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Mission Design
Instruments: L band active/passive with shared 6-m rotating antenna
Polarization: H, V, U (radiometer) HH, VV, HV (radar)
Accuracy: 0.5 dB (radar), 1 K (radiometer)
Resolution: 3 km (radar), 40 km (radiometer)
Orbit: 6 am/pm sun-synch at 670 km; wide swath (1000 km) at constant look
angle of 39° Revisit: 2-3 days (mid-lat.), 1-2 days (polar)
Bus: Spectrum Astro SA-200HP
Power: 1283 Watts EOL Mass: 627 kg Data Rate: 31 Mbps peak; 26 Mbps average
Telecom: S- and X-band
Science Return Hydros Was to Deliver the First Global Views of the Earth's Water Cycle State: Soil Moisture Content and Freeze/Thaw Soil Moisture is a Variable That Links the Global Water, Energy and Carbon Cycles |
Applications Return Hydros Was to Open a New Era in the Capability to Predict Costly Natural Hazards (Extreme Rain, Floods, Droughts) Initialization of the Soil Moisture State in Numerical Models With Observations Extends the Predictability of Processes Influenced by Surface Fluxes |
National Security Return Hydros Was Going to Make Global All-Weather Mapping to Support Military Decision Makers Air Force: Low-Level Fog and NWP |
Mission Statement
The Hydrosphere State (Hydros) mission was going to provide the first global view of the Earth’s changing soil moisture and land surface freeze/thaw state. These together define the land hydrosphere state.
Knowledge of the land hydrosphere state is vital to understanding the Earth
system cycling of water, energy, and carbon. (See http://watercycle.gsfc.nasa.gov/)
Fluxes of these quantities over land are strongly influenced by a surface resistance
that is dependent on the soil moisture and surface freeze/thaw state. This resistance
exerts the dominant control on evaporation, transpiration, and carbon exchange
over most of the global land surface and is a fundamental determinant of the global
water, energy and carbon cycles.
Currently, there are neither space-borne nor in situ networks of measurements
that can provide a characterization of the global hydrosphere state. The new and
unique Hydros data was going to yield large science and application gains, with breakthroughs
in understanding of processes linking the water, energy, and carbon cycles.
Hydros data was to be used in weather and climate prediction where initialization
of models with hydrosphere state measurements has been shown to bring significant
improvements in forecast accuracy and reliability. Hydros observations were going to also
benefit climate-sensitive socioeconomic activities (water management, agriculture,
and fire, flood, and drought hazards monitoring) by extending the capability to
predict regional water availability and seasonal climate.
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