SSL-SWT 1 Aug 6-8, 2007 THEMIS Extended Phase Summary of THEMIS team discussions (Please note: this is work in progress)

SSL-SWT 2 Aug 6-8, 2007 P3,4,5 will be uniquely suited to study microphysics at small scale separations –Equatorial magnetosphere at 9-12 R E was not studied by Cluster Having explored R ,  planes during prime mission, THEMIS ready to explore 3 rd dimension: R  R  plane is optimal three-probe configuration for studying currents in the tail and at the magnetopause –Tail Region 9-12R E is unique to substorms: Auroras and substorm onset currents map there Region is important for MI coupling during substorms and storms –Dayside Region 9-12R E is unique to Solar Wind – Magnetosphere coupling: Sub-solar Magnetopause streamlines affect energy entry along entire magnetopause boundary Reconnection topology and rate have not been studied before due to lack of multi-point observations –Exciting new possibilities with THEMIS P3,4,5 at km separations at those regions Prepares the ground for MMS-like studies –Early dayside period on THEMIS (coast phase) provides a glimpse of capabilities –Early dayside period shows operational complexity of achieving small scale separations P1 will be unable to contribute to the above goals due to extreme shadows –Inclination changes don’t help because apo-apsis is at the equator/ecliptic intersection –Apogee lowering is costly and cumulative precession post-prime mission does reduce shadows –Anticipated since CDR but could not afford time/cost to verify or fix by design changes P2 may be able to contribute uniquely to inner magnetosphere science –Requires further study of tetrahedral configuration and fuel requirements Preamble

SSL-SWT 3 Aug 6-8, 2007 P1: = 387 minP2: = 276 min 3 rd year shadows exceed design limit = 180min RAP~330deg Representative shadow trends for typical P1 orbits (from THEMIS CSR). [Note: underestimates] P1, P2 shadows, nominal orbits

SSL-SWT 4 Aug 6-8, 2007 P1 180/360 Minute Eclipse Power  Battery Capacity = 11.8 Ah  Battery Depth of Dishcarge (DoD) Requirement < 65%  3hr Eclipse DoD = 63%  Margin = 2%  Battery Average Voltage = 28.8V  Battery Capacity = 340 Wh  Eclipse Power Req’s = 69.5W  Max Eclipse Sustainable = 4.8h  No recovery for BAU if battery is drained and BAU stops operating

SSL-SWT 5 Aug 6-8, 2007 Thermal Design and Test Limits Predicts Operational Limits Acceptance Limits Qual Limits 5°C 10°C Maximum Predicted Minimum Predicted 5°C 10°C -100°C Bus Thermal Design goal was to be at least 5 °C inside Operational Limits for passive design components. For side panels, Qual limit was –120 ° C FM-1 (TH-A, P5) Qual-tested at 10°C beyond Operational Limits FM 2-5 Acceptance tested at 5°C beyond Operational Limits -120°C-110°C

SSL-SWT 6 Aug 6-8, 2007 P1 180 minute Eclipse Temperatures A 15deg difference between Local and Bulk Side Panel temperatures Cold spots on the arrays would result in break of the vaulted interconnects and the cell glass LOSS OF PRIME POWER

SSL-SWT 7 Aug 6-8, 2007 P1 180/360 Minute Eclipse Transient Temperature Results -95 o C Side Panel local temperatures may exceed operational cold limits (-95 o –15 o = -110 o C)

SSL-SWT 8 Aug 6-8, 2007 P1: consuming all 300m/s (remaining at end of mission) in Earth orbit, options: –Apogee reduction to 18R E on Oct 1, 2009 (300m/s) – Exacerbates P1 shadows – Not an option –Inclination change in June 2009 (change in 2 nd dayside season) may reduce shadows (TBD) 40deg inclination change slows down APER changes, may go through minimum shadow in 2010 In 2011 the long shadow will be inevitable Basic reason: line of apsides is at the equator/ecliptic intersection No de-orbit fuel left (128m/s are required) - Does not meet de-orbit requirements – Not an option –Summary: P1 cannot be salvaged with remaining fuel in Earth orbit Would have to deplete all fuel and placed on a re-entry path If it survives shadows, Lunar perturbations will render orbit polar. Even less useful for P2-5 then. P2: consuming 450m/s (remaining at end of mission) in Earth orbit, options: –Additional inclination change and perigee change may reduce shadows further Requires further investigation Depends on fuel margin consumed in prime mission At same altitude not so helpful for extended science with P3,4,5 –Apogee reduction to 12R E on Oct 1, 2009 (210m/s) builds 5deg additional precession Can be brought closer to P3,4,5 Can be used to validate current sheet orientation assumption –Summary: P2 can be salvaged with its remaining fuel in Earth orbit; but scientific usefulness and orbit optimization require further study P1, P2 can they be saved at Earth orbit?

SSL-SWT 9 Aug 6-8, 2007 P1 P2 P3 P4 P5 Focus at 10-12R E post prime-THEMIS: –Most important unresolved substorm questions: Magnetosphere-ionosphere coupling at onset –How are tail currents diverted to ionosphere? –How are plasma sheet particles accelerated? –How do quasi-static electric fields build up? Micro-physics of onset mechanism –If at CD site, extended THEMIS can address –If at Rx site, MMS will do that in the future –1 st extended year Take P5 to P3,4 altitude (Dec 1, 2009), dV~60m/s Separate P3-P4 in radial direction (both siderial) Study 0.1 – 1R E scale sizes: currents, flows, CD –2 nd, 3 rd extended year: Take P5, P3 closer to P4 (Dec 1, 2010) APER~180, P5: d(inc) ~ 6deg, dV~ 110m/s Tune period and phase to optimize geometry Study 10km-1000km scale sizes By the 1 st year of THEMIS extension: –P1, P2: If they survive in their orbits: peripheral science –P2: If it can be brought in, it is more useful near 12R E (see next page) THEMIS: April 15-19, 2010 w/o maneuvers P3,4,5 tail science; P1&P2 relation Science of P1,P2 at current orbits: peripheral

SSL-SWT 10 Aug 6-8, 2007 Focus at 10-12R E post prime-THEMIS: –Most important unresolved substorm questions: Magnetosphere-ionosphere coupling at onset –How are tail currents diverted to ionosphere? –How are plasma sheet particles accelerated? –How do quasi-static electric fields build up? Micro-physics of onset mechanism –If at CD site, extended THEMIS can address –If at Rx site, MMS will do that in the future P3,4,5 tail science

SSL-SWT 11 Aug 6-8, 2007 P1 P2 P3 P4 P5 THEMIS: April 15-19, 2010 w/o maneuvers P3,4,5 tail science; P1&P2 relation Science of P1,P2 at current orbits: peripheral Consensus: –Use P3,4,5 for Cluster-like science Study equatorial magnetosphere –Cluster did not visit 10-12R E plasma sheet Optimize orbits to do cutting edge research –In different configuration than before –Send P2 to join P3-5? Determine whether or not fuel permits P2 to join P3-5 in a tetrahedral formation Finalize decision no earlier than 10/2008 –Send P2 to join P1 in ARTEMIS at moon? Determine whether ARTEMIS needs one or two THEMIS S/C (in view of pending LuSIE and LEO selections) Finalize decision no later than 03/2009

SSL-SWT 12 Aug 6-8, 2007 X Z P3 P4 P5 T3, GSE coord’s View from tail along NS dZ(P3-P5) ~ km dR(P3-P4)~1R E > dZ [every 8 days] Y P3,4,5 tail science: T3 ( )

SSL-SWT 13 Aug 6-8, 2007 P3 P4 P5 Y X Z T3, GSE coord’s View from dawn along NS dZ(P3-P5) ~ km dR(P3-P4)~1R E > dZ [every 8 days] P3,4,5 tail science: T3 ( )

SSL-SWT 14 Aug 6-8, 2007 P3,4,5 dayside science: D3 ( ) Y X Z D3, GSE coord’s View from Sun along Ecliptic dZ(P3-P5) ~ km dR(P3-P4)~1000km < dZ [every day] Apogee~12Re P3 P4 P5

SSL-SWT 15 Aug 6-8, 2007 P3,4,5 dayside science: D3 ( ) Z Y X P3 P4 P 5 D3, GSE coord’s View from dawn along Ecliptic dZ(P3-P5) ~ km dR(P3-P4)~1000km < dZ [every day] Apogee~12Re

SSL-SWT 16 Aug 6-8, 2007 P3,4,5 tail science: T4 ( ) 1000km Z Y X T4, GSE coord’s View from dawn along NS dZ(P3-P5) ~ km dR(P3-P4)~1000km > dZ [every day] Apogee ~ 12R E

SSL-SWT 17 Aug 6-8, 2007 P3,4,5 dayside science: D4 ( ) Same configuration as D3, except smaller separations: dZ (P3-P5) = km dR (P4-P3/P5) = 200km P3,4,5 dayside science: T5 ( ) Same configuration as T4, except except smaller separations : dZ (P3-P5) = km dR (P4-P3/P5) = 1000km P3,4,5 science during last year FY12

SSL-SWT 18 Aug 6-8, 2007 Summary P3,4,5 science at 10-12R E : Cluster-class science at an uncharted region Key science questions in the tail at 10-12R E region – How does the cross-tail current get disrupted at substorm onset? If current disruption is responsible for substorm onset, what is the plasma physical process? If reconnection causes current disruption, how does incoming flow disrupt the cross tail currents? Which are the cross-tail current carriers and how does their free energy get reduced? – How does the cross-tail current get diverted into auroral ionosphere at onset? By vorticity generation, by pressure gradient redistribution, by flow breaking or by Alfven waves? THEMIS’s unique R  configuration provides unprecedented measurements in this region of space. With Cluster-quality instrumentation and orbital separations, in a region never before visited in such a formation, THEMIS will measure cross-tail and field aligned current measurements, particle distributions, and waves will be able to answer which mechanism is responsible for the current disruption and diversion at substorm onset. Key science questions in the dayside at 10-12R E region – How solar wind energy couple through the subsolar magnetopause? Do cold ions in the equatorial magnetosphere affect reconnection rate and energy coupling? What is the extent, topology and rate of reconnection at the subsolar magnetopause? THEMIS’s unique R  configuration provides unprecedented reconnection inflow measurements from P4, with simultaneous bracketing of the diffusion region by P3 and P5. With Cluster-quality instrumentation and orbital separations, THEMIS’s three satellites measure (assuming azimuthal invariance) magnetopause and field aligned currents for the first time in this critical region.

SSL-SWT 19 Aug 6-8, 2007 How can P2 help P3,4,5? Ans. If it creates good tetrahedron P2: can be brought to siderial orbit –Daily conjunctions with P3,4,5 –Optimized separations to ~1R E Provides additional CD timing/context Validates 2D planar current sheet P2: can be further tuned: –Tetrahedral formation with P3,4,5 Requires MMS/Cluster know-how –Study initiated (Concha/Hapgood) –P2 may require inordinate fuel Significant science return –Cluster was never there –MMS will not have 0.1-1R E scale –Summary: P2 may be able to do significant additional science if placed at tetrahedral formation with P3,4,5 but it is unclear at this point if fuel margin is sufficient for orbit maintenance. P3 P4 P :00:00 X Y P2

SSL-SWT 20 Aug 6-8, 2007 Optimal use of P1, P2: ARTEMIS P1, P2 have sufficient fuel to raise apogee to the moon: –Easier to go up than down –Lunar gravity perturbs orbits sufficiently to remove long shadows Probes need not stay any longer in Earth orbit –Mission design and operations can become complex and expensive unless new target is found Use the moon as anchor to perform new tail and new Solar Wind science Permits exploration of a unique Lunar-Solar and Lunar-Tail environment like never done before Optimal use of de-orbit fuel (lunar re-entry) Design considerations for Lunar insertion, result in a robust mission: –Spin axis at ecliptic normal throughout mission: optimal communications –Equatorial Lunar orbit: stable for many years –After Lunar Orbit Insertion operations are routine –A 24hr orbit guarantees: »Less than 3.5hr shadows, acceptable for probe design »Familiar, low risk power, thermal and operations environment –Mission design that satisfies above criteria is robust: Under study by JPL since April 2005 By same team which validated the THEMIS mission design in JPL review on 2007-Nov-02 found no technical issues –Further Navigation work to minimize fuel maintenance under way –Further cost-optimization work to minimize operations costs under way ARTEMIS mission design has undergone several iterations and reviews and is quite robust

SSL-SWT 21 Aug 6-8, 2007 ARTEMIS “Acceleration, Reconnection, Turbulence and Electrodynamics of the Moon’s Interaction with the Sun” ARTEMIS

SSL-SWT 22 Aug 6-8, 2007 What are the important magnetospheric questions after THEMIS, before MMS? Distant magnetotail (after Geotail and WIND – single spacecraft) What is the nature and extent of the distant tail neutral line? Does the tail vanish in response to Interplanetary Coronal Mass Ejections? What are the dimensions and topology of plasmoids (carry ½ energy of storms) Answers necessitate multiple THEMIS-type satellites at R E scales Solar Wind and Shocks (after multiple missions: Cluster, ISEE1/2) How do shocks accelerate particles? (Shock acceleration or diffusion) What is the nature of solar wind turbulence in 1-10RE scale lengths (no data) Answers necessitate multiple THEMIS-type satellites at 1-20R E scales Lunar Wake (after Lunar Prospector and WIND) What are the plasma waves that make up the nature of the Lunar Wake? How does the wake fill-in from near the moon to far down What makes up, sustains and dissipates the electric fields behind the wake Answers necessitate multiple THEMIS-type satellites at ,000km scales

SSL-SWT 23 Aug 6-8, 2007 ARTEMIS Science Objectives Acceleration in shocks, tail and lunar environment What is the nature of acceleration at shocks? Follow evolution of particle distributions at two points along the shock. How do MeV electrons get accelerated in the tail? Measure field topology, particle spectra and evolution in time and space. How do energetic (100s of keV) ions and electrons get accelerated in the wake? Measure particles and fields in the wake and the solar wind simultaneously. Reconnection What is the distant tail reconnection onset mechanism, effects and response to solar wind drivers? Spontaneous or induced? Continuous or impulsive? Answers necessitate multiple THEMIS-type satellites at 1-20R E scales Lunar Wake (after Lunar Prospector and WIND) What are the plasma waves that make up the nature of the Lunar Wake? How does the wake fill-in from near the moon to far down What makes up, sustains and dissipates the electric fields behind the wake Measure particles and fiels in the wake and outside at ,000km distance

SSL-SWT 24 Aug 6-8, 2007 ARTEMIS Mission Profile

SSL-SWT 25 Aug 6-8, 2007 ARTEMIS Mission Phases Phase I (Oct ’09 – Oct ’10) - placement

SSL-SWT 26 Aug 6-8, 2007 ARTEMIS Select Orbits Phase II (Oct ’10 – Jan ’11) Opposite Sides – Sun-Earth Alignments

SSL-SWT 27 Aug 6-8, 2007 Phase II (Oct ’10 – Jan ’11) Opposite Sides– Dawn-Dusk Alignments ARTEMIS Select Orbits

SSL-SWT 28 Aug 6-8, 2007 Phase III (Jan ’11 – Apr ’12) Same Side – Sun-Earth Alignments ARTEMIS Select Orbits

SSL-SWT 29 Aug 6-8, 2007 Phase III (Jan ’11 – Apr ’12) Same Side – Dawn-Dusk Alignments ARTEMIS Select Orbits

SSL-SWT 30 Aug 6-8, 2007 ARTEMIS Wake Crossings: Phase II,III

SSL-SWT 31 Aug 6-8, 2007 ARTEMIS Wake Crossings: Phase II,III

SSL-SWT 32 Aug 6-8, 2007 ARTEMIS Distant Wake Crossings: A Perspective BB

SSL-SWT 33 Aug 6-8, 2007 Phase IV (Apr ’12 – May ’13) ARTEMIS After Insertion

SSL-SWT 34 Aug 6-8, 2007 ARTEMIS Wake Crossings

SSL-SWT 35 Aug 6-8, 2007 ARTEMIS Ground Operations Concept DSN, 34m TLM, TRK, CMD Translunar Orbits OVRO, 40m TLM Receive Only BGS, 11m TRK & CMD Lunar Orbits Flight Dynamics –Translunar Orbit: JPL: Mission Design, Orbit Determination, Ephemeris, Maneuver Planning UCB: Attitude Determination –Lunar Orbit: UCB: Mission Design, Orbit/Attitude Determination, Ephemeris, Maneuver Planning Mission Operations (UCB) –Pass Scheduling, Mission Planning & Command Generation –Data Trending & Anomaly Resolution, ITOS CMD & Control Science Operations (UCB) –Follows Standard THEMIS practices Alternate Downlink: OVRO – Refurbishment+Ops: ~1M – Can track >3hrs/day – A 40m dish: better than DSN – Saves government >$10M

SSL-SWT 36 Aug 6-8, 2007 ARTEMIS Science Team Tail Plasmoids, ScalesSlavin, Murphy Rx/HeatingOieroset, Schriver TurbulenceWeygand, Velli Acceleration, ScalesSlavin, Murphy Solar Wind Shock accelerationEastwood, Bale TurbulenceVelli, Weygand ForeshockEastwood Wake Computer sim’sTravnicek, Schriver, Farrell Laboratory sim’sGekelman ExosphereDelory Refilling, BeamsHalekas, Farrell, Bale

SSL-SWT 37 Aug 6-8, 2007 Senior Review panel – Decides how to apportion funds between continuing missions (Voyager, Cluster …) – Evaluates and approves plans for FY09/10; hears proposals for FY11/12 THEMIS ends in FY09, would request funding for FY10 and present plan for FY11/12 THEMIS – extension funding request for FY10 with further extension in FY11/12 ARTEMIS – proposal to slowly ramp up in FY08/09 and move to operations in FY11/12 Costs – Cost Guidance would be sufficient to continue THEMIS with minimal operations Hinges on scientific publications and discoveries made by THEMIS now Reviewed on basis of past performance as indicator for future output – Guest Investigator program to accompany THEMIS extended mission, also possible Hinges on quality and accessibility of THEMIS data, and community involvement – Cost increase due to ARTEMIS team and mission operations may necessitate new funds Senior review panel chair may have to obtain additional funding from Heliophysics director Received recommendation to proceed with a combined proposal Timeline – Proposal due February 21 Review of Mission Archive Plan: March Presentations: April Selection Jun 12, 2008 THEMIS Extended Phase Proposal