ment data). Routine processing of EOS data to 
level two (swath-oriented geophysical products) 
and above will be done according to science 
requirements developed or approved by the IWG. 
Data from foreign instruments on NASA platforms 
will be transmitted to ground via TDRSS, pro 
cessed to level zero, and made available for 
pick-up by the foreign agency. Likewise, data 
from NASA instruments on foreign platforms will 
be downlinked by the foreign agency, processed 
by them to level zero, and made available for 
pick-up by NASA for further processing in 
EOSDIS. Raw data from NASA prototype opera 
tional instruments will be made available to 
NOAA for pick-up at the TDRSS White Sands Ground 
Station. Plans are also in progress to develop 
an X-band direct downlink capability for the 
NASA platforms in addition to the primary TDRSS 
downlink. This direct downlink system will pro 
vide the capability for transmitting a pre 
selected EOS data stream in real-time to 
receiving stations worldwide in support of field 
experiments, real-time needs, and special 
international requirements. The data rate 
capacity (between 10 to 100 Mbps) and other 
operating characteristics of this system are 
still under consideration. 
4.2 Data Policy and User Access 
EOS data and products generated in EOSDIS will 
be made available immediately upon acquisition 
and processing to all users. There will be no 
period of exclusive access. EOSDIS will provide 
the capability for archiving and making avail 
able all standard science data products, models, 
algorithms, and documentation produced by EOS 
investigations. In addition, all data products 
derived from EOS data upon which referreed arti 
cles are based, including associated models, 
algorithms and documentation, will be made 
available for archival in EOSDIS. 
Under current policy it is envisaged that there 
will be three basic categories of EOS data 
users: research users (including U.S. government 
sponsored and other research users); operational 
agency users (e.g. NOAA); and others (primarily 
commercial users). Specific policies for access 
to EOS data are still under negotiation, and may 
be for some time, however the following defini 
tions and arrangements are currently planned: 
(1) Research users are those who agree to pay 
the nominal incremental costs to the EOS project 
of reproducing and delivering the data 
requested, and who agree to sign a "research 
agreement" that: they will publish in the open 
literature results of research based in whole or 
in part on data obtained from EOS including 
derived data sets and the algorithms and models 
used; they will provide a copy of such results 
to the distributing agency at the time these re 
sults are published in the open literature; the 
data seta are for the researcher's use and for 
bona-fide research purposes only; and the data 
will not be reproduced or distributed to any 
other parties without the other parties agreeing 
to the same conditions. Research users will in 
clude those affiliated with EOS participating 
countries (i.e. US, ESA member states, Japan, 
Canada, and any country which the ICWG agrees 
should have special privileges in exchange for 
some contribution "in kind", such as countries 
participating in complementary in situ studies 
and agreeing to open exchange of data) . Users 
from other countries, whether researchers or 
not, will have access to EOS data but on commer 
cial terms. (2) Operational agency users (e.g. 
NOAA, EUMETSAT) will obtain real-time access to 
data from instruments of interest through their 
own direct readout facilities and/or via 
national agency data relay satellites. NOAA 
will perform its own data processing and will 
maintain its own archive for these data. Non- 
real-time access to EOS research data will be 
provided by EOSDIS at the incremental cost of 
reproduction and delivery and will be subject to 
the terms of the research agreement. (3) NASA 
will develop a procedure, consistent with the 
Land Remote Sensing Commercialization Act or 
other applicable statutes, for commercial 
distribution on a non-discriminatory basis to 
non-research/non-operational users. 
5 IMPLEMENTATION APPROACH 
Development of EOSDIS is managed by the EOS pro 
ject at the Goddard Space Flight Center. Two 
parallel Phase B studies have recently been com 
pleted (April 1990) with industry teams led by 
TRW and Hughes Aircraft Company. These studies 
resulted in detailed-level requirements and pro 
posed architectures and designs for EOSDIS. The 
results are currently being integrated and a 
request for proposals will shortly be issued 
(-Spring, 1991) for the Phase C/D final design 
and development (contract award -mid-1992). 
The IWG Science Advisory Panel for EOS Data and 
Information has met several times during the 
past year to review the progress of EOSDIS 
development. In their reports the panel has 
stressed the need for an EOSDIS implementation 
approach that provides continuity with present 
systems, an evolving design and architecture, 
and perhaps most importantly the need for par 
ticipation of scientists in EOSDIS development. 
EOS data will provide a continuation of existing 
measurements some of which currently extend for 
more than a decade. Thus, work is beginning now 
to involve scientists in the development of cur 
rent and historical "pathfinder" data sets, so 
that the EOS community can gain experience in 
data processing (or reprocessing) , archiving, 
and distribution in the mode anticipated for the 
EOS era. Examples of such pathfinder activi 
ties, underway or planned, include the process 
ing of data from ERBE (Earth radiation budget), 
CZCS (global ocean chlorophyll), SSM/I (sea ice, 
hydrology), TOMS (ozone), AVHRR (sea surface 
temperature and vegetation index), ISCCP (cloud 
climatology), GOES (cloud winds), and TOVS 
(atmospheric profiles). NASA plans to increase 
the number of these activities in the coming 
years, under EOSDIS auspices, in order to gain 
experience in prototyping the EOSDIS DAAC design 
and operations. 
Precursor missions to EOS will offer special op 
portunities to put in place and test the infras 
tructure and standards that will be required for 
EOSDIS. In addition, NASA has under development 
a number of cataloging, archiving, and distribu 
tion systems such as the NASA Ocean Data System, 
NASA Climate Data System, Pilot Land Data 
System, SAR Data Catalog System, Alaskan SAR 
Facility, NASA Master Directory, and others, 
which serve to manage many of the current NASA 
Earth science data sets. NASA is also cooperat 
ing actively with agencies such as NOAA, the 
U.S. Geological Survey, the European Space 
Agency, and others to prototype data exchange 
formats, software and documentation standards, 
and electronic network connections for science 
user access. EOSDIS will provide a focus for 
integrating these activities and incorporating 
the successful elements into the EOSDIS design. 
It is essential that EOSDIS be designed with an 
open system of standards and protocols for all 
functions. This is necessary to enable modular 
growth and upgrades of EOSDIS during the mission 
and to facilitate software portability and data 
interchange between investigators and with 
EOSDIS. Emphasis will be placed by EOSDIS on 
working with existing international standards 
organizations, such as the American National 
Standards Institute (ANSI), the Committee on 
Earth Observations Satellites (CEOS), the 
Consultative Committee on Space Data Standards 
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