Critical Design Review
December 9, 2014
Project Manager:
Gabrielle Massone
Systems Engineer:
Jesse Ellison
Deputy Project Manager
Financial Lead
Tanya Hardon
Software Lead:
Cy Parker
Optics Lead:
Jon Stewart
Mechanical Lead
Jake Broadway
Test and Safety Lead:
Franklin Hinckley
Thermal Lead:
Brenden Hogan
Customers:
Brian Sanders
Colorado Space Grant (COSGC)
JB Young and Keith Morris
Lockheed Martin (LMCO)
Faculty Advisor:
Dr. Xinlin Li
Dept. Aerospace Engineering
Laboratory for Atmospheric and
Space Physics (LASP)
Electrical Lead:
Logan Smith
Purpose and Objectives
Design Solution
Requirement Satisfaction
Verification/Validation
Planning
1
Presentation Overview




Project Purpose and Objectives
Design Solution
Critical Project Elements
Design Requirement Satisfaction
• Optical and Mechanical
• Thermal
• Electronics and Software
 Verification and Validation
 Project Risks
 Project Planning
Purpose and Objectives
Design Solution
Requirement Satisfaction
Verification/Validation
Planning
2
PROJECT PURPOSE AND
OBJECTIVES
Purpose and Objectives
Design Solution
Requirement Satisfaction
Verification/Validation
Planning
3
Mission Motivation
 Growing interest in
asteroid rendezvous
missions
 Requires precise
knowledge of target
asteroid attitude and
angular velocity vector
for rate-matching
operations
Purpose and Objectives
Design Solution
Example asteroid mission, not PHOENIX design concept
Requirement Satisfaction
Verification/Validation
Planning
4
Phoenix Mission Objective
Develop a proto-flight, angular-velocity sensor payload that
can observe an object in mid-wave infrared and determine the
angular velocity of the object in the field of view
Proto-flight Unit:
Defined as hardware that is designed to flight form-factor, but will be tested
exclusively on the ground and is not required to undergo environmental testing.
Purpose and Objectives
Design Solution
Requirement Satisfaction
Verification/Validation
Planning
5
Mission Concept
Example angular velocity sensor concept
ω
6U CubeSat with
Rate Sensor Payload
Observing asteroid in FOV
Characterize rotation of asteroid for
rendezvous operations
Bennu 101955
Asteroid
Video courtesy of www.asteroidmission.org
Purpose and Objectives
Design Solution
Requirement Satisfaction
Verification/Validation
Planning
6
Mission Concept
Use this sequence of images to determine the object’s
angular velocity vector in the camera FOV
Report this observed rate to
the bus
Effectively an infrared
angular velocity sensor
Purpose and Objectives
Design Solution
Requirement Satisfaction
Verification/Validation
Planning
7
Assumptions
 Ground Testing Unit with Simulated Target
• Simulated test target properties representative of
asteroid 101955-Bennu
 Zero Relative translational velocity between object
and bus during observation
 Phoenix payload is not exposed to direct sunlight
 Will calculate observed angular velocity
• Knowledge of range between Phoenix and target not
needed
 Physical
Effectiverange
range
between
Phoenix
and target will be
much
smaller
~ 1 meter
<100
• km
Refer to test setup on following slide
Purpose and Objectives
Design Solution
Requirement Satisfaction
Verification/Validation
Planning
8
Concept of Operations
Test two major subsystems independently to simplify test
setup and feasibility
Optics Integrated System Testing
Thermal Integrated System Testing
 Conducted in atmosphere
 Verify ability to capture focused
image in MWIR and determine
rotation rate
 External cooling (i.e. dry ice heat
sink)
 Conducted in Hard Vacuum
 Test Thermal system
 Optical system acts only as
thermal mass
 No focusing or operation of
optics required
Fully Verified System
Purpose and Objectives
Design Solution
Requirement Satisfaction
Verification/Validation
Planning
9
Concept of Operations
Optics Integrated System Test
Phoenix and
Cooling Structure Collimating Lens
Cold Background
Target/Motor/
Encoder
Light rays observed from a target over
10km away are essentially parallel
Therefore, the test setup needs to also
provide parallel rays (collimated light) so
optics can be focused and tested as they
would be on-orbit
Purpose and Objectives
Design Solution
Collimating Lens
Requirement Satisfaction
Verification/Validation
Planning
10
Concept of Operations
Optics Integrated System Test
Phoenix and
Cooling Structure Collimating Lens
Cold Background
Target/Motor/
Encoder
Structure will not be able to
reach its nominal temperature
in open atmosphere - structure
panels are cooled externally
Cold background (cooled
with dry ice) ensures
high contrast between
target and background
(representative of space)
Cooling Structure
Purpose and Objectives
Design Solution
Requirement Satisfaction
Verification/Validation
Planning
11
Concept of Operations
Optics Integrated System Test
Phoenix and
Cooling Structure Collimating Lens
Target/Motor/
Encoder
Assemble
Test Setup
Purpose and Objectives
Design Solution
Requirement Satisfaction
Verification/Validation
Planning
12
Concept of Operations
Optics Integrated System Test
Assemble
Test Setup
Cool
Structure
Purpose and Objectives
• Fill cooling structure
with methanol
• Slowly add dry ice to
reduce thermal shock
Design Solution
Requirement Satisfaction
Verification/Validation
Planning
13
Concept of Operations
Optics Integrated System Test
Assemble
Test Setup
Cool
Structure
Take/Store
Image
Mid-Wave IR image of the moon
provides idea of what a rocky
body in space looks like at our
wavelength
Purpose and Objectives
Design Solution
Requirement Satisfaction
Verification/Validation
Planning
14
Concept of Operations
Optics Integrated System Test
Assemble
Test Setup
Cool
Structure
Take/Store
Image
Rotate
Target
Stepper motor rotates target a small amount,
rotation angle is verified by a shaft encoder
Purpose and Objectives
Design Solution
Requirement Satisfaction
Verification/Validation
Planning
15
Concept of Operations
Optics Integrated System Test
Assemble
Test Setup
Cool
Structure
Take/Store
Image
Rotate
Target
Take/Store
Image
Second image is captured after a set delay or angular change.
Observed angular velocity is computed from the measured rotation
angle, apparent distance to target, and delay between images
Does not require software to know actual distance from target
Purpose and Objectives
Design Solution
Requirement Satisfaction
Verification/Validation
Planning
16
Concept of Operations
Optics Integrated System Test
Assemble
Test Setup
Cool
Structure
Take/Store
Image
Rotate
Target
Take/Store
Image
Compute
Rate/Axis
Software produces vector field of observed motion,
computes axis and rotation angle from this field.
Rate is simply rotation angle divided by the delay between
images.
Purpose and Objectives
Design Solution
Requirement Satisfaction
Verification/Validation
Planning
17
Concept of Operations
Thermal Integrated System Test
1. Test ability of thermal system to
maintain focal-plane temperature
2. Verify functionality of electronics in
thermal environment
Phoenix
• Bus Simulator
• Aluminum Structure
• Heaters
• Simulate bus heat load
• Thermocouples
• Monitor interface
temperature
• Test in Thermal Vacuum (TVAC) Bus Simulator
• Realistic environment
• Accessibility confirmed with
Lockheed-Martin
Purpose and Objectives
Design Solution
Requirement Satisfaction
Verification/Validation
Planning
18
DESIGN SOLUTION
Purpose and Objectives
Design Solution
Requirement Satisfaction
Verification/Validation
Planning
19
Design Objectives
1. The payload shall integrate electrically and structurally into
the 2U payload section of the Lockheed Martin 6U CubeSat
bus
2. The payload shall determine the angular velocity and axis of
rotation within 1σ of6U
an CubeSat
observed object with characteristics
of the reference asteroid 101955-Bennu
LMCO Bus
Phoenix
3. The payload shall use the 3.5 µm mid-wave infrared (MWIR)
wavelength
4. The payload shall maintain all components in their operating
20 cm
temperature1Uranges
MWIR Focalplane
Operates ≤ 150 K
10 cm
10 cm
Purpose and Objectives
Design Solution
Requirement Satisfaction
Verification/Validation
Planning
20
Design Overview
Phoenix Interfaces with the 6U LMCO Bus
•
Inhabits 1/3 of spacecraft volume
Purpose and Objectives
Design Solution
Requirement Satisfaction
Verification/Validation
Planning
21
Design Overview
Infrared Optics and Focusing
•
•
Two Mirror Design
Manually adjust position of primary
mirror using micrometers
• Precision: 1 micron
• Total Travel: 5 mm
Bus Interface Side
Purpose and Objectives
Design Solution
Requirement Satisfaction
Verification/Validation
Planning
22
Design Overview
Infrared Optics and Focusing
•
•
Two Mirror Design
Manually adjust position of primary
mirror using micrometers
• Precision: 1 micron
• Total Travel: 5 mm
Hyperbolic
Primary Mirror
Hyperbolic
Secondary
Mirror
Focal-Plane
3-Axis Focusing
Mechanism
Micrometer
Primary Mirror
Secondary Mirror
Purpose and Objectives
Design Solution
Requirement Satisfaction
Verification/Validation
Planning
23
Design Overview
Thermal Control
•
•
•
Thermal Electric Cooler
Thermal braids to exterior radiator panels
Focalplane requires cooling to 150 K for
operation in infrared band
Purpose and Objectives
Design Solution
Requirement Satisfaction
Verification/Validation
Planning
24
Design Overview
Thermal Control
•
•
•
Thermal Strap
Thermal Electric Cooler
Thermal braids to exterior radiator panels
Focalplane requires cooling to 150 K for Image Sensor
operation in infrared band
Module
Thermoelectric
Coolers
MWIR Focalplane
Operates ≤ 150 K
Purpose and Objectives
Design Solution
Requirement Satisfaction
Verification/Validation
Planning
25
Design Overview
Electronics
Software
•
•
•
•
•
•
MWIR Sensor module
Image Processing board
Power and thermal control board
Image
Purpose and Objectives
Design Solution
Requirement Satisfaction
Capture and save IR image
Determine rate of object in FOV
Verification/Validation
Planning
26
Design Overview
Electronics
Software
•
•
•
•
•
•
MWIR Sensor module
Image Processing board
Power and thermal control board
Image
Capture and save IR image
Determine rate of object in FOV
Power and Thermal
Control Board
Sensor Interface
Module
Purpose and Objectives
Design Solution
Requirement Satisfaction
Verification/Validation
Image Processing
Board
Planning
27
Functional
Block
Diagram
Purpose and Objectives
Design Solution
Requirement Satisfaction
Verification/Validation
Planning
28
Critical Project Elements
Critical Element
Subsystem Driving Requirements
Capture Mid Wave
Infrared (MWIR) image
Optical
The payload shall determine the angular
velocity and axis of rotation of an observed
object (O.2), The payload shall use the 3.5 µm
mid-wave infrared (MWIR) wavelength (O.3)
Control focalplane to
operating temperature
of ≤ 150 K
Thermal
The payload shall maintain all components in
their operating temperature ranges (O.4)
Determine angular
velocity vector of object
in sensor field of view
Software
The payload shall determine the angular
velocity and axis of rotation of an observed
object (O.2)
Custom board designs
Electrical
The payload shall maintain all components in
their operating temperature ranges (O.4)
The payload shall interface with the bus (O.1)
Purpose and Objectives
Design Solution
Requirement Satisfaction
Verification/Validation
Planning
29
OPTICAL AND MECHANICAL
Purpose and Objectives
Design Solution
Requirement Satisfaction
Verification/Validation
Planning
30
Purpose
To capture a sequence of images of the target
object in the field of view
 Image at the 3.5 µm wavelength
• Mid-Wave Infrared (MWIR) Band
 Resolve target at a distance of 16 km so that target
fills full field of view
 Signal to Noise Ratio ≥ 6
 Tolerances change the spatial cutoff frequency
by < 15%
Purpose and Objectives
Design Solution
Requirement Satisfaction
Verification/Validation
Planning
31
Design Overview
Ritchey-Chretien Optics Design - Ray Trace Diagram
Incoming
Light Ray
Hyperbolic
Primary Mirror
On-axis ray
9.5 cm
Hyperbolic
Secondary
Mirror
nBn Focal
Plane
14.3 cm
Purpose and Objectives
Design Solution
Requirement Satisfaction
Verification/Validation
Planning
32
Focal-Plane: Mid-Wave Infrared Detector
 Mid-Wave Infrared detector
• Operating Temperature: 150 K
• Resolution: 1.3 MPx or 1280x1024
• Pixel Size: 12 µm
 Customer Required Component
First MWIR detector Feasible for CubeSat Operations
1.3 MPx (1280x1024) nBn detector Image
Purpose and Objectives
Design Solution
Requirement Satisfaction
Image of Moon in MWIR
Verification/Validation
Planning
33
Sampling


Sampling size is the detector pixel size
(i.e. 12 µm)
Nyquist Theorem
•

2.OPT.1
Diffraction limited spot
size < 20 µm at λ =3.5 µm
sampling size = optical spot size
Oversampling
•
Nyquist Sampling
sampling size < optical spot size
Normalized Diffraction Limited Spot Cross Section
Over-sampling
Spot Size
Purpose and Objectives
Design Solution
Nyquist sampling versus over-sampling,
exaggerated for effect
Requirement Satisfaction
Verification/Validation
Planning
34
Spot Size
Spot sizes calculated using Zemax simulations
Optically
Limited
Designs
Diffraction
Limited
Designs
On & Off Axis Beams
Diffraction Limited
2.OPT.1
Diffraction limited spot
size < 20 µm at λ =3.5 µm
Purpose and Objectives
Design Solution
Requirement Satisfaction
Verification/Validation
Planning
35
Signal to Noise Ratio (SNR)
 Assuming operation at 3.32-3.60 µm wavelengths
 Primary source of noise: thermal background and dark
current
 SNR ≥ 6 reduces probability of false alarms from noise
to ~10-12 in sensing and tracking functions
Signal to Noise Ratio vs. Range from Target
2.OPT.3
SNR
SNR ≥ 6
SNR = 6.28
Range (km)
Purpose and Objectives
Design Solution
Requirement Satisfaction
Verification/Validation
Planning
36
Tolerance Diagram
 Tolerances calculated using built in Zemax functionality
 All tolerances feasible to manufacture
+ 0.15°
2.OPT.4
Tolerances shall change
the spatial cutoff
frequency ≤ 15 %
+ 0.15°
+ 0.015”
+ 0.015”
+ 0.008”
+ 0.008”
+ 0.008”
Purpose and Objectives
Design Solution
Requirement Satisfaction
Verification/Validation
Planning
37
Mirrors & Focusing Mechanism
 Design requires custom ordered mirrors
 Lead time / Cost: 8-12 weeks / $10k
 Focusing Mechanisms need 0.008’’ accuracy:
• Primary mirror: 3 Micrometers in X-Y-Z Axes
• Secondary mirror: Fixed but can be adjusted with shims
 Change in focus between room and operating temperatures

Need to compensate for thermal contraction when focusing at room
temperature
Solidworks Model: Primary Focusing Mechanism
Side View of PHOENIX
Purpose and Objectives
Design Solution
Requirement Satisfaction
Primary Focusing Mechanism
Verification/Validation
Planning
38
Mass Budget
Subsystem
Mass (g)
Structures
328
Optics
81
Electronics
59
Thermal Control
157
Total
625
Allowable Mass
2000
Contingency
1375
 Large Mass Contingency
 Values from Solidworks
Model Estimates
Mass Distribution Structure
16.4%
Margin
68.75%
Purpose and Objectives
Design Solution
Requirement Satisfaction
Verification/Validation
Optics 4.1%
Electronics
2.9%
Thermal
Control 7.8%
Planning
39
Status





Design baffles to reduce thermal background
Procurement of mirrors
Design alignment procedure for optical system
Carry out point spread function and aberration tests
Finalize and manufacture mechanical assembly
Purpose and Objectives
Design Solution
Requirement Satisfaction
Verification/Validation
Planning
40
THERMAL
Purpose and Objectives
Design Solution
Requirement Satisfaction
Verification/Validation
Planning
41
Purpose
Purpose: to control and monitor the temperature of the
Phoenix system
 Monitor the temperature of critical components
 Report health and status, including temperature data
 Control the thermal adjustment mechanisms
 Control temperature of all critical components to within
operating range
• Focalplane and Optics Assembly (Require Cooling)
• Electronics Boards (Require Heating)
Purpose and Objectives
Design Solution
Requirement Satisfaction
Verification/Validation
Planning
42
Initial Thermal Analysis
Apayload = 0.07 m2
εpaint = 0.92
Constants
Qbus=6W
Qpayload = 4W
Qin = 10W
Qin = Apayload εpaint σ Ts4
Temperature
of Payload
Ts=229K
3.THM.2
Maintain electronics within
233-358 K
Purpose and Objectives
Design Solution
3.THM.2
Maintain reflectors below
230 K ± 5 K during operation
Requirement Satisfaction
Verification/Validation
Planning
43
Primary Paths
Legend
Q2
Heat
Radiation
Q3
EPS
Asteroid
Albedo
Conduction
α1
Thermal Node
CDH
R6
R5
Q1
ε3
Bus
ΔT
Optics
ε1 Focalplane
R1 Control
R1
Sensor Interface
Board
Cold Side
Hot Side
R1 Thermal Strap R2
Structure
R4
ε3
R3
Focal Plane
Cold Space
Thermal Electric Coolers
Thermal Strap
Bus To Structure
Titanium Panels
Purpose and Objectives
Design Solution
Requirement Satisfaction
Verification/Validation
Planning
44
Thermoelectric Cooler (TEC)
TEC Model:
RMT 4MCO4-115-15
Thermal Straps
to Structure
TEC 2: ∆T = 30K
4 Pin= 0.336W
2
TEC 1: ∆T = 60K
Pin = 0.71W
Face
Temp
1
150K
2
180K
3
180K
4
230K*
1
3
Focalplane
Heat Flow From Focalplane
* Steady State
2.THM.5
Power Lines
Aluminum Plate
9.6 x 9.6 x 0.5 mm
 Two 4-Stage TECs in Series

TEC efficiency drops linearly with temperature
Purpose and Objectives
Design Solution
Requirement Satisfaction
Verification/Validation
Power ≤ 4W
3.THM.3
Focalplane temp.
≤ 150 K ± 5K
Planning
45
Other Hardware
Not Shown in Model
• MLI Insulation
• Heaters for Electronics Boards
• Thermal Epoxy
2.THM.1
Monitor temp of critical
components within 2K
2.THM.4
Control temp of components
within operating range
3.THM.1
Thermal
Sensors 7 Total
Radiators
Dissipate 10 W of heat
Thermal Electric Coolers
White Paint
•
All component selection
and price quotes in
backup slides
Thermal Strap
Bus To Structure
Titanium Panels
Purpose and Objectives
Design Solution
Requirement Satisfaction
Verification/Validation
Planning
46
Modeling
Object
Temperature
Optics
206 K
Focal Plane
150 K
Sensor Interface
150 K
Cold Side
150 K
Hot Side
230 K
Thermal Strap
228 K
Structure
230 K
Bus
303 K
Cold Space
3K
 Simulink Model
• Converted the thermal circuit
into a Simulink model to
evaluate steady state
temperature values
Legend
Heat
Radiation
Q2
Q3
EPS
Asteroid
Albedo
Conduction
α1
Thermal Node
CDH
R6
R5
Q1
ε3
Bus
ΔT
Optics
ε1 Focalplane
R1 Control
SensorBoard
R1
Cold Side
Hot Side
R1 Thermal Strap R2
Structure
Interface
ε3
R3
Purpose and Objectives
Design Solution
R4
Requirement Satisfaction
Verification/Validation
Planning
Cold Space
47
Implications
 The current thermal design meets all requirements
 Risks associated with the active design can be
mitigated with thorough testing
 The thermal design is below budget
• Using $1,880 of $2,000
Purpose and Objectives
Design Solution
Requirement Satisfaction
Verification/Validation
Planning
48
ELECTRONICS
Purpose and Objectives
Design Solution
Requirement Satisfaction
Verification/Validation
Planning
49
Purpose
 Hardware Platform for Software
• Capture and store image data from sensor module
• Run image processing algorithms
• Report results to bus
 Thermal Monitoring and Control
• Drive thermal actuators
• Implement software control laws
• Convert thermal sensor outputs to engineering units
 Bus Interface
• Regulate power
• Protect sensitive hardware
• Isolate communication lines
Purpose and Objectives
Design Solution
Requirement Satisfaction
Verification/Validation
Planning
50
Design Overview
Power and Thermal Board
Imaging Board
Power Regulation
Surge Protection
Image Sensor Module
Interface
TEC and Heater Control
Processor
Sensor Conditioning and
Monitoring
Communication Bus
Isolation
Memory
Detailed schematics can be found in the backup slides
Purpose and Objectives
Design Solution
Requirement Satisfaction
Verification/Validation
Planning
51
Power and Thermal Board
Purpose and Objectives
Design Solution
Requirement Satisfaction
Verification/Validation
Planning
52
Power and Thermal Board
Communication Bus Isolation
2.ELEC.1
The electrical system shall interface
with the LMCO 6U CubeSat Bus
Purpose and Objectives
Design Solution
Requirement Satisfaction
Verification/Validation
Planning
53
Power and Thermal Board
TEC Control
Heater Control
2.ELEC.1
The electrical system shall provide all
hardware necessary for thermal
monitoring and control
Purpose and Objectives
Design Solution
Requirement Satisfaction
Verification/Validation
Planning
54
Power and Thermal Board
3.ELEC.4
3.ELEC.5
The electrical system shall guarantee
all power provided to sensitive
hardware is within specifications
The electrical system shall protect the
payload from power surges and over
current events
Power Regulation and Surge Protection
Purpose and Objectives
Design Solution
Requirement Satisfaction
Verification/Validation
Planning
55
Image Processing Board
Purpose and Objectives
Design Solution
Requirement Satisfaction
Verification/Validation
Planning
Image Processing Board
Memory
Processor
2.ELEC.3
The electrical system shall provide a
hardware platform for the flight
software
Purpose and Objectives
Design Solution
Requirement Satisfaction
Verification/Validation
Planning
Image Processing Board
Image Sensor Module Interface
2.ELEC.2
The electrical system shall interface
with the MWIR Image Sensor Module
3.ELEC.3
The electrical system shall utilize an
FPGA to house the image module
interface IP core
Purpose and Objectives
Design Solution
Requirement Satisfaction
Verification/Validation
Planning
Image Processing Board
3.ELEC.6
The electrical system shall
utilize the I2C, SPI, and
Ethernet specifications
Purpose and Objectives
Design Solution
Requirement Satisfaction
Verification/Validation
Planning
Flow of Information
2
1
4
3
1. Sensor data sent to FPGA Core
2. Image Sensor Core streams images into RAM
3. CPU Reads and Processes Images
4. CPU Sends results to bus when requested
Purpose and Objectives
Design Solution
Requirement Satisfaction
Verification/Validation
Planning
Development
Mitigating Risk of Custom Circuit Boards
 Schedule for 2-3 revisions
 Team Members with Prior experience
•
•
•
•
Power Regulation and Isolation
BGA Components
High-Speed Memory (DDR2, DDR3)
Multi-Layer Designs (8 Layer)
Prior Work – Star Camera
FPGA interface with CMOS
(4 Layer PCB)
Prior Work – DDR2, BGAs, Power Regulation and
Monitoring (8 Layer PCB)
Purpose and Objectives
Design Solution
Requirement Satisfaction
Prior Work – DDR3, BGAs,
FPGA Design (8 Layer PCB)
Verification/Validation
Planning
61
Power Budget
Budget 5W nominal, 15W 10 minute burst
Design Element
Reference Component
Nominal Power
Consumption
TEC
Laird MS2 series
1.0 W
CPU
ARM Cortex A9 667MHz
0.5 W
Image Sensor Interface
Xilinx Zynq-7030 Fabric
0.8 W
Focal Plane
nBn-sensor
0.05 W
Memory
Micron DDR3L-1066
0.65 W
Power Regulation
Buck/Boost 90% efficient
0.80 W
TEC Control
Buck 90% efficient
0.10 W
Raw Total
No Margin
3.9 W
System Margin
20%
0.78 W
Total + Margin
4.68 W
Contingency
0.32 W
Overview
Baseline Design
Optics
Thermal
Electrical
Testing
Logistics
62
Status




Schematics in final phase
Layout starting mid-December
Boards ordered before spring semester
$3500 Budget
Purpose and Objectives
Design Solution
Requirement Satisfaction
Verification/Validation
Planning
63
SOFTWARE
Purpose and Objectives
Design Solution
Requirement Satisfaction
Verification/Validation
Planning
64
Software Overview
Purpose: Determine the angular velocity vector of a target
object from a sequence of images and report this solution
to the bus
 System Control
• Communicate with LMCO Bus & parse bus commands
• Gather data from power board
• Command TEC temperature set-point
 Image processing
• Filter image
• Determine delta vectors
• Determine rotation attitude
• Compress raw image for transfer to bus
Purpose and Objectives
Design Solution
Requirement Satisfaction
Verification/Validation
Planning
65
Software Overview
System Control Software
Communication
Module
Facilitates communication
between the bus and payload.
 SPI Driver
 Message Handlers
Image Interface
Module
Set of functions for accessing and
manipulating the image file
 Object or “Image Class”
Temp. Control
Module
Control and Monitor Thermal
System
 Monitor thermal sensors
 Control Thermoelectric Cooler
(TEC)
 Operate focalplane only in
acceptable temperature range
and avoid thermal shock
Purpose and Objectives
Design Solution
Requirement Satisfaction
Verification/Validation
Planning
66
Software Overview
Image Processing
Reduce image noise prior to
processing
 Noise reduction algorithm
Noise Reduction
Module
Produces a vector field from two
or more images
Optical Flow
Module
Determines angular velocity of
given vector field
 Correlates to spin of target
Rate
Determination
Module
Image
Compression
Module
Purpose and Objectives
Compresses images for
communication to the bus
Design Solution
Requirement Satisfaction
Verification/Validation
Planning
67
Angular Velocity Determination
 Vector field obtained using Optical Flow algorithm
 Curl of vector field computed
• A trough will appear along the axis of rotation
• Point along trough with the smallest magnitude
vector is the center of rotation (pierce point)
Overview
Baseline Design
Optics
Thermal
Electrical/Software
Testing
Logistics
68
Angular Velocity Determination
 Can determine orientation of axis
• Angle ρ between axis and horizontal camera frame
directly measured
• Position of pierce point relative to center of target
provides angle ϕ between axis and plane parallel to
sensor
D1
ϕ = arcsin(D2/(D1+D2)
Overview
Angle ρ
D2
Baseline Design
Optics
Thermal
Electrical/Software
Testing
Logistics
69
Status
 MATLAB simulations of the optical flow and rate
determination modules underway
 Bus communication module implemented, currently
undergoing testing
 Baseline MATLAB Algorithm by Jan 2015
 Implementation of C/C++ Software Modules Spring
Semester
Purpose and Objectives
Design Solution
Requirement Satisfaction
Verification/Validation
Planning
70
VERIFICATION AND
VALIDATION
Purpose and Objectives
Design Solution
Requirement Satisfaction
Verification/Validation
Planning
71
Primary Test Flowdown
Optics/Structures
Thermal
Electronics/Software
Focusing Tolerance Test
• Use collimated laser and
focusing mechanisms to focus
to smallest spot size
Bring-Up Testing
• Test basic circuit
functionality
Thermistor Characterization
• Establish scale factor
Point Spread Function Test
• Vary collimated laser
incidence angle to determine
the PSF
Interface Tests
• Test file transfers and
commands with
simulated bus
Characterize Heat Paths
• Ensure model accurately
reflects system
Image Sensor Tests
• Test ability to set image
capture parameters and
capture image
TEC Characterization
• Verify temperatures at
TEC interfaces (thermal
gradient)
Aberrations Test
• Use PSF to determine optical
aberrations
Integrated Optics Test
Integrated Thermal Test
Fully Verified System
Purpose and Objectives
Design Solution
Requirement Satisfaction
Verification/Validation
Planning
72
Materials and Facilities
Materials
 Thermal
Facilities
 Thermal
• Bus simulator
• Thermal Vacuum Chamber
• Power resistors
• Aluminum structure
• Lockheed-Martin Waterton
Canyon Facility
• Accessibility Confirmed
 System
•
•
•
•
Dry ice/Methanol
Steel test assembly
Collimating lens
Electrical Ground Support
Equipment
• Stepper Motor/Encoder
Purpose and Objectives
Design Solution
 System
• No special facilities
required
Requirement Satisfaction
Verification/Validation
Planning
73
System Requirement Verification
Req.
Summary
Verification
O.1
The payload shall integrate to the bus
Inspection
O.2
The payload shall determine the rotation rate and axis of
rotation
Integrated
Optics Test
O.3
The payload shall use the 3.5µm wavelength
Inspection
O.4
The payload shall maintain all components in their
operating temperature ranges
Integrated
Thermal Test
Purpose and Objectives
Design Solution
Requirement Satisfaction
Verification/Validation
Planning
74
Project Risk Assessment
 Risk related things!
5
Unable to keep
focalplane at
150 K
Probability Increases
4
Unable to
evenly
distribute heat
TECs too
inefficient
when cold
Manufacturer
extends mirror
lead time
Unable to use
LMCO TVAC
SNR too low to
determine rate
2
3
4
3
2
1
Probability
Severity
1
5
Severity Increases
Purpose and Objectives
Design Solution
Requirement Satisfaction
Verification/Validation
Planning
75
PROJECT PLANNING
Purpose and Objectives
Design Solution
Requirement Satisfaction
Verification/Validation
Planning
76
Organizational Chart
Aerospace Dept.
Customers
COSGC & LMCO
Phoenix Team
Deputy PM/Finance
Project Manager
Systems Engineer
Tanya Hardon
Gabrielle Massone
Jesse Ellison
Thermal Lead
Optics Lead
Electronics Lead
Software Lead
Manufacturing Lead
I&T Lead/Safety
Brenden Hogan
Jon Stewart
Logan Smith
Cy Parker
Jacob Broadway
Franklin Hinckley
Support
Support
Franklin Hinckley
Jacob Broadway
Brenden Hogan
Jon Stewart
Support
Tanya Hardon
Gabrielle Massone
Support
Support
Support
Jacob Broadway
Jesse Ellison
Logan Smith
Purpose and Objectives
Design Solution
Requirement Satisfaction
Verification/Validation
Planning
77
Work Products Breakdown Structure Summary
Please refer to backup slides for complete WPBS hierarchy
Planning and Design
Optics/Structure
 Solidworks Model
 Zemax Optical Simulation
Testing
Manufacturing and Integration
 Manufactured Structure
 Optics Mirrors in-house
 Optics Bench Test
 Focalplane characterized
 TEC Integrated
 Thermal Strap Integrated
 TEC characterized
 Thermal Paths Characterized
Electrical/Software
 Electrical Schematics and
Layout
 Software Architecture
 MATLAB Rate Algorithm
 Manufactured and
Populated PCBs
 Implemented Software
Modules in C/C++
 Electrical Test Report
 Image Capture Test Report
 Angular Velocity
Determination Test Report
Systems/Management
 Requirements Matrix
 Schedule and WBPS
 Budget
 Wire Harness
 Complete Subsystem
Integration
 Integrated Optics Test
 Integrated Thermal Test
 Requirements Verified
Thermal
 Thermal Circuit and Heat
Paths
 Simulink Model
Purpose and Objectives
Design Solution
Requirement Satisfaction
Verification/Validation
Planning
78
Work Plan
*See Phoenix
documentation for
complete schedule
Purpose and Objectives
Planning and
Design
Design Solution
Manufacturing and
Integration
Requirement Satisfaction
Verification/Validation
Testing
Planning
79
Overall Cost Plan
Total Funds Available: $20,000
($5000 ASE Dept + $15000 Customer)
Category
Major Components
Optics
$10,000 Mirrors
Bandpass Filter
Electronics
TEC Controller Board
Power Board (2 Revs)
300, $200, 1%
1,400, $3,400,
17%
3,000,
$1,200, 6%
CDH Board (2 Revs)
Thermal
1,400, $700, 4%
$150 TECs (2)
$ 600 Thermal Braids
10,400, $10,500,
52%
2,900, $3,000,
15%
Insulation
Thermistors (5)
Testing
$300 Collimator
Test Target, Bus Simulator, etc…
Structures
Aluminum Stock & Misc.
Misc.
General Supplies
600, $1,000, 5%
Optics
Structures
Thermal
Testing
Electronics
Miscellaneous
Margin
Purpose and Objectives
Design Solution
Requirement Satisfaction
Verification/Validation
Planning
80
CONCLUDING STATEMENTS
81
Conclusions
Thank you for your time
Acknowledgements
 PAB Faculty and Staff
 Faculty Advisor
• Dr. Xinlin Li
 Our customers
• Brian Sanders (COSGC)
• JB Young (LMCO)
• Keith Morris (LMCO)
82
References
[1] Adams, Arn. "ADVANCES IN DETECTORS: HOT IR Sensors Improve IR Camera Size, Weight, and
Power." Laser Focus World. PennWell Corporation, 17 Jan. 2014. Web. 13 Sept. 2014.
[2] "An Introduction to the NBn Photodetector." UR Research. University of Rochester, 2011. Web. 12 Sept. 2014.
[3] "ARCTIC: A CubeSat Thermal Infrared Camera." TU Delft. Delft University of Technology, 2013. Web. 13 Sept.
2014.
[4] Cantella, Michael J. "Space Surveillance with Infrared Sensors." The Lincoln Laboratory Journal 1.1 (1989): n.
pag.Lincoln Laboratory. MIT, June 2010. Web. 9 Sept. 2014.
[5] Cleve, Jeffrey V., and Doug Caldwel. "Kepler: A Search for Extraterrestrial Planets." Kepler Instrument
Handbook (2009): n. pag. 15 July 2009. Web. 12 Sept. 2014.
[6] "James Webb Space Telescope - Integrated Science Instrument Module."ISIM. Space Telescope Science Institute,
n.d. Web. 13 Sept. 2014.
[7] "NBn Technology." IR Cameras. IRC LLC, n.d. Web. 13 Sept. 2014.
[8] Nolan, M.C. et al, “Shape model and surface properties of the OSIRIS-Rex target Asteroid (101955) Bennu from
radar and lightcurve observations,” Icarus, Vol. 226, Issue 1, 2013, pp. 663-670.
[9] Otake, Hisashi, Tatsuaki Okada, Ryu Funase, Hiroki Hihara, Ryoiki Kashikawa, Isamu Higashino, and Tetsuya
Masuda. "Thermal-IR Imaging of a Near-Earth Asteroid." SPIE: International Society of Optics and Photonics. SPIE,
2014. Web. 13 Sept. 2014.
[10] "Spitzer Space Telescope Handbook." Spitzer Space Telescope Handbook 2.1 (2013): n. pag. Spitzer Space
Center, 8 Mar. 2013. Web. 8 Sept. 2014.
[11] Vanbebber, Craig. "Lockheed Martin Licenses New Breakthrough Infrared Technology." Lockheed Martin
Corporation, 7 Dec. 2010. Web. 9 Sept. 2014.
83
BACKUP SLIDES
84
CubeSat Bus Design Constraints
Bus Electrical Constraints
3.3 V
6.0 A Max
12 V
4.0 A Max
Unregulated Voltage
6.5 V – 8.6 V
6.0 A Max
Total Power
5 W Nominal Average
15 W Peak
Command Communication Bus
SPI Slave
High-Speed Communication Bus
Ethernet, Magnetics-Less Differential
Backup Communication Bus
I2C
Regulated Voltage Lines
Bus Structural Constraints
Total Volume
2U (10x10x20 cm)
Total Mass
2.66 kg + 0.1 kg/ - 0.5 kg
85
OPTICS BACKUP
86
Requirements
Requirement
Driver
The optical system shall have a diffraction limited spot
size of less than 20 µm at a 3.5 µm wavelength
Detector pixel size
The optical system shall image at the 3.5 µm wavelength
Customer
The optical system shall have an SNR of no less than 6
Image processing
The optical system tolerances shall change the spatial
cutoff frequency by no more than 15 percent
Imaging quality &
mechanical feasibility
87
Focusing Mechanism
Y
Z
X
•
•
•
•
3 Axis Position Control
1 µm Precision
5 mm total travel (±2.5mm)
Spring Loaded for pressure
against micrometers
• Travels along slider pins
Y
• Standa Mini Micrometer
• Ground adjusted by hand
• Fixed with lock nut
• COTS component
Z
X
Secondary Mirror Support
89
Secondary Mirror Support Vibration
• 50G Amplitude
• Random Frequency up
to 100 Hz
• 3.54 MPa max Von
Mises
• Large Factor of Safety
• Kept to reduce
vibrations during
machining
90
Mirror Support Modal Analysis
• All natural frequencies above 100 Hz
• (Req. from Air Force Research Labs (AFRL) - UNP Handbook)
91
nBn Detector
InAs N-doped Semiconductor Layers
Sandwiching 100 nm AlAsSb Barrier
Reduced Dark Current, Operating
Temp. of 140+ K vs 77 K (Traditional)
Figures courtesy of: Applied Physics Letters, October 9, 2006 - 151109
92
Design Overview
Ritchey-Chretien Cassegrain design
 Eliminate coma aberrations
Coma in Cassegrain Reflector
Effects of Coma on Image Sharpness
93
Imaging Results
Simulated Image of Optical System
Note blur at
edge of field of
view
Overview
Baseline Design
Optics
Thermal
Electrical/Software
Testing
Logistics
94
Bandwidth
 COTS bandpass filters work for our application
 Low cost, low lead time
 Pass band: 3.32 – 3.60 µm
3.46 µm Bandpass Filter
2.OPT.2
Transmittance
Capture images at the 3.5
µm wavelength
Wavelength (nm)
Overview
Baseline Design
Optics
Thermal
Electrical/Software
Testing
Logistics
95
Probability of Detection
 Kamerman estimation
• Assumptions: SNR > 2, 10−12 < 𝑃𝑓𝑎 < 10−3
1
𝑃𝑑 = ∗ 1 + erf
2
1
1
+ 𝑆𝑁𝑅 − 𝑙𝑛
2
𝑃𝑓𝑎
 Thus for SNR > 6 and 𝑃𝑓𝑎 < 10−10 the probability
of detection is essentially 100 percent
96
Thermal Stresses
 Z-axis thermal expansion
•
•
•
•
𝛼
= 22.2 ∗ 10
𝑎𝑙𝑢𝑚
Focusing @ 300K
𝑑𝐿 = 𝛼𝑎𝑙𝑢𝑚 𝐿 𝑑𝑇 𝑑𝑇 = 70 𝐾
Take images @ 230K
𝐿 = 0.15 𝑚
dL = 233 µm
Will require us to unfocus optics @ 300K so they
shift into focus when cooled for testing
−6
1
𝐾
 X,Y-axis thermal expansion
• Will not change focus
 Steady-state temperature operation
• Max dT ~ 4K (Simulink simulation)
• dL ~ 10 µm
• Far below tolerances and depth of focus
z
y
x
97
Mirror Fabrication
 Mirrors constructed from aluminum blanks
 Using magneto-rheological diamond turning
machining
• Easily fabricate custom aspheres
 12:1 aspect ratio on diameter to thickness
 CAST polishing to achieve surface roughness
 Profilometry test (cheap)
• Interferometric testing is
not needed
MagnetoRheological
Diamond Turning
Diagram
98
Aberrations
 Seidel Coefficients (in 𝜆):
99
Aberration Effects
Ritchey-Chretien Cassegrain design
 Eliminate coma aberrations
Coma in Cassegrain Reflector
Effects of Coma on Image Sharpness
10
0
Spot Diagram
10
1
Risk Assessment
5
 Risk related things!
4
Detector dark
current reduces
SNR of images
3
2
Thermal
stresses
misalign optics
Manufacturer
extends lead
time
Damage occurs
to the custom
optics
Unable to focus
system within
tolerances
1
Probability
1
2
3
4
5
Severity
10
2
ELECTRONICS BACKUP
10
3
Requirements
Ref
Description
Electrical Subsystem Requirements (2.ELEC)
2.ELEC.1
The electrical system shall interface with the LMCO 6U CubeSat Bus (ALL-STAR Bus Reference)
2.ELEC.2
The electrical system shall interface with the MWIR Image Sensor Module
2.ELEC.3
The electrical system shall provide a hardware platform for the flight software
2.ELEC.4
The electrical system shall provide all hardware necessary for thermal monitoring and control
Electrical Subsystem Requirements (3.ELEC)
3.ELEC.1
The electrical system shall not consume more than 5W average power and 10W peak power
3.ELEC.2
The electrical system shall have a form factor dictated by the structural system
3.ELEC.3
The electrical system shall utilize an FPGA to house the image module interface IP core
3.ELEC.4
The electrical system shall guarantee all power provided to sensitive hardware is within specifications
3.ELEC.5
The electrical system shall protect the payload from power surges and over current events
3.ELEC.6
The electrical system shall utilize the I2C, SPI, and Ethernet specifications
10
4
Imaging Board – Power Domains
10
5
Imaging Board – Schematics
Top Level Interfaces
(Note: This does not include power nets)
10
6
Imaging Board–Clock/JTAG/Decoupling
10
7
Imaging Board – Ethernet PHY
10
8
Imaging Board – DRAM References
10
9
Imaging Board – DRAM IC
11
0
Imaging Board – DRAM Controller
11
1
FPGA Options
 Option 1: Artix-7
• Low Cost : $40 ~ $128
• Easy to use form factor: 1mm pitch, 16x16 grid
• 4-layer PCB (6-layer preferred) = $$$
 Option 2: Kintex-7
• Reuse proven design
• 8 Layer PCB = $$$$
 Option 3: Zynq-7000
• Highest Performance
• Hard silicon is more reliable
• 6 Layer PCB = $$$
CPU Comparison
Artix 7
Kintex 7
Zynq 7000
MicroBlaze
Dual Core Cortex A9
329 MHz
1 GHz
DMIPS 302
440
2500
DMIPS / MHz 1.34
1.34
2.5 ~ twice as efficient
CPU MicroBlaze
FMax 226 MHz
• Integrated Power is key!
• It’s not just about active/standby power. The
Zynq draws more power than the MicroBlaze,
but will get the job done faster with less power
per CPU cycle.
IO Requirements
Pins Signal
Voltage
Device
Max IO
Banks
4 SPI
3.3
XC7A100T-2FTG256 170
4
1 Interrupt
3.3
XC7K160T-3FBG484 285
6
2 I2C
3.3
XC7Z010-2CLG225 140
5
16 Ethernet MII
3.3
XC7Z030-1FBG484 293
6
32 DDR3
1.35
~20 Sensor Interface
75 TOTAL
1.8?
3 Banks
Device
LVDS?
CMOS
XC7A100T-2FTG256 Yes
Yes
XC7K160T-3FBG484 Yes
Yes
XC7Z010-2CLG225 Yes
Yes
XC7Z030-1FBG484 Yes
Yes
All devices have sufficient IO Capabilities
Zynq 7000 Family Comparison
 Low End – XC7Z010-1CLG225
• $128
• Fewer pins to route
• Smaller Size
 Mid-Range – XC7Z030-1FBG484
•
•
•
•
•
•
•
•
$300
Best Option
Integrated Decoupling
Flip-Chip Package
1mm pitch pads
Defense Grade Option
Digitally Controlled Impedance
High-Performance IO Bank
Faster FPGA Fabric
Design Drivers
Req.
Description
2.SFW.1
The software shall communicate with the LMCO 6U CubeSat Bus
2.SFW.2
The software shall determine the angular velocity vector of a
target object
2.SFW.3
The software will not capture an image until the focal-plane is
within operational temperature bounds
Overview
Baseline Design
Optics
Thermal
Electrical/Software
Testing
Logistics
11
6
THERMAL BACKUP
11
7
Requirements
Purpose of the thermal system: to control and monitor the temperature of
the Phoenix system
Ref
Description
Thermal Subsystem Requirements (2.THM)
2.THM.1
The thermal system shall monitor the temperature of all critical components during operation to within 2 K. (TBR)
2.THM.2
The thermal system shall control the thermal adjustment mechanisms.
2.THM.3
The thermal system shall report health and status data, including temperature data.
2.THM.4
The thermal system shall control the temperature of all critical components to within operating range
2.THM.5
The thermal system shall not consume more than 4 (TBR) W of continuous power
2.THM.6
The thermal system shall achieve the operating temperature of the optical assembly within TBD [unit of time]
11
8
Resistances and Heat Loads-Primary
Resistance
Description
Value Emissivity/
(K/W) Absorptivity
Description
Value
R1
Thermal epoxy between
components
0
ε1
Emissivity of the mirror
thermally
0.02
R2
Individual resistance of a single
strand of the thermal strap
18.37
ε2
Emissivity of MLI
shielding(12 layers)
0.01
R3
Estimated resistance between
primary mirror and structure
50
ε3
Emissivity of white paint
0.92
R4
Resistance between bus and
payload structure (6 Parallel)
21.78
α1
Absorptivity of the
mirror
0.09
R5
EPS to rear payload panel(8
Parallel)
16.32
R6
CDH to EPS standoffs (8
Parallel)
12.49
Heat Loads
Description
Value (W)
Q1
Power used by the cooling
mechanism
2
Q2
Power used by CDH system
0.66
Q3
Power used by the EPS
0.33
11
9
Performance Analysis Results
Based on the thermal resistivity analysis the following requirements are verified
Ref
3.THM.2
3.THM.4
Description
Verified
The thermal system shall maintain the electronic components within a temperature
of 233 - 358 K during operation
The thermal system shall maintain the reflectors at a temperature of 230 K or below,
(± 5 K) during operation


Based on the thermo-electric cooler performance analysis the following
requirements are verified
Ref
Description
2.THM.5
The thermal system shall not consume more than 4 (TBR) W of continuous
power
2.THM.6
The thermal system shall achieve the operating temperature of the optical
assembly within TBD [unit of time]
3.THM.3
The thermal system shall maintain the nBn sensor at a temperature of 140 K or
below, (± 5 K) during operation
Verified



12
0
Other Hardware – Thermal Materials
• Temperature Monitoring via Thermistors
• Insulating Materials
• MLI Insulation
• Titanium Interface plates
• White Paint for Radiators
• Heaters for Electronics Boards
• Thermal Epoxy
Ref .
Description
Thermal Material
2.THM.1
The thermal system shall monitor the temperature of all critical
components during operation to within 2 K. (TBR)
Thermistors
2.THM.3
The thermal system shall report health and status data, including
temperature data.
Thermistors
2.THM.4
The thermal system shall control the temperature of all critical
components to within operating range
TEC, Radiators, Thermal Straps, Thermal
Paint, Insulation, Titanium, Board Heaters
3.THM.1
The thermal system shall be able to dissipate 11 W (TBR) of heat
Radiators, TEC, Thermal Straps, Thermal
Paint
3.THM.5
The thermal system shall utilize temperature sensors to monitor
the temperature of critical components
Thermistors
Verf.





12
1
Suppliers of Thermal Hardware

MLI
•
Dunmore
• Contacted and material properties verified

Paint
•
AZ Technology
• Price and quote obtained
– $350

TEC
•
TEC Microsystems
• Contacted and quote obtained
– $187.00

Titanium
•
LHI Metals
• Contacted and material properties, price, and availability verified
– $200

Platinum RTD’s
•
Quality Thermistor Inc
• Quote obtained
– $100 with 2 needed
• 6 test sensors obtained
12
2
Temperature Sensors
 Quality Thermistor Inc
• International Standard: IEC60751
• ±0.8°K accuracy or better
• Change of 3.851 Ω per degree K
• Using whetstone bridge
– Additional error of ±0.5°K accuracy
• Total Accuracy: ±1.3°K
12
3
Titanium
 LHI Metals
•
•
•
•
Grade 2 titanium
Lead Time: 3-4 days
0.5’’x3.6’’x3’’
Conductivity: 16.4 W/(m K)
http://www.nuclead.com/images/matitanium_420x280.jpg
12
4
Thermal Electric Cooler
 TEC Microsystems
• 4MC04-115-15
• Lead Time: 5-6 Weeks
• Properties
•
•
•
•
DeltaT Max: 127 K
Qmax: 0.2 W
Imax: 0.4 A
Umax 8.4W
12
5
Paint
 AZ Technology
• AZ-93
• Emissivity: 0.91 ± 0.02
• Absorptivity: 0.15 ± 0.02
• Curing Time: 7 days
• Lead Time
• 2-4 weeks
126
Primary Thermal Paths
QSun
Key
Bus Interface T = -21 to 30 ºC
Radiation
Qbus
Wbus
Phoenix Payload
Thermal Isolation
High Resistance
Electrical Power and Bus Interface Board
Low Resistance
Electric Work
Command and
Data Handling
(CDH) Board
QRadiated
Cooling
Mechanism
nBn Focal
Plane
Optics Assembly
Conduction
Qalbedo
Aluminum Radiator 700cm2 (White Paint Coating α=0.09 ε=0.92)
QRadiated
Overview
Baseline Design
Optics
Thermal
Electrical
Testing
Logistics
127
MLI Effectiveness
Layers
Effective Emissivity
Heat Through (W)
6
0.03
0.1915
9
0.015
0.0958
20
0.007
0.0447
30
0.005
0.0319
Apayload = 0.02 m2
εeffective = [0.03 0.015 0.007 0.005]
Constants
Ts=303K
Tsur=230K
Heat Via
Radiation
Qin = Apayload εeffective σ (Ts4-Tsur4)
Q=[0.1915 0.0958 0.0447 0.0319]
12
8
Interface Panel Analysis

There are 6 paths into the system from the bus all of the same length.
So 6 parallel paths.
• 𝑄𝑖𝑛 =8W
• ∆𝑇=(273+32)-230=75K
• Paths=6

𝑅𝑟𝑒𝑞𝑢𝑖𝑟𝑒𝑑 =

Values acutely achieved using different configurations
•
R= 14.78 K/W
Titanium Panels w/ Steel bolts
•
•
•
•
R=6.26 K/W
Aluminum Panels w/ Titanium bolts and Washers
•
•
= 56.25 K/W
Aluminum Panels w/ Steel bolts
•
•
∆𝑇 𝑃𝑎𝑡ℎ𝑠
𝑄𝑖𝑛
R= 74.45 K/W
Solution
FOS=1.32
Titanium Panels w/ Titanium bolts
•
R= 75.47 K/W
12
9
Structures Circuit
13
0
Structure Values
Resistance
Description
Value
(K/W)
Emissivity/
Absorptivity
Description
Value
RLong
Resistance between the long
structural panels
0.015
εWP
Emissivity of the white
paint coating the
structure
0.92
RShort
Resistance between short
structural panels
0.04
εMLI
Emissivity of MLI
shielding(12 layers)
0.01
RBus
Resistance between bus and
payload
56.0
13
1
Electronics Circuit
13
2
Electronics Values
Resistance
Description
Value
(K/W)
RStandoff1
Resistance between the CDH
board and EPS standoffs
32.64
RStandoff2
Resistance between EPS and
structural panels
16.32
Emissivity/
Absorptivity
Description
Value
13
3
Sensor Circuit
Sensor Interface
13
4
Sensor Values
Resistance
Description
Value
(K/W)
Emissivity/
Absorptivity
Description
Value
RLow
Resistance between surfaces
that are in very close contact
0
αmirror
Absorptivity of
mirror
0.09
RStandoff3
Resistance between mirror
and control board
16.32
αcoldstop
Absorptivity of
coldstop
~1
(TBD
)
RStrap
Resistance of a single strand
of the thermal strap
18.4
αfocalplane
Absorptivity of
focalplane
~1
(TBD
)
13
5
Optics Circuit
13
6
Optics Values
Resistance
Description
Value
(K/W)
Emissivity/
Absorptivity
Description
Value
RPrime
Resistance between surfaces
that are in very close contact
40.0
αWhitePaint
Emissivity of the white
paint coating the
structure
0.12
RStrut
Resistance between
structural panels and
secondary mirror
22.69
αMirror
The absorptivity of the
mirror
0.09
εMirror
The emissivity of the
mirror
0.02
13
7
Home Made Thermal Strap
 Strands needed in a 3 split thermal strap: x
Qout = 1.5W
RStrap=18.4 K/W
Constants
T1=230K
T2=228K
Kalum=235 W/(m K)
Splits=3
Temperature
Gradient across the
surface
= 5 Strands
FOS = = 1.2
13
8
Panel Efficiency
 Temperature gradient across structural panel: T2
 Assumes the thermal strap is at the center of each
panel
Qout = 1.5W
T1=228K
t=0.00127m
Constants
W=0.1m
L=0.09m
Kalum=235 W/(m K)
Splits=3
w/(m K)
Temperature Gradient
across the surface
=226.25K
Percent Efficiency= 94%
13
9
Design Solution – Thermoelectric Cooler
 Operates using the Peltier Effect
• P and N type semiconductors physically in parallel but electrically in
series
• Draws heat from one side to the other
 Can be stacked in series to produce additional cooling
 At a steady state temperature of 230K no single TEC can
accomplish the necessary /DeltaT of 90K. However, connecting 2 in
series can accomplish this goal
140
Unmitigated Risk Assessment
5
 Risk related things!
Unable to evenly
distribute the
heat from the
thermal straps
4
3
2
Unable to
connect the
TEC’s in series
Unable to
calibrate
thermistors
Unable to buy
thermal material
1
Probability
1
2
3
4
5
Severity
14
1
Mitigated Risk Assessment
5
Riskrelated
mitigation:things!
thorough testing
 Risk
4
of connecting TEC’s in parallel.
This testing will start post CDR
with cheaper TEC’s to mitigate
financial strain
Unable to
connect the
TEC’s in series
3
2
1
Probability
1
2
3
4
5
Severity
14
2
Mitigated Risk Assessment
5
Risk related
mitigation:things!
thorough
 Risk
4
simulation of heat
distribution based on
thermal strap location.
Unable to evenly
distribute the heat
from the thermal
straps
3
2
1
Probability
1
2
3
4
5
Severity
14
3
Mitigated Risk Assessment
5
Riskrelated
mitigation:things!
Ability to purchase
 Risk
4
3
calibrated thermistors. These
thermistors have a short lead time and
the team has contingency in the budget
Unable to
calibrate
thermistors
2
1
Probability
1
2
3
4
5
Severity
14
4
Mitigated Risk Assessment
5
Risk related
mitigation:things!
The thermal team has
 Risk
4
thoroughly researched each product
and there is a sufficiently large margin
for unexpected purchases
3
2
Unable to
afford thermal
material(s)
1
Probability
1
2
3
4
5
Severity
14
5
Requirement Verification
Ref
Description
Verf.
Thermal Subsystem Requirements (2.THM)
2.THM.1 The thermal system shall monitor the temperature of all critical components during operation to within 2 K. (TBR)

2.THM.2 The thermal system shall control the thermal adjustment mechanisms.

2.THM.3 The thermal system shall report health and status data, including temperature data.

2.THM.4 The thermal system shall control the temperature of all critical components to within operating range

2.THM.5 The thermal system shall not consume more than 4 (TBR) W of continuous power

2.THM.6 The thermal system shall achieve the operating temperature of the optical assembly within TBD [unit of time]

Thermal Subsystem Requirements (3.THM)
3.THM.1 The thermal system shall be able to dissipate 11 W (TBR) of heat

3.THM.2 The thermal system shall maintain the electronic components within a temperature of 233 - 358 K during operation

3.THM.3 The thermal system shall maintain the nBn sensor at a temperature of 140 K or below, (± 5 K) during operation

3.THM.4 The thermal system shall maintain the reflectors at a temperature of 230 K or below, (± 5 K) during operation

3.THM.5 The thermal system shall utilize temperature sensors to monitor the temperature of critical components

14
6
TESTING BACKUP
14
7
Convection in Test Setup
 Free convection for sensor, assume room
temperature ambient as worst case
Q=0.992W
𝑁𝑢 ∗ 𝑘
ℎ=
𝑙
 If 194.5K ambient
Q=0.202W
𝑇∞ − 𝑇𝑠
𝑄=
𝑟
1
r= 2
ℎ𝑙
𝜈
𝑃𝑟 =
𝛼
14
8
Freezing Point of Coolant





Fractions by volume, remainder is water
100% methanol: -98oC
92%: -90oC
83%: -87oC
75%: -82oC
 Dry ice sublimates at -78.5oC at 1atm
14
9
Bennu-101955
 Near Earth Asteroid
 One of highest probabilities of Earth-Impact
 Interest in Rate-Matching for rendezvous
Bennu Asteroid Radiometry (above)
and CGI Model (right)
15
0
Project Purpose
Phoenix is a sensor that can determine the angular
velocity of an observed object it its field of view
d
 Utilizes a Mid-Wave Infrared camera at 3.5 µm wavelength
 Captures and processes sequence of images
 Designed for use in a Lockheed Martin 6U CubeSat Asteroid
Mission
 Characterize rotation of asteroid for rendezvous operations
15
1
Convection in Test Setup
 Free convection for sensor, assume room
temperature ambient as worst case
Q=0.992W
 If 194.5K (dry ice) ambient
𝑁𝑢 ∗ 𝑘
ℎ=
𝑙
Q=0.202W
𝑇∞ − 𝑇𝑠
𝑄=
𝑟
1
r= 2
ℎ𝑙
𝜈
𝑃𝑟 =
𝛼
15
2
Freezing Point of Coolant





Fractions by volume, remainder is water
100% methanol: -98oC
92%: -90oC
83%: -87oC
75%: -82oC
 Dry ice sublimates at -78.5oC at 1atm
15
3
Collimating Lens
 CaF2 material
• ~90% transmission at mid-wave IR
 76.2mm diameter
• Not full aperture, this causes oversampling which
reduces contrast
• Looking for larger lenses to address this
 1m or 2m focal lengths
• Determines test target size
 Cost is within budget and lead time is tolerable
• $500, 4 week lead time
15
4
Test Target
 Appropriate size for full field-of-view given focal length of
collimating lens
• 1m focal length: 3.24cm diameter
• 2m focal length: 6.48cm diameter
 Same surface temperature as Bennu (310K/37oC)
• Determines peak of emission spectrum
 Appropriate contrast
• Test target is a heat source surrounded by a hollow sphere,
separated by low thermal conductivity
• Heat source at 310K
• Sphere made of teflon (semi-transparent at MWIR) and has
a pattern created by varying the thickness, this varies the
transmitted brightness
• Sphere is dark where thick, brighter as the thickness
decreases
• Thickness of outer sphere and taper of cutout edges controls
diffusion at cutout edges
15
5
Safety Concerns
 Materials Hazards
• Beryllia (TEC)
• No special handling procedures
• Inhalation hazard from dust
– Can cause a severe lung disease
– Only a hazard if TEC is physically damaged
• Calcium Fluoride (collimating lens)
• Mild toxicity, particularly as dust (inhalation)
– Only a hazard if lens is damaged
• Handle with PVA gloves
• Highly dangerous if brought in contact with acid
– Extremely unlikely to occur
15
6
LOGISTICS BACKUP
15
7
Work Products Breakdown Structure
Structures
Electronics*
Thermal
Software
• Primary &
Secondary Mirror
Drawings
• Rev 1 Board
Schematics
• Block Diagram of
Thermal Paths
• Communications
Module
• Rev 1 Board Layout
• Focusing
Mechanism
Drawings
• Rev 1 Populated
Board
• Resistance Values
for Thermal
Contacts
• Sensor Interface
Module
• Thermal Mounting
Hardware
Drawings
• Load/Vibration
Analysis on Mirror
Supports
• Drawing Package
for all Components
• Drawing Tree
• CAD Model
• Machined
Components
• Rev 1 Board Test
Report
• Rev 2 Board
Schematics
• Rev 2 Board Layout
• Rev 2 Populated
Board
• Rev 2 Board Test
Report
• Integrated
Electronics
• Simulink Model
• Thermal Desktop
Model
• Integrated Thermal
System
• Rate
Determination
Module
• Image Interface
Module
• Temperature
Control Module
Optics
• Thermal
Background
Calculations
• Photon & SNR
Budgets
• Mirror Designs
• Baffle & Cold-Stop
Design
• Focused Optical
Assembly
• OP Code Dictionary
• Software
Reference
Document
• Software Package
• Assembled Units
* These deliverables pertain to both the Power and C&DH Board
15
8
Work Products Breakdown Structure
Management
Testing
Systems
• PDD
• Procedure for TVAC Test
• CDD
• Procedure for Optics Test
• Test Procedures per
Subsystem
• PDR Presentation
• Integration Procedures
• ICD per Subsystem
• CDR Presentation
• MSDS Documentation
• Integrated Payload
• FFR
• Liner for Optics Test
• MSR Presentation
• Payload Bracket for
Optics Test
• TRR Presentation
• AIAA Paper
• Payload to Bus ICD
• SFR
• Aligned & Focused
Collimator
• Test Target
• Bus Simulator for TVAC
Test
• Test Results
15
9
Optics Cost Plan
BandPass Filter,
$400.00 , 4%
Margin, $100.00 , 1%
Primary Mirror,
$5,000.00 , 47%
Secondary Mirror,
$5,000.00 , 48%
16
0
Structures Cost Plan
Margin, $75.00 , 8%
Stock Aluminum,
$300.00 , 30%
Micrometers, $325.00
, 32%
Washers, $70.00 , 7%
Screws, $30.00 , 3%
3D Printing, $200.00 ,
20%
16
1
Testing Cost Plan
Steel Sheet, $56.32 ,
8%
Silicone, $98.29 , 14%
Margin, $270.39 ,
39%
Dry Ice, $50.00 , 7%
Isopropyl Alcohol,
$75.00 , 11%
Collimator, $100.00 ,
14%
Aluminum Stock,
$50.00 , 7%
16
2
Thermal Cost Plan
Misc Thermal
Supplies, $80.00 , 2%
Margin, $120.00 , 4%
Thermisitors, $500.00
, 17%
TECs, $900.00 , 30%
Insulation, $200.00 ,
7%
Thermal Braids,
$1,200.00 , 40%
16
3
Electronics Cost Plan
Margin, $300.00 ,
20%
TEC Demo Board,
$100.00 , 7%
FPGA, $200.00 , 13%
CDH Board
Components, $200.00
, 13%
PCBs, $500.00 , 34%
Power Board
Components, $200.00
, 13%
16
4
Miscellaneous Cost Plan
Margin, $50.00 , 25%
Printing, $50.00 , 25%
Symposium Poster
Materials, $100.00 ,
50%
16
5