Preliminary Design Review
October 21, 2014
Project Manager:
Gabrielle Massone
Systems Engineer:
Jesse Ellison
Deputy Project Manager
Financial Lead
Tanya Hardon
Software Lead:
Cy Parker
Customers:
Brian Sanders
Colorado Space Grant (COSGC)
JB Young and Keith Morris
Lockheed Martin (LMCO)
Test and Safety Lead:
Franklin Hinckley
Optics Lead:
Jon Stewart
Mechanical Lead
Jake Broadway
Faculty Advisor:
Dr. Xinlin Li
Dept. Aerospace Engineering
Laboratory for Atmospheric and
Space Physics (LASP)
Thermal Lead:
Brenden Hogan
Electrical Lead:
Logan Smith
Overview
Baseline Design
Optics
Thermal
Electrical
Testing
Logistics
1
Presentation Overview
 Mission Overview
 Baseline Design
 Feasibility Analysis
• Optics and Mechanical Design
• Thermal Design
• Electrical and Software Design
 Testing Plan and Feasibility
 Design Summary
 Logistics
Overview
Baseline Design
Optics
Thermal
Electrical
Testing
Logistics
2
PROJECT OVERVIEW
Overview
Baseline Design
Optics
Thermal
Electrical
Testing
Logistics
3
Mission Background
Lockheed Martin 6U CubeSat Bus Design Reference Mission
to Asteroid 101995-Bennu
Overview
Baseline Design
Optics
Thermal
Electrical
Testing
Logistics
4
Mission Background
Lockheed Martin 6U CubeSat Bus Design Reference Mission
to Asteroid 101995-Bennu
Relevant IR Camera Payload Operations that Drive Phoenix ConOps
Overview
Baseline Design
Optics
Thermal
Electrical
Testing
Logistics
5
Mission Background
 LMCO Bus IR Camera Payload will capture sequence of
images of Bennu asteroid and measure the observed angular
rate
 3.5 µm wavelength in Mid-Wave Infrared (MWIR)
 Range and geometry specified below:
Observed:
θ = 21.93 µrad/s
Bennu Asteroid (Reference Environment)
ω = 0.4061 mrad/s
Tamb = 3K
FOV
IR Camera
Tsur = 180-310K
ε = 0.035
D = 492 m
Bennu
Distance: 10 km
Overview
Baseline Design
Optics
Thermal
Electrical
Testing
Logistics
6
Mission Background
 Utilize MWIR nBn detector (Lockheed Martin Santa Barbara
Focalplane)
• Operating Temperature: 140 K
• Resolution: 1.3 MPx or 1280x1024
 First MWIR detector Feasible for CubeSat Operations
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
Overview
Baseline Design
Optics
Thermal
Electrical
Testing
Logistics
7
Mission Background
1.3 MPx (1280x1024) nBn detector Image
Figure courtesy of: laserfocusworld.com January 17, 2014
Overview
Baseline Design
Optics
Thermal
Electrical
Testing
Logistics
8
Phoenix Objectives
To develop and test the 2U CubeSat MWIR Camera
Proto-Flight Payload, a precursor to the flight camera unit
for the LMCO Bus Mission

Proto-flight Unit:
Defined as hardware that is designed to flight form-factor, but may
require additional design, development, testing or flight certification.
Not required to undergo environmental testing (thermal-vacuum
cycling, vibe, radiation testing, etc…) and will not be flown.
Overview
Baseline Design
Optics
Thermal
Electrical
Testing
Logistics
9
Phoenix Objectives
Req.
Description
Parent
O.1
The payload shall integrate electrically and structurally into the 2U
payload section of the Lockheed Martin 6U CubeSat bus
MS
1.SYS.1
The electrical system shall interface with the LMCO 6U CubeSat bus
O.1
1.SYS.2
The mechanical system shall interface with the LMCO 6U CubeSat bus
O.1
1.SYS.3
The Software system shall interface with the LMCO 6U CubeSat bus
O.1
O.2
The payload shall capture a sequence of IR images at the 3.5 µm
wavelength and determine the angular velocity and axis of rotation
of an observed object with characteristics of the reference asteroid
101995-Bennu
MS
2.SYS.1
The electrical system shall capture and store an image from the image sensor.
O.2
2.SYS.2
The optical system shall be able to observe and image the reference target
O.2
O.3
The payload shall maintain all components in their operating
temperature ranges.
MS
Overview
Baseline Design
Optics
Thermal
Electrical
Testing
Logistics
10
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
Overview
Baseline Design
Optics
Thermal
Electrical
Testing
Logistics
11
Timeline and Assumptions
Senior Design
Oct 21
May 2015
Potential Post-Senior Design
Development
Phase 1
Milestones
Phase 2
Prototype of all subsystems
First integration and
ground-testing
Flight Revision
Continue Remaining
Development
Delivery
Fully-tested,
flight certified
Phase 1: Simplifying Assumptions
 Simulated range between Phoenix and target will vary between 10
km and 100 km
 Zero Relative translational velocity between object and bus during
observation (Phase 2 unit software will account for relative motion)
 Phoenix payload is not exposed to direct sunlight (i.e. bus
orientation or deployables shade payload volume)
 All test target properties are representative of asteroid 101955Bennu to the extent feasible
Overview
Baseline Design
Optics
Thermal
Electrical
Testing
Logistics
12
Phoenix ConOps
Phoenix is measuring the observed angular rate
(theta), not the rotation rate of the object (omega)
d
Instantaneous observed angular rate of the
nearest point is the arctangent of the
translational velocity of the surface divided by
the observation distance
Overview
Baseline Design
Optics
Thermal
Electrical
Testing
Logistics
13
Phoenix ConOps
 Culmination of design is fully-integrated ground-test
of sensor and representative target object
Overview
Baseline Design
Optics
Thermal
Electrical
Testing
Logistics
14
BASELINE DESIGN
Overview
Baseline Design
Optics
Thermal
Electrical
Testing
Logistics
15
Design Overview
2U CubeSat Payload
10cmx10cmx20cm
10 Cm
Radiator
Panels
Primary Mirror
Power Board
CDH Board
Bus Mechanical Interface
Secondary Mirror
Overview
Baseline Design
Optics
Thermal
Sensor Board
Electrical
Testing
Thermal Strap
Logistics
16
Functional Block Diagram
Phoenix Camera Payload
Structure and Optics Focusing Assembly
Post-Processed
Image Data
Electronics
Bus Power and Data Interface
Bus Thermal Isolation
* LMCO 6U CubeSat Bus
Bus Power
Supply
Image Data,
Sensor Control
*Sensor
Interface
(COSGC)
PWR
Power Regulation
PWR
*Image
Sensor
(LMCO)
Field of
View
Optics Assembly
Camera Controller
• Main Processor
• Image Processing
and Compression
Software
PWR
PWR
Thermal Controller
PWR
Thermal Feedback
Thermal Control Mechanism
Structure
Data
Power
*COTS or Customer-Provided
Overview
Baseline Design
Optics
Thermal
Electrical
Testing
Logistics
17
Critical Project Elements
 Mechanical Optics Assembly Design
 Thermal System Design
• Cooling the nBn sensor
 Electronics and Software System
• Interfacing with nBn sensor
• Measuring Rate from Image Sequence
 Testing Plan
• Ground testing to simulate flight functionality
Overview
Baseline Design
Optics
Thermal
Electrical
Testing
Logistics
18
OPTICS AND STRUCTURE
Overview
Baseline Design
Optics
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Electrical
Testing
Logistics
19
Bennu Radiometry
 Percentage of total light in 3 to 4 µm band due to
• Solar irradiance (~12-15%)
• Bennu blackbody radiation (~85-88%)
 Photon Budget:
Total Photon Flux
Photon Flux (photon/s)
Cassegrain Optics
3x1013
Refractive Optics
2x1013
1x1013
Range (km)
40
Overview
Baseline Design
Optics
60
Thermal
80
Electrical
100
Testing
Logistics
20
Bennu Radiometry
Overview
Baseline Design
Optics
Thermal
Electrical
Testing
Logistics
21
Baseline Optical Design
 CDD baseline designs:
• Multi-element refractive & Cassegrain optical systems
 MWIR bandwidth is diffraction limited
Diffraction Limit Illustration
Resolvable Airy Disk
Resolvable Airy Disk
Airy Disk
Unresolvable Airy Disk
Unresolvable Airy Disk
Source: http://microscopy.berkeley.edu/courses/tlm/optics/imaging.html
Overview
Baseline Design
Optics
Thermal
Electrical
Testing
Logistics
22
Baseline Optical Design
 Chief deciding factors: Mass, Thermal Control, Size, etc…
Cassegrain
Refractive
Mass ~ 1.0 kg
Passive Thermal Cooling
No Chromatic Aberrations
Length ~ 10 cm
Bandwidth: 3.0 to 3.61 µm
Mass ~ 1.8 kg
Active Thermal Cooling
Chromatic Aberrations
Length ~ 12.5 cm
High Design Complexity
Bandwidth: 3.0 – 3.74 µm
Cassegrain selected for Optical Design
Overview
Baseline Design
Optics
Thermal
Electrical
Testing
Logistics
23
Zemax Simulation
 Utilized paraxial ray tracing equations to derive
design constraints
 Zemax simulation to prove design methodology
Primary
Mirror
• 𝐿𝑒𝑛𝑔𝑡ℎ = 10 𝑐𝑚
• 𝐹𝑝𝑟𝑖𝑚𝑎𝑟𝑦 = −12.5 𝑐𝑚
• 𝐹𝑠𝑒𝑐𝑜𝑛𝑑𝑎𝑟𝑦 = 8.5 𝑐𝑚
Secondary
Mirror
Spot Diagram
Overview
Baseline Design
FPA
Cassegrain Simulation
Optics
Thermal
Electrical
Testing
Logistics
24
Mechanical 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%
Overview
Baseline Design
Optics
Thermal
Electrical
Testing
Optics 4.1%
Electronics
2.9%
Thermal
Control 7.8%
Logistics
25
Path Forward
 Design aspherical lenses to reduce aberrations and
add bandpass filter
 Make Zemax program to optimize system PSF and
minimize ΔT impacts on system
 Design cold stop to reduce background thermal
noise
 Thorough calculation of SNR and SBR with respect
to all noise inducing elements
 Call prospective suppliers to check for issues with
budget and feasibility constraints
Overview
Baseline Design
Optics
Thermal
Electrical
Testing
Logistics
26
THERMAL
27
Current Thermal Concept
 Bus will shield the payload from solar
rays
 Bus interface within -24 to 61 ºC
• Interface will be isolated using
low conductance bolts and/or
structural elements
• MLI insulation between bus and
payload
 Aluminum radiators coated in highemissivity white paint on all payload
sides
 TEC to reduce focal plane
temperature to ~140K
• From manufactures specification
6U Bus Conceptual Configuration
2U Phoenix Camera Volume
Overview
Baseline Design
Optics
Thermal
Electrical
Testing
Logistics
28
Thermal Electric Cooler (TEC)
 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 to produce additional cooling
 Two Stage Baseline Model
• ~1W of consumed power
• Max heat in: 0.3W
• Delta Tmax: 92 K
• Small Size
• 3.9mm x 3.9mm x 4.4mm
• Long operating life
Source: https://www.ferrotec.com/images/thermalsite/twoStage.png
• <100,000 hrs
Overview
Baseline Design
Optics
Thermal
Electrical
Testing
Logistics
29
Primary Thermal Paths
QSun
Key
Bus Interface T = -21 to 64 ºC
Conduction
Qbus
Wbu
Phoenix Payload
s
High Resistance
Thermal Isolation
Electrical Power and Bus Interface Board
Low Resistance
Electric Work
Command and
Data Handling
(CDH) Board
QRadiated
nBn Focal
Plane
TEC
Optics Assembly
Radiation
Qalbedo
Aluminum Radiator 700cm2 (White Paint Coating α=0.09 ε=0.92)
QRadiated
Overview
Baseline Design
Optics
Thermal
Electrical
Testing
Logistics
30
Thermal Modeling Strategy
Goal: Full System Thermal Model using
Thermal Desktop Software
 Fall 2014:
• Develop basic thermal models comparing ~10-25 nodes in
both Simulink and Thermal Desktop
 Post-CDR:
• Continue Thermal Modeling with Thermal Desktop
• Goal: model agrees to within ± 5 K of actual hardware
temperatures (AFRL Standard)
 Driving Issue:
• Thermal Desktop results are complex - it can be difficult to
identify errors in basic model
 Solution:
• Develop two independent models
• Verify results of Thermal Desktop model before moving
forward
Overview
Baseline Design
Optics
Thermal
Electrical
Testing
Logistics
31
Thermal Desktop Model (Steady State)
Cold Space
~3K
Aluminum
Radiators with
White Paint
Coating
EPS Board (NotPictured, behind
CDH board)
• ~0.7W
CDHEPS
Board
Board
EPSCDH Board
• ~0.3W
Board
Not currently in model
• Thermal Electric Cooler
• ~1W
• nBn Focal Plane
• ~0.3W
• Optics Assembly
Bus Simulator
Bus-Payload
Hottest part
• Modeled
as of the
Mechanical
payload
is
the bus
10W constant
Interface
interface
heat source
• ~10W
•
•
•
•
Green Arrows-Conduction to parts contacting that face
Brown Arrows-Conduction receiving nodes from other parts contacting that face
Red Arrows-Heat loads on that surface
Balls-Nodes of the model
Overview
Baseline Design
Optics
Thermal
Electrical
Testing
Logistics
32
Simulink Thermal Model
 Major components modeled as Simulink subsystems with heat
inputs and outputs
 Subsystem blocks contain models of thermal resistivities and
conductivities
Overview
Baseline Design
Optics
Thermal
Electrical
Testing
Logistics
33
Feasibility Analysis (Simulink)
Simulink Simulation Assumptions & Parameters:
Bus Inputs
Radiator
Area
700 cm2
Max Qin
10 W
Emissivity
0.92
Qin to Electronics
7 W (30%)
Material
Aluminum
Qin to Optical Assembly
3 W (70%)
Qin to TEC/Focalplane
0 W (negligible)
Thermal Conductivities
Aluminum
237 W/(m*K)
Asteroid Inputs
PCB (FR4/Copper)
0.33 W/(m*K)
Max Qin
1.56 μW
Glass (Optical Lenses)
1.05 W/(m*K)
Qin to Focalplane
0.312 μW (20%)
Qin to Optical Assembly
1.248 μW (80%)
Qin to TEC/Focalplane
0 W (negligible)
Other Properties
Glass Emissivity
0.93
Time to Steady State
10,000 seconds
Overview
Baseline Design
Optics
Thermal
Electrical
Testing
Logistics
34
Feasibility Analysis
Simulation Outputs
Simulation Inputs
Heat from Bus into Sys.
10 W
Heat out of Radiator
11.2 W
Heat from Asteroid
1.5 μW
Heat out of Optics
3.0 W
Power into Focalplane
0.3 W
Heat out of TEC
2.4 W
Power into Electronics
1.0 W
Heat out of Electronics
7.3 W
Power into TEC
1.0 W
Heat out of Focalplane
0.8 W
Total Energy into Sys.
12.3 W
Steady State Tradiator
235.4 K
Using the worst case power inputs, the steady state temperature
is low enough for the TEC to cool the focal plane to 143K (ΔT
~92K). While this is higher than the optimal 140K, the noise
induced by the higher temperature could be processed out.
Additionally the optical assembly does not need to be cooled
Overview
Baseline Design
Optics
Thermal
Electrical
Testing
Logistics
35
Feasibility Analysis
Considering a case where the payload receives less heat from the bus (the
bus is in a power saving mode, and less subsystems are turned on,
therefore less heat is generated)
Simulation Outputs
Simulation Inputs
Heat from Bus into Sys.
9.0 W
Heat out of Radiator
10.2 W
Heat from Asteroid
1.5 μW
Heat out of Optics
2.70 W
Power into Focalplane
0.3 W
Heat out of TEC
2.24 W
Power into Electronics
1.0 W
Heat out of Electronics
6.6 W
Power into TEC
0.3 W
Heat out of Focalplane
0.69 W
Total Energy into Sys.
10.6 W
Steady State Tradiator
230.0 K
The steady state temperature drops by 5K, reducing the necessary ΔT to
90K. This shows that with a 10% reduction in heat from the bus the TEC
can cool the focal plane to the desired temperature.
Overview
Baseline Design
Optics
Thermal
Electrical
Testing
Logistics
36
Path Forward
 Continue adding payload elements to the Thermal
Desktop Model
 Update the Simulink Model material properties as
materials are chosen
 Compare the results of the two models to verify
consistency and accuracy
 Use Thermal Desktop Model for final thermal
analysis
 Extra volume available if additional active thermal
control required
• Linear Stirling Cooler or multiple TECs
 Exploring Thermal Isolation mechanisms
• MLI, high thermal-resistance materials
Overview
Baseline Design
Optics
Thermal
Electrical
Testing
Logistics
37
ELECTRICAL AND SOFTWARE
Overview
Baseline Design
Optics
Thermal
Electrical
Testing
Logistics
38
Electronics Overview
Baseline Design: Custom PCB Stackup
nBn Image Sensor
• Small Adapter Board for nBn MidWave IR Sensor
• Low Thermal Resistance Substrate
Image Sensor Backplane
Raw Image Data
• Processes Images and Commands
• High-Density Multi-Layer Board
Command and Data Handling
Power
• Provides power regulation and
isolation from the bus
• Primary bus interface
Power Regulation
Overview
Baseline Design
Optics
Thermal
Electrical
Testing
Logistics
39
Electronics
Power Regulation & Isolation
Isolation
Bus Interface
Power
Regulation
Monitoring
&
Protection
Circuitry
Image Sensor
Backplane
Command and Data
Handling
CPU
Image
Sensor
Interface
nBn
Sensor
Memory
Thermal Electric Cooler
Switching
Overview
Baseline Design
TEC
Optics
Thermal
Electrical
Testing
Logistics
40
Power Budget
Budget 5W nominal, 15W 10 minute burst
Design Element
Reference Component
Nominal Power
Consumption
TEC
Laird MS2 series
1.0 W
CPU
Atmel SAMA5D4 series
0.20 W
Image Sensor Interface
Xilinx Spartan3 series
0.16 W
Focal Plane
nBn-sensor
0.05 W
Memory
Micron SDRAM
0.39 W
Power Regulation
Buck/Boost 90% efficient
0.80 W
TEC Control
Buck 90% efficient
0.10 W
Raw Total
No Margin
2.7 W
System Margin
20%
0.54 W
Total + Margin
3.2 W
Contingency
1.8 W
Overview
Baseline Design
Optics
Thermal
Electrical
Testing
Logistics
41
Software Flow Diagram
Standby Mode
Active Mode
Initialize
Get Focalplane Temp
No
Wait for Command
nBn Cool?
Picture
Command
Command
?
Yes
Take Picture Burst
Report Health
and Status
Baseline Design
Optics
Thermal
Electrical
Determine
Rate
Rate Determination
Algorithm
(Cont. Next Slide)
Compress Image and
Package
Send Data to Bus
Overview
Picture
Cmd Type
Send Image
to Bus
Package Data
Testing
Logistics
42
Software Flow Diagram
 Harris Corner Detection
Rate Determination Algorithm
• Interest point identifier
• Invariant to translations
and rotations
Noise Reduction (Optional)
Harris Corner Detection &
SIFT Keypoint Descriptors
 SIFT
Repeat for 2+ Image
Sequence
• Used to classify each
interest point and keep
only those robust to local
affine distortion
Match SIFT Keypoints
Calculate Rate Solution
Send Solution to Bus
Overview
Baseline Design
Optics
Thermal
Electrical
Testing
Logistics
43
Examples
 HarrisSIFT Algorithm
• Interest Point Detection and Matching
• Image Rotated 180º
Figure generated using Integrated Vision Toolkit and HarrisSIFT Algorithm
Overview
Baseline Design
Optics
Thermal
Electrical
Testing
Logistics
44
Temporal Budget
 Maximum allowable exposure time 2.28 seconds
• Bennu rotation rate + 1σ = ~22μradians/second
• Rotation of 50 μradians corresponds to a single pixel
• Corresponds to minimum spacing of images
 Maximum image capture spacing
• Case of rotation gives about 9 hours
• Will use as baseline limit
T = 9 Hrs
T = 0 Hrs
Surface
Feature
Overview
Baseline Design
Optics
Thermal
Electrical
Testing
Logistics
45
Path Forward




Determine data rates and create data budget
Select Processor and Electrical Components
Begin Electrical Schematics
Select Software Platform
• Operating System (i.e. Linux)
• Bare Metal
 Software Algorithm development
46
TESTING FEASIBILITY
Overview
Baseline Design
Optics
Thermal
Electrical
Testing
Logistics
47
Preliminary Testing Plan
Setup and Procedure



Test Equipment
Test Chamber contains
• Phoenix Camera and Test Target
• Optics Adapter
• MGSE structure
• EGSE conduits
Phoenix captures MWIR images,
determines observed angular rate
Compare theoretical and actual
angular rate
Overview
Baseline Design
Optics


Vacuum chamber capable of < 1 torr
(procurable)
Liquid Nitrogen cooled to 75K
(procurable)
•
•
•

Thermal
Radiative heat transfer error 5% at Tsurr
= 108.9 K
0.632 L/min circulation rate for
∆T = 5K
16.6 mL/min vaporization rate
EGSE and MGSE
Electrical
Testing
Logistics
48
Environmental Control
 Phoenix Camera and
test hardware mounted
to sled
 LN2 cooling jacket
maintains ~75 K wall
temperature
 12.5” fiberglass
insulation (two layers of
R19 batt) to reduce LN2
loss
12.5”
Cross Section of Test Chamber, with minimum required
dimensions
Overview
Baseline Design
Optics
Thermal
Electrical
Testing
Logistics
49
Test Target and Scaling
Parameter
Value (Bennu)
Value (Target)
Diameter
492 m
10 cm
Observation Distance
10 km
203 cm (effective)
Rotation Rate
0.4061 mrad/s
0.8904 mrad/s
Observed Angular Rate
21.93 µrad/s
21.93 µrad/s
Test Target Objective: To replicate the scale, motion, and spectral
qualities of reference asteroid 101995-Bennu
 Hollow Sphere, 10 cm diameter
 Internal heating elements heat to 310 K (illuminated side) and 180 K
(dark side)
•

Heater wires through slip-ring to allow target rotation
Optics Adapter (Zoom 0.300X)
•
•
Overview
Scaled distance: 203 cm
Actual distance: 61 cm
Baseline Design
Optics
Thermal
Electrical
Testing
Logistics
50
Phoenix Scaled Testing
Bennu Asteroid (Reference Environment)
ω = 0.4061 mrad/s
Observed:
θ = 21.93 µrad/s
Tamb = 3K
Tsur = 180-310K
ε = 0.035
FOV
Camera
D = 492 m
101995Bennu
Distance: 10 km
Phoenix (Scaled Ground Test)
Observed:
θ = 21.93 µrad/s
ω = 0.8904 mrad/s
Tamb = 75 K
Tsur = 180-310K
ε = ~0.035
FOV
Phoenix
D = 10 cm
Optics Adapter
Zoom: 0.300X
Actual Distance: 63 cm
Overview
Baseline Design
Optics
Test Target
• Hollow Sphere
• Heated
Effective Distance: 203 cm
Thermal
Electrical
Testing
Logistics
51
Path Forward
 Explore testing opportunities and capabilities
at Space Operation Simulation Center
(SOSC) at Lockheed Martin in Waterton
 Confer with Matt Rhode for all LN2 Handling
and Testing
 Detail intermediate testing plans for system
build-up
 Determine required optical/thermal properties
of test target to accuracy required for
construction
Overview
Baseline Design
Optics
Thermal
Electrical
Testing
Logistics
52
DESIGN SUMMARY
Overview
Baseline Design
Optics
Thermal
Electrical
Testing
Logistics
53
Design Summary
Cassegrain Reflector Optics
2U MWIR Camera Volume,
700 cm2 Radiator Area
nBn Image Sensor
Image Sensor Backplane
Raw Image Data
Command and Data Handling
Power
Power Regulation
Two-Stage Thermoelectric Cooler
Overview
Baseline Design
Optics
Custom Electronics and Software
Thermal
Electrical
Testing
Logistics
54
LOGISTICS
Overview
Baseline Design
Optics
Thermal
Electrical
Testing
Logistics
55
Fall Schedule
12/29-01/05
12/22-12/28
12/15-12/21
12/08-12/14
12/01-12/07
December
11/24-11/30
11/17-11/23
11/10-11/16
11/03-11/09
November
10/27-11/02
Major Milestones
10/20-10/26
10/13-10/19
October
PDR
Simulink Thermal Model
Thermal Desktop Model
Zemax Optics Model
Solidworks Model
Electrical Component Selection
Electrical Schematics
Electrical Layout
CDR
FFR
Overview
Baseline Design
Optics
Thermal
Electrical
Testing
Logistics
56
Monetary Budget
Component
Cost Estimate
Optics (mirrors, lenses)
$5,000
Electronics
$1,500
Thermal
$1,000
Mechanical
$1,000
Test Equipment
$1,000
Total
$9,500
Margin 20%
$1900
Total + Margin
$11,400
Contingency
$8600
Funds available to team: $20,000
Overview
Baseline Design
Optics
Thermal
Electrical
Testing
Logistics
57
Team Management Tools
 Redmine
• Project Management Web Application
• Issue tracking system
• Gantt Chart and Calendar
 Configuration Management
• Git version control
• Central file storage – Odyssey servers
• File and component naming schemes
SYS.###.Rev_FileDescriptor
Ex: STR101.2_MassBudget
 Test/Requirements Verification Software
Overview
Baseline Design
Optics
Thermal
Electrical
Testing
Logistics
58
CONCLUDING STATEMENTS
Overview
Baseline Design
Optics
Thermal
Electrical
Testing
Logistics
59
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)
Overview
Baseline Design
Optics
Thermal
Electrical
Testing
Logistics
60
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.
61
BACKUP SLIDES
62
TRADE STUDIES BACKUP
63
Trade Study Scoring
 10 Excellent, design best satisfies the criteria compared to
the other design options
 8-9 Good, satisfies the criteria well
 5-7 Mediocre, satisfies the criteria with some difficulty or
challenge
 3-4 Poor, difficult to satisfy design criteria, presents technical
challenges
 1-2 Very poor, presents significant challenge to satisfy
criteria
R = Raw Score W = Raw Score*Weight
Total = Sum(W)
64
Optics Trade Study
Sensitivity Analysis
65
Thermal Trade Study
Sensitivity Analysis
66
Electronics Trade Study
Sensitivity Analysis
67
OPTICS BACKUP
68
Paraxial Ray Tracing Equations
Equation 1: 𝑢𝑘′ = 𝑢𝑘 − 𝑦𝑘 𝜑𝑘
Equation 2: 𝑦𝑘+1 = 𝑦𝑘 + 𝑢𝑘′ dk ′
69
http://ecee.colorado.edu/~ecen5616/WebMaterial/05%20paraxial%20ray%20tracing.pdf
Optics Design Equations
 Photon Budget:
• Planck’s Blackbody Radiation Equation
𝐼𝑏𝑙𝑎𝑐𝑘𝑏𝑜𝑑𝑦
2ℎ𝑐 2
=
∗
𝜆5
1
ℎ𝑐
𝑒 𝜆𝑘𝑇
−1
• Stefan-Boltzmann’s Law
𝑃𝑆𝐵 = 4𝜋𝑅2 𝜎𝑇 4
 Cassegrain Constraints:
𝑅𝑝𝑟𝑖𝑚𝑎𝑟𝑦 = −
𝑅𝑠𝑒𝑐𝑜𝑛𝑑𝑎𝑟𝑦
2 ∗ 𝑡𝑝𝑠 ∗ 𝐸𝐹𝐿
𝐸𝐹𝐿 − 𝐵𝐹𝐷
2 ∗ 𝑡𝑝𝑠 ∗ 𝐵𝐹𝐷
=−
𝐸𝐹𝐿 − 𝐵𝐹𝐷 − 𝑡𝑝𝑠
EFL – effective focal length
BFD – back focal distance
tps – mirror separation
70
Transmissive Design
 Cooke Triplet Constraints
−(Φ𝑝 𝑛𝑝 𝑣𝑝 − 2Φ𝑣𝑎 ) +
Φ𝑝 𝑛𝑝 𝑣𝑝 − 2Φ𝑣𝑎
Φ𝑝𝑜𝑠𝑖𝑡𝑖𝑣𝑒 = −
2 𝑣𝑎 −
Φ𝑛𝑒𝑔𝑎𝑡𝑖𝑣𝑒 = − Φp −
2
− 4 𝑣𝑎 −
𝑛𝑎
𝑣 𝑣 Φ2
𝑛𝑏 𝑏 𝑎
𝑛𝑎
𝑣
𝑛𝑏 𝑏
2Φ𝑎
𝑛𝑏
𝑛𝑎
 Zemax Simulation
Cooke Triplet
Custom
Gauss Triplet
71
Optical Thermal Analysis
 Used Stefan-Boltzmann equation to calculate light
passing through Cold Stop
 Signal to background ratio for 230° K optical system
Bennu
72
THERMAL BACKUP
73
Peltier Effect in TEC
Thermoelectric coolers use the Peltier Effect to generate
temperature gradient
𝑄 = Π𝐴 − Π𝐵 𝐼
Where Π𝐴 is the Peltier coefficient of the conductor A, Π𝐵 of the
conductor B, and I is the electric current from A to B.
Peltier coefficients represent how much heat is carried per unit
charge. If A and B are different, and a simple thermoelectric
circuit is closed then the Seebeck effect will drive a current,
which in turn will always transfer heat from the hot to the cold
junction.
74
Simulink – Electronics Subsystem
Subsystem Specific Values:
Electronic Board Area – 200cm^2
Electronic Board Thickness – 0.173cm
Radiation Coefficient of PCB – 4.82E-8 W/m^2*K^4
Specific Heat of PCB – 810 J*K/kg
75
Simulink – Optical Subsystem
Subsystem Specific Values:
Optical Assembly Area – 314cm^2
Radiation Coefficient of Glass – 1.1E-9 W/m^2*K^4
Specific Heat of Glass – 447 J*K/kg
76
Simulink – Focalplane Subsystem
Subsystem Specific Values:
Focal Plane Area – 19.625cm^2
77
Simulink – TEC Subsystem
Subsystem Specific Values:
TEC Area – 15.21mm^2
TEC Thickness – 4.4mm
78
Simulink – Radiator Subsystem
Subsystem Specific Values:
Radiator Area – 700cm^2
Radiator Thickness – 5mm
Radiation Coefficient – 5.21e-8 W/m^2K^4
Radiator Mass – 0.25 kg
Specific Heat of Aluminum – 900 J*K/kg
79
ELECTRONICS BACKUP
80
Custom PCB Examples
 Previous designs by Phoenix team members
Communications Board: Xilinx Kintex 7 FPGA, high-speed DDR3 Memory
81
Custom PCB Examples
Attitude Determination and Control: SAMA5 ARM Processor and HighSpeed Memory
82