Most large NASA missions have an average delay of almost a year and are launched over budget, according to a new report by official US spending watchdogs.

The Governmental Accountability Office (GAO) found that of 13 missions for which NASA provided figures, a total of 10 were delayed by, on average, 11 months and cost 13% above the original estimates. Two projects came in on schedule and under budget and one was delayed but stayed on budget.

Glorious overspend

The mission with the biggest overspend is NASA’s $347m Glory satellite, which is designed to look at aerosol and carbon levels in the atmosphere. First conceived in 2003, it will cost 53% more than originally planned and has been delayed from its June launch because of the loss of the $273m Orbiting Carbon Observatory (OCO), which crashed in the Pacific Ocean shortly after take-off last month.

Also hit hard has been the Mars Science Laboratory, which was recently delayed by two years and is now estimated to cost $2.3bn, up by $700m from its initial estimate of $1.6bn.

Of the 13 projects, the only two that come in on schedule and under budget are the $300m Wide-field Infrared Survey Explorer (WISE) and the Dawn spacecraft. WISE is set to launch in November to perform an “all-sky" survey in the 3–25 µm wavelength range and was 1% less than planned, while the $465m Dawn spacecraft was launched in 2007 — 2% below initial estimates — to visit the dwarf planet Ceres and a large asteroid.

Some missions omitted

NASA did not give the GAO data on five missions including the James Webb Space Telescope, the Hubble Space Telescope’s successor, which is expected to launch in 2013, as well as the Ares crew launch vehicle and the Orion exploration capsule, which are expected to take astronauts to the Moon.

The GAO does not make recommendations on what should be done to reverse the current trend.

A table summarizing the GAO's findings is shown below.