1. Jet Propulsion Laboratory
California Institute of Technology
NASA Project Management
Challenge
February 9-10, 2010
Juno Project Overview and
Challenges for a Jupiter Mission
Sammy Kayali
Mission Assurance Manager
February 9-10, 2010
Slide - 1

2. Jet Propulsion Laboratory
California Institute of Technology
Outline
• Juno Mission Overview
• Spacecraft Design
• Instrument Suite
• The Juno Challenge
• Jupiter Environment
– Radiation Environment
– Charging Environment
– Solid Particle Environment
– Magnetic Environment
• Summary
February 9-10, 2010
Slide - 2

3. Jet Propulsion Laboratory
California Institute of Technology
Project Overview
Salient Features
• First solar-powered mission to Jupiter EFB
10/9/2013 Launch
• Eight instrument payload to conduct gravity, magnetic and
atmospheric investigations 8/05/2011
• Single polar orbiter (simple spinner) launches in August 2011
– 5 year cruise to Jupiter, JOI in July 2016
– 1 year operations, EOM via de-orbit into Jupiter in 2017
• Elliptical 11 day orbit swings below radiation belts to
minimize radiation exposure
• Key Juno partners: SwRI, JPL, ASI, LM-Denver and GSFC DSM
Sep 2012
Science
To improve our understanding of the solar system by
Understanding the origin and evolution of Jupiter, Juno will:
• Determine the global O/H ratio (water abundance) in Jupiter’s
atmosphere
• Measure latitudinal variations in Jupiter’s deep atmosphere
(composition, temperature, cloud opacity, and dynamics) JOI
• Map Jupiter’s magnetic and gravitational fields 7/5/2016
• Characterize Jupiter’s polar magnetosphere and aurorae Tilted Ecliptic Pole View (Vernal Equinox Direction
Up) 30-day Tick Marks
February 9-10, 2010
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4. Jet Propulsion Laboratory
California Institute of Technology
Juno Science Objectives
• Origin
– Determine O/H ratio (water abundance) and constrain core
mass to decide among alternative theories of origin.
• Interior
– Understand Jupiter's interior structure and dynamical properties
by mapping its gravitational and magnetic fields.
• Atmosphere
– Map variations in atmospheric composition, temperature, cloud
opacity and dynamics to depths greater than 100 bars.
• Polar Magnetosphere
– Explore the three-dimensional structure of Jupiter's polar
magnetosphere and aurorae.
February 9-10, 2010
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5. Jet Propulsion Laboratory
California Institute of Technology
Juno Flight System
SA Wing #3
Spacecraft: 1600 Kg dry mass
3625 kg wet mass
Power at 1 Au (theoretical): 15 kW
Power at JOI: 486 W
Power at EOM: 428 W
8.86 m
SA Wing #1
2.647 m 2.02 m
2.36 m
2.64 m
SA Wing #2
February 9-10, 2010
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6. Jet Propulsion Laboratory
California Institute of Technology
Spacecraft
Solar Wing #3
HGA
JADE Electron (3)
MWR A5
JEDI (3)
MWR A6
Solar Wing #1
Solar Wing #2
A4
A3
Nutation Damper
Fuel Tank Oxidizer Tank
55 Ah Li Ion
Battery (2)
Main Engine MWR A2 Toroidal Antenna
Waves MSC
Cover
February 9-10, 2010
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7. Jet Propulsion Laboratory
California Institute of Technology
Instrument Suite
February 9-10, 2010
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8. Jet Propulsion Laboratory
California Institute of Technology
The Juno Challenge
Solar
Thermal Environments
Radiation
Particles
Plasma Requirement
EM Fields Input
Magnetics
Instruments need
to measure But environmental
Jupiter’s exposure is a
environment threat to the
spacecraft
Measurement System Design
Capability
Science Signal Noise Spacecraft
Design
The spacecraft cannot create excess
noise which would disguise instrument
signals
February 9-10, 2010
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9. Jet Propulsion Laboratory
California Institute of Technology
Juno Trajectory Through Radiation Belts
• Juno trajectory exposes
spacecraft to the Jovian
radiation belts for less than
one day per orbit
– Electrons
– Protons
• Early orbits are relatively
benign
– ~25% of the mission
TID received by the
end of Orbit 17
• Late orbits are severe
– ~25% of the mission
TID received over the
last 4 orbits
Perijove Passage through Jupiter’s Radiation Environment
February 9-10, 2010
Slide - 9

10. Jet Propulsion Laboratory
California Institute of Technology
Juno Radiation Environment
Jupiter Trapped Peak Average Proton &
Electron Flux
• Juno radiation environment has several 1.E+08
challenging features 1.E+07
Proton & Electron Flux
– Large population of electrons > 10 MeV that Electrons
(particles/cm2-s)
1.E+06
Protons
cause high mission TID and DDD 1.E+05
– High electron flux near Perijove that causes 1.E+04
noise in sensors and charging of surfaces and 1.E+03
shielded dielectric materials 1.E+02
1.E+01
1 10 100 1000
Energy (MeV)
February 9-10, 2010
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11. Jet Propulsion Laboratory
California Institute of Technology
Juno TID Environment Comparison
1.0E+09
1.0E+08
1.0E+07
Mission TID rad(Si)
GLL dose through J35 (GIRE)
1.0E+06
Cassini
1.0E+05
MRO Juno
1.0E+04
1.0E+03
1.0E+02
1 10 100 1000 10000
Aluminum Spherical Shell Thickness, mil
• Galileo TID > Juno TID > Cassini > MRO TID
• Juno TID behavior parallels Galileo for shield thickness > 100 mils aluminum
Juno TID is ~ 1/4 of Galileo TID
February 9-10, 2010
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12. Jet Propulsion Laboratory
California Institute of Technology
End of Mission Radiation TID Levels
Solar Wing #3 Solar Cell Coverglass
(> 100 Mrad)
Deck Component
Surface Dose Z
(under blanket)
(11 Mrad) Vault Electronics
(25 Krad)
Solar Wing #1
MAG Boom
Solar Wing #2
Solar Cell
Junctions Instruments Outside Vault
(3 Mrad) (<0.6 Mrad in 60 mil housing)
February 9-10, 2010
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13. Jet Propulsion Laboratory
California Institute of Technology
Titanium Vault Protects Electronics
• Juno spacecraft electronics are shielded by a
vault
– The thickness and composition of the
vault walls are optimized to attenuate
Juno’s mix of electrons and protons using
the minimum mass
– Vault equipment packing factor
maximizes shielding from neighboring
electronics boxes
– Vault shielding designed to limit the TID
of all internal electronics to 25 Krad or
less
– Divided into zones for equipment with
different lifetimes and radiation hardness
• Electronics outside the vault have local
shielding designed for their location and part
hardness
February 9-10, 2010
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14. Jet Propulsion Laboratory
California Institute of Technology
Juno Charging Environment – Comparison
• The Jovian electron environment
1.E+10
Juno WC IESD Flux (10x) deposits charge in materials
Galileo Orbiter Peak Flux
1.E+09 Juno Spatially Worst 10-hour flux (1x) – Dielectric materials
GEO WC Flux
– Ungrounded metals
1.E+08
-1
• Juno electron charging
Flux, (cm s)
environment threat is severe
2
1.E+07
– ~2X higher than Galileo
1.E+06 – >10X higher than GEO
spacecraft threat
1.E+05
• Juno charging mitigation
1.E+04 – Grounding non-conducting
0.1 1 10 100 surface materials
Energy, MeV – Prohibit ungrounded metals
– Analyze charge deposition in
internal dielectric materials
– Test hardware that is
expected to discharge
• Harness
February 9-10, 2010
14
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15. Jet Propulsion Laboratory
California Institute of Technology
IESD Mitigation – Analysis and Test
Coax cable in test chamber
MWR G10 washer in antenna element
Electric field: 1.02 x 104 V/cm
No discharges expected
Spacecraft Space
Steel Connector
Housing View
G10 Washer
(20mil thick, .33” dia.)
• Electric field analysis of dielectrics Hollow Brass Annulus
(15mil thick walls, .26” dia.)
– Circuit boards
– Gaskets and washers
BeCu Probe
• Testing to characterize IESD pulses
– Harness
Aluminum Wall
Aluminum Walls
with Slots
(40mil thick each)
(40mil thick)
February 9-10, 2010
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16. Jet Propulsion Laboratory
California Institute of Technology
Juno Micrometeoroid Environment
• Spacecraft velocity and Jupiter gravity well result in
impact velocities > 100 km/sec
• Jupiter environment has a significant high velocity
meteoroid flux relative to cruise
• Spacecraft and payloads analyzed to determine
probability of failure due to meteoroid strikes
– Shielding is used to reduce impact damage
February 9-10, 2010
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17. Jet Propulsion Laboratory
California Institute of Technology
Micrometeoroid Analysis - Example
JIRAM Instrument
View
Instrument Component Assumptions Factor Failure Criteria
Assuming penetration of the
JIRAM Instrument Material: Al, Impact Angle: 0, 0.125 60 mil top of sensor will cause
failure
Particle penetrating 29.6 mils
of Cu (includes 4 mil of Cu
over wrap, 3.4mils of Cu
Material: Cu, Thermal Blanket: Kapton, Impact shielding (twisted pair braid),
Angle: 0, ASSUMES NO STAND OFF B/W and full conductor diameter
Data Cables 0.125
THERMAL BLANKET AND CABLE. 40 of 155 16); Insulator and thermal
conductors exposed. 0.8 m exposed length. blanket converted in to Cu
thickness using areal density.
Failure is severance of one of
the exposed conductors.
• Micrometeoroid analyses determine the
probability of failure of critical spacecraft Instrument Component
Survival
Probability
components.
JIRAM Instrument 98.1%
– View factors and shielding
Data Cables 99.1%
– Equipment redundancy
– Materials of construction
– Failure criteria
– Minimum science requirements
February 9-10, 2010
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18. Jet Propulsion Laboratory
California Institute of Technology
Juno Magnetic Field Challenge
JOI
Earth LEO
• The Juno spacecraft is exposed to intense magnetic fields at each perijove pass
– 5-6 Gauss typical, 12 Gauss maximum
– ~10X LEO spacecraft magnetic field strength; ~1000X GEO magnetic field strength
• The AC magnetic field represents an operational challenge
– Developed an AC Magnetic Susceptibility requirement and extensive test program
• The effects of a spinning spacecraft in a magnetic field (VxB) were addressed
• DC Magnetic cleanliness requirement represented a challenge for material selection and usage.
February 9-10, 2010
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19. Jet Propulsion Laboratory
California Institute of Technology
AC Magnetic Susceptibility
Mitigation Approach
Design Shield Model Shield Build & Test Shield
• Implemented plan of early assessment and mitigation by identifying and testing
hardware that is susceptible to rapidly changing magnetic fields
– Components with soft magnetic materials, solenoids, isolators, ferrites, large
current loop areas etc.
• AC magnetic susceptibility test approach developed
– 2X margin on expected magnetic field at JOI and 1.3 during science
– Equipment tested to +/- 9 Gauss at 5 RPM at JOI
– Equipment tested to +/-16 Gauss at 2 RPM during science
February 9-10, 2010
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20. Jet Propulsion Laboratory
California Institute of Technology
Effects on Spinning Spacecraft in a
Magnetic Field (VxB)
• Plasma sees a potential φ=0
difference across the
B
moving spacecraft
• Most positive part of the θ
ITO coated array floats
φ ≈ -300 V
near local plasma potential v
• Maximum difference
between spacecraft and
plasma is vxB potential
plus array voltage –full
batttery charge φ ≈ -615 V
• Vmax ≈ -615 V
• Grounding design practices implemented
throughout the spacecraft mitigate the issue
•Solar Array coupon tests conducted to
validate analysis
Juno Spacecraft
February 9-10, 2010
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21. Jet Propulsion Laboratory
California Institute of Technology
DC Magnetic Cleanliness
Mitigation Approach
Typical
Mag
Mapping QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
Tests of
Small and
Large Items
Juno Telecom x4 Multiplier
• Key magnetic cleanliness impact items identified early, tracked and resolved
– Latch valves identified as significant magnetic field contributors
• Self compensation design implemented
– Telecom components identified as a potential magnetic cleanliness contributor
• Key components were analyzed, tested and self-compensated
• Complete review of all materials for magnetic contribution
– Expert panel reviewed material lists and identified areas of concerns
– Changed or modified magnetic materials to suitable non-magnetic materials
– Analysed and approved use of magnetic materials if low risk was determined
February 9-10, 2010
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22. Jet Propulsion Laboratory
California Institute of Technology
Summary
• The environmental challenges on Juno are
considerable but surmountable
• Early planning and attention to details have
been essential in avoiding environmentally
related problems
– Having the “right” experts
– Team Education
– Utilize appropriate analysis tools
– Detailed and thorough test to prove
the design
• Minimize new designs and rely on proven
architecture
February 9-10, 2010
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