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Justin Kasper CRaTER Instrument Scientist Boston University

Cosmic RAy Telescope for the Effects of Radiation (CRATER) Spacecraft Requirements Review Presentation August 2005. Justin Kasper CRaTER Instrument Scientist Boston University. CRaTER Organization Chart. Theory of Operation. Pairs of thin and thick Silicon detectors.

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Justin Kasper CRaTER Instrument Scientist Boston University

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  1. Cosmic RAy Telescope for the Effects of Radiation(CRATER)Spacecraft Requirements Review PresentationAugust 2005 Justin Kasper CRaTER Instrument Scientist Boston University

  2. CRaTER Organization Chart

  3. Theory of Operation Pairs of thin and thick Silicon detectors A-150 Human tissue equivalent plastic (TEP)

  4. Moon D6 D5 A2 D4 D3 A1 D2 D1 Space Theory of Operation • Energetic charged particle enters the telescope • Particle deposits energy in components through ionizing radiation • Nuclear interactions produce energetic secondary particle • Primary and secondary particles interact with one or more detectors • Thin detectors respond to high LET particles • Thick detectors respond to low LET particles • Detectors with sufficient energy deposition cross trigger threshold • Digital logic compares coincidence with event mask of desirable events • Pulse height analysis (PHA) is conducted on every detector to measure energy deposition

  5. Heritage • CRaTER is not directly derived from an existing instrument. • The three teams (BU, MIT, Aerospace) with engineering tasks have all produced particle instruments for spaceflight. • The company providing the silicon semiconductors (Micron Semiconductor) has produced detectors for many successful flights. The particular detectors we are purchasing for the engineering model (and likely for the flight model) use dies developed for a previous mission. • Tissue equivalent plastic (TEP) has been flown in space, including investigations on the space station.

  6. Instrument Documents • LRO Program Requirements Document; ESMD-RLEP-0010 • LRO Mission Requirements Document; 431-RQMT-00004 • LRO Technical Resource Allocations; 431-RQMT-000112 • Instrument Payload Assurance Implementation Plan • Instrument to Spacecraft Interface Control Documents (Mechanical 431-ICD-000085, Thermal 431-ICD-000118, Electrical 431-ICD-000094 & Data 431-ICD-000104) • CRaTER Project controlled documents (Configuration database: http://snebulos.mit.edu/crater/) • 32-01200 Instrument Requirements, Plans, and Procedures • 32-01201 A ..Configuration Management and Peer Review Process • 32-01201.01 ....Aerospace Procedure • 32-01201.02 ....BU Procedure • 32-01201.03 ....MIT Procedure • 32-01202 01 ..Risk Management Plan • 32-01203 06 ..Contamination Control Plan • 32-01204 A ..Performance Assurance Implementation Plan • 32-01205 01 ..Instrument Requirements Document • 32-01206 01 ..Performance and Environmental Verification Plan • 32-01206.01 01 ..Environmental Verification Text Matrix • 32-01207 ..Instrument Calibration Plan • 32-02000 Interface Control Documents • 32-02001 B ..Spacecraft to CRaTER Data ICD • 32-02002 02 ..Spacecraft to CRaTER Electrical ICD GSFC 431-ICD-000094; Draft 6/23/05 • 32-02002.01 04 ....Generic LRO EICD GSFC 431-ICD-000008; Draft 6/20/05 • 32-02003 03 ..Spacecraft to CRaTER Mechanical ICD GSFC 431-ICD-000085; Draft 6/27/05 • 32-02003.01 01 ....Generic LRO MICD GSFC 431-ICD-xxxxxx; Draft 4/15/05 • 32-02003.02 A ....Mechanical Interface Drawing • 32-02004 02 ..Spacecraft to CRaTER Thermal ICD GSFC 431-ICD-000118; Draft 1.1 4/16/05 D • 32-02004.01 01 ....Outline Drawing • 32-02052 01 ..Analog to Digital Subsystem Electrical ICD • 32-02053 ..Telescope to Electronics Subsystem Mechanical ICD

  7. Mission Level RequirementsESMD-RLEP-0010

  8. Instrument System Level Requirements

  9. Instrument System Level Requirements

  10. Instrument Subsystem Level Requirements

  11. Instrument Subsystem Level Requirements

  12. Instrument Subsystem Level Requirements

  13. Data Product Traceability

  14. Instrument Constraints on LRO • Handle peak data rate of 100 kbps • 1250 events/second during peak solar activity • No obstructions in 40 degree zenith field of regard • Deep space field of view for D1D4 event is 35 degrees • No obstructions in 80 degree nadir field of regard • Lunar field of view for D3D6 event is 35 degrees • Pointing knowledge to within 10 degrees • Telescope axis aligned within 35 degrees of lunar surface during nominal operations

  15. Instrument Block Diagram MIT Aerospace

  16. Development Flow

  17. Instrument Verification • The CRaTER Performance and Environmental Verification Plan (32-01206) describes the plan to verify the CRaTER requirements in accordance with the CRaTER Calibration Plan (32-01207), CRaTER Contamination Control Plan (32-01203), and the CRaTER Performance Assurance Implementation Plan (32-01204) • The verification program is designed to provide the verifications listed below: • The instrument meets its functional and design requirements. • Fabrication defects; marginal parts, and marginal components (if any exist) are detected early in the test sequence. • The instrument can survive and perform as required in the environments predicted to be encountered during transportation, handling, installation, launch, and operation. • The instrument has met its qualification and acceptance requirements. • The most significant verification testing beyond the standard set of environmental tests is a series of runs in particle accelerators to verify the performance of the detectors and the evolution of the LET spectrum after propagation through the TEP • Reporting • If a test or analysis cannot be satisfactorily completed, then a malfunction report will be produced by the test conductor. It will provide all the particular information detailing the malfunction. A malfunction may result in premature test termination, depending on operation procedures. Regardless of this, a malfunction report will be filed with the Verification Report for the activity. • Detailed test procedures and specifications will be written, reviewed, and approved by the CRaTER Project, prior to instrument-level verification testing. The lead individual for each procedure depends upon the category:Environmental Requirements (Project Engineer); Performance Requirements (Project Scientist); Contamination Requirements (Contamination Engineer); Interface Requirements (Cognizant Design Engineer); Calibration Requirements (Project Scientist)

  18. Instrument Current Status • Major trade studies since Instrument inception which have been closed • We have decided to use two pieces of TEP with different lengths instead of the three TEP sections in the original proposal • We have increased the thickness of the shielding to raise the minimum energy up to 17 MeV for protons from the several MeV limit in the proposal • We have increased the total number of detectors from 5 to 6 • The detectors now come in pairs of thin and thick detectors to span the expected range of LET • We varied the diameter of the detectors and the height of the telescope to optimize the geometrical factor, the fields of view, and the uncertainty in pathlength • Major ongoing trade studies which could impact either Instrument top-level requirements or the interface to the Spacecraft • None • Analyses currently being performed • Thermal model of the instrument supplied to Goddard, spacecraft model supplied by Goddard and integrated. Simulations are time-dependent and have been run over multiple lunar orbits understand thermal variations • Numerical simulations of radiation transport through the current telescope design to study the expected range of LET measurements • Mechanical model • Hardware currently in development (breadboards, prototypes) • Designing and procuring parts for our engineering model • Eight detectors for the engineering model have been ordered

  19. Schedule

  20. Schedule

  21. Summary • We have documented the flow of requirements from project to subassembly • overall LRO Level 1 requirements down to CRaTER measurements • CRaTER Level 2 instrument requirements • CRaTER Level 3 subassembly requirements • Telescope • Electronics • Constraints on LRO have been flowed down and captured in the MRD. • We have shown that the CRaTER design can meet the data products we are responsive to • CRaTER is a low-risk project with mass, power, budget, and schedule margins • Detectors for the engineering model have been ordered and beam tests are being planned • The science and engineering teams are converting the instrument requirements into a functional instrument description in preparation for PDR

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