IV&V’s Contribution to JPSS-1

Update: (Vandenberg Air Force Base, Calif., Nov. 6, 2017) – The ULA Delta II rocket carrying the JPSS-1 mission for NASA and NOAA is delayed due to a faulty battery. The delay allows the team time to replace the battery on the Delta II booster. The vehicle and spacecraft remain stable. Launch of the JPSS-1 mission is scheduled for no earlier than Tuesday, Nov. 14, 2017.

There isn’t just one satellite hovering above Earth that provides humans the ability to constantly monitor the potentially dangerous weather, but rather there are actually several of them. Soon, there will be one more hovering up there when the Joint Polar Satellite System (JPSS) adds JPSS-1, the second of what will be a five-satellite JPSS constellation, when JPSS-1 launches on November 10, 2017. While the construction of the satellite itself was managed by NASA, once it is launched, it will belong to the National Oceanic and Atmospheric Administration (NOAA). NOAA operates 16, soon to be 17, satellites in various orbits, ranging from low Earth orbits (LEO), starting at around 200 miles above the Earth, all the way out to geostationary orbits (GEO), which is around 22,000 miles above the Earth. The newest of NOAA’s fleet, JPSS-1, will be launched from Vandenberg Air Force Base in California, as Vandenberg provides the best US-based launch location to place JPSS-1 in its own unique LEO orbit, called a “polar sun-synchronous” orbit. This particular type of orbit will allow JPSS-1 to circle the Earth from pole-to-pole at an altitude of about 512 miles above the Earth’s surface, crossing the equator 14 times daily, and allowing for full global coverage with its five onboard weather-hunting instruments twice a day!

What do these instruments do and how do they help me?

The instruments on board JPSS-1 provide real-time environmental data that allow people around the world to make important decisions about protection of life and property, national security, economic interests and vital environmental resources like coasts, oceans and ecological habitats. Of course let’s not forget they also provide some of the essential data for those weather maps your local meteorologist uses on the nightly news. The Advanced Technology Microwave Sounder (ATMS) and Cross-track Infrared Sounder (CrIS) are two instruments that work together to provide profiles of atmospheric temperature, moisture and pressure. The Visible Infrared Imaging Radiometer Suite (VIIRS) provides daily high-resolution imagery and radiometry across the visible to long wave infrared spectrum (those weather maps that were just mentioned). The Ozone Mapping and Profiler Suite (OMPS) uses a spectrometer with UV bands for ozone measurements. Finally, the Clouds and the Earth’s Radiant Energy System (CERES) works as a scanning radiometer, which measures reflected sunlight and thermal radiation emitted by the Earth. Versions of all five of these instruments have flown on previous satellites, but all the instruments that are going up on JPSS-1 have been improved since they were last flown. That means that with these upgraded instruments, JPSS-1 will be more effective in forecasting flooding, tropical cyclones, hurricanes, tornadoes, blizzards and other high-impact weather events, providing more lead time to for Earth’s inhabitants to make important life and property decisions. JPSS-1 will also help in assessment of environmental hazards such as droughts, forest fires, poor air quality, and harmful coastal waters.

How did NASA Independent Verification and Validation (IV&V) Program play a part in the development of the JPSS-1 satellite?

In short, our team worked on the “brains” of the satellite, the flight software (FSW). The primary activities in controlling the satellite were split into two different bins, each being handled by its own processor or computer. The computer that handles the control of the spacecraft, such as extending the solar panel, changing spacecraft attitude, or igniting the thrusters to change orbit, is called the Spacecraft Control Processor (SCP). The Command Data Processor (CDP) is the computer that handles the communications of the spacecraft, both externally to the ground network on Earth and internally to all of the spacecraft subsystems, like the instruments. The CDP is additionally responsible for collecting, storing and downloading to Earth the science data that was captured by the five onboard instruments.

IV&V also assessed the CDP interfacing to two of the instruments, VIIRS and CrIS, as those instruments were using a new-to-JPSS data interface, called SpaceWire, to create a connection from the CDP to those instruments. IV&V followed along with and assessed the development of the FSW from the point when requirements were being determined for what the computers needed to do to satisfy the mission objectives, all the way to the point where the completed FSW was loaded onto the computers, connected to other flight hardware, and was tested to see if it worked the way it was supposed to. IV&V made sure the JPSS-1 FSW works as it is supposed to, does not do what it is not supposed to do, and responds as expected when the spacecraft encounters adverse conditions.

Now with JPSS-1 soon to be watching over us all, we will all be able to watch our nightly weather forecast with much more confidence in determining if we will need our umbrella for the following workday.

Jeremy Fienhold
Systems Engineer