NOAA-N PRIME

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On February 4, 2009, the National Aeronautics and Space Administration
(NASA) is scheduled to launch the last of the Advanced Television
Infrared Observation Satellite (TIROS)-N spacecraft for the National
Oceanic and Atmospheric Administration (NOAA). Built by Lockheed Martin
Space Systems Company (LMSSC), NOAA-N Prime is the last in the K, L, M,
N and N Prime series of satellites. These satellites have served the
nation well since 1960, when the world's first weather satellite was
launched by the National Aeronautics and Space Administration (NASA).
 In 1978, TIROS-N was launched, revolutionizing weather satellite
capabilities.  NOAA has worked with NASA to continuously improve the
TIROS satellites, and in 1983 began the Advanced TIROS-N (ATN) program.
NOAA-N Prime carries a suite of instruments that provides critical
global data for weather and climate predictions.  Like its predecessors,
NOAA-N Prime will provide global images of clouds and surface features
and vertical profiles of atmospheric temperature and humidity for use in
numerical weather and ocean forecast models, as well as data on ozone
distribution in the upper part of the atmosphere, and near-Earth space
environments \-- information important for the marine, aviation, power
generation, agriculture, and other communities.  NOAA-N Prime is part of
the international satellite-aided search and rescue missions which have
been credited with saving over 22,000 lives since 1982.  NOAA is
dedicated to enhancing economic security and national safety through
research and prediction of weather and climate-related events and by
providing environmental stewardship of the nation's coastal and marine
resources. 

NASA builds and NOAA obtains funding for and operates the Polar-orbiting
Operational Environmental Satellites (POES) for the benefit of all. The
POES Project Office at NASA GSFC is responsible for the acquisition of
the NOAA-N Prime spacecraft and instruments for NOAA. A diverse
integrated Government and Industry team with international partners has
worked effectively for decades to ensure the economical, timely, and
successful delivery of a highly capable space and Earth environment
observing satellite system used to predict the weather and climate
change; protect life, property, and the world's vital interests;
America's safety and economic security; and enhance the global quality
of life.  The POES team includes thousands of people across the world
who dedicated a substantial portion of their careers to making this
program a success.

The primary mission of the POES system is to provide daily global
observations of weather patterns and environmental measurements of the
Earth's atmosphere, its surface and cloud cover, and the proton and
electron flux at satellite altitudes; and to establish long-term data
sets for climate monitoring, assessment, and change predictions. Since
the beginning of the POES program, environmental data and products
acquired by its satellites have been provided to users around the globe.
NOAA is responsible for the production of the various operational polar
data products that originate from the NOAA-N Prime instrument data after
NASA activates and evaluates the newly launched spacecraft and hands it
over to NOAA for operational use as NOAA-19.

## NOAA-N Prime INSTRUMENTS

**Advanced Microwave Sounding Unit (AMSU-A and MHS)**

NGES/EUMETSAT

The AMSU suite is a 20-channel scanning passive microwave radiometer.
AMSU-A uses 15 channels to provide data for vertical temperature
profiles and additional information on surface water and precipitation
to enhance sounding measurements. The MHS (Microwave Humidity Sounder)
provided by EUMETSAT, is a five-channel microwave radiometer for
measuring atmospheric water vapor. AMSU instruments provide the
capability for remote sensing of atmospheric and surface properties on a
global basis, as well as improving the detection of precipitation and
surface features such as ice and snow cover.

The AMSU-A is a microwave radiometer consisting of two separate units:
AMSU-A1 (Channels 3 to 15) and AMSU-A2 (Channels 1 and 2). The primary
purpose of AMSU-A is to obtain global temperature and humidity profile
data. AMSU-A Channels 3 through 14 sample the 50.3 to 89.0 GHz oxygen
band to provide data for a vertical temperature profile of the
atmosphere up to 48 km. The \"window\" channels 1 and 2 (23.8 -- 31.4
GHz), and 15, provide data that enhances the temperature sounding by
correcting for surface emissivity, atmospheric liquid water, and total
precipitable water. The AMSU-A1 instrument has two 6-inch diameter
antennas, and the AMSU-A2 instrument has one 11-inch diameter antenna.
Each antenna has a 3.3 degree nominal field of view at the half power
points, and provides a crosstrack scan of ±48.33 degrees about nadir
with a total of 30 earth fields per eight-second scan period. On-orbit
calibration is via internal warm load blackbody target and cold space
view.

The MHS is a five-channel self-calibrating microwave radiometer. It is
complementary to the AMSU-A, and flew for the first time on NOAA-18. Its
primary function is to provide global data on the atmospheric water
vapor profile as an essential input to the overall meteorological
models. Radiances from discrete levels of the atmosphere and the earth's
surface are detected via a scanning parabolic antenna, which directs the
associated frequencies to five radiometric channels -- H1, H2, H3, H4,
and H5. The output of these channels, as well as housekeeping
measurements, is processed by the Processing and Interface Electronics
(PIE). The resulting PIE telemetry is transmitted to the spacecraft
every scan period (2.67 seconds).

### Advanced Very High Resolution Radiometer (AVHRR/3)

**ITT**

The AVHRR/3 is a six channel cross track scanning imaging radiometer
operating in the visible, near infrared (IR), mid IR and far IR
wavelength regions. A sixth channel was added for near-IR data. This
channel, referred to as 3A, provides the ability to discriminate between
clouds and snow and ice. It is time shared with the previous channel 3,
now referred to as 3B. Operationally, channel 3A is active during the
daytime part of each orbit and 3B is active during the night time part
of each orbit. The scientific purpose of the AVHRR/3 is to examine land
surface imagery, cloud imagery, sea surface temperature, ice cover, snow
cover extent, vegetation index, land/water boundary, volcanic ash and
aerosol concentrations. Channels 1, 2 and 3A characterize radiance
whereas Channels 3B, 4 and 5 measure scene brightness temperature in
their respective pass bands.

### High Resolution Infrared Radiation Sounder (HIRS/4)

**ITT**

The HIRS/4 is a 20-channel infrared sounder consisting of one visible,
12 longwave IR, and 7 shortwave IR channels. The instantaneous field of
view (IFOV) and ground sample distance (GSD) for the HIRS/3 were 20 km.
The HIRS/4 flying on NOAA-18 (also on N Prime and MetOp-A) has a 10 km
IFOV with a 20 km GSD. This change was made to increase the number of
clear (i.e., cloud free) observations taken by the HIRS instrument. The
purpose is to examine atmospheric temperature profiles, ozone (total
column), cloud top height, surface albedo, water vapor profile, and sea
and land surface temperature.

### Solar Backscatter Ultraviolet Spectral Radiometer (SBUV/2)

**Ball**

The SBUV/2 is an operational spectrally scanning, nadir pointing remote
sensor. The instrument is designed to map, on a global scale, total
concentrations and vertical distribution of stratospheric ozone. The
SBUV/2 has the capability to measure the solar irradiance or atmosphere
radiance and continuously measure the earth\'s surface brightness
outside the ozone absorption band. The SBUV/2 provides estimates of the
global ozone distribution by measuring back-scattered solar radiation in
the ultraviolet Hartley-Huggins bands and produces radiometric data at
an average rate of 0.32 kbps.

### Space Environment Monitor (SEM)

**Assurance Technology Corporation**

The SEM is a multi-channel, charged particle spectrometer that measures
the population of the Earth's radiation belts and the particle
precipitation phenomena resulting from solar activity. The SEM-2
contains two separate sensors with a common Data Processing Unit (DPU).
The Total Energy Detector (TED) uses a programmed swept electrostatic
curved-plate analyzer to select particle type/energy and a channeltron
detector to sense/quantify the intensity of the sequentially selected
energy bands. The particles of interest range from 50 eV to 20 KeV. The
Medium Energy Proton Electron Detector (MEPED) senses protons,
electrons, and ions with energies from 30 KeV to several tens of MeV.
The MEPED utilizes solid-state nuclear detectors and appropriate
arrangements of moderating materials to establish the energy band
resolution.

**Advanced Data Collection System (A-DCS)**

**CNES/France/Thales**

The A-DCS is an environmental monitoring system that assists NOAA in its
overall environmental mission and supports the Global Atmospheric
Research Program. More than 2000 environmental platforms are located
around the Earth measuring such environmental factors as temperature,
pressure, and currents. Some of these platforms are immersed in a moving
fluid, such as the ocean and the atmosphere. These moving platforms,
buoys and balloons, provide additional environmental information on
velocity and direction of the ocean and wind currents. Another use of
these beacons is tracking migratory animals.

The A-DCS receives information from fixed and moving platforms,
processes it and transfers the data for storage by the spacecraft
recorders. These stored data are transmitted to a ground station during
station contacts and the RF signal from these beacons contains a Doppler
shift which allows the location of beacons to be determined. The ground
stations record and transmit the A-DCS data to the French Centre
National d\'Etudes Spatiales (CNES) and to service Argos in Landover,
Maryland. CNES is the responsible manufacturing, system engineering, and
data distribution agency for the A-DCS.

A wide variety of data collection platforms dedicated to environmental
study and protection collect and transmits data within the 401.610 MHz
receiver bandwidth. These platforms consist mainly of drifting and
moored buoys, subsurface floats, remote weather stations that serve
meteorological and oceanographic applications, fishing vessels for
fishing resource management, and tracking animals for biological and
species protection purposes. These platforms relay data such as
atmospheric pressure, sea surface temperature and salinity, surface and
subsurface ocean currents, sea and river levels, vessel positions, and
animal temperature and activity. The A-DCS onboard the satellite
collects the messages transmitted by these platforms, measures their
received frequency, time tags, demodulates and reformats the data and
retransmits them to the ground. The data is transmitted in real time
along with the High Resolution Picture Transmission (HRPT) data and is
also stored onboard for later transmission from the satellite.

The stored data is transmitted once per orbit to NOAA Command and Data
Acquisition (CDA) stations primarily at Wallops Island, Virginia and
Fairbanks, Alaska, and then relayed to Argos ground processing centers
in Largo, Maryland and Toulouse France for data processing and
dissemination. EUMETSAT will also be receiving NOAA-19 data at Svalbard
Norway. The ground processing centers process the frequencies measured
onboard the satellite to locate the mobile platforms using the Doppler
Effect. Location accuracies range from 150-1000 m. For special
applications, Global Positioning System fixes included in the messages
sent by the platforms also help obtain better accuracy for regular and
frequent locations.

POES satellites prior to N-Prime carry the Data Collection System-2
(DCS-2) which differ significantly from the A-DCS in design and
operation. In addition to the capabilities of the previous Data
Collection Systems, the A-DCS has a down-link transmitter (TXU). The
function of the TXU is to transmit messages to beacons on the ground. In
general these messages are commands to a beacon to modify the beacons
performance in some manner. In addition, the A-DCS is capable of
receiving and processing messages from the next generation of beacons
currently under development.

**Search and Rescue Satellite Aided Tracking (SARSAT)**

**Search and Rescue Repeater (SARR) Canada/EMS**

**Search and Rescue Processor (SARP) CNES/France/Thales**

NOAA-N Prime, along with Russia's Cospas spacecraft, are part of the
international Search and Rescue Satellite-Aided Tracking System, called
COSPAS-SARSAT. This system uses a network of satellites to quickly
detect and locate distress signals from emergency beacons on board
aircraft and boats and from handheld personal locator beacons (PLBs).
After 25 years of operation, COSPAS-SARSAT has been credited with more
than 24,500 rescues worldwide, including more than 5,949 in the United
States and its surrounding waters. 

The SAR Instrument Package on the POES Satellites carries a SARR for
receiving and re-broadcasting the 406 MHz signals to a ground station
where they can be detected and located by measuring their Doppler shift.
In addition to the SARR, the current NOAA satellite SAR Instrument
Package carries a 406 MHz processor which receives transmissions from
406 MHz emergency transmitter beacons, recovers their digital message,
measures the Doppler shift, and both stores the data for later
transmission and transmits it in real time. This system is designed to
be compatible with the satellite and the system provides full global
coverage. NOAA-N Prime caries an improved version of the SARP-2 406 MHz
processor designated SARP-3. This unit has improved performance in
system capacity, bandwidth, and protection against interference. The SAR
Instrument Package for the NOAA-N Prime spacecraft consists of antennas,
diplexer, filters, a SARR, and a SARP-3.

The SARP-3 provides stored data interleaved with the real-time data sent
through the downlink transmitter. The SARR transmitter outputs real-time
SARP-3 data and data stored in the SARP-3 memory. This data output
consists of a Doppler frequency measurement, appropriately time-tagged,
and includes the SAR data message from Emergency Locator Transmitters
carried on aircraft or from Emergency Position Indicating Radio
Beacons**.** For the regional coverage mode, real-time data are
transmitted to a Local User Terminal (LUT) via the SARR downlink. Global
area coverage is provided by storing global data in a 406 Processor
memory. These data are transmitted to a LUT via the SARR downlink, but
only during times when there is no real-time data to be transmitted.

The SAR instruments are part of the international COSPAS-SARSAT system
designed to detect and locate Emergency Locator Transmitters (ELTs),
Emergency Position Indicating Radio Beacons (EPIRBs), and Personal
Locator Beacons (PLBs) operating at 121.5 MHz, 243 MHz, and 406 MHz.
Starting in February 2009 the 121.5 MHz and 243 MHz beacons will no
longer be supported by the COSPAS-SARSAT system and are not expected to
be activated on the NOAA-N Prime spacecraft. PLBs are portable units
that are designed to be carried by a person and must be activated
manually. Some newer PLBs allow Global Positioning System (GPS) units to
be integrated into the distress signal so that you can be located within
100 meters as opposed to within 2-3 miles. To learn more about this very
successful international search and rescue system please visit the
<http://www.sarsat.noaa.gov/> web site.

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**Supplemental Information**

NOAA-N Prime has a new Advanced Data Collection and Location System
(A-DCS) Antenna (ADA), an improved search and rescue processor (SARP)
system, and an updated Inertial Measurement System (IMS) with Ring Laser
Gyros. The activation phase begins at launch and continues for
approximately 21 days. The primary goal during the first 100 hours is to
establish the spacecraft bus functional operability. During this period,
most instruments will be either off or in a standby mode, i.e., not
transmitting data. By the end of the activation phase, all instruments
will be on. The evaluation phase starts at handover from NASA to NOAA
and lasts until approximately 45 days after launch. This phase will
characterize the performance of subsystems and instruments, which will
be functionally tested and assessed for compliance with performance
specifications. System performance will be evaluated on how well NOAA-N
Prime supports instrument requirements; maintains earth pointing;
provides electrical power for all sun angles; collects, stores and
transmits instrument and spacecraft data; receives commands and executes
valid stored and real-time commands; collects, stores and transmits
telemetry data over communication links; and maintains spacecraft
components within specified temperature limits.

The Attitude Determination and Control Subsystem (ADACS) performs
initial acquisition and control of spacecraft attitude. The ADACS
provides closed loop maintenance of the local vertical and orbit normal
after separation from the launch vehicle. In addition to damping
separation rates, the ADACS performs in deployment mode to maintain
local vertical orientation/orbit normal during spacecraft appendage
deployments. It provides reacquisition of the local vertical and orbit
normal if required. The ADACS maintains three-axis control of the
spacecraft within attitude and rate requirements, and provides on-board
attitude determination solutions which can be further refined on the
ground. The ADACS provides momentum unloading, using magnetic coils,
nitrogen thrusters, or both. The ADACS consists of four reaction wheels,
redundant roll/yaw coils, redundant pitch coils, one earth sensor (with
redundant electronics), one sun sensor, and a redundant IMS.

The Reaction Control Subsystem (RCS) provides control authority during
separation and deployments when commanded by the ADACS. The RCS becomes
active 10 seconds after separation from the launch vehicle. The RCS can
provide reaction wheel momentum management as a back-up to the primary
unloading provided by the magnetic torquing coils or at any time large
attitude disturbances occur that would otherwise overwhelm the momentum
wheels. The RCS remains active until placed into a stand-by mode when
the spacecraft is handed over to the nominal on-obit ADACS operations
mode.

The Communications Subsystem (CS) receives and demodulates ground
commands to the spacecraft and transmits spacecraft data to ground
stations. The CS consists of three data transmitters in the
meteorological S-band (STX1, STX2, and STX3), one launch telemetry
transmitter in the Air Force Satellite Control Network band (STX4), two
Very High Frequency (VHF) real-time Automatic Picture Transmission (APT)
Transmitters (VTXs), two VHF Beacon Transmitters (BTXs), four S-band
Omni-telemetry Antennas, two S-band omni-command antennas, a beacon
antenna, an Ultra high frequency Data Collection System Antenna (UDA), a
diplexer for coupling received signals to both the A-DCS and SAR
Processor (SARP-3), a SAR Receiver (SARR) Receiver Antenna (SRA), and a
SARR L-band transmitter antenna.

The Command and Control Subsystem (C&CS) controls the spacecraft
attitude and operating modes in orbit. This control is exercised by
using commands and data from the ground, and signal data from the
onboard subsystem. The C&CS consists of Redundant Crystal Oscillator
(RXO), Controls Interface Unit (CIU), Central Processing Unit (CPU) 1,
CPU 2, Signal Conditioning Unit (SCU), CIU Annex (CXU), and Decryption
Authentication Unit (DAU).

The Data Handling Subsystem (DHS) processes and formats all housekeeping
telemetry data and all payload data with the exception of the SARR. The
DHS has the following components: TIROS Information Processor (TIP),
Advanced Microwave Sounding Unit (AMSU) Information Processor (AIP),
Manipulated Information Rate Processor (MIRP), Digital Data Recorders
(DDRs), the Cross-Strap Unit (XSU) and the MIU.

The Electrical Power Subsystem (EPS) is based on the principle of direct
energy transfer from the solar array. It implements a centralized
regulation concept utilizing partial shunts on an electrically segmented
solar array during orbit day, and a multi-phase boost regulator during
orbit night. It consists of a single-wing, sun-oriented solar array to
convert solar radiation into electrical energy. Some of the array power
is stored in the batteries, via the Battery Charge Assembly (BCA), which
supply power through the Boost Voltage Regulator (BVR) to the loads
during orbital eclipse and during the periods when the load power demand
exceeds the solar array capability.

Deployment mechanisms and electromechanical devices include the Solar
Array Drive (SAD) and its electronics, as well as the deployment
mechanisms for the solar array, VHF Real-time Antenna (VRA), UDA, SRA,
Instrument Mounting Platform (IMP) sunshades, and the new ADA.