Nasa has killed a new X-ray telescope mission, two years before its planned launch.
The Gravity and Extreme Magnetism Small Explorer mission, or GEMS, was supposed to blast off in 2014 to study black holes and neutron stars. But external reviews found the project would probably come in considerably over budget.
Gems was selected under a strict cost cap, Nasa officials said, unlike the price-busting James webb Space Telescope to be launched in 2018.
"That cost cap is a very important aspect of the development of the project," said Paul Hertz, director of Nasa's astrophysics division. He said webb "is different".
Billions over budget and years behind schedule, webb is Nasa's largest science project and considered the successor to Hubble Space Telescope. Both webb and Gems are managed by Goddard Space Flight Centre in Maryland.
Adjusted for inflation, Gems was supposed to hold at $119m (£76.7m), not counting the rocket, but independent reviews estimated the final cost at 20-30% above that, Mr Hertz said.
He told a news conference that the technology needed for the instrument took longer to develop than expected, and that drove up the price.
It will cost Nasa an estimated $13m (£8.3m) to close out the project, Mr Hertz said. After adding in the money already spent on Gems, the final tab for the space agency will be $50m (£32.2m).
No rocket had yet been purchased for the mission, and the telescope itself had not yet been built.
A number of existing observatories can address some of Gems' science questions, Mr Hertz said, including the NuStar telescope due to lift off next week from Kwajalein Atoll in the Pacific.