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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