The mission, called Gravity and Extreme Magnetism Small Explorer (GEMS), was running significantly over budget, said Paul Hertz, director of NASA's Astrophysics Division.
"The GEMS project was initiated under a very well-defined cost cap. As they approached their confirmation review, it was clear they would not be able to complete it within their cost cap. NASA made the very difficult decision not to confirm GEMS into the implementation phase," Hertz said was quoted as saying by LiveScience.
The mission team had almost completed the design stage of the project and was nearing the point where hardware for the mission would begin to be built. No working instruments were yet constructed, Hertz said.
The project was initiated as a "small explorer" class mission, with a cost limit of USD 105 million, not including the price of launching the spacecraft. But the US space agency which has recently commissioned an independent review of GEMS' budget found that the ultimate price tag for the spacecraft was likely to be 20 to 30 per cent over budget.
Because of the cost overrun, the agency decided to pull the plug on GEMS last month. On June 5, the GEMS team, led by Jean Swank of the Goddard Space Flight Center in Greenbelt appealed the decision and submitted documents to show they had identified new areas of cost savings. But NASA was not swayed.
According to Hertz, NASA will have to pay an estimated USD 13 million in close-out costs now to cancel the mission.
It was to use three telescopes to capture the bent X-ray light from extremely dense objects like black holes, neutron stars and stellar remnants. The mission would have launched no earlier than 2014 and lasted two years.
"Although there aren't any other projects in the queue right now to measure polarised X-ray sources, there are a number of observatories which can address the science questions from different areas," including NASA's NuSTAR space mission, due to launch June 13, Hertz said.
The key factor behind the cost overrun was the trickiness of developing the technology needed for the mission, he said.
