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The Bridge Between Research and Operations
Dave Jones
Stanley R. Schneider
Peter Wilczynski
Craig Nelson
This is the third in a series of articles on the National Polar-orbiting
Operational Environmental Satellite System (NPOESS). This month
we review the NPOESS Preparatory Project (NPP) that will be
flown as a precursor to POESS. NPP is the “Bridge” to span the
transition and reduce risk as the program moves from NASA research
to NOAA and DoD operations.
Introduction
More than 40 years after the launch of the first weather satellite
in April 1960, the United States is changing the way that environmental
satellites are acquired, managed, and operated. Weather forecasters,
scientists, and decision-makers are counting on the future converged
weather satellite system, the National Polar-orbiting Operational
Environmental Satellite System (NPOESS), to meet their needs
for Earth science data and information in the 21st Century.
NPOESS marks the transition from a time when polar-orbiting
weather satellites were operated by two separate government
agencies with separate missions to a modern cost-effective,
single operational environmental satellite system providing
global, simultaneous observation of the Earth system. NPOESS
builds on research and technology development by the National
Aeronautics and Space Administration (NASA) and will be operated
by the National Oceanic and Atmospheric Administration (NOAA)
and the Department of Defense (DoD) through an integrated program
office.
To ensure that the research to operations transition is successful
and that the best technology and instrument concepts meet both
weather and climate needs, NASA and the tri-agency NPOESS Integrated
Program Office (IPO) have partnered on the NPOESS Preparatory
Project (NPP). NPP is a unique satellite mission scheduled for
launch in October 2006 as a precursor to NPOESS. NPP serves
the complementary research objectives of NASA and the pre-operational
test objectives of the IPO. For NASA, NPP ensures continuity
of many of the critical climate data sets begun with the launch
of NASA’s Earth Observing System (EOS) Terra satellite in 1999.
For the IPO, NPP provides risk reduction for four critical sensors
that will be flown operationally on NPOESS several years later
and for the associated algorithms which convert the sensor measurements
into environmental data products. NPP also serves as an early
test of the NPOESS ground segments—command, control & communications,
and data processing and will provide access to data from the
next generation of operational sensors for early evaluation
by users. Early access and evaluation will ensure that data
from NPOESS will be incorporated into NOAA and DoD operations
soon after its availability.
Partnerships Pave the Way
NASA and NOAA have collaborated on the development and operation
of weather satellites in one of the most effective and beneficial
partnerships in the United States government for more than 40
years. That partnership continues with NPP.
Due to the importance of NPOESS to the military and civilian
communities, the partnering agencies in the IPO were directed
to undertake a robust risk reduction effort to help ensure success
of the program. Laboratory, airborne, and Space Shuttle-based
efforts were considered and incorporated into the risk reduction
plan. The most desirable approach was to actually test some
of the NPOESS developmental sensors on-orbit in a quasi-operational
environment. The IPO looked at the feasibility of flying some
of the NPOESS sensors on the last of the DoD Defense Meteorological
Satellite Program (DMSP) and NOAA Polar-orbiting Operational
Environmental Satellite (POES) spacecraft, but available space
for additional instruments, restricted fields of view, limited
onboard data systems, and costs were prohibitive for these 1970s
era satellites.
The NASA Earth Observing System satellites were designed to
further the study of the Earth’s systems and their interactions,
including global climate change, through the systematic study
of terrestrial, oceanic, biospheric, and atmospheric phenomena
from a variety of space borne platforms. EOS Terra was launched
in December 1999 to focus on land and ocean surface measurements;
EOS Aqua was launched in May 2002 to improve understanding and
prediction of the hydrologic cycle; and EOS Aura is scheduled
for launch in June 2004 to study the Earth’s ozone, air quality,
and climate. Originally, NASA planned for two successor flights
for each of these 6-year missions for a total of 18 years of
coverage. However, the program took a new direction in 1998
that led to a strategy of careful analysis of the data from
the first round of EOS missions before deciding which data sets
needed to be continued.
Renewed emphasis was put on partnering to transition these research
data sets to sustained monitoring programs within operational
agencies. This culminated in the NPOESS Preparatory Project,
the joint mission with the IPO to carry forward selected EOS
measurements while meeting the NPOESS risk reduction goals.
Dr. Ghassem Asrar, NASA’s Associate Administrator for Earth
Science says, “NPP represents an exciting opportunity for NASA
and NOAA to combine their organization’s strengths for the advancement
of both science and operational needs. NPP and NPOESS capitalize
on NASA’s observational breakthroughs with Terra and Aqua, and
NOAA and DoD’s sustained operational capabilities with POES
and DMSP, thus providing long-term, critical observations for
understanding climate change mechanisms as well as weather.”
The NPP program is jointly managed by the IPO and NASA while
responsibilities for the mission are shared between the parties.
NASA is responsible for:
n Mission systems engineering;
n Integration, and test;
n Development of the Advanced Technology Microwave Sounder (ATMS)
instrument;
n Spacecraft and integration;
n Launch vehicle and associated activities;
n Science Data Segment (SDS).
The IPO, together with the NPOESS prime contractor, Northrop
Grumman Space Technology (NGST), is responsible for:
n Visible/Infrared Imager Radiometer Suite (VIIRS);
n Cross-track Infrared Sounder (CrIS);
n Ozone Mapping and Profiler Suite (OMPS);
n Command, Control, and Communications Segment (C3S);
n Interface Data Processing Segment (IDPS);
n NPP mission operations.
NOAA’s National Environmental Satellite, Data, and Information
Service (NESDIS) is responsible for:
n Archive and Distribution Segment (ADS).
The ADS will provide users access to near real-time and archived
data from NPP.
Continuity of Data: The Basis for Climate Research
Remote sensing of the planet has generated science records that
now represent decades of continuous observations of the atmosphere,
oceans, and land. Much like a medical record in human health
care, this Earth “record” is essential to assemble and understand
the long-term history of the planet and its dynamic climate.
NPP will play a significant role in continuing and maintaining
the long-term Earth environmental data record into the NPOESS
era. NPP will be in orbit in advance of the expected end-of-life
of EOS Aqua (~2008), and should provide significant overlap
with the first NPOESS spacecraft. NPP will be an effective “bridge”
between the Terra and Aqua EOS missions and NPOESS with numerous
opportunities for cross-calibration and validation among existing
sensors and the advanced instrumentation for NPOESS.
For climate researchers, NPP and NPOESS will be the sources
for much of the satellite-derived climate data in the future.
Selected near real-time Environmental Data Records (EDRs) from
NPP and NPOESS will form the basis of Climate Data Records (CDRs).
The quality of these EDRs for climate research will be validated
during the NPP mission by NASA’s Science Data Segment (SDS).
NASA’s goal, through partnership with the IPO, is to maintain
the space-based climate record by having research-quality measurements
on operational environmental satellites. In the long-term, beyond
the EOS Terra and Aqua missions, NASA will rely on NPOESS for
systematic global mapping of the Earth’s surface at moderate
resolution. NOAA initiatives for use of NPP and NPOESS data
for climate monitoring will be the subject of a forthcoming
article in this series.
NPP Keystone Sensors
and Systems
The four instruments selected for flight on the NPP spacecraft
trace their heritage to NASA instruments on EOS Terra, Aqua,
and Aura, but push the technology envelope even further. The
following sensors are designed to perform imaging, atmospheric
sounding, and ozone monitoring functions and are identified
below:
VIIRS—Visible/Infrared Imager Radiometer Suite
The VIIRS imager on NPP is the follow-on instrument to the imagers
on DoD’s DMSP, NOAA’s POES, and the EOS Terra and Aqua satellites.
The constant resolution Operational Linescan System (OLS) imager
on the DMSP satellite contains only three channels; visible,
infrared, and a day/night band. The day/night channel detects
low levels of visible-near infrared radiance at night from sources
on the Earth’s surface, including clouds illuminated by moonlight.
Detection of these types of features can be critically important
for military operations. The OLS can also detect lights from
cities, towns, industrial sites, gas flares, heavily lit fishing
boats, and fires. This low-light capability will be carried
forward to VIIRS on NPP and NPOESS, but at a much higher horizontal
resolution than is currently available.
The VIIRS (being developed by Raytheon’s Santa Barbara Remote
Sensing (SBRS) Group, the same company that manufactured the
Moderate Resolution Imaging Spectroradiometer (MODIS) that is
on EOS Terra and Aqua) will fly on NPP as well as on all NPOESS
platforms. VIIRS will provide complete global coverage in one
day over the visible, short, mid-, and long-wave infrared regions
at horizontal spatial resolutions of 370m at nadir. In addition,
VIIRS will image at a near constant horizontal resolution across
its ~3000 km swath, a significant improvement over the Advanced
Very High Resolution Radiometer (AVHRR—on POES) and MODIS instruments.
VIIRS will produce environmental data such as sea ice, sea surface
temperature, ocean color, aerosols, albedo, cloud parameters,
vegetation, and surface type.
CrIS & ATMS—Atmospheric Sounders
The atmospheric sounders on NPP consist of the CrIS (Cross-track
Infrared Sounder) and the ATMS (Advanced Technology Microwave
Sounder). Together these make up the Cross-track Infrared and
Microwave Sounding Suite (CrIMSS). The suite will be used to
provide vertical profiles of atmospheric temperature, humidity,
and pressure from the surface to the top of the atmosphere.
The CrIS, a Michelson Interferometer-based sensor, is being
developed by ITT Aerospace of Fort Wayne, Indiana. CrIS will
succeed the Atmospheric Infrared Sounder (AIRS) which operates
on EOS Aqua and the operational High Resolution Infrared Sounder
(HIRS) on POES. As the follow-on instrument to AIRS, CrIS is
designed to provide vertical temperature profiles at 1°
K accuracy for 1 km layers in the troposphere, a standard currently
being achieved by AIRS globally and approximating the accuracy
of the data obtained from radiosondes, which are carried aloft
by weather balloons. Radiosondes collect critical weather information
through many atmospheric layers and are what world-wide weather
services have traditionally used to initialize their weather
forecast models.
The ATMS is a 22-channel passive microwave sensor that will
scan synergistically with CrIS and provide soundings even in
the presence of clouds. The ATMS is being built by Northrop
Grumman Electronic Systems (NGES) in Azusa, California as the
successor to the Advanced Microwave Sounding Units (AMSU which
have flown on NOAA satellites since the mid- 1990s and are currently
aboard EOS Aqua. By using state-of the-art technologies, the
functionality of three AMSU units (AMSU- A1, A2, and Microwave
Humidity Sounder-MHS) will be compressed into a single unit
with a payload mass savings of 100 kilograms.
Ozone Mapping & Profiler Suite
The Ozone Mapping and Profiler Suite (OMPS) on NPP consists
of two sensors; a nadir pointing scanner that will be used to
obtain measurements of the total column ozone and a limb scanner
which looks past the forward edge of the spacecraft to obtain
vertical profiles of ozone in the Earth’s stratosphere. Both
units operate in the ultraviolet (UV) portion of the spectrum.
The OMPS is being developed by Ball Aerospace and Technologies
Corporation in Broomfield, Colorado, the same company that built
the Solar Backscatter Ultraviolet Radiometer 2 (SBUV/2) instrument
that is on the NOAA POES. Heritage for the nadir total column
scanner goes back to the Total Ozone Mapping Spectrometer (TOMS),
which first flew on Nimbus-7 in 1978 and has been flown three
more times since then, as well as to the Ozone Monitoring Instrument
(OMI) that will fly on EOS Aura in June 2004. The TOMS has been
used to identify and monitor the changes in the ozone hole over
Antarctica. The technology for the limb-profiling unit is derived
from the Shuttle Ozone Limb Scanning Experiment (SOLSE) that
flew on NASA’s Space Shuttle missions STS-87 in 1997 and STS-107
which was lost tragically on February 1, 2003. The UV limb scanner
is intended to provide vertical profiles of ozone concentrations
for 3 to 5 km thicknesses of the atmosphere as compared to the
7 to 10 km thicknesses obtained from the SBUV/2 on NOAA POES.
Data collected by OMPS will help fulfill U.S. treaty obligations
under the Montreal Protocol to monitor ozone depletion in the
atmosphere and determine if synthetic chemicals are affecting
the Earth’s climate and its habitability.
NPP Spacecraft
The NPP spacecraft being developed by Ball Aerospace under contract
to NASA is a variation of Ball’s commercial spacecraft design
used by NASA in prior Earth Science missions such as QuikSCAT
(Quick Scatterometer) and ICESat (Ice, Cloud, and Land Elevation
Satellite). The launch is planned for October 2006 from Vandenburg
Air Force Base, California. A Delta II launch vehicle will be
used to inject NPP into an 824 km, sun-synchronous polar orbit
with a 1030 AM descending equatorial nodal crossing time. The
mid-morning crossing time was chosen to take advantage of minimum
cloud cover over land surfaces. Although average cloudiness
in the mid-morning differs little from the mid-afternoon, there
tend to be almost twice as many days with less than 10 percent
cloud cover in the mid-morning than mid-afternoon. The expected
mission duration for NPP is five years with 7.5 years of consumables
(i.e., fuel for orbital station keeping of +/-10 minutes of
equatorial nodal crossing time).
The satellite will be commanded from the NPP-NPOESS Mission
Management Center (MMC) in Suitland, Maryland. The MMC is the
heart of the NPOESS Command, Control and Communications Segment
(C3S), developed by Raytheon Space Systems in Aurora, Colorado.
Global, or stored mission, data will be down-linked at X-band
frequencies (8212.5 MHz) to a 13-meter ground receiving antenna
located at Svalbard, Norway. Unlike the SafetyNet communications
network that will acquire NPOESS data, NPP will have only one
data receiving station at Svalbard which is located at high
enough latitude (78 degrees north) to be able to “see” all 14
daily NPP satellite passes. Real-time data will also be broadcast
on a continuous basis via an X-band (7750-7850 MHz) High Rate
Data (HRD) link. Anyone with a ground station designed to receive
and process NPP data will be able to do so when the satellite
comes into range of the receiving antenna.
The global data will be transmitted from Svalbard within minutes
to the U.S. via a fiber-optic cable system that was completed
in January 2004 as a joint venture between the IPO, NASA, and
the Norwegian Space Centre. NPP will generate approximately
1.5 terabytes of data per day, which is similar to the current
data volumes from EOS Terra and Aqua. The four sensors on NPP
will provide 80 percent of the data rate assigned to all fourteen
sensors on NPOESS. This will be a significant step toward completing
the data handling processes needed to accommodate even more
data when NPOESS comes online.
NPP’s four sensors will also provide 25 of the 55 NPOESS Environmental
Data Records (EDRs). Once the data stream is in the U.S., the
Raw Data Records (RDRs) will be processed into Sensor Data Records
(SDRs) and EDRs by the Interface Data Processing Segment (IDPS),
also being developed by Raytheon Space Systems in Aurora, Colorado.
Raw Data Records (Level 0/1A) will be full resolution, unprocessed
sensor data, time-referenced, with earth location, radiometric
and geometric calibration coefficients appended, but not applied,
to the data. Sensor Data Records (Level 1B) will be full resolution
sensor data that are time referenced, earth located, and calibrated.
Environmental Data Records (Level 2) are fully processed sensor
data that contain the geophysical parameters or imagery that
must be generated as user products. All three levels of data
records (RDRs, SDRs, and EDRs) will be available to users.
Two IDPS systems will be installed to support NPP at operational
weather facilities (Centrals): NOAA’s NESDIS in Suitland, Maryland
for processing and distribution of data to civilian organizations;
and the Air Force Weather Agency (AFWA) in Omaha, Nebraska to
support the military. By the time the first NPOESS is available
for launch in late 2009, IDPS systems will also be located at
U.S. Navy facilities in Monterey, California and at Stennis
Space Center in Bay St. Louis, Mississippi. All records from
NPP will be archived by NOAA from which access can be obtained
by other agencies and the public.
Calibration/Validation:
Solid Support for Science
NPP has already passed important milestones on its path to the
launch pad. This includes a Critical Design Review in October
2003 for the systems and the overall mission and a successful
Mission Confirmation Review in the fall of 2003 that moved NPP
into the implementation phase. A calibration/validation plan
for NPP has been drafted and selected “ground-truth” assets,
such as the NPOESS Airborne Sounder Testbed, are already deployed.
A NASA NPP Science Team was competitively selected in September
2003 and had their inaugural meeting in November 2003. As the
“bridge” between EOS and NPOESS, NPP will provide “lessons learned”
and allow for any required modifications to hardware systems
or algorithms in time to support readiness for the first NPOESS
launch.
Continuity of data from EOS to NPOESS will require calibration
of the NPP instruments and validation of algorithms following
EOS-type approaches and cross-calibration of these instruments
on-orbit with the corresponding EOS instruments (e.g., VIIRS
and MODIS; CrIS and AIRS; ATMS and AMSU/MHS). NPP will allow
scientists to develop, evaluate, and modify NPOESS algorithms
using data collected by actual sensors on orbit instead of having
to approximate data through synthetic generation, as is usually
done for new sensors.
To facilitate these sensor calibration and algorithm validation
efforts, certain “ground-truthing” activities have been initiated
for programs such as EOS (e.g., MODIS) and the Sea-viewing Wide
Field-of-view Sensor (SeaWiFS). For example, in the area of
ocean color, these activities include the Marine Optical Buoy
(MOBY), coastal and island site augmentations of the Aerosol
Robotic Network (AERONET), calibration round-robins, bio-optical
and atmospheric field data archives, and development and evaluation
of in situ measurement protocols. Experience gained during these
programs has demonstrated that such calibration activities for
NPP and NPOESS will be essential for establishing algorithms
that meet science accuracy requirements; for conducting pre-launch
sensor characterization and post-launch validation; and to evaluate
on-orbit sensor performance.
Taking Research into Battle
A primary mission of NPP is to test and deliver high resolution
imaging and sounding data to operational users so that they
can familiarize themselves with the new capabilities and prepare
for NPOESS. The IDPS system at NESDIS will deliver more accurate
and timely data for use in NOAA’s numerical weather prediction
models that support a wide variety of civil applications. A
second IDPS system at the Air Force Weather Agency is intended
to provide direct support for military operations. But the military
is not waiting for the arrival of NPP to realize the benefits
of advanced remote-sensing technologies. For example, the Naval
Research Laboratory in Monterey, California has already processed
MODIS data from NASA’s EOS Terra and Aqua satellites. The data
provided time-critical information about sandstorms and water
clarity to U.S. forces operating in the Persian Gulf, Arabian
Sea, and Indian Ocean. This cooperation came about due to the
work done by the IPO, NOAA, NASA, and the DoD in planning for
NPP.
Despite the technological sophistication of today’s “smart”
weapons and support systems, all are impacted directly or indirectly
by weather and environmental situations. The data from NPP and
NPOESS will help shift the tactical and strategic focus from
“coping with weather” to “anticipating and exploiting” atmospheric
and space environmental conditions for worldwide military advantage.
For the warfighter, this should translate into more reliable
long-term planning, more efficient selection and use or performance
of weapon systems which are sensitive to weather, fewer aborted
sorties, reduced munitions expended and, most importantly, reduced
casualties. The improved capabilities from NPOESS for weather
“intelligence” will be explored further in the next issue.
NPP will provide significant risk reduction to the NPOESS mission,
important data continuity to NASA’s and NOAA’s climate mission,
and accelerate the delivery of improved data from advanced technologies
to users while facilitating user preparation for the NPOESS
era.
For more information about NPP visit these two websites: www.npoess.
noaa.gov and http://jointmission.gsfc. nasa.gov/.
About the Authors
Dave Jones is Founder, President and CEO of StormCenter
Communications, Inc. He is also President of the ESIP Federation
(esipfed.org) and Chairman of the Board for the Foundation for
Earth Science. He can be reached at: [email protected].
Stanley R. Schneider is the Associate Director for Technology
Transition and Senior NASA official at the NPOESS Integrated
Program Office (IPO) and can be reached at: Stanley.Schneider@noaa.
gov.
Peter Wilczynski is the NPP Program Manager at the NPOESS IPO
and can be reached at: Peter.Wilczynski@ noaa.gov.
Craig Nelson is the former Executive Director of the NPOESS
Integrated Program Office and can be reached at: [email protected].
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