GPM Global Precipitation Measurement

1. GPMGlobal Precipitation Measurement GPM Microwave Instruments Addition of High Frequency Channels August 30, 2001 Mark Flaming 301/286-7374 gilbert.m.flaming@gsfc.nasa.gov Goddard Space Flight Center

2. GPM Microwave InstrumentsDiscussion Topics • GPM Instrument Background - Salient Points from Briefing to Industry on 5/30/01 • Generalized Industry Response to RFI • Alternatives available to GPM for high frequency channels • Questions for the Workshop

3. GPM Microwave Instruments Salient Points from GPM Briefing to Industry May 30, 2001

4. GPM Microwave InstrumentsGPM Briefing to Industry Modest financial resources are available for instruments. • GPM described as a “Low Risk” program. • Technology used on TRMM provided acceptable results • There is limited need for new technology developments for GPM • Minor modification of existing instrument designs will be pursued, where appropriate, to reduce non-recurring engineering expenses • Multiple copies the same instrument design will be obtained, when possible, to minimize cost • Cost to the GPM Program will be a significant consideration in all Program decisions

5. GPM Microwave InstrumentsGPM Briefing to Industry Three Types of Instruments Under Consideration • Conical-scan microwave radiometer Anticipate placing on both • Core Spacecraft • Constellation Spacecraft • Nadir-viewing microwave radiometer Currently evaluating • Benefits of its use on the Core Spacecraft • Alternative designs • Narrow-beam, nadir-looking radar Investigating the cost and benefit for use on the Constellation Spacecraft

6. GPM Microwave InstrumentsGPM Briefing to Industry The Science Community is very satisfied with the TRMM Microwave Imager (TMI). Its characteristics provide a reference point for defining instrument characteristics for GPM. Significant characteristics of TMI include: • Conical-scan which provides constant ground spatial resolution (spot size) and constant incident angle • 36 km ground spatial resolution (IFOV-CT) at 10.65 GHz (from 350 km altitude) • Nadir half-cone angle of 49° • Channel set 10.65, 19.35, 37.0, 85.5 GHz H&V Pol, and 21.3 V Pol

7. GPM Microwave InstrumentsGPM Briefing to Industry GPM Capabilities desired in addition to, or in lieu of, those provided by TMI • The addition of a 150 GHz H&V Pol channel to the TMI channel set • Ground spatial resolution at least equivalent to that achieved by TMI at 350 km • Desired, as a minimum, for the Core spacecraft at 400 km • A goal for the Constellation spacecraft at ~600 km • Who provides momentum compensation (spacecraft or by the instrument) is currently an open issue • Industry comments requested

8. GPM Microwave InstrumentsGPM Briefing to Industry Modification of existing instrument design viewed as a cost-effective approach • Minimize expenditures on Non-Recurring Engineering • Substantial production experience for conical-scan designs provide confidence in: • cost estimates • performance projections • reliability of hardware • Relevant known examples include SSM/I, SSMIS, TMI, and possibly CMIS Are there others?

9. GPM InstrumentsGPM Briefing to Industry Current Plans for Acquisition - Key Dates • Request for Information • Released May 8, 2001 • Responses due June 22, 2001 • Multiple Phase B Studies • RFP Release Jan 2002 • Contract Award April 2002 • Contract period of performance concludes with PDR in Jan 2003 • Phase C/D Procurement • RFP Release Jan 2003 • Contract Award April 2003 • Instrument Delivery October 2005? DRAFT

10. GPM Briefing to IndustryDevelopment Schedule FY 3Q01 4Q01 1Q02 2Q02 3Q02 4Q02 1Q03 2Q03 3Q03 Program Milestone RFI Review RFI Response Finalize Instrument Requirements Mission Concept Selection Mission SRR HQs Review PDR DRAFT Briefing to Industry Phase B Studies RFP Release Proposal Prep Selection Contract Award Mid-Term Instrument PDR Phase B Contracts Phase C/D Procurement Requirements RFP Release Proposal Prep Ahead Selection C/D Contract Awd Plan Contract Performance

11. GPM Microwave Instruments Generalized Industry Response to RFI

12. GPM Microwave Instruments Industry Response to RFI Responses included: • Modifications to existing instrument designs TMI SSMIS -Adaptation of designs which are in development CMIS

13. GPM Microwave Instruments Industry Response to RFI TMI Modifications Existing TMI channel set includes: 10.65 (H/V), 19.35 (H/V), 21.3, 37 (H/V) and 85 (H/V) GHz The addition of 150 GHz channel was discussed in the response to the RFI, and can be added.

14. Current SSMIS channel set consists of 24 channels Ch 1-7: 50 - 60 Ghz Ch 8: 150.0 H Ch 9-11: 183.31 +/-1, 3, 6.6 Ch 12/13: 19.35 H/V Ch 14: 22.235 Ch 15/16: 37.0 H/V Ch 17/18: 91.655 H/V Ch 19-24: 60.792 +/- Potential GPM Channel Set Ch 1-7: 50 - 60 Ghz - Remove Ch 8: 150.0 H - Keep, add V-Pol? Ch 9-11: 183.31 - Keep? Ch 12/13: 19.35 H/V Ch 14: 22.235 Ch 15/16: 37.0 H/V Ch 17/18: 91.655 H/V Ch 19-24: 60.792 - Remove Also: - Add 10.65 H/V per RFI - Modify channel center frequencies and bandwidth GPM Microwave Instruments Potential SSMIS Modifications:

15. GPM Microwave Instruments Industry Response to RFI Applicability of NPOESS CMIS for GPM Why is it under consideration? • Delivery of first units should coincide with GPM need dates • Production cost  cost of modifications to TMI or SSMIS • All desired GPM channels will likely be included in channel set since measurement requirements extend from soil moisture to atmospheric water vapor • Aperture  2.0 m likely (which may be too large for the GPM Constellation Spacecraft launch vehicle) • Physical size may be difficult for GPM to accommodate

16. GPM Microwave Instruments Industry Response to RFI CMIS alternatives for GPM • Procure without modifications • Remove all channels but those desired

17. GPM Microwave Instruments Summary of Alternatives TMI derivative: High frequency channels must be added to TMI baseline design at additional cost SSMIS derivative : High frequency channels are included in SSMIS baseline design - anticipate nominal impact if they are required for GPM CMIS derivative : High frequency channels are included in SSMIS baseline design - anticipate nominal impact if they are required for GPM

18. GPM Microwave Instruments Questions for the Workshop

19. GPM Microwave Instruments Questions for the Workshop • Is the desire for the high frequency channels sufficient that GPM should incorporate them if there is a significant cost impact? • What channels and polarizations are important? If a derivative of the SSMIS is procured, should GPM invest significant additional funds to obtain 150.0 GHz V-pol in addition to the 150.0 GHz H-pol already present? • What are the requirements co-registration and alignment of measurements? Is it necessary to have multiple feedhorns for increased spatial coverage at the higher frequencies? e.g.