1. THEMIS INSTRUMENT PDROVERVIEW- 1 UCB, October 15, 2003 THEMIS SYSTEM OVERVIEW Dr. Vassilis Angelopoulos, Science Overview Dr. Ellen Taylor, Mission and Requirements Overview University of California - Berkeley

2. THEMIS INSTRUMENT PDROVERVIEW- 2 UCB, October 15, 2003 THEMIS was selected on March 20, 2003 as the next NASA/MIDEX mission (#5) to study the: Onset and evolution of magnetospheric substorms Addresses a 30yr old question (the holy grail) in magnetospheric physics A 5 spacecraft (probe) mission Single launch vehicle (Delta 2925) Launch in August of 2006 In Tail (midnight) on February 21, 2007/2008 Two year nominal duration Extended phase of 2 years possible (overlap with Cluster and MMS) Details at: http://sprg.ssl.berkeley.edu/themis

3. THEMIS INSTRUMENT PDROVERVIEW- 3 UCB, October 15, 2003 Auroral eruptions and substorms Auroral eruptions… Aurora …are a manifestation of magnetospheric substorms MAGNETOSPHERE SOLAR WIND EQUATORIAL PLANE

4. THEMIS INSTRUMENT PDROVERVIEW- 4 UCB, October 15, 2003 Compelling science driver Substorms are: Sun-Earth-Connections Objective #1: “Understand the changing flow of energy and matter through … planetary magnetospheres” US National Academy of Sciences: “A strategic question in space physics” SEC Objective#2: Explore fundamental physical processes of plasma systems SEC Objective #3: “Define origins and societal impacts of variability in SEC” Fundamental processes… …and important for space science …for understanding magnetospheric transport … for basic physics … for space weather and society

5. THEMIS INSTRUMENT PDROVERVIEW- 5 UCB, October 15, 2003 Most important science result and its science impact Answers how substorms operate – Explains how magnetospheres process solar wind energy –Explains how auroras erupt MERCURY: 10 min EARTH: 3.75 hrs JUPITER: days ASTROSPHERE GALACTIC CONFINEMENT SUBSTORM RECURRENCE:

6. THEMIS INSTRUMENT PDROVERVIEW- 6 UCB, October 15, 2003 Events occuring during a substorm Current Disruption Auroral Eruption Reconnection

7. THEMIS INSTRUMENT PDROVERVIEW- 7 UCB, October 15, 2003 Flows Primary Objectives, Goals and Means Onset and evolution of substorms Time History of Events (Onset)… –Delineate cause and effect Measure When  Where … and Macroscale Interactions during Substorms (Evolution) –Coupling in the magnetosphere Measure plasma flows and waves –Coupling to the ionosphere Measure currents and structures Distinguishes among competing models: impartially answers a well-posed question… Current Disruption Model timeEvent 0 secCurrent Disruption 30 secAuroral Eruption 60 secReconnection Reconnection Model timeEvent 0 secReconnection 90 secCurrent Disruption 120 secAuroral Eruption ? ? Rarefaction wave ? P1 P2 P3 P4 P5 GBO …as implied by Themis, goddess of impartial justice

8. THEMIS INSTRUMENT PDROVERVIEW- 8 UCB, October 15, 2003 Mission elements Probe conjunctions along Sun-Earth line recur once per 4 days over North America. Ground based observatories completely cover North American sector; determine auroral breakup within 1-3s … … while THEMIS’s space-based probes determine onset of Current Disruption and Reconnection each within <10s. : Ground Based Observatory

9. THEMIS INSTRUMENT PDROVERVIEW- 9 UCB, October 15, 2003. THEMIS’s goal is to study >10 substorms w/ 4- or 5–probe alignments along X [limit case]. Met w/ >50% margin by a fault-tolerant orbit strategy. Need 188hrs; have 300hrs/yr (>50% margin) – computation includes lunar, solar, drag, J2 terms – Conditions:  Y P1,2,3,4,5 <±2R E ;  Z P2,3,4/NS <±2R E Ascent: – minimizes shadows and post-L&EO ops – maximizes science (conjunction durations) Mission immune to probe insertion errors – RCS capability of  V<8cm/s exceeds rqmt  V<80cm/s … 3 rd stage insertion errors – long duration piece-wise major  Vs with ground contact Extensive orbit study shows high event yield

10. THEMIS INSTRUMENT PDROVERVIEW- 10 UCB, October 15, 2003 Mission overview: Fault-tolerant design has constellation and instrument redundancy D2925-10 @ CCAS Instrument I&T UCB Mission I&T Swales Encapsulation & launch BGS Operations UCB Probe instruments: ESA: Thermal plasma (UCB) SST: Super-thermal plasma (UCB) FGM: Low frequency magnetic field (TUBS/IWF) SCM: High frequency magnetic field (CETP) EFI: Electric field (UCB, LASP) Ground SST ESA EFIa EFIs FGM SCM T spin =3s

11. THEMIS INSTRUMENT PDROVERVIEW- 11 UCB, October 15, 2003 –Ideal overlap of objectives and orbits Synergy with Cluster and MMS With Cluster/DoubleStar (2006) With MMS (2008)

12. THEMIS INSTRUMENT PDROVERVIEW- 12 UCB, October 15, 2003 THEMIS Instruments Radial EFIs ESA IDPU FGM SCM Axial EFIs FGM Axial EFIs Radial EFIs SCM SSTs

13. THEMIS INSTRUMENT PDROVERVIEW- 13 UCB, October 15, 2003 Requirement Development Top-Level requirements developed during Phase A Concept Study Report provides basic mission concept Outlines top-level requirements imposed by science and programmatic objectives Mission requirements flown down (to subsystem level), formalized and documented early in Phase B All elements of the THEMIS CSR concept and mission requirements reviewed by development team Mission Requirements Database (MRD) developed and reviewed MRD finalized and put under Configuration Control at System Requirements Review (SRR), July 2003 Subsystem Interfaces and Component Requirements further detailed in Phase B Interface Control Documents between Subsystems and Institutions System and Subsystem Specifications (Electrical Spec, SOWs, etc) Mission Plans and Policies (Safety Plan, Risk Mitigation Plan, etc) Control Plans (Magnetics, Electrostatic Cleanliness, Contamination)

14. THEMIS INSTRUMENT PDROVERVIEW- 14 UCB, October 15, 2003 Requirement Verification Requirement Verification Plans developed in Phase B and C Development of Verification Matrix ensures a test or analysis is scheduled for all Mission Requirements in MRD Performance Verification and Environmental Test Plan provides launch and space environments and outlines comprehensive component, subsystem and system level test program Requirements Compliance and Verification Matrices completed in Phase D Mission Requirements Document evolves into summary of test program as run Documents Verification and Compliance Status of all Requirements Provides direct trace-ability from requirements to test procedures and reports

15. THEMIS INSTRUMENT PDROVERVIEW- 15 UCB, October 15, 2003 Key Requirement Documents Interface Control Plans: Sign-off by PDR Instruments-to-IDPU ICDs (covers software, data, electrical) Instruments-to-Probe ICDs (covers mechanical, thermal, contamination) Probe-to-IDPU ICD (electrical and mechanical) Probe-to-Probe Carrier ICD Launch Vehicle ICD (Boeing Mission Specification) Ground System ICDs (Space-to-Ground link, Ground Station, Data System) Contamination Control Plans: Draft by PDR, Sign-off by CDR Separate Plans for Magnetics, Electrostatic Cleanliness (ESC) and Molecular Contamination Provides contamination budgets, best design practice guidelines and verification plans Verification Plan and Environmental Specification: Draft by PDR, Sign-off by CDR Performance Verification Plan Qualification Philosophy and Test Levels (Acceptance, Qualification, Protoflight) Vibration/Loads/Shock Environments Thermal Vacuum/Balance Environments EMI/EMC/Magnetics/ESC Test Requirements Mission Simulations and RF Compatibility Testing

16. THEMIS INSTRUMENT PDROVERVIEW- 16 UCB, October 15, 2003 Radiation Requirements IN-1 The Instrument Payload shall be designed for at least a two-year lifetime IN-2 The Instrument Payload shall be designed for a total dose environment of 33 krad/year (TBR) (66 krad for 2 year mission, behind 5mm of Al, RDM 2) Initial estimate in Phase A GSFC Radiation Report and Innovative Concept (IC) Report validation IN-3 The Instrument Payload shall be Single Event Effect (SEE) tolerant and immune to destructive latch-up GSFC Radiation Report environment will be provided (est. Nov 2003) Innovative Concept (IC) Report environment provided Part analysis being done for upset rate on specific parts Parts list provides an assessment of the THEMIS radiation environment; determination of the radiation susceptibility of the THEMIS flight component parts lists; leading the radiation test regime required for any parts; and working with Product Development Leads and the Parts Engineer to assess any implementation measures that need to be applied to mitigate radiation concerns.

17. THEMIS INSTRUMENT PDROVERVIEW- 17 UCB, October 15, 2003 Mass Allocation IN-6 The Instrument Payload shall not exceed a mass of 23.6 kg. IN-7 No component of the Instrument Payload shall exceed the allocated mass budget (documented in THM-SYS-008 THEMIS Mass Budget) Project Margin for Probe Dry Mass is 26% Project Margin for Probe Carrier Assembly is 25%

18. THEMIS INSTRUMENT PDROVERVIEW- 18 UCB, October 15, 2003 Power Allocation IN-8 The Instrument Payload shall require less than 14.7 W (on-orbit average) IN-9 No component of the Instrument Payload shall exceed the allocated power budget (documented in THM-SYS-009 THEMIS Power Budget) Project Margin for Probe Power is 40%

19. THEMIS INSTRUMENT PDROVERVIEW- 19 UCB, October 15, 2003 Thermal Requirements IN-13 The Instrument Payload shall survive the temperature ranges provided in the ICDs IN-14 The Instrument Payload shall perform as designed within the temperature ranges provided in the ICDs IN-15 The Instrument Payload shall be able to cold start as provided in the ICDs

20. THEMIS INSTRUMENT PDROVERVIEW- 20 UCB, October 15, 2003 Contamination Requirements IN-16 The Instrument Payload shall comply with the Magnetics Cleanliness standard described in the THEMIS Magnetics Cleanliness Plan THM-SYS-002 THEMIS Magnetics Cleanliness Plan, Rev A, In Progress Bi-weekly meetings with Swales, UCLA, UCB Swales Solar Array Specification reviewed by UCB and UCLA Magnetics Modeling (AC and DC) to be done by UCLA Magnetics Budget at preliminary stage Magnetics Verification and Test planning at preliminary stage IN-17 The Instrument Payload shall comply with the THEMIS Electrostatic Cleanliness Plan THM-SYS-003 THEMIS Electrostatic Cleanliness Plan, Rev A, In Review Swales Solar Array Specification Reviewed by UCB IN-18 The Instrument Payload shall comply with the THEMIS Contamination Control Plan THM-SYS-004 THEMIS Contamination Control Plan, Draft, In Progress

21. THEMIS INSTRUMENT PDROVERVIEW- 21 UCB, October 15, 2003 Interface Requirements IN-20 The Instrument Payload shall be compatible per IDPU-Instrument ICDs THM-SYS-101 IDPU-to-Probe ICDRev EIn Progress IN-21 The Instrument Payload shall be compatible per the IDPU-Probe Bus ICD THM-SYS-103 EFI Digital Fields Board-to IDPU ICDRev BIn Progress THM-SYS-104 EFI Boom Electronics Board-to-IDPU ICDRev A In Review THM-SYS-105 ESA and SST I/F Card Spec (ICD)DraftIn Progress THM-SYS-106 FGM I/F Requirement Document (ICD)Rev BIn Review THM-SYS-107 SCM I/F Requirements Document (ICD)Rev BIn Progress IN-22 The Instrument Payload shall be compatible per Instrument-Probe Bus ICDs THM-SYS-108 Radial EFI Booms-to-Probe ICD Rev D2In Review THM-SYS-109 Axial EFI Booms-to-Probe ICDRev D2In Review THM-SYS-110 ESA-to-Probe ICD Rev D2In Review THM-SYS-111 SST-to-Probe ICDRev D2In Review THM-SYS-112 FGM Mag Boom-to-Probe ICDRev D2In Review THM-SYS-113 SCM Mag Boom-to-Probe ICDRev D2In Review

22. THEMIS INSTRUMENT PDROVERVIEW- 22 UCB, October 15, 2003 Test Requirements IN-23 The Instrument Payload shall verify performance requirements are met per the THEMIS Verification Plan and Environmental Test Specification IN-24 The Instrument Payload shall survive and function prior, during and after exposure to the environments described in the THEMIS Verification Plan and Environmental Test Specification THM-SYS-101 THEMIS Verification Plan and Test Specification, Draft, In Progress Mechanical Design Specifications have been provided Environments and Test Matrix will be presented during IDPU PDR (Oct 16)