST will have to perform in deep space. Hubble was famously delayed by seven years, from a 1983 launch to a 1990 launch, and had just about tripled in cost by the time it reached orbit, according to a 1992 U.S. General Accounting Office (now the Government Accountability Office) report (pdf). By the time of that GAO report, the Hubble's price tag was roughly $3 billion in 2011 dollars. Its cost over the years has swelled to several times that amount, thanks to two decades of operations and five space shuttle visits to the telescope for servicing. (A single shuttle servicing mission costs about $2 billion, according to one NASA estimate.)

Who knows if Congress would have given a greenlight to Hubble if its total cost were known from the start? But few would argue now that the orbiting observatory has been a poor investment. In fact it has revolutionized humankind's view of the universe.

And who knows what would have happened if Congress had not canceled the Superconducting Super Collider (SSC)? The SSC, a mammoth particle physics experiment in Texas, was axed in 1993 when its price tag grew too large for Congressional funders' liking. Roughly $2 billion had already been sunk into the project by 1993, but its estimated cost had doubled from $5.3 billion to more than $11 billion. (That is about $17 billion in 2011 dollars.)

The SSC would have been the successor to the much less powerful Tevatron in Illinois, a workhorse particle collider that is scheduled to be shut down this year. Instead the title of most powerful collider moved to Europe, when the Large Hadron Collider (LHC) came online in late 2009 and quickly eclipsed the Tevatron by colliding particles at higher energies than had ever been achieved. But whereas the LHC is designed to be about seven times as powerful as the Tevatron, the SSC would have been 20 times as powerful as the Tevatron and nearly three times as powerful as the LHC.

Photo of a JWST model in Germany: EADS Astrium