MINNEAPOLIS (WCCO) — On Tuesday, NOAA gave us an update on a problem with the GOES-17 weather satellite that was first announced back in May 2018. This critical problem 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 — a 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 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.”
FIXES FOR THE FUTURE
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.”
“The team has also recommended design modifications for the GOES-T and U ABIs to make sure that we do not experience cooling system issues moving forward. We will not launch GOES-T and GOES-U until we fully understand and have resolved the problem.”
Despite the limitations, 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.”