ON MAY 23, 2018 NOAA’S SATELLITE SERVICES ANNOUNCED A PROBLEM HAD BEEN DETECTED WITH ONE OF THE MAIN INSTRUMENTS ONBOARD THE NEW GOES-17 SATELLITE, ORBITING 22,000 MILES OVERHEAD.
GOES-17 was launched into space in March 2018, the second in a series of next-generation earth-observing satellites that will deliver high-resolution images and help improve forecasting. One of the satellite’s primary sensors — the Advanced Baseline Imager, or ABI — using 16 different wavelengths of light to detect clouds and create 34 informational products for forecasters to use.
THREE MONTHS INTO A PLANNED 6-MONTH POST-LAUNCH TESTING AND CALIBRATION, ENGINEERS FOUND A PROBLEM WITH THE ABI’S COOLING SYSTEM.
In the extreme environment of space a temperature-control system is critical to keep satellite instruments operating properly. The cooling system that ABI utilizes did not “wake up” when engineers tried to power it up the first time following launch, or in subsequent tries since late April 2018.
On a conference call with reporters Tim Walsh, the System Program Director for the GOES-R Program Team, explained how a problem with the ABI’s cooling system could hobble the instrument.
“The cooling system on board the ABI is utilized to keep the focal planes used to image the earth at proper temperatures. The visible wavelengths are actually able to be kept at a proper temperature throughout the whole day; the whole 24-hour cycle. The other wavelengths — the near-infrared and infrared wavelengths, the other 13 — need to be cooled to some extent beyond the capability of the system at present. So there’s a portion of the day, centered around satellite local midnight, where the data is not usable.”
What does this mean? It seems to mean that, right now, GOES-17 is effectively blind at night and that detailed atmospheric temperature and wind data isn’t available during the day either.
Joe Pica, Director of the Office of Operations of NOAA’s National Weather Service, explained how this could impact forecast models and forecasts.
“The primary input into the numerical weather prediction models is, basically, the derived-motion winds […] and the input of the infrared bands is very key, particularly for height-specification of those winds.”
Dr. Stephen Volz, the Assistant Administrator for NOAA’s Satellite & Information Services helped to put the current challenges into perspective.
“This is a serious problem. This is the premiere earth-pointing instrument on the GOES platform. If [the ABI is] not functioning properly it is a loss and a performance issue we have to address.”
At the same time, Dr. Volz cautioned against jumping to conclusions.
“We are still assessing performance degradation under current operating conditions for the instrument, and the different infrared channels require different degrees of cooling and are impacted in different amounts. [The impact] will vary from channel-to-channel and product-to-product; it’s a fairly complex mix.”
Asked if the data may be partially usable, Volz replied “oh, it is entirely partially usable even if we get no better performance than we’ve seen.”
The other instruments are all checking out fine — 4 space-weather instruments and the Geostationary Lightning Mapper.
WHAT IS BEING DONE?
Experts from NASA and NOAA are working together to try to find a solution to the problem. If the ABI coolant system can’t be fixed then NASA and NOAA will need to come up with a workaround to maximize the effectiveness of GOES-17, which is designed to operate in the U.S. “West” orbital slot, keeping an eye on storms over the Pacific Ocean.
Pica reiterated that the current GOES-West satellite (GOES-15) remains operational, and that the National Weather Service is already making us of “…derived-motion vectors from [the Japanese Meteorological Agency’s satellie] Himawari at this time in our models.”
Another option is to move-up the launch date of the next satellite in line (GOES-T) as a possible replacement for GOES-17. While the same technology is currently in-use and functioning correctly aboard GOES-16, a thorough examination of Harris Corporation’s ABI design needs to be completed before any future launch.