Space Agency (ESA), and one by Japan, each with
an international payload, and including both re
search and operational instruments for Earth ob
servations. The series of platforms, beginning
with the planned launch of EOS-A in 1997, will
operate in space for at least fifteen years.
NASA will also launch Earth-observing instru
ments during this period as attached payloads on
Space Station Freedom, and as a continuing
series of shuttle and Earth probe missions. As
an adjunct to the EOS mission, NOAA will con
tinue with provision of operational instruments
on its series of polar-orbiting satellites.
Coordination of instrument selection, mission
operations, and data policy for the interna
tional EOS mission is performed by the Earth
Observations International Coordination Working
Group (EO-ICWG) made up of representatives of
the four Space Station partners (NASA, ESA,
Japan, and Canada) and of the operational satel
lite meteorological agencies in the respective
countries (NOAA, Eumetsat, Japanese Meteorolog
ical Agency, and Canadian Atmospheric Environ
ment Service) . The major goal of the in
ternational program is to select, launch, and
operate an integrated mission payload for Earth
observations which will meet the EOS mission ob
jectives. A key element in meeting these objec
tives will be the provision of unrestricted,
low-cost, and timely exchange of data across in
ternational boundaries - an element in which
EOSDIS will play an essential role.
Within the international framework of the EOS
mission, NASA responsibilities include the NASA
platforms, NASA instruments on all EOS plat
forms, ground reception and level zero process
ing of data from NASA platforms, and delivery of
fully processed data to all users from NASA
instruments. NASA's primary objective for its
instruments, platforms, and data system is to
conduct a research and "prototype operational"
mission. Accordingly, data from research instru
ments determined as having operational potential
(prototype operational instruments) will be made
available to NOAA in near real-time and in a
manner permitting these instruments to be evalu
ated for future operational status.
Consistent calibration of EOS data and cross
calibration of EOS and non-EOS data are essen
tial to achieving the long-term scientific goals
of the mission. An integrated calibration
approach will be developed for EOS which will
include comprehensive pre- and post-launch
instrument calibrations and a well documented
and complete calibration history for the entire
mission. Scientific validation of processed EOS
data and products will also be essential to mis
sion success. The extensive activities required
to accomplish this validation on a global scale,
including aircraft, balloon, and ground-based
campaigns, require that many of these activities
be managed cooperatively with organizations ex
ternal to NASA's EOS program, i.e. through ac
tivities such as NASA's Research and Analysis
program, the U.S. Global Change Research Pro
gram, the International Geosphere Biosphere
Program, and others. Validation activities
within the scope of NASA's EOS program will be
those contained within investigations selected
through the EOS Announcement of Opportunity.
2 EOS INVESTIGATIONS
EOS data will be made available to all users
with no period of exclusive access (see section
4.2). In order to fulfill the objectives of the
global change program it will be essential for
EOS data to be as widely disseminated and uti
lized as possible. This will require the joint
efforts of diverse funding agencies and organi
zations to support the necessary research and
data analysis. The following sections discuss
the plans within the NASA EOS program to gener
ate validated data products for research use.
2.1 Types of Investigation
Three types of investigations have been provi
sionally selected by NASA for EOS: (1)
Individual scientists to be Team Member or Team
Leader on one of the teams formed to provide
scientific guidance for development of the NASA
Research Facility instruments, and to develop
processing algorithms for and to analyze and
interpret data from these instruments; (2)
Instrument investigations involving a group of
scientists in the provision of a scientific in
strument for flight on the polar platforms or as
an attached payload on Space Station Freedom,
with responsibility for the reduction, analysis,
and interpretation of the resulting data; (3)
Interdisciplinary investigations for analysis,
interpretation, and model development by a group
of scientists using data from EOS instruments.
Definition phase selections for the three cate
gories of investigation were made in February
1989 following receipt of responses to the in
ternationally coordinated EOS Announcement of
Opportunity. Final selection of NASA instru
ments for the first platform (EOS-A) is planned
for September, 1990. EOS investigators include
Instrument Principal Investigators and their Co-
Investigators, Facility Instrument Team Leaders
and Team Members, and Interdisciplinary Investi
gation Principal Investigators and their Co-
Investigators, a total of some 500-plus indi
viduals. The Principal Investigators and Team
Leaders, including designated representatives of
foreign facility instruments on NASA platforms,
comprise the Investigator Working Group (IWG), a
total of some 60-plus individuals.
2.2 EOS Investigator Roles
The EOS IWG is responsible for coordination of
the long term EOS data acquisition strategy
through provision of an EOS science and data re
quirements plan. They also provide advice to
the EOS project concerning the specification,
production, validation, archival, and dissemina
tion of the suite of standard data products that
are the EOS mission deliverables. Development
of science algorithms and software to generate
these standard data products is the responsibil
ity of the EOS scientists as part of their
selected investigations. Most of the algorithm
development will be done on Scientific Computing
Facilities (SCFs) provided locally to investiga
tors by the EOS program, which will also be used
for data analysis and model development using
EOS (and non-EOS) data. The standard product
algorithm software will be delivered prior to
launch by the investigators for integration and
implementation on the EOSDIS Institutional Data
Product Generation Facilities (IDPGFs). The
IDPGFs will then be responsible for routine gen
eration of the standard products. Development
of standards for algorithm software, data for
mats, and documentation, and procedures for con
tinued maintenance, validation, and upgrading of
the processing software, will require a close
working relationship between science investiga
tors and EOSDIS, for the entirity of the EOS
mission. A special panel of the IWG, the
Science Advisory Panel for EOS Data and
Information, has been formed to foster this
close working relationship. The Panel includes
non-EOS scientists in its membership and is
intended to be broadly representative of scien
tific researchers wishing to utilize EOS data.
3 EOSDIS ELEMENTS
3.1 System Architecture
The EOSDIS conceptual architecture is shown in
Figure 1. EOSDIS will provide capabilities for
command and control of the NASA polar platforms
and for command and control of all NASA payloads
including those on foreign platforms. EOSDIS
Distributed Active Archive Centers (DAACs) will
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