This article originally ran in the Nov. 6, 2017 issue of SpaceNews magazine. JPSS-1 launched Nov. 18.
Forecasters are breathing a sigh of relief as the U.S. National Oceanic and Atmospheric Administration prepares to launch the first of four next-generation weather satellites into polar orbit to provide detailed global atmospheric data for the next two decades.
Since 2010 when the Obama administration canceled the National Polar-orbiting Operational Environmental Satellite System, which was designed to handle military and civil requirements, meteorologists have expressed concern that existing polar-orbiting weather satellites would fail before new ones could take their place leaving critical gaps in the atmospheric temperature and moisture readings needed for accurate forecasts.
Instead of a gap, however, it looks like NOAA will have two extremely capable weather satellites in polar orbit when it launches the first spacecraft in the Joint Polar Satellite System (JPSS) Nov. 10 at 1:47 a.m. Pacific time on a United Launch Alliance Delta 2 rocket from Vandenberg Air Force Base in California. That satellite, known as JPSS-1 before launch and NOAA 20 once in orbit, is slated to travel in an 824-kilometer orbit 50 minutes behind the NOAA-NASA Suomi National Polar-orbiting Partnership (NPP) satellite, which the agencies launched in 2011 to demonstrate new sensors and bridge any gap between NOAA’s previous generation of polar-orbiting environmental satellites and JPSS.
By working together, sensors onboard NPP and JPSS-1 will provide a wealth of data, which could lead to improve weather forecasts. The National Weather Service feeds data gathered by sensors on polar orbiting and geostationary satellites into sophisticated weather models to create three-, five- and seven-day forecasts.
“The major contribution for JPSS is to the three- to seven-day weather forecast, said Mitch Goldberg, NOAA’s JPSS program scientist. “Eighty-five percent of all data that goes into forecast models come from polar-orbiting satellites.”
Polar satellites also provide the observations forecasters use to pinpoint the track and intensity of hurricanes and other severe storms.
“Polar satellites are the backbone of the global observing system we use to predict extreme events,” Louis Uccellini, director, NOAA’s National Weather Service, said in an Oct. 11 press briefing.
To get JPSS-1 data into the forecasts more quickly, NOAA plans to downlink it to a ground station in Svalbard, Norway, that also serves NPP as well as a second site at McMurdo Station, Antarctica.
“That is a big deal for us,” said Mark DeMaria, Technology and Science Branch chief at the NOAA’s National Hurricane Center in Miami, Florida.
At night, meteorologists use the Visible Infrared Imaging Radiometer Suite (VIIRS) day-night band, which needs very little light to gather imagery, to watch hurricanes evolve and to identify their center. With VIIRS flying on only one satellite, NPP, and that data traveling once per orbit to a single ground station in Norway, the National Hurricane Center sometimes got data that was two- to three-hours old. “Having the low-latency data will help us make better use of the VIIRS data,” DeMaria told SpaceNews.
JPSS-1 carries five instruments. Northrop Grumman’s Advanced Technology Microwave Sounder measures atmospheric temperature and moisture day, night and through clouds. Harris Corp.’s Cross-track Infrared Sounder, provides even more accurate temperature and moisture data for cloud-free areas. Raytheon’s VIIRS lets forecasters see hurricanes, floods, fires and sea ice. Ball Aerospace’s Ozone Mapping and Profiler Suite-Nadir tracks the health of the Earth’s ozone layer. Northrop Grumman also built the Clouds and the Earth’s Radiant Energy System to monitor solar energy reflected by Earth and Earth’s emitted thermal energy.
NPP carries the same instruments plus an additional ozone mapper. Since NPP was planned as an experimental mission, the spacecraft and instruments were not designed to last in space as long as operational weather satellites. NASA and NOAA directed NPP prime contractor Ball Aerospace & Technologies Corp. of Boulder,Colorado, to design the NPP spacecraft to work for at least five years in orbit, a period it already has exceeded. Although NPP continues to work well, NOAA is eager to launch JPSS to ensure the agency will have a new polar-orbiting weather satellite to provide data whenever NPP fails.
Until then, the two spacecraft will work in tandem.
The European Organization for the Exploitation of Meteorological Satellites, Eumetsat, has shown a significant positive impact on forecasting since it began operating its two polar-orbiting weather satellites, MetOp-A and MetOp-B, spaced 50 minutes apart, Goldberg told SpaceNews.
After launch, JPSS-1 will spend approximately 60 days moving from its injection orbit into its mission orbit. NASA plans to handoff satellite operations to NOAA 30 days later.
NOAA would like to launch additional JPSS satellites every five to six years.
“These missions are critical,” Goldberg said. “The data are critical.” That’s why NOAA can’t wait for one polar-orbiting weather satellite to fail before launching its replacement, he added.
JPSS-2 is scheduled to launch in 2022, but it remains to be seen when JPSS-3 and JPSS-4 will fly because Congress and the Trump administration have not yet agreed on funding their development in a program called Polar Follow-On.
“We don’t have any clear indication of the fiscal year 2018 budget,” Ajay Mehta, NOAA Satellite and Information Service acting deputy director for systems, said during the Oct. 11 briefing. “Our plan is to build to a robust constellation and to operate two satellites at all times so we have a backup in space.”
