New satellites - new bugs: The GOES-17 satellite's infrared sensor does not cool well

    The GOES-17 meteorological satellite, launched in March, has a problem - an infrared camera of a new generation works only partially due to the fact that it is badly cooled. And now one team of engineers is trying to reduce the periods of incomplete working capacity, and the second is to establish the cause of the problem. Both tasks are important because analyzing the telemetry of the predecessor, GOES-16, showed that there are also signs of an abnormal operation of the cooling system, and it seems that the fourth generation of meteorological satellites GOES faced a systemic problem.

    Preparations for the launch of GOES-17, NASA photo

    Chronology of events

    The launch of

    GOES-17 was launched on March 1. On March 12, the vehicle reached the geostationary orbit and began testing onboard systems. And here an unpleasant surprise came to light. For normal operation of the main optical instrument of the satellite, Advanced Baseline Imager (ABI), low temperature was required. Infrared sensors need to be cooled, some up to 60 ° Kelvin (-213 ° C) so that they can function normally. And it turned out that the cooling system can not cope with their responsibilities. Fortunately, the temperature load of the satellite depended on the time of day and day of the year, so the device turned out to be partially efficient, but, nevertheless, 13 of the 16 frequency bands were unavailable every day for several hours.


    The GOES-17 satellite is the second in the fourth generation of meteorological geostationary satellites GOES. The first in 2016 went to orbit GOES-16. According to the plan of the GOES program, two satellites occupy the standing points east and west of both Americas in order to have high-quality coverage of the US territory. Two more points are used to check and store spare satellites.

    GOES satellite location map, fill - area of ​​visibility. Illustration of NASA

    GOES-16 occupied the eastern point, while the western one was intended for 17 satellite. Prior to launch, the satellites have alphabetic names, so the sixteenth was designated as GOES-R, and the seventeenth was S. Structurally, the devices are built on the platform of the Lockheed Martin A2100, which was developed for telecommunications satellites and GPS, and carry devices for various purposes.

    Satellite placement, a NASA

    Geostationary Lightning Mapper (GLM) circuit works in the near infrared and is used to detect lightning.

    Extreme Ultraviolet and X-ray Irradiance Sensors (EXIS) is aimed at the Sun, measures insolation (exposure to sunlight) and can capture potentially dangerous solar flares.
    Solar Ultraviolet Imager (SUVI) is also aimed at the Sun and is a telescope operating in the ultraviolet range and intended to observe coronary holes, mass ejections and other phenomena of sunny weather.

    Magnetometer (MAG)and the Space Environment In-Situ Suite (SEISS) monitor magnetic fields and high-energy particle fluxes, respectively.

    But the most important tool is Advanced Baseline Imager (ABI) , which in 16 frequency ranges from visible to infrared captures atmospheric phenomena occurring on the globe. Many ranges are needed because, for example, snow and ice are best seen in the 1.58–1.64 micrometer wavelength range, and fog, fires and volcanism - at 3.80–4.00 micrometers.

    AHI, ABI type, without heat shield. Photo Exelis

    The optical resolution depends on the range and is at best 0.5 km per pixel, which is twice the resolution of the GOES satellites sensor of the previous third generation. Also, for comparison, it is worth noting that the third-generation GOES sensors had only 5 ranges.

    After the launch of GOES-16, NOAA and NASA rightfully boasted their images.

    Progress clearly, I recommend to watch in large size

    16 ABI channels, by reference in large size


    But alas, those listed in the previous chapter of beauty are spoiled by a technical problem - the heat pipes intended for cooling the sensors do not cope with their task. The heat carrier, propylene, does not circulate well enough in them. The reason for this has not yet been established, the following versions are considered: excessive non-condensable gas (in heat pipes the coolant is gasified and condensed, gas bubbles in the liquid will interfere with circulation), pipe contamination by foreign particles or mechanical damage to the pipes. It will take another 1-2 months to research the cause and reproduce the problem on the ground.

    Sensors, similar to ABI GOES-17, in space now works four. One is installed on GOES-16, and two more AHI of the same type are installed on the Japanese geostationary meteo-satellites Himawari-8 and -9. Japanese instruments work fine, but a detailed analysis of the GOES-16 telemetry showed that the cooling system, which is considered to be functioning properly, encountered the same problems, only to a lesser extent. The temperature of the ABI GOES-16 remained within acceptable limits, so no attention was paid to signs of insufficient circulation of the coolant. The repetition of the situation speaks of a systemic problem - either during the design or during production, they made a mistake, and the new GOES satellites cannot be launched before the defect is fixed.

    In parallel, another group of engineers struggled with the problem on the satellite. After the measures were taken (unfortunately, they did not specify which ones), the availability of the ranges increased. Now 13 of the 16 ranges operate 24 hours a day, and the remaining 3 - 20 hours. But it's too early to relax - September is approaching, when the Sun will shine almost directly into the sensor, seriously increasing the heat load. The exact numbers are not yet known, but it is expected that 10 out of 16 ranges will be available around the clock, and the remaining ones most of the time.


    As with any complex technology, new instruments on satellites can always bring surprises. And the story of GOES-17 shows the usually inconspicuous, but no less interesting, work to keep the satellites in working order, updating their software and setting the operating parameters of the hardware.

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