WASHINGTON -- Managers at NASA's Jet Propulsion Laboratory (JPL) have opened an investigation into how a recently-launched satellite designed to study the sun is so off-kilter that it can't do any science.
The $8 million Active Cavity Radiometer Irradiance Monitor satellite (AcrimSat) has been unable to take any measurements of the sun since its launch December 20 aboard an Orbital Sciences Taurus rocket from Vandenberg Air Force Base in California.
The Earth-orbiting satellite, managed by JPL in Pasadena, California, was designed to measure the amount of sunlight falling on Earth's atmosphere, oceans and land to help scientists improve predictions of long-term climate change.
But AcrimSat has been unable to look directly at the sun's center because it is pointed slightly off course -- enough to render it useless for science.
"No one really knows why," Ron Zenone, JPL project manager, told SPACE.com. "We're doing a fault-tree analysis to see who or what's at fault. Right now, it does not appear to be a human error...but we just dont know."
Project managers on Tuesday began a formal internal review into the problem. Among the potential culprits are bad software, excessive vibrations at launch or heat from the sun that might have somehow warped the satellite's frame.
But managers also are reviewing whether the satellite's science instrument may have been improperly installed when it was assembled at the Orbital Sciences facility in McLean, Virginia.
"You have to consider that as a possible scenario," said Barron Beneski, a spokesman for Orbital. "But at some point it either gets ruled in or ruled out We're still expecting to get [the satellite] worked out and expecting this mission to be successful."
In the meantime, engineers have been sending up software patches to try to bring AcrimSat into the right alignment. So far, no luck.
Complicating matters is that AcrimSat is a so-called "spinning" satellite that maintains its stability by rotating at 12 revolutions per minute. It lacks any thruster rockets that ground controllers could fire to help position it correctly in space.
As far as anyone knows, NASA never has been able to correct the pointing of an off-course spinning satellite.
"None that I'm aware of," Zenone said. "That's what it makes it tough for us."
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