Organization: National Aeronautics and Space Administration (NASA)

Research Title: EOS Special Spacecraft

Funding Level (millions of dollars):

FY94 17.4
FY95 81.7
FY96 71.7

Committee on Environment and Natural Resources (CENR) Component:
(a) Subcommittee: Global Change Research Committee (100%)
(b) Environmental Issue: Climate change (100%)
(c) Research Activity: System structure and function: Observations (100%)

Organizational Components:
Flight Systems Division
Office of Mission to Planet Earth
NASA Headquarters
Washington, DC 20546

Point of Contact:
Cheryl Yuhas
Phone: 202-358-0746

Research Goals:
To build, integrate, launch, and operate various special spacecraft to provide data for application to a broad range of Earth system scientific problems. EOS Special Spacecraft

Research Description:
The special spacecraft program consists of the following elements: Tropical Rainfall Measuring Mission (TRMM), Clouds and Earth's Radiant Energy System (CERES)/Lightening Imaging Sensor (LIS) Follow-on, Stratospheric Aerosol and Gas Experiment (SAGE III) Flight of Opportunity (FOO), Active Cavity Radiometer Irradiance Monitor (ACRIM) FOO, Solar Stellar Irradiance Comparison Experiment (SOLSTICE) (FOO), SeaWinds, Altimeter (ALT)-RADAR 1, ALT-RADAR2, and ALT-LASER 1.

See the Research sheet for the program description for TRMM.

The instruments of the CERES investigation will provide the Earth Observing System (EOS) with an accurate and self-consistent cloud and radiation database. CERES will permit retrieval of cloud parameters in terms of measured areal coverage, altitude, liquid water content, and shortwave and longwave optical depths. LIS will investigate the global occurrence of lightening, its correlation with rainfall, and its relationship with the global electric circuit.

SAGE III will accomplish the following science objectives:

- Retrieve global profiles of atmospheric aerosols, ozone, water vapor, (NO)2, (NO)3, OClO, temperature, and pressure in the mesosphere, stratosphere, and troposphere,

- Investigate the spatial and temporal variability of the measured species in order to determine their role in climatological processes, biogeochemical cycles, the hydrologic cycle, and atmospheric chemistry,- Characterize tropospheric and stratospheric aerosols and upper tropospheric and stratospheric clouds, and investigate their effects on the Earth's environment, including radiative, microphysical, and chemical interactions,

- Extend the SAM II, SAGE I, and SAGE II self-calibrating solar occultation data set enabling the detection of long term trends,

- Provide atmospheric data essential for the calibration and interpretation/correction of other satellite sensors, including EOS and ground-based sensors.

The ACRIM experiment will sustain the NASA long-term solar luminosity database. Its primary objective is to monitor the variability of total solar irradiance with state-of- the-art accuracy and precision. SOLSTICE will provide precise daily measurements of the full disk solar ultraviolet (UV) irradiance. The sun's UV radiation is the dominant energy source to the Earth's atmosphere, where small changes in the radiation field have an important effect on atmospheric temperature, chemistry, structure and dynamics.

Program Interfaces:
CERES data has been requested for the international programs of the World Climate Research Program (WCRP), including the Tropical Ocean Global Atmosphere (TOGA) campaign, World Ocean Circulation Experiment, and the Global Energy and Water Cycle Experiment. All of the instruments investigations listed above will contribute to several important EOS mission objectives and help provide a better understanding of the extent, causes, and regional consequences of global climate change.

Program Milestones:
FY 94 plans were for EOS-ALT1 to be launched into a sun-synchronous polar orbit in 2002, with subsequent launches scheduled for 2007 and 2012. TRMM is scheduled for launch in August 1997. Launch dates for the FOOs are to be determined.

Policy Payoffs:
A better understanding of the extent, causes, and regional consequences of global climate change.