A balky cooling system in the chill of space is throwing the future of the United States’s most recent multibillion-dollar weather satellite, the Geostationary Operational Environmental Satellite-17 (GOES-17), in doubt, the National Oceanic and Atmospheric Administration (NOAA) reported today. Technicians are now scrambling to understand the problem, which first arose several weeks ago on the satellite’s primary instrument.
Launched on 1 March, GOES-17 is NOAA’s second next-generation geostationary weather satellite, the second of a four-part, $11 billion program. Following 6 months of evaluation, the satellite was set to monitor the western half of the United States, much as its sibling, GOES-16, launched in 2016, now surveys the country’s eastern half. To do so, GOES-17 would use a 16-channel camera, called the Advanced Baseline Imager (ABI), that is capable of capturing wind height, rain, and clouds in fine detail.
To capture 13 of these channels, namely the infrared and near-infrared bands, the ABI must be kept cool at –213°C—no small feat thanks to the rapid heating and cooling it experiences from its daily exposure to the sun. And right now, for half the day, with a peak around midnight Eastern Standard Time, the cooling system is simply not reaching those temperatures. “We’re treating this very seriously,” said Joe Pica, director of the office of observations for NOAA’s National Weather Service in Silver Spring, Maryland. “We’re trying to understand the anomaly and trying to find ways to start the engines of the cooling system to function properly.” GOES-16 has an identical camera but its cooling system has so far operated flawlessly.
The problem comes as a blow to NOAA, which has been riding high after successfully launching three next-generation weather satellites—GOES-16 and -17 and the Joint Polar Satellite System—in a span of 18 months. These spacecraft have faced delays and continued to consume more and more of NOAA’s budget, drawing sustained congressional attention. With the ABI malfunction, that attention is likely to return.
The agency is still seeking to diagnose the exact problem, which seems to be a mechanical issue involving the ABI’s cooling pipes and radiator. Around midnight, at geostationary orbit 36,000 kilometers above the equator, the sun peers “over the shoulder” of Earth and directly into the ABI’s camera. On GOES-16, the solar heat is passed through to liquid coolant, which transitions to a vapor and is then passed through a radiator to dissipate the heat into space. For some reason, this cooling is not happening with the newer satellite’s system.
The technical problem has no immediate impact on the country’s weather forecasts—beyond GOES-16, NOAA has two older geostationary satellites operating in orbit, one covering the country’s western flank and one serving as a backup. Both of these satellites can likely last into the next decade. But what is at risk of being lost are the forecast improvements that would come from a fully operational satellite, says Steve Volz, who leads NOAA’s Satellite and Information Service in Silver Spring. “If efforts to restore the cooling system are not successful, we’re looking into concepts to maximize its utility.”
In particular, the infrared bands provide important inputs to weather models for detecting wind motions at various levels in the atmosphere, Pica says. And the ABI is also critical for providing vertical temperature and moisture profiles, a product that had previously been handled by a separate instrument on older satellites, adds Cliff Mass, an atmospheric scientist at the University of Washington in Seattle. In the worst case, for nearly half the day, these capabilities could be lost. Even in such a situation, however, the satellite’s five other instruments, focused on space weather and lightning mapping, all appear to be operating as planned, Volz added.
NOAA already has finished ABI cameras for the final two satellites of this generation, the next of which is due for launch in 2020. Beyond evaluating and attempting to fix GOES-17, the agency is working closely with the ABI’s manufacturer, Harris Corporation, to diagnose whether changes will be necessary for the instruments it has on hand. It’s too early to say whether the problem could speed up or delay the next GOES launch, Volz added.
“It’s obviously not what you want to see. It’s deflating,” Volz said. But it’s also part of the territory that comes with operating in space. During his long career at NOAA and NASA, Volz says he’s seen a half-dozen anomalies like this. It’s always a challenge, but, he added, “It’s never as bad as it looks the first time you see it.”