MISSION PLAN - PDS Small Bodies Node

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** vectors evaluated at the time of closest approach This attitude description is also used in the formulation of a predict attitude C-kernel file. The DSM attitude option is used primarily for this purpose. It is not used during small forces calculations as turns related to DSMs are assumed to be part of the DSM design. The inclusion of slew events in the modeling also expands the number of deadband options available to the analyst. In addition to those listed in Table 10.1-2, deadband options are made available for OPNAVs and MGA communications. The near encounter option in Table 10.1-2 is the same as is used for HGA communications. Table 10.2-4 lists the complete set of deadband options available in the slew ∆V model. Table 10.2-4 Spacecraft Deadband Options - Slew ∆V Model Option Deadband Comments 1 x, y, z = 15° Cruise option 1 2 x, y, z = 10° Cruise option 2 3 x, y = 2°, z = 10° HGA comm / Near encounter 4 x, y, z = 6° MGA comm 5 x, y, z = 0.25° Image The spacecraft’s attitude and slew history contribute to the calculation of the slew ∆V’s by providing the initial and final attitudes that allow computations of turn angles. In a semi-iterative process, the turn angles are used by the analyst to schedule the appropriate slew group for each slew event. This process places the burden of selecting the appropriate slew group on the analyst, but this approach is selected in favor of the extensive coding that would be required to make the slew group selection completely autonomous. Three events are considered in the construction of the slew history: communications, OPNAVs and background attitude mode transitions. Slews for communications comprise the bulk of slewing activity on STARDUST with 630 events. Current plans call for 44 OPNAV events and 30 background attitude mode transitions. There are 40 different attitude modes, but 9 transitions occur naturally and do not require a slew. Construction of the communications schedule is strongly guided by the desired to maintain the +x-axis of the spacecraft pointing away from the sun to eliminate shadowing across the solar panels from the whipple shields. This results in the pitch-yaw-pitch slew sequence described in the slew group options (Table 10.2-2). Some mitigation to using this sequence is possible at low Sun-Probe-Earth angles, where the off-sun angles required for communications and corresponding array shadowing is minimal. Selection of this strategy typically involves scheduling of the HGA instead of the MGA to eliminate the 7 deg off-z-axis boresight angle of the MGA and invoking a ‘spacecraft flip’ input flag that overrides the typical HGA attitude and the +x-axis to be pointed toward the sun. 122
The communications schedule only includes those communications events that require a slew. This results in no slews for some portions of launch (LGA comm: L+0-30 days), EGA (LGA comm: L+708-727 days), encounter (L+1789-1804 days), and return (LGA comm: L+2509-2535 days). 10.2.3 Model Parameters and Characteristics The background attitude schedule, communications and OPNAV schedules used in the current modeling runs are summarized in Tables 10.2-5 through 10.2-7. The resultant ∆V magnitudes and directions are illustrated in Figures 10.2-2 through 10.2-4. dV magnitude (m/s) Declination (deg) [eme'2000] 0.030 0.025 0.020 0.015 0.010 0.005 0.000 40 30 20 10 0 -10 -20 -30 -40 pitch/yaw/pitch 5,6-8-1,2-5,6-8-5,6 yaw/pitch (8,1,5,8) pitch/yaw combined (slews 3,7) pitch < 15° (slews 1,5) pitch > 15° (slews 2,6) d/b clamp (slew 4) mode comm opnav 0 2 4 6 8 10 12 14 16 18 20 22 24 26 Time (100 days from Launch) Figure 10.2-2 Slew ∆V Magnitude Profile dV ToSun ToEar all mode chgs one-way 0 2 4 6 8 10 12 14 16 18 20 22 24 26 Time (100 days from launch) Figure 10.2-3 Slew ∆V Direction Comparison - Declination 123
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STARDUST MISSION PLAN February 1, 1
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STARDUST MISSION PLAN Edward A. Hir
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Table of Contents Table of Contents
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10.1.1 Spacecraft Attitude History
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Figure 6.2-1.a Wild-2 Encounter Com
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Table 10.1-3 Spacecraft Attitude Pr
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kg km L L/O Kilogram Kilometer Laun
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Change Log Change Letter Date Affec
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1.0 Introduction 1.1 Purpose The pu
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2.0 Mission Overview 2.1 Mission Ob
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Fairing STARDUST Second Stage Star3
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propulsive maneuvers. To avoid pote
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The STARDUST camera is necessary to
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of-view is smaller, as described in
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Backshell Avionics Deck Parachute C
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Earth Gravity Assist 01/15/01 Earth
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Cruise 2 (Earth-Wild-2) ISP Collect
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2.3.2 Launch Period Strategy 2.3.2.
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Table 2.3-2 Baseline Mission Parame
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Table 2.3-2 Baseline Mission Parame
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*B plane angle (deg) -41.051 -40.96
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2.3.2.2 ∆V Budget The total ∆V
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Accumulation of Radiation with Time
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Table 2.3-4 STARDUST Alternate-2 Mi
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calculations will require more deta
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10 17 10 16 10 15 10 14 10 13 Fluen
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8 10 flare, no shielding 6 10 4 10
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The orbit of comet Wild-2 was drast
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• Dust density = Nucleus density
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2.4.4 Interstellar Dust Science Pla
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Launch Initial Acquisition TCM-1 Ac
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Stage II ignition t=277.5 s h=66.4
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Special ‘coming-off-theperiscope
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phases are very similar to the stan
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presented in tables contained in Ap
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Figure 4.2-4.b. Beta Meteoriod Impa
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180 Off-SEP & ORBIT normal angle (d
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2/6 launch Events Attitude 74 days
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yaw, while continuing to meet solar
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Time Image Description images pixel
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(EGA-60d to +30d) TCM 4 (EGA-60 d)
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6.0 Wild-2 Encounter Phase (E-100 t
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the installation of the HGA. The su
Page 90 and 91: Date Sept-03 Oct-03 Nov-03 Dec-03 J
Page 92 and 93: Coma images will be acquired primar
Page 94 and 95: mirror via a simple one dimension t
Page 96 and 97: The cross track error corresponds t
Page 98 and 99: 14 12 10 24 km 3 sigma distance 1 s
Page 100 and 101: All 34-m HEF except selective 70-m
Page 102 and 103: SRC Entry / Descent Atmospheric Ent
Page 104 and 105: Two TCM’s are planned within this
Page 106 and 107: It is important to note that, other
Page 108 and 109: 8.0 Planetary Protection The object
Page 110 and 111: Earth-Probe Range Sun-Earth-Probe A
Page 112 and 113: 9.1 Mission Data Set (cont) 14.00 E
Page 114 and 115: 14.00 MOON-PROBE RANGE Launch Phase
Page 116 and 117: 180.00 SUN-EARTH-PROBE ANGLE EGA Ph
Page 118 and 119: 180.00 SUN-PROBE-MOON ANGLE EGA Pha
Page 120 and 121: 180.00 SUN- WILD-2 -PROBE ANGLE Enc
Page 122 and 123: Cone & Clock Angles of Wild-2 Cone
Page 124 and 125: 180 Cone & Clock Angles of Sun 180
Page 126 and 127: 9.4 Wild-2 Encounter Data Set (cont
Page 128 and 129: 16.00 MOON-PROBE RANGE Return Phase
Page 130 and 131: 10.0 Appendix B: Unbalanced Attitud
Page 132 and 133: spacecraft attitude when the spacec
Page 134 and 135: Time From Launch Off-sun Angle (deg
Page 136 and 137: Acceleration (1E-11 km/s/s) 12 10 8
Page 138 and 139: +z, yaw +y, pitch +x, roll Figure 1
Page 142 and 143: Rgt Ascen (deg) [eme'2000] 360 300
Page 144 and 145: Table 10.2-6 Communications Schedul
Page 146 and 147: Table 10.2-6 Communications Schedul
Page 148 and 149: 031228 19180 0 031229 19180 0 03123
Page 150 and 151: TRAJECTORY CORRECTION MANEUVERS EVE
Page 152 and 153: 2453509.10737773 50518. 143437. 229
Page 154 and 155: 50204. 3437. 2189.12 outb SEP = 3 d
Page 156 and 157: Table 12-1 ISP #1 Collection Period
Page 158 and 159: Table 12-2 ISP #2 Collection Period
Page 160 and 161: Table 12-4 ISP #2 Spacecraft Attitu
Page 162 and 163: Table 12-5 CIDA #1 Collection Perio
Page 164 and 165: Table 12-6 CIDA #2 Collection Perio
Page 166 and 167: 908.000 41.659 20.000 9.272 175.100
Page 168 and 169: Table 12-8 CIDA #1 Spacecraft Attit
Page 170 and 171: Table 12-9 CIDA #2 Spacecraft Attit
Page 172 and 173: Table 12-11 CIDA #3 Solar Conjuncti
Page 174 and 175: 13.0 Appendix E: PRD Traceability M
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