PROGRAM TITLE: 	Earth Observing System (EOS)
ACTIVITY STREAMS: 	Observations, Process Studies, Integrative 
Modeling and Prediction, Assessment
SCIENCE ELEMENTS:	Climate and Hydrological Systems
				Biogeochemical Dynamics
				Ecological Systems and Dynamics
				Solid Earth Processes
				Solar Influences
				Data and Information Management

NATIONAL AERONAUTICS AND SPACE ADMINISTRATION


SCIENTIFIC MERIT:  EOS will provide an integrated, 
comprehensive measurement program for systematic observation of 
the whole Earth from space that will enable scientists to both 
monitor global change and study a wide range of processes 
governing the environment.  In particular, EOS will provide 
observations and focused research on:

1. Water and Energy Cycles
--	Cloud formation, dissipation, and radiative properties, 
	which influence response of the atmosphere to greenhouse forcing
--	Large-scale hydrology and moisture processes, including 
	precipitation and evaporation

2. Oceans
--	Exchange of energy, water, and chemicals between ocean 
	and atmosphere, and between the upper layers of the ocean and 
	deep ocean (includes sea ice deformation of bottom water)
--	Sources and sinks of greenhouse gases

3. Chemistry of Troposphere and Lower Stratosphere
--	Links to the hydrologic cycle and ecosystems, transformations 	
	of greenhouse gases in the atmosphere, and interactions inducing 
 	change

4. Land Surface Hydrology and Ecosystem Processes
--	Improved estimates of runoff over the land surface and into 
	the oceans
--	Sources and sinks of greenhouse gases
--	Exchange of moisture and energy between the land surface 
	and atmosphere
--	Changes in land cover

5. Glaciers and Polar Ice Sheets
--	Predictions of sea level and global water balance

6. Chemistry of the Middle and Upper Stratosphere
--	Chemical reactions, solar-atmosphere relations, and sources and 
	sinks of radiatively important gases

7.  Solid Earth
--	Volcanoes and their role in climate change.

EOS research will be accomplished, in part, through the flight 
of advanced research sensors on polar orbiting platforms and 
other low-altitude, Earth-orbiting spacecraft.  These satellites will 
provide global coverage to observe all land, oceans and atmosphere.  
This observing system will be operated for at least 15 years 
beginning in 1998.

EOS is based on a rich scientific heritage; each instrument 
type baselined for EOS has flown, or will fly, prior to EOS launch, as 
a satellite, Space Shuttle, aircraft, or balloon payload.  All the 
data will be reduced, analyzed, and made readily available to the 
EOS research community and others through the EOS Data and 
Information System (EOSDIS).

Scientific guidance of the development and deployment of EOS 
measurement capabilities is provided by selected interdisciplinary 
research teams and other scientific participants affiliated with and 
supporting each of the EOS instruments.  The scientists funded under 
the EOS are developing new models and extending the capabilities of 
those that now exist, as well as analyzing current data that 
contribute to global change research.  Their activities include 
developing conceptual, diagnostic, and predictive models along with 
data assimilation techniques for incorporating satellite and other 
data into such models.  Current benefits from EOS-supported 
research include the enhanced production and availability of key 
geophysical data sets from past and ongoing satellite observations 
and new modeling results.

EOS is the centerpiece of the Global Change Research Program (GCRP).  
As such, the EOS mission embraces the overall goal and addresses 
each of the three scientific objectives of the U.S. GCRP.  All of the 
scientific research elements of EOS have been selected through peer 
evaluation and have been reviewed by science advisory committees 
both at NASA and at the National Academy of Sciences.  The EOS 
mission was reviewed and endorsed by the Earth System Sciences 
Committee.  Appropriate agency, interagency, scientific, and 
international reviews have demonstrated that EOS is both 
scientifically and technically sound.

EOS activities include participation by NOAA, USGS, and DOE in 
the development and operation of the EOSDIS.  The NOAA Polar-
Orbit Earth Observation Mission is coordinated with EOS activities, 
and EOS will provide new instruments with operational potential.  
NOAA will sample data streams from EOS instruments, and 
incorporate selected units into their operational meteorological 
satellite program once they are deemed sufficiently reliable.

EOS has been planned and coordinated with the Earth 
observations programs of the European Space Agency (ESA), Canada, 
and Japan.  A coordinated set of platforms and payloads will be 
launched, and the resulting data will be fully exchanged.  
Instruments from ESA, France, Canada, and Japan are slated for 
flight on NASA EOS platforms.  NASA EOS instruments will also fly 
on Japanese Advanced Earth Observing System (ADEOS) platforms 
and the joint U.S-Japan Tropical Rainfall Measuring Mission (TRMM).
 
STAKEHOLDERS:  Overall activities are guided by recommendations 
of the interagency Committee on Earth and Environmental Sciences 
(Working Group on Global Change) , the relevant panels of the 
National Research Council (e.g., Climate Research Committee of the 
Board on Atmospheric Sciences and Climate, and the Committee on 
Global Change), and other committees which work to define the U.S. 
Global Change Research Program. On the International level, EOS has 
scientific linkages to projects of the World Climate Research Program 
(e.g., GPCP, GEWEX, ISCCP, ISLSCP, TOGA, and WOCE) and of the 
International Geosphere Biosphere Program (e.g., BAHC, GCTE, 
GLOBEC, IGAC, JGOFS, and LOICZ).  The EOS Program also sponsors 
NASA participation in climate impact assessments by 
the Intergovernmental Panel on Climate Change.  Japan and ESA are 
developing complementary programs, which together with EOS win 
make up the International Earth Observing System.
 
POLICY RELEVANCE: 	
		Primary: 	Climate Change Assessment

		Secondary: 	Global Warming
				Biogeochemical cycles (Water, C)
				Tropospheric greenhouse gases
				Ecological change and biodiversity
				Polar ice sheets and sea level
				Stratospheric ozone and UV-radiation
				Solid Earth (volcano impacts on)

PROGRAM CONTACT:	Ghassem Asrar
				Office of Mission to Planet Earth
				NASA Headquarters, Code YS
				Washington, DC  20546
				Tel: 202-358-0266
				email: G.ASRAR/Omnet
				email:gasrar@sedsparc.ossa.hq.nasa.gov/Internet