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THEMIS Orbit Updates: Nominal 2 nd Year Extended Baseline Inner Probes S.Frey,

THEMIS Orbit Updates: Nominal 2 nd Year Extended Baseline Inner Probes S.Frey, University of California - Berkeley. Timelines. Nominal 2 nd Year Tail Season 2 Dec, 2008 - Apr, 2009 WD Feb-07-2009  Bringing outer probes closer to neutral sheet, longer shadows for P1 (4h)

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THEMIS Orbit Updates: Nominal 2 nd Year Extended Baseline Inner Probes S.Frey,

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  1. THEMIS Orbit Updates: • Nominal 2nd Year • Extended Baseline Inner Probes • S.Frey, • University of California - Berkeley

  2. Timelines • Nominal 2nd Year • Tail Season 2 Dec, 2008 - Apr, 2009 WD Feb-07-2009 •  Bringing outer probes closer to neutral sheet, longer shadows for P1 (4h) • Orbit swing maneuvers worked out fine • Dayside 2 Jun, 2009 - Jul, 2009 WD Aug-10-2009 outer probes  Shorter to start ARTEMIS ascent for P1,P2 • Extended Mission Inner Probes WORK in PROGRESS • Jul 2009 – Oct 2009 finish dayside 2 • Nov 2009 – Feb 2010 radiation belt, tail • Mar 2010 – Aug 2012 extended mission

  3. Tail 2008/2009 WD+60d Apr -08 WD+24d Mar-03 WD Feb-07 WD-24d Jan-14 WD-60d Dec-09 Nominal THEMIS 2008/2009/2010 Dayside 2009/ Dawn 2010 WD-68d Jun-03 WD-40d Jul-01 WD Aug 10 Wd+60d Oct 09 2010-Mar-10 2010-Jan-10 Dusk 2009 2009-Apr-09 to WD-96 May 07

  4. 08-03-2008 08-27-2008 03-25-2008 02-26-2008 02-07-2009 03-07-2009 08-10-2009 09-03-2009 Inner Probe Conjunctions • Tail season 1: TP5 = 4/5*TP34 • 5-probe conjunctions – every 4 days • Dayside 1: TP5 = 8/9*TP34 • 5-probe conjunctions – every 8 days • Tail season 2: TP5 = TP34 • 5-probe conjunctions – every 4 days • Dayside 2: TP5 = 8/7*TP34 • 5-probe conjunctions – every 8 days

  5. dzNS [Re] Time [d] dzNS [Re] Y-GSM [Re] dzNS [Re] X-GSM [Re] Tail Season Conjunctions • Dec 2008-Feb 2009 orbits much Results x<-10 Re, dy<2 Re, 4 probes • closer to neutral sheet than in Tail1 dzNS < 1 Re: 31h+ 60h+10h=101h • Due to overlap with shadow about dzNS < 2 Re: 44h+ 94h+37h=175h • 90h within 1 Re useful Nominal criteria: 64h+101h+94h=259h Blue conjunctions

  6. 1 Re to Neutral Sheet Dawn Midnight Dusk Overlapping with shadows

  7. 2010 2010 • 2011 • 2012 8/7*24h D3 end P4, P5 D4 end Geographic longitudes of Apogee Passes P3,P4,P5 T [h] Ra [re] Rp [Re] Inc APER RAP P3 P4 P3,P5 P4 P4 P4 T3 D3 T4 D4 T5 T3 D3 T4 D4 T5 T3 D3 T4 D4 T5 Inner Probes Extension • No changes since SWT Sep. 2008 • Close formation still work in progress • D3 P3,P5 in 8/7*24h, P4 in 24h orbit • T3-T5 all in 24h orbits, P4 is shifting along line of apsides+/- 1000k • P3,P5 need more adjustments after D3 to account for eastward drift of apogee passes (similar to P4) T-end Orbital Elements

  8. Fuel, dV *THEMIS SR-8_02_13m.doc ^Minimum impulsive maneuvers, no maintenance of close formation included yet

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