GPM 05/17/01 1 GPM Global Precipitation Measurement Overview May 17, 2001 Jim Adams 301/ Goddard Space Flight Center

GPM 05/17/01 2 US Const Evolution of International Precipitation Satellite Constellation EuroGPM-1 EuroGPM DMSP SSM/I Number of Satellites DMSP SSM/I DMSP SSMIS DMSP SSMIS NPOESS CMIS NPOESS CMIS AQUA AMSR ADEOS-II AMSR GCOM-B1 AMSR F/O 7 Years 90% Global Revisit Time (Hours) 24 Partner-1 Partner-2 3 NPOESS CMIS TRMM TMI + PR GPM Core TMI + DPR 8

GPM 05/17/01 3 GPM Feb ‘01 Reference Concept Core Satellite Dual Frequency Radar Multi-frequency Radiometer H2-A Launch TRMM-like Spacecraft Non-Sun Synchronous Orbit ~70° Inclination ~ km Altitude ~4 km Horizontal Resolution (Maximum) 250 m Vertical Resolution Constellation Satellites Multiple Satellites with Microwave Radiometers Aggregate Revisit Time, 3 Hour goal Sun-Synchronous Polar Orbits ~600 km Altitude OBJECTIVE: Understand the Horizontal and Vertical Structure of Rainfall and Its Microphysical Element. Provide Training for Constellation Radiometers. OBJECTIVE: Provide Enough Sampling to Reduce Uncertainty in Short-term Rainfall Accumulations. Extend Scientific and Societal Applications. Global Precipitation Processing Center Capable of Producing Global Precip Data Products as Defined by GPM Partners Precipitation Validation Sites Global Ground Based Rain Measurement

GPM 05/17/01 4 GPM Comparison to TRMM Global Precipitation Measurement Systematic Measurement Pre-Cursor ~3 hour Global Revisit Time, Goal Science Communities –Climatology –Climate Prediction –Hydro-meteorology –Oceans –Applications Validation Across All Latitudes 40 GB/day Data Products 600 kbps Data Streams Risk; Low -- All Elements Flight Proven Tropical Rainfall Measurement Mission 3 Year Mission +1 year wrap-up ~28 hour Tropical Revisit Time Science Communities –Climatology –Climate Prediction Validation of Tropical Rainfall 20 GB/day 100 kbps Data Streams Risk; Medium -- New Technologies & Development

GPM 05/17/01 5 Core TMI + DPR H2-A Part-1 Part-2 Euro GPM-1 Euro GPM-2 DMSP SSMIS DMSP SSMIS GCOM-B1 AMSR F/O US Const GPM Partners Diagram At the Center of GPM is a Critical Partnership with Japan NASA will Supply the Core Spacecraft and TMI+ NASDA will Supply the Rain Radar and Launch All other Adjuncts to GPM are pairs of Data Streams (DS) 2 DS from IPO 1 DS from NASDA 1 DS from NASA 2 DS from ESA/ESTEC* 2 DS from Additional Partners * Currently in Competition Global Coverage Revisit Time (TBR) 6 hrs 4 hrs 3 hrs 11 hrs

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GPM 05/17/01 7 Objectives of GPM Advanced Study Primary Goals –Define Mission Requirements –Examine Options –Define Partnerships –Gain Agency Approval to Proceed into Formulation with a Single Concept Complete an Independent Assessment (IA) –Options were Fully Explored –Sufficient Justification for Proceeding with the Recommended Option Select a Mission Concept and Proceed to MCR –Define Scope a Instrument Suite to Meet Science Requirements –Adequate Rationale to Selection Official to Begin Acquisition

GPM 05/17/01 8 Milestone Abbreviations: Formulation Plan FY01 FY02 FY03 Form. Start  Orbit Optimization Trades SRR Schedules Cost MCR  IA  Manpower Assess Technology AcqInstrument ØB’s Mission Design Revise Schedule Revise Cost Inst Acq Inst. DesignMeasurement Approach Spacecraft Accom. Assess L/V S/C Acq Acq. Approach SCR  System RqmtsSystem Definition Spacecraft Accom. Ground System Trades Science Program and Partner Definition Ground System Rqmts Element Rqmts Assess L/V  CSPDR  SWT - Science Working Team SCR - System Concept Review IA - Independent Assessment CS - Concept Selection SRR - System Requirements Review RR - Receiving Review PDR - Preliminary Design Review MCR - Mission Confirmation Review Mission Project Systems Measurement Spacecraft Gnd/Data Sys. Science  SWT  RR

GPM 05/17/01 9 System Engineering System Drivers/Inputs Scientific Objectives & Considerations Scientific Measurements Related Program Exp. IMDC Reference Concept Partner Considerations System Requirements Development Derivation Allocation Validation Cost Development Vendor Quotes Eng. Estimates Risk Management Plan Identification Analysis Mitigate Architecture Development Functional Description Operational Concept Physical Architecture Configuration Management Design Trades System Segment Element System Engineering Tools and Processes Provide Knowledge Base for Execution Independent Cost Assessments RAO IPAO?

GPM 05/17/01 10 GPM Trade Space Science Requirements & Partnership Development Systems Engineering & Systems Effectiveness Mission Architecture Measurement Approach –Radiometer(s) –Radar Ground and Data System Programmatic Considerations H2-A Dual Launch Configuration

GPM 05/17/01 11 Science Formulation Activities Encourage Participation via Workshops, AO’s & Colloquia –SWT Meetings, International Workshops –GPM Seminars Refine Primary Science Requirements Systematic Measurement Approach – Future Mission Scope Definition – Developing Operational Agency Involvement – Technology Roadmaps and Infusion Approaches Sensitivity Studies in Support of Trades –Define Impact of Data Gap’s –Assess Radiometer Approach

GPM 05/17/01 12 Measurement Approach Trades Radiometer(s) –Frequencies 10.7, 19, 22, 37, 85, ?? –Scan Method Conical vs Cross Track –Antenna Size Orbit Altitude Spatial Resolution Cost & Complexity –Technology Readiness Assessment –e.g., TMI, SSMI/S, CMIS, CMR/STAR Radar –Accommodations –Technology Readiness Assessment

GPM 05/17/01 13 TMI+ Status “TMI+” Nomenclature is Only Temporary Currently Seeking US Industry Ideas – http//nais.msfc.nasa.gov/cgi-bin/EPS/bizops.cgi?gr=D&pin=51#RFI – Results Due in Late June – Multiple Phase B Studies Planned to Start in January 2002, Phase C/D April 2003 Current Engineer’s Guess of TMI+ Functionality –10, 19, 22, 37, 85 GHz (V&H Polarization) –Conical Scanner –Hold Current TMI Spatial Resolution (minimum) Antenna Size (1.0m-1.5m) Driven By –US Constellation Satellite Altitude –US Constellation Satellite Mass & Volume Budget After Science Workshops Consider –150 GHz Channel Addition to TMI+ –Possible Auxiliary Single Channel Cross-Track Scanner Matched to DPR Footprint

GPM 05/17/01 14 Potentially Enhancing Technology Low-power Transceiver (Digital Rx includes GPS) Sensor Web “Smart node” Synthetically Thinned Array Radiometer Flight Dynamics –Constellation Management –Coverage Optimization with Non-controlled Resources Composite Propellant Tanks (reduce mass & debris casualty area) Composite Structure Autonomous Navigation (desire for orbit maintenance to  1 km) Design for Disposal –Controlled: develop independent system –Uncontrolled: eliminate titanium, stainless steel from spacecraft design Advanced Propulsion Techniques for Drag Makeup

GPM 05/17/01 15 GPM 3 hour Coverage w/o Drones Core, DMSP-F18, DMSP-F19, GCOM-B1, Megha-Tropiques

GPM 05/17/01 16 World-Wide Coverage Every 3 Hours Existing satellites are a good start, but there are large coverage gaps. The Challenge: GPM will not operate as a fixed constellation. Satellites at different altitudes move relatively; coverage varies. Satellites are not optimally spaced for adding “fill” satellites. Satellites added to fill gaps will overlap,“wasting” coverage. High resolution and coverage are competing objectives: –Good coverage with few satellites => high altitude, while –Good resolution with a small (aperture) instrument => low altitude. Other factors than coverage can drive orbit altitude and inclination.

GPM 05/17/01 17 Engineering Splinter Engineering Issues Session will Discuss –orbit and optimization alternatives: Tradeoffs in resolution, coverage, and revisits. –Dual Frequency Radar Status –Current Thinking about US GPM Microwave Radiometers Thursday, 1:40 PM, Room 2109