"If our nation's spacecraft programs are responsible for providing important long-term records requiring continuity, maintaining planned schedules is critical," Kopp said.
Graeme Stephens, the director of the Center for Climate Sciences at NASA's Jet Propulsion Laboratory, chaired a National Academy of Sciences committee that evaluated how NOAA planned to bridge the gap between its solar irradiance sensors.
"Monitoring the whole Earth climate system continuously without gaps is fundamental," Stephens said. Yet, he added, the United States' historic approach to this has been "piecemeal" and "ad hoc."
Many satellites are reaching the end of their life span, and few are being built to take their place, observers say.
In February, the Government Accountability Office warned of impending gaps in weather satellite data and put weather satellite systems on its high-risk list due to the failure of NPOESS.
And although Landsat 8, the U.S. Geological Survey-operated satellite that monitors changes on the Earth's surface, recently launched successfully, a follow-up mission, which will take years to build, is not yet in the works. On Thursday, the National Research Council issued a report saying current management practices and the "historical pattern of chaotic programmatic support" have made the program's mission unsustainable.
"We have no real concerted or visionary approach to monitor the climate system over the long haul," Stephens added.
A crucial flip-turn in space
A quirk in how the new solar irradiance sensor will work illustrates how cobbling together last-minute solutions leads to imperfect outcomes.
Known as the TSI Calibration Transfer Experiment (the acronym, TCTE, is pronounced "tecate"), the instrument must face the sun in order to measure solar irradiance.
Yet the Air Force STPSat-3 satellite carrying it is otherwise full of sensors that gaze earthward. So once a week, the satellite will flip around and face the sun for a full orbit, capturing solar irradiance.
Once-weekly readings are not as good as continuous ones. But they are good enough to maintain a consistent record until the full-time sensor goes up, likely in 2017.
In a time of budget cuts, some in the aerospace industry are arguing for a change in the entire satellite planning and purchasing process to smaller, nimbler systems.
Colorado's Kopp, who has built small, single-purpose satellites to monitor solar irradiance, thinks that approach could be a viable way forward.
"To reliably monitor long-term inputs affecting the Earth's climate, small dedicated missions have large advantages in cost and schedule over 'do-everything' spacecraft programs," he said.
But whether satellites are big or small, the nation still needs a plan for how it monitors the Earth, NASA's Stephens pointed out. Otherwise, there will be more situations like that of the solar sensor's.
"It comes down to the need to develop a kind of coherent strategy that includes big systems, and little systems, and mini-systems, and micro-systems -- the whole sort of portfolio," Stephens said. "And we don't have that."
Reprinted from Climatewire with permission from Environment & Energy Publishing, LLC. www.eenews.net, 202-628-6500