9:10 AM | *NOAA’s newest GOES weather satellite has a problem*

Artist rendering of GOES-17 in orbit (credit NOAA)

Overview
NOAA’s newest weather satellite – part of the $11 billion GOES constellation series to operate for the next 20 years – is broken and officials are not sure exactly what is wrong.  There are four satellites in the series (GOES-R, GOES-S, GOES-T and GOES-U) with six primary instruments on each that will help to improve weather forecasting around the world by providing advanced imaging with faster coverage and increased spatial resolution, real-time mapping of lightning activity, and improved monitoring of solar activity. NASA successfully launched the GOES-R satellite in November 2016 and then GOES-S was launched on March 1st of this year.  
 

The benefits of the next generation satellites
The US has several weather satellites in orbit, but GOES-R is taking high-resolution images of the Western Hemisphere four times better than the prior satellites.. Instruments onboard the satellite can also take high-resolution observations of weather parameters such as wind speed, rainfall rate, snow cover and lightning.   In addition to providing higher quality information for meteorologists, GOES-R has been sending back data at a greater rate of speed as often as once every 30 seconds which has helped weather forecasters; especially, with respect to severe weather outlooks.  This greater rate of speed can make a significant difference during extreme weather events such as tornado outbreaks. The ability to observe targeted areas of severe weather every 30-60 seconds is allowing forecasters to see what is happening in near real-time and provide information not captured in prior satellite imagery, such as the formation and evolution of rapidly-developing severe weather.  Another big benefit to meteorologists by the GOES-R series of satellites will be with respect to the forecasting of tropical systems in the Atlantic Ocean. Specifically, GOES-R is providing meteorologists with better information on what is going on inside a tropical system.  This advanced capability is better than relying on airplanes which can be costly and quite difficult if the tropical storm is far away from land.

Sample product from GOES-16 with an image of the current low-level water vapor in the Northeast US (ABI band #10) Credit NOAA, College of DuPage

Band Type: Infrared
Spatial Resolution: 2km
Approximate Central Wavelength: 7.3 μm
Temporal Usage: Night and Day

ABI 10 is the last of three water vapor bands available from GOES-R Series satellites. It has similar applications to the Mid-Level Water Vapor band but can add further clarity to jet-streaks and shortwave features embedded within large scale atmospheric flow patterns. It also has been proven to be useful in identifying/tracking volcanic plumes. Additionally, in combination with the other two water vapor bands, this data can be ingested by numerical weather models to improve forecasts by better approximating initial conditions of the atmosphere at large scales. 
 

GOES-R is just the first step in producing more accurate weather forecasts. In 2018, another weather satellite with similar capabilities called GOES-S will be launched providing even more information about weather across the Western Hemisphere.  The GOES-R series will maintain the two-satellite system implemented by the current GOES satellites flying at more than 22,000 miles above the equator matching the speed of the Earth’s rotation. The GOES system currently consists of GOES-13 operating as GOES-East in the eastern part of the constellation and GOES-15, operating as GOES-West.  The locations of the operational GOES-R series satellites will be 75⁰ W and 137⁰ W. The latter is a shift from current GOES at 135⁰ W in order to eliminate conflicts with other satellite systems.  The GOES-R series program is a collaborative effort between NOAA and NASA that will extend the availability of the operational GOES satellite system through 2036.  GOES-R, which will be known as GOES-16 once it reaches geostationary orbit, will transition into operations immediately following an extended checkout and validation phase of approximately one year.

The problem on GOES-17 impacts its primary instrument
According to NOAA, the critical problem on GOES-17 prevents the Advanced Baseline Imager, or “ABI,” from functioning properly; and, since the ABI is the primary earth-observing instrument aboard all four of the U.S.’s next-generation weather satellites, scientists and meteorologists are pretty anxious to hear what’s going on. As the satellite was first being powered up in orbit — 22,000 miles above the Equator — the problem with the ABI’s cooling system was discovered.  Without this cooling system the detectors that measure infrared energy (heat) coming from the earth can be swamped by heat coming from the satellite itself, rendering parts of the ABI useless at certain times of day and certain times of the year.  The high-resolution visible-light channels (that we often show you during the daylight hours on TV) are not affected by this cooling-system issue.

Because of its high orbit there’s no sending humans into space to fix it; and, because of a limited on-board fuel supply, there’s no way to steer the satellite into a lower orbit.  Since the problem was discovered, though, teams of scientists on the ground have been trying to figure out a workaround; according to the director of the NOAA GOES-R System Program Pam Sullivan there has been some progress.  “The team that’s working on optimizing the GOES-17 ABI has been successful at finding techniques that increase the available observing time of the infrared channels.”

Through testing new operating temperature guidelines for the sensors, and changing the satellite’s orientation relative to the horizon (attitude), Sullivan said that things are looking much better today than they were several months ago. “We have just completed the coolest part of the season on-orbit [for GOES-17], where we experience the best performance from the instrument.  Under these conditions — the coolest conditions — we project that 13 of the 16 ABI channels will be available 24 hours a day, with the other 3 channels available for 20 hours or more per day. “Under the warmer — the worse conditions — we are currently projecting that 10 of the channels will be available all day, with the other 6 channels available for most of the day, to varying degrees, depending on their wavelengths.  “The warmest part of the season for the satellite is coming up in early September and our performance estimates will need to be confirmed through observations during that time.”

In addition to figuring out how to work around the limitations of GOES-17, there is also some concern that this problem doesn’t occur again on GOES-16 (launched in November of 2016, and also known as GOES-East), or on the forthcoming GOES-T and GOES-U satellites that will launch in the future. “There is some evidence of reduced functionality from [the cooling system] as well. However, GOES-East continues to perform well and the potential impact of that reduced cooling capacity is not in any way affecting the delivery of observations from GOES-16.”

Looking ahead
Despite the limitations, NOAA says GOES-17 will still move into its operational orbital slot as GOES-West later in 2018, provided no further problems are discovered.  “Even during this checkout phase, GOES-17 is observing with more channels at a higher resolution with more rapid refresh than what we currently have with the current [old-model] GOES-West satellite,” Sullivan commented.  “While we are not going to get the full GOES-17 functionality we are going to receive more and better data than we currently have.”

Meteorologist Paul Dorian
Perspecta, Inc.
perspectaweather.com