1. Using the Systems Engineering
Process for a Conceptual
Mercury CubeSat Mission
Karen Grothe
SELP 695: Systems Engineering Integrative Project
Advisor: Dr. Bohdan Oppenheim
Loyola Marymount University
Fall 2015

2. Overview
• Mission objectives
• Ethical considerations
• Stakeholders
• Mission timeline
• Top-level requirements
• Alternative mission
architectures
• Concept of operations
• System drivers and key
requirements
• Trade studies
• Propulsion
• Power generation
• Communications
• Mission utility
• Mission risks and mitigation
• Baseline mission concept
and architecture
• Proposed subsystem block
diagrams
Karen Grothe 212/1/2015
This project uses a systems engineering process to propose a
conceptual interplanetary CubeSat mission to gather science
data at Mercury’s poles.

3. CubeSat History
1999
• CubeSat
concept
defined
2003
• First flight –
university
CubeSats
2006
• First NASA
CubeSat –
GENESAT
2007
• First CubeSat
launched by
commercial
company
(Boeing)
2013
• First USAF SMC
CubeSats
launched
• First PlanetLabs
Doves
launched
2015
• 101st
PlanetLabs
Dove launched
Karen Grothe12/1/2015 3

4. CubeSat Mission Types By Year
Karen Grothe12/1/2015 4
NumberLaunched
Year

5. The Decadal Survey
In 2011, the National
Academy of Sciences
released Vision and
Voyages for Planetary
Science in the Decade
2013 – 2022 outlining
science priorities for
NASA’s planetary science
missions.
12/1/2015 Karen Grothe 5
Image source: http://solarsystem.nasa.gov/2013decadal/

6. Space Missions Are Expensive
NASA Funding Limits the Number of Missions
Karen Grothe12/1/2015 6

7. NASA’s Planned Interplanetary CubeSat
Missions
Auxiliary Payload on Europa Mission
(2020s)
MarCO (March 2016)
Lunar Flashlight (July 2018)
NEA Scout (July 2018)
Karen Grothe12/1/2015 7

8. Methodology:
Space Mission Engineering Process
1. Define Broad (Qualitative) Objectives and Constraints
2. Define Principal Players (Stakeholders)
3. Define Program Timescale
4. Estimate Quantitative Needs, Requirements, and
Constraints
5. Identify Alternative Mission Architectures
6. Identify Alternative Mission Concepts
7. Identify Likely System Drivers and Key Requirements
8. Conduct Performance Assessments and System
Trades
9. Evaluate Mission Utility
10. Define Baseline Mission Concept and Architecture
11. Revise Quantitative Requirements and Constraints
12. Iterate and Explore Other Alternatives
13. Define System Requirements
14. Allocate Requirements to System Elements
This project covers
the first ten steps of
the 14-step Space
Mission Engineering
Process presented
in Space Mission
Engineering: The
New SMAD.
Image Source: http://www.sme-smad.com/index.asp
Karen Grothe12/1/2015 8

9. Mission Objectives and Constraints (Step 1)
Proposed Mercury CubeSat Mission Statement
After the success of the
MESSENGER spacecraft in
mapping Mercury, planetary
scientists have more questions
about Mercury, but the expense
of a large mission means that it
may be many years before
another mission to Mercury is
undertaken. The United States
needs a less expensive class
of spacecraft to perform such
planetary science in a more
timely fashion.
Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie
Institution of Washington
Karen Grothe12/1/2015 9

10. Mission Objectives and Constraints (Step 1)
Proposed Mercury CubeSat Mission Objectives
•Primary Objective: To
investigate the state,
extent, and chemical
compositions of surface
volatiles in the polar
regions of Mercury
•Secondary Objective: To
demonstrate the
functionality of small
spacecraft designed to the
CubeSat standard in
planetary exploration
Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie
Institution of Washington/National Astronomy and Ionosphere Center, Arecibo
Observatory
Karen Grothe12/1/2015 10

11. Ethical Considerations
• Environmental Ethics
• Human-centered
• Utilitarian: Human survival on Earth may depend on
understanding solar system beginnings and the
planetary process through time. *
• Justice: Smaller, and thus cheaper, interplanetary
spacecraft can reduce the inequality inherent thus far in
space exploration by opening up possibilities to more
nations.
• Ecocentric: Understanding the nature of the
volatiles on the surface of Mercury can prepare us
for what precautions to take to preserve the
planetary environment if landers are sent later.
Karen Grothe12/1/2015 11

12. Stakeholders (Step 2)
• NASA – Determines science objectives with NSF; manages
spacecraft development and operates spacecraft
• NSF – Determines science objectives with NASA and provides
funding for scientific investigations
• Federal Government – Provides funding for NASA and NSF
• Suppliers – Tyvek, Vacco, launch provider, etc.
• Universities – Prime Investigators (PIs) and partners with
NASA and NSF
• Scientists – End users of data returned from mission
• Community – Educators and the general public benefit from
scientific findings
• Media – Disseminates announcements from NASA, NSF,
Federal Government, Universities, and Scientists.
Karen Grothe12/1/2015 12

13. Mission Timeline (Step 3)
Phase End Defined By Duration
Typical Duration *
(Small Program)
Concept Exploration
Start of tech. funding; preliminary
requirements release 3 months 1-6 months
Detailed Development
Risk Reduction/Technology
Development Start of program funding 3 - 6 months 0 - 12 months
Detailed Design and
Development Formal requirements release 6 months 2 - 12 months
Production and Deployment
Production Ship to Launch Site 6 months 6 - 24 months
Launch Lift-Off and Arrival in LEO 1 month 1 month
On-Orbit Checkout/Transfer
to Operational Orbit Start of operations 6 years
Up to 10 years
interplanetary
Operations and Support
Operations
Spacecraft dies or decision to be
put to sleep 1+ years 1 month - 5 years
Disposal Re-entry or turn-off 0 years 0 - 5 years
Karen Grothe 13
* Typical Durations come from SME-SMAD [14, Table 3-3, Page 54]
12/1/2015

14. Top-Level Requirements Summary (Step 4)
1. Spacecraft payload shall be appropriate to investigate surface
volatiles in the polar regions of Mercury.
2. Spacecraft shall fit into 12U CubeSat size specification.
3. Spacecraft lifetime shall be at least 8 years.
4. Spacecraft shall be capable of communicating with Earth from
Mercury’s orbit.
5. Thermal management shall protect components from the
extreme temperatures present near Mercury.
6. Spacecraft shall be capable of providing power and fault
protection to sensor payload.
Karen Grothe12/1/2015 14

15. Alternative Mission Architectures (Step 5)
• Operational views
• OV-1: Overview
• OV-5: Operational Activities Chart
• System views
• SV-1: System Interface Description (for two options)
• SV-4: Systems Functionality Description
• Spacecraft, Ground Segment, Launch Segment
• SV-5: Operational Activity to System Functionality
Traceability Matrix
Karen Grothe12/1/2015 15

16. Karen Grothe 16
Space Flight
Operations Facility
Deep Space
Network
Users/CustomersPasadena, CA
Launch
Mercury CubeSat
Mission Architecture
Overview
CubeSat
Image Credit: Tomas Svitek
12/1/2015

17. Mercury CubeSat Mission
Operational Activities
Program
Office
Build
Spacecraft
Build Systems
Integrate
Systems
Launch
Spacecraft
Operate
Spacecraft
Send
Commands
Collect
Science Data
Receive Data
on Ground
Monitor
Spacecraft
Health
Manage
Budget
Manage
Mission Data
Process Data
Distribute
Data
Karen Grothe12/1/2015 17

18. Mercury CubeSat Mission
System Interface Description (Option A)
18Karen Grothe12/1/2015

19. Mercury CubeSat Mission
System (with Relay) Interface Description (Option B)
19Karen Grothe12/1/2015

20. Ground Segment
JPL’s Space Flight
Operations Facility Deep Space Network
Karen Grothe 20
(Source: NASA/JPL-Caltech)
12/1/2015

21. Typical Ground Segment
Functionality Description
Ground Segment
Ground
Communications
Transmit Receive
Ground Network
Operations
Ground Flight
Operations
Commands Planning
Monitoring
Health
Ground Data
Processing
Karen Grothe 2112/1/2015

22. Launch Segment
• CubeSat Mercury
Mission shall launch as a
secondary payload.
• A Canisterized Satellite
Dispenser (CSD) will be
used to encapsulate the
spacecraft on the launch
vehicle and dispense it
on an appropriate Earth
orbit.
Karen Grothe 22
Images Source: Planetary Systems Corporation
12/1/2015

23. Typical Launch Segment
Functionality Description
Launch
Segment
Launch
Facility
Launch
Vehicle
Launch
Control
Karen Grothe 2312/1/2015

24. Top Level Spacecraft Block Diagram
Karen Grothe 24
Command and Data Handling
Subsystem
Electrical Power Subsystem
Attitude Determination &
Control Subsystem
Communications
Subsystem
Payload Subsystem
Propulsion Subsystem
Thermal Control Subsystem
Solar
Array
Battery
S/C
Ground
Power
Mgmt.
Ckts.
Power
Distrib.
Module
Battery
Charge
Reg. To Other
Subsystems
On-Board Data Storage
On-Board Computer (OBC)
Commands to
Subsystems
Data
Handling
Function
ADCS
Function
Command
Function
Transceiver
Antenna
Mission Data
Attitude
Determination
Sensors
Attitude
Control
Actuators
Instrument 1
Commands
from OBC
Data to OBC
HeatersRadiatorsHeat Pipes Coatings Multi-Layer Insulation
Commands
from Earth
Propellant
Thrusters
Sun Shield
Commands to
Thrusters
Instrument 2
Flow Control
Valve
Commands
from OBC
12/1/2015

25. Typical Spacecraft Systems
Functionality Description
Spacecraft
Data Collection
(Payload)
Communications
Transmit Receive
Command and
Data Handling
Attitude Control Propulsion Power
Storing Generating
Telemetry and
Command
Thermal Control
Karen Grothe 2512/1/2015

26. Mercury CubeSat Mission
Operational Activity to System Functionality Traceability Matrix
12/1/2015 Karen Grothe 26
Build Spacecraft Launch Operate Spacecraft Manage Mission Data
Build
Systems
Integrate
Systems
Launch
Spacecraft
Send
Commands
Collect
Science Data
Receive
Data on
Ground
Monitor
Spacecraft
Health
Process
Data
Distribute to
Users
SpaceSegment
Payload Sensing
X
Spacecraft
Power
Power
X X X X
Spacecraft
Comms.
Transmit
X X
Receive
X
Ground
Equipment
Ground
Handling
X X
Systems Test
Equip.
Systems
Test
X
LaunchSegment
Launch
Facility
X X
Launch
Vehicle
X
Launch
Control
X
GroundSegment
Ground
Comms.
Ground
Transmit
X
Ground
Receive
X X
Flight Operations
X X X
Network Operations
X
Data Processing
X
Comms. = Communications
Equip. = Equipment

27. Concept of Operations (Step 6)
Launch and Trajectory
• Launch as a
secondary payload
• Take a trajectory
similar to that of the
MESSENGER
spacecraft
• Orbit insertion at
Mercury in about 6
years Example trajectory: MESSENGER
Image source: http://messenger.jhuapl.edu/the_mission/trajectory.html
Karen Grothe12/1/2015 27

28. Mercury CubeSat Concept of Operations
(Step 6)
 Mission Timeline/Schedule (The overall schedule for planning,
building, deployment, operations, replacement, and end-of-life) – 1
spacecraft developed over 2 years, launched in the earliest available
window, operates for 8 years.
 Tasking, Scheduling & Control (How the system decides what to do
in the long term and short term) – Single mission operations center
 Communications Architecture (How the various components of the
system talk to each other) – Space/Ground: Either direct downlink to
Deep Space Network or relayed to Earth via nearby spacecraft;
Ground/User: Internet distribution
 Data Delivery (How mission and housekeeping data are generated or
collected, distributed & used) – Sensor data and spacecraft health and
orbit/attitude data sent to ground and distributed to users
Karen Grothe12/1/2015 28

29. System Drivers and Key Requirements
(Step 7)
• Mass and power are typical spacecraft system drivers.
• Using the CubeSat standard adds the volume that
subsystems occupy as a constraint.
• Additional system drivers and key requirements are imposed
on the subsystems.
• Payload
• Electrical Power Subsystem (EPS)
• Communications
• Attitude Determination and Control Subsystem (ADCS)
• Thermal Control
• Propulsion
12/1/2015 Karen Grothe 29

30. Proposed Mass, Volume, and Power Budget
System Description Heritage
Mass
(kg)
Volume
(U)
Power (W)
(Peak)
ADCS
Star tracker, sun sensor,
reaction wheels, IMU
BCT XACT (star trackers, IMU), sun sensor,
reaction wheels 1 1 3
Propulsion Microthrusters Busek electrospray thrusters 1 1 30
C&DH/
Processing
Science & Engrg.
Management, processing SpaceCube Mini, Lunar Ice CubeSat 0.5 0.5 5
Thermal/
Radiation
Passive shielding, passive
cooling, heaters, sun shield
MESSENGER's sunshade and other thermal
defense 3 2 8
Structures/
Mechanisms
Frame, deployer, deployables
(gimballed, stowed solar
panel array, antennas)
Planetary Systems Corp. 12U deployer, MMA
Design Ehawk gimballed solar panels 8 - 1
Comm Antenna, transceiver
SERC's deployable high gain antenna, JPL's
IRIS X-Band Radio 3.5 2.5 10
Power
Electrical system, conversion,
regulation, batteries 1.5 1.5 5
Payload:
Near Infrared
Spectrometer
Detector, optics, associated
electronics, cryocooling
JPL Lunar Flashlight's spectrometer, Lunar
IceCube's Broadband InfraRed Compact High
Resolution Explorer Spectrometer (BIRCHES),
Moon Mineralogy Mapper 2.5 1.5 7
Laser Altimeter
Optics, associated electronics,
cryocooling (If required)
JPL Lunar Flashlight's laser, MESSENGER
Laser Altimeter (MLA) 4 2 14
Total without
propulsion 25 12 83
Karen Grothe12/1/2015 30

31. Payload
Driving Requirements
• Scientific objectives
• Investigate the state, extent, and chemical compositions of
surface volatiles in the polar regions of Mercury
• Thermal environment
• Small size
Karen Grothe 3112/1/2015

32. Electrical Power Subsystem
•Design Drivers
• Orbit: Mercury orbit requires enough battery power to
supply the spacecraft power during eclipse.
• Payload requirements: Instruments require power, fault
protection, bursts of power when imaging a particular
commanded area.
• Distribute power to all subsystems
• Spacecraft lifetime of 8 years
Karen Grothe 3212/1/2015

33. Communication Subsystem
Driving Requirements
• Distance of the mission from Earth
• Pointing requirements
• Small size of satellite
• Power availability
• Thermal control
• Telemetry and sensor data downlinked at X-band
• In the range 8400 - 8450 MHz for DSN
• Commands uplinked at X-band
• In the range 7145 - 7190 MHz for DSN
• Data rate – If the data rate is too slow, data storage
capability will need to increase.
Karen Grothe 3312/1/2015

34. Attitude Determination & Control
Subsystem (ADCS)
Driving Requirements
• Three-axis stabilization
• Power: Solar panels need to point to the sun to
produce sufficient power
• Pointing accuracy necessary to complete the
science objectives
Karen Grothe 3412/1/2015

35. Thermal Control Subsystem
Driving Requirements
• Thermal Environment: Orbiting Mercury presents
extreme temperatures as the spacecraft moves
between eclipse and sun exposure
• Large thermal effect from sunlight reflected up from
Mercury
• Infrared heat emanating from the planet's
scorching day-side surface
• Spacecraft size
• Instruments may need extra thermal control
Karen Grothe 3512/1/2015

36. Propulsion Subsystem
Driving Requirements
•Distance to destination
•Fuel
•Influence on weight and size
•High performance  less weight
•Spacecraft lifetime of 8 years
Karen Grothe 3612/1/2015

37. Performance Assessments and Trade
Studies (Step 8)
Trade studies:
12/1/2015 Karen Grothe 37
Source: http://www.tethers.com/Products.html
Credit: NASA Jet Propulsion Laboratory
Image Credit: USC
Propulsion
Power Generation
Communications

38. Performance Assessments & Trade Studies (Step 8)
Measures of Effectiveness
• The following measures of effectiveness are used to
evaluate propulsion, power, and communications
alternatives:
• Technology Readiness Level (TRL)
• Performance specifications
• Propulsion: Thrust, Isp, and power required
• Power generation: Power output (W)
• Communications: Data rate and power required
• Mass
Karen Grothe12/1/2015 38

39. Performance Assessments & Trade Studies (Step 8)
Propulsion Alternatives
1. VACCO Propulsion Unit for CubeSats –
a COTS propulsion system which
includes a warm gas thruster
2. CubeSat Ambipolar Thrusters (CAT)
3. HYDROS™ Water Electrolysis Thruster
4. Solar sail
5. Solar Electric Power/Solar Electric
Propulsion (SEP^2)
6. Colloidal Thruster, a.k.a. electrospray
thruster
Karen Grothe12/1/2015 39
Image Sources: 1. VACCO Industries
2. http://pepl.engin.umich.edu/thrusters.html
3. Tethers Unlimited, Inc.
4. NASA
6. Busek Co., Inc.
No
picture
available
1
2
3
4
5
6

40. Propulsion Trade Study
Alternative Measures of Effectiveness Comments
TRL Thrust Isp Power Mass
VACCO
Propulsion Unit
for CubeSats
TRL-7+ 5.4 mN 70 s 15 W < 1 kg Includes Warm Gas
Thruster, Useful for
attitude control
CubeSat
Ambipolar
Thruster
TRL-3 ≤ 2 mN Up to 2000 s
(About 800 s
in July 2015
tests with
Xenon ions)
≤ 10 W ≤ 1 kg Flexible propellant
(water or iodine,
ideally); first launch
planned for early 2017
HYDROS™ Water
Electrolysis
Thruster
TRL-5
(Expected to
mature to TRL-6
Winter 2015)
≤ 1 N 300 s Water propellant;
“green”
Solar sail TRL-5 < 7mN 4 – 10 kg
(NanoSail-D
was ~ 4 kg)
Thrust from solar
pressure on sail
Solar Electric
Power/Solar
Electric
Propulsion
(SEP^2)
TRL-3 (est.) TBD by
mfr.
Up to 3000 s Generates
80 W,
20 W when
thrusting
TBD Xenon propellant;
System comes with solar
panels
Colloidal
(Electrospray)
Thruster
TRL-7+
TRL-5
100 µN
≤ 1 mN
2300 s
400 s to
> 1300 s
5 W
15 W
320 g (wet)
1.15 kg
Busek has delivered
100-µN thrusters to
NASA
Karen Grothe12/1/2015 40

41. Performance Assessments & Trade Studies (Step 8)
Power Alternatives
1. Solar panels
2. Mini-Radioisotope
Generator (Mini-RTG)
3. Solar Electric
Power/Solar Electric
Propulsion (SEP^2)
Karen Grothe12/1/2015 41
1
2
3
Image Sources:
1. Tethers Unlimited, Inc.
2. University of Bristol

42. Power Trade Study
Alternative
Measures of Effectiveness
CommentsTRL
Power
Generated Mass
Deployable
Solar Panels
TRL-9 Typically up to
80 W
6U side panel:
≤ 340 g
3U side panel: ≤ 190 g
Readily
available;
scalable
Mini-RTG ≤ TRL-3
(est.)
40 – 250 mW 300 – 600 g Thermoelectric
Solar Electric
Power/Solar
Electric
Propulsion
(SEP^2)
TRL-3 (est.) 80 W,
20 W when
thrusting
TBD
Karen Grothe12/1/2015 42

43. Performance Assessments & Trade Studies (Step 8)
Communications Alternatives
1. Laser communication
2. Direct microwave
communication with
deployable high-gain
antenna
3. Integrated Solar Array &
Reflectarray Antenna
4. Using a relay spacecraft
Karen Grothe12/1/2015 43
Image Sources:
1. NASA
2. USC
3. NASA
4. ESA
1
2
3
4

44. Communications Trade Study
Alternative Measures of Effectiveness Comments
TRL Data Rate Power Used Mass
Laser
Communication
TRL-6 < 625 Mbps to <
2.88 Gbps
40 – 50 kbps from
2 AU
50 – 140 W
(LADEE)
0.5 W average
30 kg
(LADEE)
Optical receiver
required; LADEE
transmitter is too
heavy
Direct Microwave
Communication
with Deployable
High Gain Antenna
X: TRL-9
K: TRL-3 to
TR-9
Antenna:
TRL-6 to
TRL-9
X: < 500 Mbps
Ka: < 3 Gbps
Ku: <150 Mbps
K: < 1.2 Gbps
X: < 90–120 W
Ka: N/A
Ku: 47 W
K: 30 W
X: ≤ 4 kg
Ka: 2.7 kg
Ku: 2.3 kg
K: 2.8 kg
JPL-developed IRIS
X-band radio is
specifically
designed for
CubeSats
Integrated Solar
Array & Reflectarray
Antenna
TRL-5
(Flying in
Nov. to
raise to
TRL-7)
≥ 100 Mbps No more than
system with
deployable
parabolic antenna
Minimal
difference
from
deployable
parabolic
antenna
High Bandwidth
Ka-band, high gain
antenna integrated
into COTS solar
array
Relay Spacecraft TRL-9 Possibility:
BepiColombo or
Akatsuki
Karen Grothe12/1/2015 44

45. Evaluating Mission Utility (Step 9)
12/1/2015 Karen Grothe 45
How much
will it cost?
Is the mission
worthwhile?
How much
meaningful
science data
can we collect?
What are
the risks?

46. Mission Risks and Mitigation
Mission Risks Mitigation
1. Launch delays Have a secondary launch
date
2. Communication failure Testing; plan an alternative
communication path or
redundancy
3. Radiation environment causing failure Ruggedize; use shielding
4. Collision with space debris or another
spacecraft
No mitigation
5. Technology readiness lacking Use technology already in
development; fly technology
that is not less than TRL 5
Karen Grothe12/1/2015 46

47. Mission Risk Matrix
Very Low Low Medium High Very High
Very High
High
Medium
Low
Very low
Likelihood
Impact
2
1
35
4
Karen Grothe12/1/2015 47
Risks:
1. Launch delays
2. Comm. failure
3. Radiation env.
causes failure
4. Collision
5. TRL

48. Baseline Mission Concept and
Architecture (Step 10)
Karen Grothe12/1/2015 48

49. Top Level Spacecraft Block Diagram
Karen Grothe 49
Command and Data Handling
Subsystem
Electrical Power Subsystem
Attitude Determination &
Control Subsystem
Communications
Subsystem
Payload Subsystem
Propulsion Subsystem
Thermal Control Subsystem
Solar
Array
Battery
S/C
Ground
Power
Mgmt.
Ckts.
Power
Distrib.
Module
Battery
Charge
Reg. To Other
Subsystems
On-Board Data Storage
On-Board Computer (OBC)
Commands to
Subsystems
Data
Handling
Function
ADCS
Function
Command
Function
X-Band
Transceiver
Deployable
Antenna
Mission Data
Star
Trackers
Sun
Sensors
IMU
Reaction
Wheels
Infrared
Spectrometer
Commands
from OBC
Data to OBC
HeatersRadiatorsHeat Pipes Coatings Multi-Layer Insulation
Commands
from Earth
Ionic
Liquid
Propellant
Electrospray Thrusters
Sun Shield
Commands to Thrusters
Laser
Altimeter
Flow Control
Valve
Commands
from OBC
12/1/2015

50. Payload Possibilities
• Near infrared
spectrometer
• Laser to illuminate
shadowed craters
• Altimeter capability
would allow mapping
spectrometer data to
depth within craters
Karen Grothe 5012/1/2015
Example Instrument
JPL’s NanoSat Spectrometer
Example of illuminating shadowed crater with laser
Images source: NASA (both)

51. Diagram of
Proposed Thermal Control Subsystem
Karen Grothe 51
Coatings
Radiators Multi-Layer
Insulation
Blankets
Heat Pipes
Sun Shield
Heaters
Dimensions in mm
12U CubeSat Payload Spec Source:
http://www.planetarysystemscorp.com/web/wp-content/uploads/2015/08/2002367C-Payload-Spec-for-3U-6U-12U-27U1.pdf
12/1/2015

52. Additional Possibilities
• MBSE: Project could be further developed using the
CubeSat SysML model developed by the INCOSE
Space Systems Working Group
• Interplanetary CubeSats in constellations
• Interplanetary CubeSats inserted in the orbit of a
planetary body from a mothership
• Weight reduction:
• Wireless intra-spacecraft communication
• Eliminate black boxes and create an optimized design
Karen Grothe12/1/2015 52

53. Lessons Learned
• The Space Mission Engineering steps are a tailored
version of the SE Process in the INCOSE SE Handbook.
• The SE process offers a disciplined approach to analyzing
possible space missions.
• System trade studies and mission analyses require more
expertise than one systems engineer usually has.
• Although a CubeSat is small and less expensive than
typical interplanetary spacecraft, it is still a complex system.
• In the next few years, there likely will be several
interplanetary CubeSat missions launched.
Karen Grothe12/1/2015 53

54. References
• [1] Committee on the Planetary Science Decadel Survey, Voyages and Vision for Planetary Science in the
Decade 2013 - 2022, Washington D.C.: National Academies Press, 2011.
• [2] S. Squyres, "Vision and Voyages for Planetary Science in the Decade 2013-2022, Rollout at LPSC," 11
March 2010. [Online]. Available:
http://solarsystem.nasa.gov/docs/Squyres_2013_Decadal_Rollout_at_LPSC.pdf. [Accessed 4 May 2015].
• [3] The CubeSat Program, , "CubeSat Design Specification Rev 13, Final2, PDF File," 6 April 2015. [Online].
Available: http://cubesat.org/images/developers/cds_rev13_final2.pdf. [Accessed 4 May 2015].
• [4] The Planetary Society, "NASA's Planetary Science Division Funding and Number of Missions 2004 - 2020,"
9 February 2015. [Online]. Available: http://www.planetary.org/multimedia/space-images/charts/historical-
levels-of-planetary-exploration-funding-fy2003-fy2019.html. [Accessed 6 May 2015].
• [5] Solar System Exploration Research Virtual Institute (SSERVI), "Lunar Flashlight," NASA, [Online].
Available: http://sservi.nasa.gov/articles/lunar-flashlight/. [Accessed 6 May 2015].
• [6] P. Banazadeh and A. Frick, "ISSC - A3_Banazadeh_Presentation.pdf," 2014. [Online]. Available:
http://www.intersmallsatconference.com/. [Accessed 6 May 2015].
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55. References
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Annual Summer CubeSat Developers' Workshop, 2014. [Online]. Available at:
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56. References
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Electrospray Propulsion Systems for Small Satellites, 1st ed. Busek Co., Inc., 2013. [Online]. Available:
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Nov- 2015].
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COTS fuel, 1st ed. University of Bristol, 2015. [Online]. Available: https://icubesat.files.wordpress.com/2015/05/icubesat-
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Nov- 2015].
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Exploration Science Forum; Moffett Field, CA, 2015. [Online]. Available:
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[Accessed: 01- Nov- 2015].
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VERIFICATION VEHICLE, 1st ed. Glasgow, UK: Clyde Space Ltd., 2010. [Online]. Available: http://www.clyde-
space.com/documents/1805 [Accessed: 01- Nov- 2015].
Karen Grothe12/1/2015 57

58. Supplemental Slides
Karen Grothe 5812/1/2015

59. Decadal Survey Recommendations
• Flagship Missions: ($2.5B cap) Probably only 1 - 2
• Mars Astrobiology Explorer-Cacher (MAX-C)
• Jupiter Europa Orbiter (JEO)
• Uranus Orbiter and Probe
• Enceladus Orbiter or Venus Climate Mission
• New Frontiers Missions: ($1B cap) Probably only 1 - 2
• Choose one:
• Comet Surface Sample Return
• Lunar South Pole Sample Return
• Saturn Probe
• Trojan Asteroid Tour and Rendezvous
• Venus In Situ Explorer
• Choose next one from remaining above candidates plus:
• Io Observer
• Lunar Geophysical Network
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60. Mercury CubeSat Concept of Operations
 Problem Definition
 Space missions are expensive!
 How can we build small spacecraft based on the
CubeSat design standard to use in deep space
missions?
 Propulsion
 Power
 Communications
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61. Project Plan and Schedule (Step 3)
Description
Planned
Start Date
Planned
End Date
Planned
Duration
Actual
Start Date
Actual
End Date
Project Proposal 9/8/2015 9/15/2015 1 week 9/8/2015 9/15/2015
Project Presentation Outline 9/10/2015 9/17/2015 1 week 9/10/2015 9/17/2015
Background research (history, related
projects, Decadal Survey, CubeSat
advancements)
9/15/2015 9/22/2015 1 week 9/17/2015 9/23/2015
Customer CONOPS, Stakeholders, and
Requirements
9/15/2015 9/25/2015 1.5 weeks 9/15/2015 10/8/2015
Alternative Architectures (operational and
system views) and Measures of Effectiveness
9/22/2015 9/29/2015 1 week 9/29/2015 10/8/2015
Risks and Mitigations 9/22/2015 10/2/2015 1.5 weeks 9/29/2015 11/2/2015
Trade Studies (Power, Communications,
Propulsion)
9/22/2015 10/6/2015 2 weeks 9/22/2015 10/31/2015
Integration, Verification, and Validation 9/29/2015 10/6/2015 1 week 9/29/2015 11/2/2015
Cost Analysis 9/29/2015 10/13/2015 2 weeks 9/29/2015 10/13/2015
Ethics 10/8/2015 10/15/2015 1 week 10/8/2015 10/15/2015
Lessons Learned 10/8/2015 10/15/2015 1 week 10/8/2015 11/2/2015
Finish Draft of Presentation 10/8/2015 10/15/2015 1 week 10/1/2015 10/17/2015
Write Draft of Report 10/1/2015 10/15/2015 2 weeks 10/8/2015 10/17/2015
Address Advisor Comments on Presentation
and Report
10/15/2015 11/12/2015 4 weeks 10/15/2015 11/10/2015
Dry Run Presentation 11/12/2015 12/6/2015 3.5 weeks 11/2/2015 12/1/2015
Finalize Project Presentation 11/12/2015 12/7/2015 3.5 weeks 11/2/2015 12/2/2015
Finalize Project Report 11/12/2015 12/7/2015 3.5 weeks 10/15/2015 12/2/2015
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62. Proposed Payload Block Diagram
Karen Grothe 62
Infrared Spectrometer Laser Altimeter
Command & Data Handling Subsystem
Commands Commands DataData
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63. Proposed Electrical Power Subsystem Block Diagram
Karen Grothe 63
Solar
Panel 3
Solar
Panel 2
Solar
Panels
Power
Management
Circuits
Spacecraft
Ground
Battery Charge
Regulator
Spacecraft
Battery
Power
Distribution
Module
Attitude
Determination
& Control
Subsystem
Communications
Subsystem
Payload
Thermal
Control
Subsystem
Command &
Data Handling
Subsystem
Power Subsystem Architecture
(Simplified)
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64. Proposed Communication Subsystem
Block Diagram
Karen Grothe 64
Command & Data
Handling Subsystem
X-Band
Transponder
Deployable
High Gain
Antenna
Commands
Telemetry Inputs Mission Data
Commands
from Earth
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65. Proposed ADCS Block Diagram
Karen Grothe 65
On-Board Computer
ADCS Function
Sun
Sensors
Star
Trackers
Attitude
Determination
Attitude
Control
Reaction
Wheels
IMU
Thrusters
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66. Proposed Propulsion Subsystem
Block Diagram
Karen Grothe 66
Ionic Liquid
Propellant
Flow Control
Valve
Electrospray Thrusters
Command & Data
Handling
Subsystem
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67. Cost Analysis
Proposed Work Breakdown Structure
1.0 Program Level
1.1 Program Management - Analogy
1.2 Systems Engineering - Analogy
1.3 System Integration and Test - Analogy
1.4 Quality Assurance - Analogy
2.0 Spacecraft
2.1 Spacecraft Bus
2.1.1 Structure - SSCM
2.1.2 Thermal Control Subsystem – SSCM
2.1.3 Attitude Determination and Control Subsystem –
SSCM
2.1.4 Electrical Power Subsystem – SSCM
2.1.5 Propulsion Subsystem – SSCM
2.1.6 Communication Subsystem – Extrapolation from
Actuals
2.1.7 Command and Data Handling Subsystem –
Extrapolation from Actuals
2.1.8 Integration, Assembly, and Test - Analogy
2.1.9 Flight Software (for controlling the spacecraft) –
COCOMO tool
2.2 Payload – SSCM
2.2.1 Instruments – NASA Instrument Cost Model (NICM)
2.2.2 Mission Software (for controlling the payload) -
COCOMO tool
2.3 Spacecraft Integration, Assembly, and Test -
SSCM
3.0 Launch Segment
3.1 Launch Vehicle Integration – Analogy to similar
missions
3.2 Launch Operations – Analogy to similar
missions
4.0 Ground Segment
4.1 Communication Services – Analogy to similar
missions
4.2 Flight Operations – Analogy to similar missions
4.3 Network Operations - Analogy to similar
missions
4.4 Data Processing - Analogy to similar missions
5.0 Ground Handling Equipment and
System Test Equipment – SSCM
Karen Grothe12/1/2015 67

68. Verification of Requirements
1. Requirement: Spacecraft payload shall be appropriate to
investigate surface volatiles in the polar regions of Mercury.
• Verification Method: Analysis
• Needs: Preliminary data on ice in the polar craters from MESSENGER
mission.
• Criteria: Spectrometer used on mission will be capable of measuring
the volatiles predicted to exist from MESSENGER data.
2. Requirement: Spacecraft shall fit into 12U CubeSat size
specification to allow for use of a containerized satellite
dispenser (CSD).
• Verification Method: Demonstration
• Needs: Accurate CSD mockup to verify fit
• Criteria: Spacecraft meets CubeSat Specification dimensions and fits
in CSD mockup.
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69. Verification of Requirements
3. Requirement: Spacecraft lifetime shall be at least 8 years to
allow spacecraft time to reach Mercury’s orbit and perform at
least one year of science.
• Verification Method: Analysis
• Needs: Lifetime data of spacecraft bus and payload
• Criteria: Spacecraft is predicted to meet lifetime requirement based on
analysis of the lifetime data of individual components and the
spacecraft bus
4. Requirement: Spacecraft shall be capable of communicating
with Earth from Mercury’s orbit either directly or via relay
satellite.
• Verification Method: Test and demonstration on orbit
• Needs: Test messages
• Criteria: Successful communication
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70. Verification of Requirements
5. Requirement: Thermal management shall protect
components from the extreme temperatures present near
Mercury.
• Verification Method: Environmental lab testing
• Needs: Environmental test procedure
• Criteria: Components withstand testing at extreme temperatures
6. Requirement: Spacecraft shall be capable of providing
power and fault protection to sensor payload.
• Verification Method: Lab testing
• Needs: Test procedure including some failure modes
• Criteria: Spacecraft provides appropriate levels of power and fault
protection to subsystems.
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