WASHINGTON — An engineering model of a NASA instrument scheduled to fly to space aboard the Japanese Astro-H X-ray observatory in 2014 malfunctioned during testing in Japan, raising the possibility of further delays for a mission whose launch has already been pushed to the right by natural disasters.

Paul Hertz, NASA’s director of astrophysics, told the NASA Advisory Council astrophysics subcommittee July 30 that a heat switch on a mockup of NASA’s Astro-H Soft X-Ray Spectrometer instrument failed when it was connected to a cryogenic dewar provided by the Japanese Aerospace Exploration Agency (JAXA).

“We’re studying why it failed and what we can do to make sure that doesn’t happen with the flight models,” Hertz said. “It will impact the functional testing that we’re going to do because without this … heat switch, it impacts how long we can stay at the operational temperatures and how stable it will be.”

Hertz acknowledged that the failure of the heat switch — one of four on the instrument — would delay tests scheduled for the week of Aug. 6. He added that while JAXA is holding to an August 2014 launch date, “the people in the NASA project working with the people in the JAXA project read the tea leaves and think they see schedules leading to a different launch date than the official launch date.”

Hertz did not say what launch date the project teams predicted. In an Aug. 1 email to Space News, NASA spokesman J.D. Harrington said JAXA told the U.S. agency that Astro-H might launch any time during Japan’s 2014 fiscal year, which ends March 31, 2015.

“Bottom line, we are working to August 2014, but are prepared to support a date as late as the end of Japanese fiscal 2014,” Harrington said.

“JAXA is working to a launch of ASTRO-H in 2014 under the strong partnership with NASA,” JAXA spokesman Eijiro Namura said in a July 31 email to Space News. “At this time, we are not aware of any major issues that would result in a launch delay.”

So far, NASA has spent $49 million on the Astro-H Soft X-Ray Spectrometer, which is being developed at the Goddard Space Flight Center in Greenbelt, Md. The instrument’s estimated lifecycle cost is $64 million. Harrington said that is enough to support NASA’s contribution to the project, even if JAXA does not launch the mission until May 31, 2015.

In March 2011, an earthquake and a tidal wave struck parts of northern Japan, devastating much of the region’s infrastructure. The damage slowed work on Astro-H, which was at the time scheduled to launch in 2013 aboard a Japanese H-2A rocket from the island nation’s Tanegashima Space Center. In 2010, when NASA held a confirmation review for its contribution to the mission, Astro-H was scheduled to launch in February 2011.

NASA selected the Goddard-built spectrometer in 2008 to fly on Astro-H as an Explorer-class mission of opportunity.

Dan Leone is a SpaceNews staff writer, covering NASA, NOAA and a growing number of entrepreneurial space companies. He earned a bachelor’s degree in public communications from the American University in Washington.