Mission description

GOES 9 (GOES-J) is the second satellite in a series of next generation geosynchronous spacecraft, referred to as GOES-NEXT and represented by the GOES I through GOES M spacecraft. The GOES-NEXT series is a joint effort on the part of NASA and NOAA to provide continued operational monitoring of weather systems primarily over the United States, distribute meteorological data to regional and national weather offices within the USA, contribute to the development of an environmental data collection network, contribute to the search and rescue program, improve the capability for forecasting and provide real-time warnings of solar disturbances, and to extend knowledge and understanding of atmospheric processes to improve short and long-term weather forecasts.

The GOES-NEXT series extends the capabilities of the previous GOES 1-7 spacecraft. The GOES I-M spacecraft will be placed over the equator at 135° West or 75° West. The spacecraft structure is based on the Space Transportation System (STS)-launched, three axis stabilized Insat (geostationary satellite for India) meteorological satellite design. The design allows unobstructed views of the Earth for operational coverage by the spacecraft sensors. The spacecraft configuration is a compact box-shaped main body that carries the Earth-observing instruments, a continuous-drive solar array attached to the south panel through a yoke assembly, and a solar pointing instrument gimbal mounted on the solar panel yoke. The main body accomodates the sensors, electronics, and support subsystems. The communication antennas, except the Tracking, Telemetry and Command (TT&C) antenna, are hard-mounted to the Earth-facing panel. The Propulsion Module consists of the fuel and oxidizer tanks for the bipropellant propulsion subsystem mounted on the central cylinder. The Attitude and Orbit Control Subsystem (AOCS) provides attitude control of the spacecraft. The AOCS consists of the sensors, electronics, and the actuators. The GOES power is generated from the solar array and two 12 Ah batteries. Power is automatically regulated during solar eclipses.

The Image Navigation/Registration (INR) system provides Imager and Sounder data products in real time to users. The Communications, Command, and Data Handling subsystem is comprised of antennas, receivers, transponders, transmitters, data encoders and encryptors and multiplexers. The Tracking Telemetry and Command (TT&C) subsystem provides the necessary monitor and command link between the spacecraft and the ground stations.

The GOES-NEXT instruments consist of the following:

1. Earth Imaging System, a 5-channel visible and infrared radiometer which provides Earth imagery 24 hours a day;
2. Sounding System, a 19 channel discrete-filter radiometer for obtaining atmospheric temperatures and moisture soundings;
3. a Space Environment Monitor (SEM) system, which consists of a magnetic field sensor, a solar X-ray sensor, an Energetic Particle Sensor (EPS), and a High Energy Proton and Alpha Detector (HEPAD);
4. a Search and Rescue subsystem (SARSAT), which receives signals from 406 MHz distress beacons and relays them to the ground;
5. a Data Collection system (DCS) for collecting and relaying real-time information from Data Collection Platforms (DCPs) such as buoys, balloons, remote weather stations, ships and aircraft; and,
6. a Weather Facsimile (WEFAX) system which relays processed weather imagery from the Wallops Island station to the user community.

Detector description

The implemented data set consists of averaged SEM measurements.

The Space Environment Monitor (SEM) System on the GOES-NEXT series of geostationary meteorological satellites (GOES I through GOES M) is designed to provide direct real-time measurement of solar activity. The SEM consists of

1. a Magnetic Field Sensor;
2. a Solar X-Ray Sensor; and,
3. an Energetic Particle Sensor (EPS)/High Energy Proton and Alpha Detector (HEPAD).

The Magnetic Field Sensor (MFS) allows for the real-time determination of the magnitude and orientation of the magnetic field. Data is telemetered twice a second for magnetic fields having a magnitude of +/- 1000 nanotesla (nT).

The Solar X-Ray Sensor permits real-time determination of the solar x-ray emission in two spectral bands: 0.5-5 Å and 1-8 Å.

The EPS makes flux measurements of protons in the 0.8 to 500 MeV range. The HEPAD monitors protons in four energy ranges above 350 MeV and alpha particles in two energy ranges above 640 MeV/nucleon.