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Letter Report
Pages 1-17

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From page 1... ... Recently, due to budget and schedule constraints, your office began to consider modifications to the original mission concept and asked the CAA to assess the scientific merits of a descoped NGST with a 6-meter-class mirror. At its meeting on April 9-10, 2001, the CAA received presentations from the NGST project office; the AASC's Panel on Ultraviolet, Optical, and Infrared Astronomy from Space; Alan Dressler, chair of NASA's Origins subcommittee; and groups involved in large ground-based telescope programs that might have complementary near-infrared capabilities. Read the entire page →
From page 2... ... This change, according to the NGST project office, will reduce the level of technical risk by permitting active thermal control and improved dimensional stability of the telescope assembly. The increase in operating temperature will not affect the scientific performance of the observatory as specified in the original baseline design. Read the entire page →
From page 3... ... Kinney Presentation to CAA by NGST Project Office cc: Richard M McCray, Co-chair, CAA Wendy L Read the entire page →
From page 6... ... of how the SIM team plans to address the recent SIM replan imposed by the OSS. This replan entails a $930 M cost cap, the requirement that terrestrial planet detection be a key mission goal, and the requirement that SIM identify potential targets for TPF. Read the entire page →
From page 7... ... they are not able to demonstrate such performance, then a significant restructuring of the program or cancellation should be considered. NGST - Next Generation Space Telescope The OS was briefed by Project Manager Bernie Seery and Project Scientist John Mather on the project's proposed rescope, aimed at returning NGST to the intended budget and schedule and at eliminating the need for a full-up technology demonstration (the proposed Nexus) Read the entire page →
From page 8... ... From the point of view of continuity within the Origins program, NGST with mid-IR capability would provide a powerful scientific descendant of SIRTF, with an improvement of a factor of 7.5 in angular resolution and two orders of magnitude in sensitivity, and also provide a technology precursor for the proposed nulling interferometer design for TPF. Putting it all together, the OS believes that mid-IR science is very important for NGST, a substantial increase in science for a modest increment in cost. Read the entire page →
From page 9... ... Because the OS also strongly endorses their scientific goals, we are pleased that the Kepler program has been approved for Phase A study and that you have provided funding for technology development of the high contrast imaging required for a coronagraphic study of the nearest stars, as has been described in the Eclipse proposal. Given the renewed interest in using coronagraphy in the TPF mission, and the potential for excellent and relatively rapid science return in a mission like Eclipse, the OS recommends that the Origins theme continue to invest in developing this and related technologies. Read the entire page →
From page 10... ... 99 00 01 02 03 04 05 06 07 08 09 Select Prime PDR NAR CDR Launch 040901 CAA NGST Mather.ppt 3 040901 CAA NGST Mather.ppt 4 NGST at L2 halo orbit L5 Rescope Process • Driven by procurement process and design to cost - must have resources consistent with the purchase plan L2 L1 L3 • Initiated by Project Office last summer with detailed in-house Earth cost estimates of all parts of project, with schedules, PERT Sun charts, test plans, risk management plans, and budget and schedule targets L4 • Based on US-only cost analyses, but ESA and CSA have agreed in the past that our methods were close enough to theirs • Single sunshield protects from Earth and Sun • Main technical changes were to meet the following objectives: • 8-16 hour visibility from single ground station – Risk reduction without Nexus flight demonstration • Simple operations compared to HST – Launch by 2009 • 0.01 AU away, but not serviceable by astronauts • Hold schedule • Halo orbit around L2 avoids Earth shadow • robustness • Unstable orbit requires ~ 3 m/sec/year corrections – Compatible with more than one launch vehicle – Stay with core instrument complement and ASWG priorities preserve science program 040901 CAA NGST Mather.ppt 6 Read the entire page →
From page 11... ... RFP Package Meeting Final RFP Selection Phase 2 Limited subaperture testing • Allows control system to see April 9 April 28, observatory-level performance Mar 20-22, April 2001 Apr 2-4, 2001 2001 Jun 2001 Jan 2002 Feb 2002 vs full aperture plane wave substantial portion of full 2001 2001 confirmation (TBR) aperture 040901 CAA NGST Mather.ppt 7 040901 CAA NGST Mather.ppt 8 Rescoped NGST Eliminates Need for Nexus ASWG Prioritized Instrument Metrics Nexus Re-scope Risk Mitigation • Sensitivity Over Wide Fields of View Risk Mitigation – Discover faint new objects WFS/C performance in the space environment Increased WFS/C bandwidth & – Support General Observer science more robust design Observatory long-term imaging Wavelength Range stability in space Raise operating temperature to Fully utilize discovery enable active thermal control space Validation of integrated models Ensure widest possible and I &T approach redshift coverage Pre-launch system-level optical testing (designed for 1-G Spectral & Spatial Resolution Establish cost curve and develop testing) Read the entire page →
From page 12... ... 040901 CAA NGST Mather.ppt 16 Design Reference Mission 7 Core Programs Requirements • DRM contains the Dressler Report science • 1: 2 µm diffraction limited imaging, wide FOV, 8m • DRM does not preempt proposal process sensitivity, 0.6-5 µm • 23 large, critical science programs that could be • 2: 1-5 µm NIR multiplexed spectroscopy, R=100 carried out in ~2.5 years 3000; 5-10 µm spectroscopy, R=3000 • 7 Core Programs • 3: Wide FOV; stable psf – 1: Form. Read the entire page →
From page 13... ... 2 for dark current or read noise limit; linear if background limited • Conclusion for NGST: Design Reference Mission takes about 2-3x as long for 6.5 m, 48 Mpix NIRCAM as for 8 m with 64 Mpix 040901 CAA NGST Mather.ppt 19 040901 CAA NGST Mather.ppt 20 Rescoped Cameras vs. other observatories 25 m GSMT / 8 m NGST: spectroscopy (6.5m, 4´x4´ 48Mpixel NIRCam, 50K) Read the entire page →
From page 14... ... 5007 A is strongest metal line expected for z > 9, • Comparative planetology - Solar System objects falls beyond 5 µm for z > 9 versus observed disks, "loose planets" 040901 CAA NGST Mather.ppt 27 040901 CAA NGST Mather.ppt 28 International Partnership Concept Instrument Partnership Concepts • ESA ~$200M (FY96) value of effort, gains 15% • Current favorite idea, from Tripartite meeting 4/4/01: observing time on HST and NGST; ESA has – NASA to provide shared instrument services (electronics, approved funding subject to successful detailed plan thermal, data system, …) Read the entire page →
From page 15... ... (571 nm p-v; 63 nm rms) Gravity Corrected 040901 CAA NGST Mather.ppt 33 040901 CAA NGST Mather.ppt 34 Validation of SBMD Cryo-Null Figuring NGST Mirror Technology Development (0.571 µm p-v; 0.083µm rms) Read the entire page →
From page 16... ... model philosophy - Wavefront Control - WCT 3 complete; PRC complete by - Gov't will continue to further – Inability to achieve planned level of integration due to international Testbed completion May 2001 refine the testbed until NAR agreements • Science • International agreements have not yielded dollar-for-dollar savings - Revitalize Science - ISWG replaced ASWG in - First face-to-face meeting in Advocacy Group November/December of 2000 January 2001 040901 CAA NGST Mather.ppt 41 040901 CAA NGST Mather.ppt 42 Read the entire page →
From page 17... ... July 1998 NGST MONOGRAPH NO. 9 NGST • Science Next Generation Space Telescope Next Generation Space Telescope Project Study Office Optical Component and System Testing Strawman Plan Project Study Office By Goddard Space Flight Center – ISWG review of the degree to which science program has Goddard Space Flight Center The Optical Testing Study Team Next Generation Space Telescope Project Study Office March 2000 Goddard Space Flight Center been preserved in rescope Next Generation Space Telescope Project Study Office Goddard Space Flight Center 040901 CAA NGST Mather.ppt 43 030601_NGST_origins.ppt 040901 CAA NGST Mather.ppt 44 44 Biggest Worries • Cost growth in Phase B after teams are selected – Unknown unknowns – Would have to rescope again to meet budget • Bureaucratic obstacles – International collaboration difficulties – ITAR regulations • But: – NAS says this is top priority – Strong international desire to cooperate – Large Phase A technology investment by NASA – Adequate time to get ready for NAR 040901 CAA NGST Mather.ppt 45 040901 CAA NGST Mather.ppt 46 Points to Remember • Rescope restores an affordable program while preserving most of science program • NGST still essential 5 years after start, but advantage shifts to longer wavelengths • Phase A Studies complete and cost estimates sufficiently mature to warrant commencing Phase B immediately after downselect 040901 CAA NGST Mather.ppt 47 Read the entire page →

From page 1...

... Recently, due to budget and schedule constraints, your office began to consider modifications to the original mission concept and asked the CAA to assess the scientific merits of a descoped NGST with a 6-meter-class mirror. At its meeting on April 9-10, 2001, the CAA received presentations from the NGST project office; the AASC's Panel on Ultraviolet, Optical, and Infrared Astronomy from Space; Alan Dressler, chair of NASA's Origins subcommittee; and groups involved in large ground-based telescope programs that might have complementary near-infrared capabilities.

Letter Report Pages 1-17

Letter Report
Pages 1-17