Engineers are investigating a significant cooling issue with the primary imaging system aboard the recently launched GOES-17 Weather Satellite that limits infrared observations critical to forecasting, officials said Wednesday.
“This is a serious problem,” said Steve Volz, deputy administrator of the National Oceanic and Atmospheric Administration’s Satellite and Information Service.
“This is the first Earth-pointing instrument on the GOES platform, and 16 channels, 13 of which are infrared or near-infrared, are important parts of our observing needs. not working fully, it’s a waste. It’s a performance issue that we need to fix.”
GOES-17 is the second of four advanced geostationary operational environmental satellites equipped with state-of-the-art instruments to monitor hemispheric weather conditions, including an advanced high-resolution camera known as the Advanced Baseline Imager, or ABI.
The ABI’s detectors are sensitive to 16 spectral channels, three in the visible light spectrum and 13 in the infrared wavelengths. The GOES-17 ABI’s visible light channels are working normally, but problems with a cooling system limit infrared observations when the satellite’s orbit allows sunlight to fall directly on the instrument.
This equates to around 12 hours a day, in the worst case.
“The worst-case scenario doesn’t mean we don’t have any channels in the infrared,” Volz said. “We’re getting degraded performance on the infrared and near infrared channels, not zero performance, but degraded performance. We’re trying to gauge what exactly the performance is.
“The visible (channels) are working quite well. We still have a very capable and functional spacecraft and mission, even under the current operating conditions.”
He said a team of experts from NOAA, NASA, Harris Corp., the instrument’s builder, and others “are actively investigating this issue and reviewing several options to correct the problem.”
“If efforts to restore the cooling system are not successful, we are investigating alternative designs and different modes to maximize the operational utility of this ABI for NOAA’s National Weather Service and other customers in the future.”
NOAA is spending $11 billion on new GOES satellites, their rockets and launch services, as well as major upgrades to ground systems and data analysis infrastructure. Each satellite is valued at around $500 million, not including development costs.
Built by Lockheed Martin Space Systems, the new GOES satellites feature an advanced high-resolution camera, sensitive magnetometer, ultraviolet X-ray sensor to measure solar radiation, ultraviolet imager to continuously monitor the sun and sensors to measure charged particles from the sun that can affect communications and navigation.
The satellites are also equipped with lightning mappers that can take pictures of lightning fields in the Western Hemisphere around 200 times per second.
But the Advanced Baseline Imager is the star of the show, and its infrared imagery is essential for forecasters.
According to a NOAA fact sheet, it is designed to track and monitor “cloud formation, atmospheric motion, convective development, land and sea surface temperatures, ocean dynamics, water, fire, smoke, volcanic ash, aerosols and air quality, and vegetative health.”
“ABI’s data helps meteorologists identify and track a developing storm area in much greater detail. Knowing how quickly storm clouds are forming leads to earlier warnings. Better Data quality and faster scan speed help reduce weather-related flight delays as well as earlier preparedness for tropical storms and hurricanes.”
The ABI’s cooling system, known as a cryocooler, is designed to dissipate heat buildup by pumping propylene through an evaporator, where the heat turns the coolant to gas, and through a radiator which is exposed to the cold of space. The cooled propylene then becomes liquid again and is returned to the evaporator.
The system is designed to cool the instrument’s infrared detectors to 60 degrees above absolute zero, or minus 350 degrees Fahrenheit.
“What we see on the 17th is that we can only get to that operating temperature for about half of the day, and that’s because during orbit we see different thermal conditions, different sunlight conditions that alter the heat of the instrument,” said Pam Sullivan, GOES project manager at the NAA’s Goddard Space Flight Center.
“During the hot part of the orbit, the heat load increases to the point that we are not able to cool the detectors.”
The instrument was built by Harris Corp. and identical cameras operate normally on board theand aboard two Japanese satellites.
“That’s obviously not what you want to see,” Volz said. “It’s deflating…given the spectacular success that GOES-16 has been, as well as Himawari 8 and 9. We expected the same performance, and we still hope. But it’s a bit overwhelming to see this happen.”
NOAA operates four GOES weather satellites to provide the familiar hemispherical views of overnight news reports, as well as large amounts of data that are used by meteorologists to track hurricanes and major storm systems and to generate the forecasts on which millions of people matter.
GOES-16 was the first of four upgraded satellites to reach orbit. It is positioned above the equator at 75 degrees west longitude – the GOES-East slot – and covers the eastern United States and the Atlantic Ocean to West Africa.
GOES-17 will eventually replace GOES-15 in the GOES-West orbital slot at 137 degrees west longitude. GOES-15 will then join another older satellite, GOES-14, serving as a reserve in orbit.
Sullivan said engineers were working hard to fix the GOES-17 cooling system issue and it was too early to tell if it could be fixed or if another workaround was possible.
“People have dug in, we’re not even out of ideas,” Sullivan said. “There are a lot of avenues of investigation…and also a lot of work on what we can do to improve the situation even if the thermal performance does not improve. There are other changes we could make on the operational plan that could mitigate this.”