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Summary of Global Tropospheric Wind Sounder (GTWS) Technology

Roadmap

Ken Miller, Mitretek SystemsJune 23, 2003

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Agenda

• Purpose• Vital National Need• Multi-year Interagency Program

Recommendation• Status• Reference Designs• DWL Alternatives• Roadmap• Summary and Recommendations• Acknowledgments

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Purpose

• GTWS: Acquire global wind profiles• Roadmap: Focus GTWS activities• Draft roadmap submitted for NASA and NOAA

consideration• Based on multi-agency input• High level • Important unknown factors• Resource needs will vary widely depending on

approach and rate of technology progress

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Vital National Need

• Global winds are the number 1 unmet observational requirement for global weather forecasts (NPOESS IPO)

• NASA Earth Science Directorate plans include global tropospheric wind observation and assimilation

• Wind data will support missions of NOAA, NASA, DOD, FAA, FEMA, Department of Homeland Security

• Benefits to government, industry, and citizens include• Weather forecasting• Atmospheric and climate studies• Transportation• Air quality forecasting • Shipping• Agriculture• Construction

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Multi-year InteragencyProgram Recommendation

• Participating agencies• Prepare a long term plan• Define appropriate agency roles• Share funding, staff, and other resource

commitments• Share user benefits

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Status

• NOAA/NASA partnership since 2000• Guided by GTWS Executive Steering Committee

(GESC)• Investigate data acquisition• GESC action item to prepare this roadmap

• Data requirements • OSSEs

• Requirements validation • Benefit quantification• Favorable preliminary benefit-to-cost ratios

• Reference instruments and missions • Assess technology readiness• Support evaluation of alternatives• Preliminary cost estimates

• NASA Laser Risk Reduction Program (LRRP)

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Status (continued)

• Instrument activities • NASA, NOAA, IPO and others demonstrating ground

and airborne DWLs• IPO funding airborne work on calibration/validation

 

• Related international missions • Japanese National Space Development Agency

(NASDA) • European Space Agency (ESA)

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Status - Measurement Concept

7.7 km/s

400 km

585 km

414 km

290 km

290 km

45°

45°

7.2 km/s

HorizontalTSV

• Vertical resolution range gates• 45 o nadir angle• Scan through 8 azimuth angles• Fore and aft perspectives in TSV• Move scan position ~ 1 sec• No. shots averaged ~ 5 sec * prf• 4 ground tracks

Aft perspective

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Status - Instrument Concepts

Telescope with Sunshade

Radiator

Rotating Deck

Coherent

Direct

Belt Drive Radiator

Component Housing

Component Boxes

Note: Large solar arrays not shown

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Status - DWL Alternatives

• Each alternative has advantages• Direct detection• Coherent• Hybrid

• Hybrid combines complementary aspects of coherent and direct detection

• Possibly the most rapid and economical approach• May complicate mission and spacecraft issues• IPO is sponsoring a hybrid DWL feasibility study

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Status -Reference Designs

• Need space-qualified DWL capable of meeting data requirements

• Coherent and direct detection reference designs completed• Large and heavy spacecraft• Massive optical components• Very high electrical power consumption

• Hybrid• Promising point design supported by IPO• Reference design not completed

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Roadmap - Near Term Issues

• Technology development needed• Lasers• Detectors• Low-mass telescopes• Scanners• Momentum compensation

• Benefits and sensitivity to data requirements• Hybrid reference design• DWL alternatives - trade studies• Impacts on data products from atmospheric

properties, DWL alternatives, and spacecraft mechanics

• Calibration and validation

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Roadmap

• Time scale depends on • Funding and resource decisions• Technology advances

• Longest lead time estimates • Flight qualified lasers – 4 years • Electro-optic scanners (alternative to rotating

telescope scanners) – up to 6 years

• Laboratory, ground, air, and space demonstrations will reduce risk and cost

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Roadmap –Major Tasks and Phasing

No time scale assigned pending planning decisions

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Roadmap – Task Descriptions

1. GESC Oversight- coordinate interagency support and management

2. Data Requirements and Data Utility Preparedness• Benefits, sensitivity to data requirements• Data assimilation• Revised data requirements, if justified

3. Achieve Technology Readiness • Lasers• Detectors• Low-mass telescopes• Scanners• Momentum compensation

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Roadmap – Task Descriptions (continued)

4. Architecture- system engineering and architecture for optimal design and acquisition, e.g.• Trades between data requirements and technology • Hybrid reference design• Trades between DWL alternatives• Atmosphere and lidar models• Impacts on data products from atmospheric

properties, DWL alternatives, and spacecraft mechanics

• Calibration and validation

5. Ground Demonstration- prototype DWLs

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Roadmap – Task Descriptions (concluded)

6. Air Demonstration• Selected DWL approach • Variety of atmospheric conditions

7. Space Demonstration• Prove ability to meet data requirements from

orbit• Shuttle, International Space Station, DOD Space

Test Program mission, or other platform

8. Operational Mission• Acquire, launch, and operate end-to-end system• Produce and distribute data products• Orbit a second instrument, as required, to meet

temporal and spatial resolution requirements

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Lower Level RoadmapsTechnology Development Direct

DetectionCoherent Detection

Hybrid Detection

Laser X X X

Optical Filters X X

Pointing X X X

Detectors and Arrays X X

Photon Efficiency X X X

Tunable LO Laser X X

Autoalignment X X

Hybrid Ref Designs X

Hybrid Integration Designs X

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Roadmap - Preliminary Resource Estimates

• Cost estimates for internal government use• Depend on a wide range of contingencies• Inference from experience is not very

accurate

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Roadmap – First Cut Fraction of Relative Cost by Task

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Overs

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Require

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Tech

Readine

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Archit

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Groun

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os

Air Dem

os

Space

Dem

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Fra

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tota

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Summary and Recommendations

• Promising preliminary benefit to cost ratio• Requires technology advances• Architecture studies

• To drive future work• Potential savings on development, space

demonstration, and mission

• Interagency team• Near term activities

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Farzin Amzajerdian (NASA/LaRC)Robert Atlas (NASA/GSFC)Wayman Baker (NOAA/NWS)James Barnes (NASA/LaRC)David Emmitt (Simpson Weather Associates)Bruce Gentry (NASA/GSFC)Ingrid Guch (NOAA/NESDIS)Michael Hardesty (NOAA/OAR)Michael Kavaya (NASA/LaRC)Stephen Mango (NPOESS/IPO)Kenneth Miller (Mitretek Systems)Steven Neeck (NASA/HQ)John Pereira (NOAA/NESDIS)Frank Peri (NASA/LaRC)Upendra Singh (NASA/LaRC)Gary Spiers (NASA/JPL)James G. Yoe (NOAA/NESDIS)

Acknowledgments