WASHINGTON — A day before NOAA was due on Capitol Hill for a progress report about its two main weather satellite programs, an agency official on Dec. 9 shed new light on component snafus that prompted a six-month launch delay for its next coastal-watchdog satellite.

“The straw that broke the camel’s back” and prompted National Oceanic and Atmospheric Administration to slip the launch of the Geostationary Operational Environmental  Satellite-R spacecraft was the failure of a transistor during a two-month environmental test at prime contractor Lockheed Martin Space Systems in July and August, Greg Mandt,  NOAA’s GOES-R system program director, said in a Dec. 9 phone interview.

Mandt spoke with SpaceNews a day before his boss, NOAA Assistant Administrator for Satellite and Information Services Steve Volz, was scheduled to testify at a joint hearing of the House Science Committee’s environment and oversight subcommittees alongside David Powner, director of Information Technology Management Issues for the Government Accountability Office.

Mandt said GOES-R’s transistor failure during a stint in Lockheed’s thermal vacuum chamber exacerbated schedule pressure NOAA and its contractor started to feel in earnest earlier this year, when another test in Lockheed’s Denver factory revealed problems with the mechanism that controls GOES-R’s solar arrays.

While Lockheed is fixing the solar array control mechanism and plans to replace the transistor — part of a bad batch manufactured in 2009 by a Lockheed supplier whose name Mandt said he could not recall —  rushing that work in time to launch next spring was deemed too risky by NOAA.

Lockheed Martin spokesman Gary Napier could not immediately be reached for comment.

GOES-R will launch on a United Launch Alliance Atlas 5 rocket, the Denver-based company’s most heavily booked launcher, so NOAA had to find another Atlas customer to swap with to get its desired launch slot.

Orbital ATK, which had booked an Atlas 5 launch for a fall cargo delivery to the International Space Station for NASA, eventually obliged, Mandt said. The Dulles, Virginia-based company agreed to move its mission up to March 2016 so GOES-R could take the October 2016 slot in ULA’s manifest.

“That’s more time than I thought we really needed, but we really didn’t have any other opportunity,” Mandt said.

NOAA announced the GOES-R slip, but not detailed reasons for it, in October. The agency conceded then that with GOES-R staying on the ground for another six months, it will have to depend on the aging GOES-13 for at least a year beyond that Boeing-built spacecraft’s 10-year design life.

Lockheed is building the GOES-R series under a $1.4 billion prime contract awarded in 2008 by NASA, NOAA’s procurement agency for spacecraft and launches. The GOES-R series is designed to keep watch on U.S. coastlines from geostationary orbit through 2036. The program, which will cost NOAA about $11 billion over that timeframe, has been dogged by delays since the beginning.

Mandt attributes these delays to an intentionally aggressive schedule that set deadlines NOAA and Lockheed were unable to meet on time, given the complexity of the GOES-R spacecraft.

“It comes down to the complexity of the design,” Mandt said.

Part of it has to do with the satellite’s communications package, which while not the main feature of a spacecraft that boasts a suite of sophisticated remote-sensing instruments, has nevertheless proved complicated beyond anyone’s expectations, said Mandt.

“Lockheed told me that this satellite is the most complex communications satellite they’ve ever built,” Mandt said. “We’ve got four different frequencies, and we’ve got to get a long life, so you have lots of cross strapping between all the different boxes, and there are so many different communication paths that when we wanted to test them all, it took us like three months. Everyone was thinking it was going to be like a month.”

Lockheed is relatively new to the GOES program. The company displaced incumbent Boeing in 2008 when NASA ruled Lockheed’s proposed design was not only cheaper than Boeing’s, but better accommodated the six GOES-R instruments.

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.