The National Oceanographic and Atmospheric Administration (NOAA) requested an Independent Review Team (IRT) look at NOAA satellite programs for possible problems. The IRT came back with issues and recommendations in two reports: one in 2012 and one in 2013. Within the report, the IRT pushed forward the possibility of no sun-synchronous LEO NOAA satellites in orbit for at least a year, starting in 2017. Their dire statement is on page 7 of the report: “Without accurate/reliable weather forecasting and severe storm warnings, lives, property and the U.S. economy are at risk.”
Previous posts guessed the current operational status of five NOAA and NASA satellites based on public satellite sub-systems status charts. As of today, the guess is the satellites still seem to be working. This status flies in the face of the IRT’s 2013 report’s chart (page 14), which shows a majority of the five satellites disappearing in 2014. I don’t know the criteria for shutting down these satellites, but the fact all five of them are operating well past their projected mission design life may well be a factor for why satellites start falling off the IRT’s chart. Hence the IRT’s recommendation of an urgent need for a gap-filling NOAA satellite.
But there may be an alternative.
Taking the A-Train
There are other sun-synchronous satellites out there. They may not belong to the NOAA, but a few may have the payloads that would compensate for the NOAA’s potentially failed ones. In fact, the Aqua satellite is part of a conga line of sun-synchronous satellites.
This conga-line of satellites is an international constellation known in the space community as the “A-Train.” A-Train satellites are all in the same sun-synchronous orbital inclination. The satellites in the A-Train are minutes apart, consisting of Aqua and four other satellites (read about the details of each one on the NASA portal). Some of the satellites are run by, or operated in conjunction with, other countries. Each A-Train satellite carries many payloads.
Would it be possible, if Aqua “disappeared,” for these remaining satellites to help fill the gap? If the need is so urgent, wouldn’t the other countries be willing to help and collect data with their satellites, especially for potential catastrophic weather. It’d definitely be cheaper than building gap-filler satellites.
Payload Alphabet soup
There must be a reason why the IRT did not approach the cooperation option. Perhaps the payload requirements are so specific, there’s no way to replace what’s lost with the other A-Train satellites. The IRT specifically recommends quickly building and placing a few “Advanced Technology Microwave Sounders (ATMS) and Cross-track Infrared Sounders (CrIS) on contract as soon as possible with their current developers.” None of the A-Train satellites have those payloads.
Of the five NOAA and NASA satellites on the chart, only one has those particular payloads—Suomi NPP. Some of the other satellites have the Advanced Microwave Sounding Unit (AMSU) as a payload, which is sort of a forerunner to ATMS. You can read about the differences between the two payloads here, if you wish. But since all NOAA LEO satellites with those payloads are projected to be gone by 2017, knowing the differences won’t matter.
The IRT’s idea, then, is to get the recommended payloads on some quickly-made satellite busses, put the satellites on a few rockets, and get them into sun-synchronous orbit before Suomi NPP can give up the ghost. Yay—everyone’s happy! Except, it’s not that simple…
- Panel Warns of ‘Catastrophic’ Gap in Weather Satellite Data (climatecentral.org)
- New NOAA Web Tool Offers Great Climate Visualizations (earthtechling.com)