Jupiter System Observer

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Jupiter System Observer

• Mission Implementation
• Polar Gateways Conference
• January 28, 2008

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Engineering Definition Team
Technical Lead Johnny Kwok Science Ops Bill Smythe
Systems Engineer Grace Tan-Wang, Sarah Hornbeck Telecom Dave Hansen
Mission Architect Tom Spilker Ground Systems Sue Barry, Greg Welz
Payload Engineer Ken Klaasen, Mark Redding Thermal Bob Miyake, Don Strayer, Glen Tsuyuki
Mission Design Nathan Strange Ryan Russell Software Suzanne Klein, Jay Brown
Concurrent Engineer Keith Warfield, Erick Sturm, Tracy Van Houten Cost Chuck Baker, Ed Jorgensen
ACS Bob Kinsey Risk Jim Kinnison (APL), Julie Wertz
CDS Brian Cox, Yutao He Radiation Shawn Kang, Insoo Jun
Mechanical Steve Kondos, Ted Iskenderian Planetary Protection Laura Newlin
Power Paul Timmerman, Hrair Antablian Report Manager Jan Ludwinski
Propulsion Chris England, Paul Woodmansee
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Architectural Elements
Launch Vehicle
Interplanetary Trajectory
Propulsion
Power Source
of S/C
Final Destination
Aperture
Atlas V
Direct
Chemical
RTG
Single
0.5 m
J. Sat. Tour
Delta IVH
DV-EGA
SEP
Solar
Sub-Sat
1 m
G. Elliptical Inc. gt 40
VEEGA
Probe
1.5m
G. Elliptical Inc. lt 40
VkEmMnGA
G. Circular
Lander
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Architectures Selection
Jovian Tour
Single S/C
0.5 m
G. Elliptical lt 40
Atlas 551
Descoped
G. Elliptical gt 40
Baseline
0.5 m
G. Circular
Single S/C
Jovian Tour
gt 1.0 m
G. Elliptical gt 40
Jovian Tour
Sub-Satellite
0.5 m
Delta IVH
G. Elliptical lt 40
G. Elliptical gt 40
Jovian Tour
Probe
0.5 m
G. Elliptical
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Descoped Options Trade Studies

• Alternative Descoped Missions
• Atlas V with circular Ganymede orbit Completed
  after report date
• Reduced Io flyby to 2
• Reduced MMRTG to 6
• Direct insertion to circular orbit
• Atlas V with slightly elliptical final Ganymede
  orbit
• Determined by available propellant
• Explore Orbit Options
• Explore transfer orbit options to reduce GOI DV
• Lagrangian point dynamics, distant retrograde
  orbit
• Study different elliptical orbit at different
  inclinations and eccentricity
• Additional Trades
• Mission lifetime
• Science payload

We are presenting two possible missions within
the study guidelines
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Jupiter System Observer
Payload for Planning Purposes

• January 28, 2008

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Planning Payload

• Notional set of instruments that will meet
  science measurement requirements
• Used to understand the engineering aspects of the
  mission design, spacecraft design, and
  operational scenarios
• Proof of concept, not final selections
• Actual instrument selections to be done via NASA
  AO process

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Payload Accommodation - 1

• Remote sensing instruments mounted on
  nadir-viewing deck
• Detector cooling provided via passive radiators
  viewing away from the Sun and away from Ganymede
  when in orbit
• Pointing requirements
• Control to 0.4 mrad
• Stability to 2 ?rad over 0.5s
• S/C scanning at rates that are slow (40 ?rad/s to
  9 mrad/s) and smooth (rate stability to lt10 of
  commanded rate) for distant spectrometer slit
  scanning
• Reconstruction to 0.08 mrad
• Trade studies ruled out both a scan platform and
  a turntable as too massive to accommodate

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Instrument View
Hi-Res Camera/ Vis IR Spectrometer
Magnetometer Boom
UV Spectrometer
Reaction Wheel Assembly (4)
Med Res Stereo Camera
Dual axis HGA Gimbal
LGA, Ka-band (2)
LGA, X-band (2)
Plasma Spectrometer/ Energetic Particle Detector
Laser Altimeter
Star Tracker (2)
Thermal Spectrometer
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Payload Accommodation - 2

• Space for electronics cards in radiation-shielded
  chassis (reduces environment to 150 krad)
• Downlink data rate ?600 kbps to support Jovian
  system science
• Periodic Jupiter global coverage and Io
  monitoring
• Near-global multi-spectral satellite imaging (UV
  through thermal IR)
• Altimetry of satellites (global of Ganymede)
• Radar mapping of satellites (global of Ganymede)
• Continuous fields and particles data
• Remote sensing coverage of 1000 selected target
  regions on each Galilean satellite and ?50,000
  targets on Ganymede
• Control of Ganymede low circular orbital period
  to provide specific ground track spacing and
  interleaving for global mapping
• Ganymede orbit reconstruction to 1 m radial
  accuracy during at least 30 days in low circular
  orbit
• Implies near-continuous Doppler tracking (dual
  frequency preferred)
• No more than one thruster firing per day

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Unique Technical Challenges

• Radiation tolerance
• Sensors and supporting electronics located
  outside shielded chassis may need their own
  shielding (included in current mass allocations)
• Cost estimates include a factor (25) for
  addressing radiation design issues
• Data rate reduction
• High-rate instruments will be required to include
  large internal data reduction factors via
  compression, editing, summing, etc.
• Frequent power cycling
• Power limitations will require frequent
  instrument duty cycling into low-power modes
  (1000s of times for all but FP instruments)

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Jupiter System Observer
Mission Design

• January 28, 2008

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Mission Design Alignment with Payload
JSO science mission is uniquely designed to meet
the science goals and fully utilize the
instrumentation
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Mission Timeline
VEEGA, 5 ½ to 7 years
5 to 5 ½ years
9 - 12 mo
6 mo
18 21 mo
2 years
Cruise
Io Tour
Icy Moon Tour
Ganymede Orbit Baseline (Ellip Cir) Descope
(Ellip only)
Capture
JOI
GOI
24 hr period 60 inclination
Polar 200 km altitude
Opportunities Launch Arrival Atlas (kg) DIV Jan
2015 Jul 2021 4964 7287 Jun 2015 Jul
2021 4627 6781 Sep 2016 Oct 2023 5050 7423 Jan
2017 Aug 2022 4888 7196 selected Sep 2018 Oct
2025 4999 7332 Mar 2020 Feb 2026 5270 7760 May
2021 Mar 2028 5053 7416
Flybys 4 Io 6 Europa 7 Ganymede 11 Callisto
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Interplanetary Trajectory

• Launch C3 10 km2/s2 over 21 day launch period
• Launch on Delta IV-H (Atlas V for descoped
  option)
• 265 m/s DSM (Feb-2019)
• Backups in 2018-2021

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Example Jovian Tour

• 3 Year Tour
• 9-12 month Io phase
• 18-21 mo. outer moon tour
• 6 month endgame
• 24-28 close flybys

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20
15
2
3
6
1
4
7
5
9
8
10
Tour reduces energy and circularizes orbit prior
to GOI
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Ganymede Science Orbits

• 24 hour Elliptical Orbit
• Novel 3-body orbit using Jupiter and Ganymede
  gravity
• Long-term stable (10 years)
• inclination varies from 50º to 60º
• near the highest inclination possible for stable
  orbits
• 44 d oscillation between near-circular and highly
  eccentric
• Close approaches are distributed around the body
• 24 hr period avoids changing shift issues for ops
• Representative of larger set of possible orbits
• 200 km Circular Orbit
• Low altitude and high inclination
• Can be sun-synchronous (with Jupiter
  perturbation)
• Could instead have varying solar phase over
  mission
• Only mildly unstable ( 0.1 m/s per day of DV to
  maintain)

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DV Budget
Baseline m/s (Low Circular Orbit) Descoped m/s (Elliptical Orbit)
Launch Injection Correction 30 (est.) 30 (est.)
Earth Biasing 50 (est.) 50 (est.)
DSM 265 (max) 265 (max)
Interplanetary TCMs 20 (est.) 20 (est.)
JOI 660 660
PJR 165 165
Tour (24 flybys) 200 (with 15 margin) 200 (with 15 margin)
Ganymede Endgame 200 (with 10 margin) 200 (with 10 margin)
Ganymede Orbit Insertion 200 (with 10 margin) 200 (with 10 margin)
Orbit Maintenance (elliptical) 25 (est.) 50 (est.)
Plane Change 230 ---
Circularization 620 ---
Orbit Maintenance (circular) 40 (est.) ---
De-Orbit --- 15 (est.)
Total 2705 1855
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Jupiter System Observer
Spacecraft Operations

• January 28, 2008

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Design Drivers on Flight System
Downlink
Higher Data Generation
Data Storage
Payload Suite Large Optics Comprehensive Payload
On-board Data Handling
Fine Pointing
Attitude Control
Shielding, Parts upgrade
Radiation Environment
Mission Design Jovian System Ganymede Orbit
Configuration
Large ?V
Structures
High Propellant Load
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Baseline Spacecraft
JSO Spacecraft is a capable robust design that
accommodates the instrumentation and the mission
while taking advantage of the environment

• 7262 kg (4612 kg, descoped) wet mass
• 228 kg (208 kg, descoped) planning payload
• Eight (seven, descoped) MMRTGs and two 38 A-hr
  batteries
• Two-axis gimbaled, 2.75 m HGA
• Two-way Doppler at both X-/Ka-band for radio
  science - gravity investigation
• USO for radio science - atmosphere
  investigation
• 600 kb/s to 70m from 6.5 AU at Ka-band
• 9.6 Gb solid state recorder
• Dual-mode propulsion system 2705 m/s (1855
  m/s, descoped)
• Reaction wheels for long arcs without
  non-gravity disturbances
• Single-fault tolerant redundant assemblies
• Radiation-hardened electronics
• 1.8 Mrad radiation design point
• 12 year mission life

Ground Penetrating Radar
Louvered Radiator (2)
Pressurant Tank
Magnetometer
HGA MGA (hidden)
Telecom Electronics Chassis
Fuel Oxidizer Tanks (inside)
MMRTG (8)
Thruster Clusters (8)
Main Engine
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Baseline vs. Descope Differences
Baseline Descope
Payload 228 kg 9 instruments 208 kg Same payload except MRC is non-stereo, PS/EPD is less TOF spectrometer
?V 2705 m/s 4775 kg propellant 1855 m/s 2627 kg propellant
Power Source 8 MMRTGs (778 W EOM) 7 MMRTGs (681 W EOM)
Mass Margin S/C dry mass (CBE) 1959 kg 27 contingency 21 system margin S/C dry mass (CBE) 1568 kg 27 contingency 33 system margin
Power Margin 30 contingency gt100 W margin on RTG modes lt20 DoD on Battery modes, plus redundant battery 30 contingency gt80 W margin on RTG modes lt40 DoD on Battery modes, plus redundant battery
Margin Remaining LV Mass/Spacecraft Dry Mass
(CBEcont)
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Mass Summary
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Dose-Depth Curves (Free Space)
Europa 30 krad/day Ganymede 1 krad/day
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Radiation TID
Ganymede Orbit
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JSO Information Flow
Flight System
Driving Scenarios
Tour Encounters Flybys of Io, Europa, Ganymede,
Callisto
High-rate Instruments with compression (e.g,
hi-res camera, hyperspectral imager, etc.)
High-data-rate Science instruments (12 to 3500
Mbps)
Orbits (at Ganymede)
Low-data-rate Science instruments (lt 1 Mbps)
Low-rate Instruments (e.g,magnetometer, plasma
spectrometer, etc.)
DSN Coverage (70 m, 8-16 hrs/day)
1553B (lt 1 Mbps)
LVDS (lt 40 Mbps)
Ka-band Downlink (gt600 kbps)
1553B (lt 1 Mbps)
MSAP-based Flight Computer (21 low-rate
compression)
Telecom/SDST (50 W TWTA, 2.75 m HGA)
LVDS (10 Mbps)
500 bps engineering data generated by FS
9.6 Gb SSR
15 packetization added to downlink
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DSN Coverage
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Capabilities and Assumptions

• Resource constraint Data return
• Downlink Rate 600 kbps (worst case)
• Function of HGA, TWTA Power, 70 m DSN antenna or
  equivalent
• Data Storage 9.6 Gbits
• Encounter Data Returned 17.6 Gb per encounter
• Function of data storage, duration, downlink,
  overhead
• Ganymede Data Returned 700 to 2100 Mb/orbit
• Function of orbit period, downlink, overhead,
  DSN coverage (1-3 passes/day)
• Scenario Assumptions
• Encounter modes 6 hrs centered at closest
  approach
• Ganymede orbits 24 hr elliptical orbits, 2.6
  hr circular orbits
• DSN
• Approach and Tour 1 pass/day
• Encounter 3 passes/day during encounter day
• Ganymede orbit 3 passes/day for initial 30 days,
  2 passes/day for 2 months, and 1 pass/day
  thereafter

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Instrument Capabilities
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Notional Encounter Scenario

• 6 hr encounter mode based on battery sizing
• Strategy
• Start with empty SSR and fully charged battery
• Turn on fields and particle instruments (on 100
  of the time)
• Altimeter and Radar can only measure near closest
  approach (800 sec)
• Turn on remaining remote sensing instruments to
  fill data capability
• Balance of regional-scale and hi-res observations
• Global color and spectral coverage probably
  obtained 2 to 5 days out on either side of
  encounter
• Best resolution areas for global coverage will be
  restricted by encounter geometry

lt100 m res HiRes lt500 m res VNIR
lt50 m res HiRes lt250 m res VNIR
lt10 m res HiRes
Altimeter, Radar ( 5 min)
Closest Approach
-120 min
-60 min
-10 min
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Notional Elliptical Orbit Scenario
Most demanding scenario 24 hr DSN coverage
5 hr SSR Playback
2 hr Jupiter system monitoring
6 hr Altimeter, radar and gravity mapping 40 cm
res _at_200km
Realtime downlink
4 hr Global mapping 40 m resolution
Realtime downlink
2 hr Jupiter system monitoring
5 hr SSR Playback
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Systems Summary

• Highlights of JSO scenarios
• Continuous measurements of magnetometer, PS/EPD,
  radio science
• Encounter 8 Tbits
• For remote sensing instruments
• gt600 data sets of Io
• 1000 data sets of Europa
• gt1100 data sets of Ganymede
• gt1800 data sets of Callisto
• Limited measurements at each closest approach for
  LA, GPR
• Elliptical orbit 5.1 Tbits
• Monochrome 40 m resolution map in first month
• Cooperative global map 80 orbits
• Includes stereo camera return, full spectral
  resolution for UV and IR, but significant
  wavelength reduction for VNIR
• Circular orbit 3.1 Tbits
• gt14,000 data sets on each of the remote sensing
  instruments
• gt37,000 data sets on LA
• gt3400 data sets on GPR
• Flight System design shows a proof of concept
• Future trade studies to provide optimization of
  design

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Jupiter System Observer
Questions?

• January 28, 2008