Applying the Systems Engineering Process to a Conceptual Merucry CubeSat Mission

Applying the Systems Engineering Process
to a Conceptual Mercury CubeSat Mission
By Karen Grothe
• Email: karen@karengrothe.com
• Website: http://karengrothe.com/
• Advisor: Dr. Bohdan Oppenheim, Loyola Marymount University
Bio:
• BS in EE from Washington University in St. Louis
• Astronautical Engineering Certificate from UCLA Extension – Spring 2015
• MS in Systems Engineering from Loyola Marymount University – Dec. 2015
• 16 years experience in aerospace as a systems engineer at McDonnell
Douglas (F/A-18 Maintenance Trainers), Boeing (MD-10/11 Avionics
Development Simulation), and Raytheon (B-2 Radar and U-2 ASARS
Radar)
• Leveraging experience managing requirements and verification testing for
airborne systems into a stellar career advancing spacecraft systems.

Overview
– Mission objectives
– Stakeholders
– Mission timeline
– Top-level requirements
– Alternative mission
architectures
– Concept of operations
– System drivers and key
requirements
– Trade studies
• Propulsion
• Communications
– Mission utility
• Mission risks and mitigation
– Baseline mission concept
and architecture
• Proposed subsystem block
diagrams
4/9/2016 Applying Systems Engineering Process to
a Conceptual Mercury CubeSat Mission
2
This project uses a systems engineering process to propose a
conceptual interplanetary CubeSat mission to gather science
data at Mercury’s poles.

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.
3
Image source: http://solarsystem.nasa.gov/2013decadal/

Space Missions Are Expensive
NASA Funding Limits the Number of Missions
4

NASA’s Planned Interplanetary
CubeSat Missions
5
Auxiliary Payload on Europa Mission
(2020s)
MarCO
(Secondary Payload with Mars INSIGHT)
Lunar Flashlight (July 2018)
NEA Scout (July 2018)

Methodology:
Space Mission Engineering Process
6
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

Mission Objectives & 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.
7
Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie
Institution of Washington

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
8
Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie
Institution of Washington/National Astronomy and Ionosphere Center, Arecibo
Observatory

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 – Busek, 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.
9

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
4/9/2016
Applying Systems Engineering Process to
10
* Typical Durations come from SME-SMAD [11, Table 3-3, Page 54]

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.
11

Alternative Mission Architectures
(Step 5)
• Operational views
– OV-1: Overview
• System views
– SV-1: System Interface Description (for two options)
12

Mercury CubeSat Mission
Architecture Overview
13
Space Flight
Operations Facility
Deep Space
Network
Users/CustomersPasadena, CA
Launch
CubeSat
Image Credit: Tomas Svitek

System Interface Description (Option A)
14

System Interface Description (Option B)
15

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
16
Example trajectory: MESSENGER
Image source: http://messenger.jhuapl.edu/the_mission/trajectory.html

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
17

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.
• Thermal environment: Temperature at Mercury
ranges from 80 K to 700 K
• Spacecraft lifetime of 8 years
18

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
19

Performance Assessments
and Trade Studies (Step 8)
20
Trade studies:
Credit: NASA Jet Propulsion Laboratory Image Credit: USC
Propulsion Communications

Performance Assessments & Trade
Studies (Step 8)
Measures of Effectiveness
• The following measures of effectiveness are used to
evaluate propulsion and communications alternatives:
– Technology Readiness Level (TRL)
– Performance specifications
• Propulsion: Thrust, Isp, and power required
• Communications: Data rate and power required
– Mass
21

Performance Assessments & Trade Studies
(Step 8)
Propulsion Alternatives
22
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
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

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 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
4/9/2016 Applying Systems Engineering Process to a Conceptual Mercury CubeSat Mission 23

Performance Assessments & Trade Studies
(Step 8)
Communications Alternatives
24
1. Laser communication
2. Direct microwave
communication with
deployable high-gain
antenna
3. Integrated Solar Array &
Reflectarray Antenna
4. Using a relay spacecraft
Image Sources:
1. NASA
2. USC
3. NASA
4. ESA
1
2
3
4

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
2016 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
25

Evaluating Mission Utility
(Step 9)
26
How much
will it cost?
Is the mission
worthwhile?
How much
meaningful
science data
can we collect?
What
are the
risks?

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
27

Mission Risk Matrix
28
Very Low Low Medium High Very High
Very High
High
Medium
Low
Very low
Likelihood
Impact
2
1
35
4
Risks:
1. Launch delays
2. Comm. failure
3. Radiation env.
causes failure
4. Collision
5. TRL

Baseline Mission Concept and Architecture
(Step 10)
Top Level Spacecraft Block Diagram
4/9/2016 Applying Systems Engineering Process to a Conceptual Mercury CubeSat Mission 29
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

Conclusion
30
• Payload Possibilities:
– Near infrared spectrometer
– Laser to illuminate shadowed
craters
• Altimeter capability would allow
mapping spectrometer data to
depth within craters
Example Instrument
JPL’s NanoSat Spectrometer
Example of illuminating shadowed crater with laserImages source: NASA (both)
By drawing upon interplanetary CubeSat projects now in progress at
NASA and on lessons learned during the MESSENGER mission, an
interplanetary CubeSat mission to Mercury could be developed in
about two years.

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, “Lunar Flashlight and NEA Scout: A NanoSat Architecture for Deep Space
Exploration," 2014. [Online]. Available: http://www.intersmallsatconference.com/ . [Accessed 6 May 2015].
• [7] R. Staehle and e. al., “Lunar Flashlight: Finding Lunar Volatiles Using CubeSats," 13 November 2013. [Online].
Available: http://sservi.nasa.gov/wp-content/uploads/2014/04/Staehle-presentation-Lunar-Flashlight-20131109.pdf
. [Accessed 6 May 2015].
• [8] Michael Swartwout, PhD, Associate Professor, Aerospace and Mechanical Engineering, Saint Louis University,
CubeSat Database. [Online]. Available: https://sites.google.com/a/slu.edu/swartwout/home/cubesat-database
• [9] NASA, “NASA Technology Roadmaps, TA 2: In-Space Propulsion Technologies”, May 2015 Draft. [Online.]
Available at:
http://www.nasa.gov/sites/default/files/atoms/files/2015_nasa_technology_roadmaps_ta_2_in_space_propulsion.p
df [Accessed 12 October 2015]
31

References
• [10] NASA, “Definition of Technology Readiness Levels.” [Online]. Available at: http://esto.nasa.gov/files/trl_definitions.pdf
[Accessed 12 October 2015]
• [11] J. Wertz, D. Everett and J. Puschell, Space Mission Engineering: The New SMAD. Hawthorne, CA: Microcosm Press,
2011.
• [12] C. Gustafson and S. Janson, 'Think Big, Fly Small', Crosslink, 2014.
• [13] NASA Ames Research Center, 'Small Spacecraft Technology State of the Art', NASA Center for AeroSpace Information,
2014.
• [14] Canisterized Satellite Dispenser (CSD) Data Sheet, 1st ed. Planetary Systems Corporation, 2015. [Online]. Available at:
http://www.planetarysystemscorp.com/web/wp-content/uploads/2015/08/2002337C-CSD-Data-Sheet.pdf [Accessed 31
October 2015]
• [15] W. Holemans, 'Lunar Water Distribution (LWaDi)-- a 6U Lunar Orbiting spacecraft SSC14-WK-22', 11th Annual
Summer CubeSat Developers' Workshop, 2014. [Online]. Available at: http://www.planetarysystemscorp.com/web/wp-
content/uploads/2014/09/Lunar-Water-Distribution-LWaDi-a-6U-Lunar-Orbiting-spacecraft.pdf [Accessed 31 October 2015]
• [16] J. Sheehan, 'PEPL: Thrusters: CubeSat Ambipolar Thruster', Plasmadynamics and Electric Propulsion Laboratory,
University of Michigan, 2015. [Online]. Available: http://pepl.engin.umich.edu/thrusters/CAT.html [Accessed: 01- Nov- 2015].
• [17] Aerojet Rocketdyne, 'MPS-160™ Solar Electric Power / Solar Electric Propulsion System', 2015. [Online]. Available:
http://www.rocket.com/cubesat/mps-160 [Accessed: 01- Nov- 2015].
• [18] Propulsion Unit for CubeSats (PUC), 1st ed. VACCO Industries, 2015. [Online]. Available:
http://www.vacco.com/images/uploads/pdfs/11044000-01_PUC.pdf [Accessed: 01- Nov- 2015].
• [19] ARTEMIS Space, 'ARTEMIS Lunar Constellation', 2014. [Online]. Available: http://www.artemis-space.com/artemis-
lunar-constellation/ [Accessed: 01- Nov- 2015].
• [20] P. Dyches, 'JPL Selects Europa CubeSat Proposals for Study', NASA JPL News, 2014. [Online]. Available:
http://www.jpl.nasa.gov/news/news.php?feature=4330 [Accessed: 01- Nov- 2015].
32

References
• [21] D. Spence, E. Ehrbar, N. Rosenblad, N. Demmons, T. Roy, S. Hoffman, D. Williams, V. Hruby and C.
Tocci, Electrospray Propulsion Systems for Small Satellites, 1st ed. Busek Co., Inc., 2013. [Online]. Available:
http://digitalcommons.usu.edu/cgi/viewcontent.cgi?filename=0&article=2960&context=smallsat&type=additional
[Accessed: 01- Nov- 2015].
• [22] Busek 100uN-Class Electrospray Thrusters, 1st ed. Busek Co., Inc., 2015. [Online]. Available:
http://www.busek.com/index_htm_files/70008516E.pdf [Accessed: 01- Nov- 2015].
• [23] HYDROS Thruster, 1st ed. Bothell, WA: Tethers Unlimited, Inc., 2015. [Online]. Available:
http://www.tethers.com/SpecSheets/Brochure_HYDROS.pdf [Accessed: 01- Nov- 2015].
• [24] L. Johnson, Solar Sail Propulsion for Interplanetary Small Spacecraft, 1st ed. NASA, 2015. [Online]. Available:
http://images.spaceref.com/fiso/2015/032515_les_johnson_nasa_msfc/Johnson_3-25-15.pdf [Accessed: 01- Nov-
2015].
• [25] J. Fleurial, Thermoelectrics in Space: A Success Story, What’s Next and What Might Be Possible, 1st ed.
Pasadena, CA: JPL, 2015. [Online]. Available:
http://www.kiss.caltech.edu/study/adaptiveII/Kiss%202015%20Workshop%20JPF%20TE%20Brief%20rev1.pdf
• [26] B. Cohen, 'Lunar Flashlight and Near Earth Asteroid Scout: Exploration Science Using Cubesats', 2nd NASA
Exploration Science Forum; Moffett Field, CA, 2015. [Online]. Available:
http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20150015511.pdf [Accessed: 01- Nov- 2015].
• [27] R. Hodges, 'ISARA: Integrated Solar Array Reflectarray Mission Overview', CubeSat Developers Workshop at
the Small Satellite Conference, 2013. [Online]. Available:
http://digitalcommons.usu.edu/cgi/viewcontent.cgi?filename=0&article=2877&context=smallsat&type=additional
33

References
• [28] M. Aherne, J. Barrett, L. Hoag, E. Teegarden and R. Ramadas, Aeneas -- Colony I Meets Three-Axis
Pointing, 1st ed. Marina del Rey, CA: Space Engineering Research Center, 2011. [Online]. Available:
http://digitalcommons.usu.edu/cgi/viewcontent.cgi?article=1181&context=smallsat [Accessed: 01- Nov- 2015].
• [29] Messenger.jhuapl.edu, 'MESSENGER: MErcury Surface, Space ENvironment, GEochemistry, and
Ranging - Thermal Design', 2015. [Online]. Available: http://messenger.jhuapl.edu/spacecraft/thermal.html
Ranging - Power', 2015. [Online]. Available: http://messenger.jhuapl.edu/spacecraft/power.html [Accessed:
01- Nov- 2015].
Ranging - Mission Design', 2015. [Online]. Available:
http://messenger.jhuapl.edu/the_mission/mission_design.html [Accessed: 01- Nov- 2015].
Ranging - The Payload Instruments', 2015. [Online]. Available:
http://messenger.jhuapl.edu/instruments/index.html [Accessed: 01- Nov- 2015].
Ranging - Working from Orbit', 2015. [Online]. Available: http://messenger.jhuapl.edu/the_mission/orbit.html
34

Supplemental Slides
35
4/9/2016

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
4/9/2016 36

CubeSat Mission Types By Year
37
NumberLaunched
Year

Ground Segment
JPL’s Space Flight
Operations Facility Deep Space Network
38
(Source: NASA/JPL-Caltech)

Launch Segment
39
• 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.
Images Source: Planetary Systems Corporation

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
40

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
41

Communication Subsystem
• 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.
42

Attitude Determination & Control
Subsystem (ADCS)
• Three-axis stabilization
• Power: Solar panels need to point to the sun to
produce sufficient power
• Pointing accuracy necessary to complete the science
objectives
43

• 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
44

Propulsion Subsystem
• Distance to destination
• Fuel
– Influence on weight and size
• High performance  less weight
• Spacecraft lifetime of 8 years
45

Proposed Payload
Block Diagram
46
Infrared
Spectrometer
Laser Altimeter
Command & Data Handling Subsystem
Commands Commands DataData

Proposed Electrical Power Subsystem
Block Diagram
47
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)

Proposed Communication Subsystem
Block Diagram
48
Command & Data
Handling
Subsystem
X-Band
Transpond
er
Deployable
High Gain
Antenna
Commands
Telemetry Inputs Mission Data
Commands
from Earth

Proposed ADCS Block
Diagram
49
On-Board Computer
ADCS Function
Sun
Sensors
Star
Trackers
Attitude
Determination
Attitude
Control
Reaction
Wheels
IMU
Thrusters
4/9/2016

Proposed Propulsion Subsystem
Block Diagram
50
Ionic
Liquid
Propellant
Flow Control
Valve
Electrospray Thrusters
Command &
Data Handling
Subsystem

Diagram of Proposed
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

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
52

Applying the Systems Engineering Process to a Conceptual Merucry CubeSat Mission

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