All of the instruments are located on the ESM and the IMP. The spacecraft power is provided by a direct energy transfer system from the single
solar array which consists of eight panels of
solar cells. The in-orbit Attitude Determination and Control Subsystem (ADACS) provides three-axis pointing control by controlling torque in three mutually orthogonal momentum wheels with input from the Earth Sensor Assembly (ESA) for pitch, roll, and yaw updates. The ADACS controls the spacecraft attitude so that orientation of the three axes is maintained to within ± 0.2° and pitch, roll, and yaw to within 0.1°. The ADACS consists of the Earth Sensor Assembly (ESA), the Sun Sensor Assembly (SSA), four Reaction Wheel Assemblies (RWA), two roll/yaw coils (RYC), two pitch torquing coils (PTC), four gyros, and computer software for data processing. The ATN data handling subsystem, consists of the TIROS Information Processor (TIP) for low data rate instruments, the Manipulated Information Rate Processor (MIRP) for high data rate AVHRR, digital tape recorders (DTR), and a cross strap unit (XSU).
High Resolution Infrared Sounder (HIRS/4) The improved HIRS/4 on the Advanced TIROS-N (ATN) NOAA K-N series of polar orbiting meteorological satellites is a 20-channel, step-scanned, visible and
infrared spectrometer designed to provide atmospheric temperature and moisture profiles. The HIRS/4 instrument is basically identical to the HIRS/3 flown on previous spacecraft except for changes in six spectral bands to improve the sounding accuracy. The HIRS/4 is used to derive
water vapor,
ozone, and
cloud liquid water content. The instrument scans 49.5° on either side of the orbital track with a ground resolution at nadir of 17.4 km. The instrument produces 56 IFOVs for each 1,125 km scan line at 42 km between IFOVs along-track. The instrument consists of 19 IR and 1 visible channel centered at 14.95, 14.71, 14.49, 14.22, 13.97, 13.64, 13.35, 11.11, 9.71, 12.45, 7.33, 6.52, 4.57, 4.52, 4.47, 4.45, 4.13, 4.0, 3.76, and 0.69 μm.
Advanced Microwave Sounding Unit (AMSU-A) The AMSU-A is an instrument on the Advanced TIROS-N (ATN) NOAA K-N series of operational meteorological satellites. The AMSU consists of two functionally independent units, AMSU-A and AMSU-B. The AMSU-A is a line-scan instrument designed to measure scene radiance in 15 channels, ranging from 23.8 to 89 GHz, to derive atmospheric temperature profiles from the Earth's surface to about 3
millibar pressure height. The instrument is a total power system having a
field of view (FOV) of 3.3° at half-power points. The antenna provides cross track scan 50° on either side of the orbital track at
nadir with a total of 30 IFOVs per scan line. The AMSU-A is calibrated on-board using a blackbody and space as references. The AMSU-A is physically divided into two separate modules which interface independently with the spacecraft. The AMSU-A1 contains all of the 5 mm
oxygen channels (channels 3–14) and the 80 GHz channel. The AMSU-A2 module consists of two low-frequency channels (channels 1 and 2). The 15 channels have a center frequency at: 23.8, 31.4, 50.3, 52.8, 53.6, 54.4, 54.94, 55.5, six at 57.29, and 89
GHz.
Microwave Humidity Sounder (MHS) The
MHS is a new instrument on the Advanced TIROS-N (ATN) NOAA K-N series of operational meteorological satellites. The
Microwave Humidity Sounder (MHS), built by
EADS Astrium and donated by the
European Organisation for the Exploitation of Meteorological Satellites (EUMETSAT), is a five-channel microwave instrument intended primarily to measure profiles of atmospheric humidity.
Space Environment Monitor (SEM-2) The SEM-2 on the Advanced TIROS-N (ATN) NOAA K-N series of polar orbiting meteorological satellites provides measurements to determine the population of the Earth's radiation belts and data on charged particle precipitation in the upper atmosphere as a result of solar activity. The SEM-2 consists of two separate sensors the Total Energy Detector (TED) and the Medium Energy Proton/Electron Detector (MEPED). In addition, the SEM-2 includes a common
Data Processing Unit (DPU). The TED uses eight programmed swept electrostatic curved-plate analyzers to select particle type and energy and
Channeltron detectors to measure the intensity in the selected energy bands. The particle energies range from 50
eV to 20 keV. The MEPED detects
protons,
electrons, and
ions with energies from 30 keV to several tens of MeV. The MEPED consists of four directional solid-state detector telescopes and four omnidirectional sensors. The DPU sorts and counts the events and the results are multiplexed and incorporated into the satellite telemetry system. Once received on the ground, the SEM-2 data is separated from the rest of the data and sent to the NOAA Space Environment Laboratory in
Boulder, Colorado, for processing and dissemination.
Solar Backscatter Ultraviolet Radiometer (SBUV/2) The
SBUV/2 on the Advanced TIROS-N (ATN) NOAA K-N series of polar orbiting meteorological satellites is a dual
monochromator ultraviolet grating spectrometer for stratospheric ozone measurements. The SBUV/2 is designed to measure scene radiance and solar spectral irradiance in the
ultraviolet spectral range from 160 to 406 nm. Measurements are made in discrete mode or sweep mode. In discrete mode, measurements are made in 12 spectral bands from which the total
ozone and vertical distribution of ozone are derived. In the sweep mode, a continuous spectral scan from 160 to 406 nm is made primarily for computation of ultraviolet solar spectral irradiance. The 12 spectral channels are (in nm): 252.0, 273.61, 283.1, 287.7, 292,29, 297.59, 301.97, 305.87, 312.57, 317.56, 331.26, and 339.89 nm.
Search and Rescue Satellite Aided Tracking System (SARSAT) The
SARSAT on the Advanced TIROS-N (ATN) NOAA K-N series of polar orbiting meteorological satellites is designed to detect and locate
Emergency Locator Transmitters (ELTs) and
Emergency Position-Indicating Radio Beacons (EPIRB). The SARSAT instrumentation consists of two elements: the Search and Rescue Repeater (SARR) and the Search and Rescue Processor (SARP-2). The SARR is a
radiofrequency (RF) system that accepts signals from emergency ground transmitters at three
very high frequency (VHF/
UHF) ranges (121.5 MHz, 243 MHz and 406.05 MHz) and translates, multiplexes, and transmits these signals at
L-band frequency (1.544 GHz) to local Search and Rescue stations (LUTs or Local User Terminals) on the ground. The location of the transmitter is determined by retrieving the Doppler information in the relayed signal at the LUT. The SARP-2 is a receiver and processor that accepts digital data from emergency ground transmitters at UHF and demodulates, processes, stores, and relays the data to the SARR where they are combined with the three SARR signals and transmitted via L-band frequency to local stations.
ARGOS Data Collection System (Argos DCS-2) The
Argos Data Collection System (DCS-2) on the Advanced TIROS-N (ATN) NOAA K-N series of polar orbiting meteorological satellites is a random-access system for the collection of meteorological data from in situ platforms (moveable and fixed). The ARGOS DCS-2 collects telemetry data using a one-way RF link from data collection platforms (such as buoys, free-floating balloons and remote weather stations) and processes the inputs for on-board storage and later transmission from the spacecraft. For free-floating platforms, the DCS-2 system determines the position to within 5 to 8 km RMS and velocity to an accuracy of 1.0 to 1.6 mps RMS. The DCS-2 measures the in-coming signal frequency and time. The formatted data are stored on the satellite for transmission to NOAA stations. The DCS-2 data is stripped from the GAC data by NOAA/
NESDIS and sent to the Argos center at
CNES in
France for processing, distribution to users, and archival. == Telecommunications ==