Devils Logic PDR presentation

83
1 INTERPLANETARY CUBESAT DESIGN IRA FULTON SCHOOL OF ENGINEERING © Devils Cube

Transcript of Devils Logic PDR presentation

1INTERPLANETARY CUBESAT DESIGN

IRA FULTON SCHOOL OF ENGINEERING© Devils Cube

2INTERPLANETARY CUBESAT DESIGN

IRA FULTON SCHOOL OF ENGINEERING© Devils Cube

Science

Question

Science

Objective

Physical

ParametersObservables

Surface

composition of

Phobos

Determine

Mineral /

Chemical

composition

Spectral

Reflectance

in IR range

Spectral Reflecatnce sampling

at 10 nm bandwidths from

1000nm to 2400nm

Historical

nature of

Phobos' surface

structure and

morphology

Imaging of

striation / crater

intersection

points

Structure

and

morphology

High resolution images of

striation intersection points

Location of L1

Stability

Observe the

stability of the L1

Lagrange Point.

Position &

Velocity of

CubeSat

Spacecraft position

Doppler velocity

Spacecraft Attitude

3

Science Objectives

INTERPLANETARY CUBESAT DESIGN

IRA FULTON SCHOOL OF ENGINEERING© Devils Cube

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Science Mission Overview

• Achieve orbit around Mars beyond Phobos

• Perform multiple fly-bys of Phobos

• Begin use of primary instrumentso Infrared Spectrometer

oHigh resolution visible light camera

oCollect Star Tracker and IMU data

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Improvements Upon Existing Science Data

• Spectroscopy

• Surface reflectance spectra will improve data previously collected byo Mars Pathfindero Mariner 9 o Viking Lander

• This information will be used too More accurately classify the moons’ compositiono Improve understanding of the origin of Phobos

• High-Resolution Visible-light Imaging

• Visible light surface images collected by LOGIC will improve upon data collected byo Mars Express HRSC Imager 50 kilometer altitude 5 meters/pixel resolution

INTERPLANETARY CUBESAT DESIGN

IRA FULTON SCHOOL OF ENGINEERING© Devils Cube

Instrument Challenges

Spectrometer

• Decreasing movement between spacecraft and camera

during image capture to avoid motion blur

• Filtering out data which exceeds transmission data

budget

Visible-light Camera

• Ensuring that the surface is within the field of vision

for a variety of orbital altitudes

• Lens must remain undamaged and free of debris

ADCS

• Must reject erroneous data

• High-accuracy clock for precise signal-delay

measurements

6

Principle Mission Challenges

INTERPLANETARY CUBESAT DESIGN

IRA FULTON SCHOOL OF ENGINEERING© Devils Cube

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Science Traceability Matrix

Science

Question

Science

Objective

Physical

ParametersObservables Instruments

Required

Instrument

Performance

Projected

Instrument

Performance

Mission

Requirements

Surface

composition

of Phobos/

Stickney

crater

Determine

Mineral /

Chemical

composition

Surface

reflectivity

in IR range

Spectral

reflectance

sampling at

6 nm

bandwidths

from

1000nm to

2400nm

Spectrometer

·<300 m/pixel

·Numerous

narrow spectral

bands

·Low integration

time

·<100 m/pixel

·>100 spectral

bands (<7nm)

·<4.096 s

integration time

·<38 km Altitude

above Phobos

·Attain orbit

around Mars

above Phobos

Historical

nature of

Phobos'

surface

structure

and

morphology

Imaging of

striation /

crater

intersection

points

Structure

and

morphology

High

resolution

images of

striation

intersection

points

High-

Resolution

Visible Light

Camera

·<5 m/pixel res.

·Large FOV

·65-500

mm/pixel res.

·14.25° FOV

·<14 km Altitude

above Phobos

·Attain orbit

around Mars

above Phobos

Gravity field

near Phobos

Measure

gravitational

field

strength

Mass

distribution

/volume of

Phobos

·Spacecraft

position

·Doppler

velocity

·Spacecraft

Attitude

·Radio

·Deep Space

Network

·ADCS

·<1m/pixel

(0.01°) accuracy

·>1°/s

·ADCS

Accuracy>1E4

·<1m/pixel

(0.01°) accuracy

·>3.5°/s

·ADCS

Accuracy>1E8

Frequent comm-

checks between

LOGIC and

Earth

INTERPLANETARY CUBESAT DESIGN

IRA FULTON SCHOOL OF ENGINEERING© Devils Cube

8INTERPLANETARY CUBESAT DESIGN

IRA FULTON SCHOOL OF ENGINEERING© Devils Cube

Science Objective Instrument Minimum requirement

Determine Mineral /

Chemical

composition

Spectrometer

Spectral range 1000 nm to 2400nm

10 nm Spectral band

100 channels

100m x 100m spatial resolution

Imaging of striation /

crater intersection

points

Visual

Spectrum

Camera

Minimum Resolution of 1.8 m / pixel

1/3rd imaging of surface

9

Requirements & Challenges

Challenges:

• Volume Constraint: under 10%

• Low Albedo: 7.1% (2.31 Lux)

• Low data relay rates: 7.8 kbps

• Spectral range selection :(VIS-NIR-SWIR)

INTERPLANETARY CUBESAT DESIGN

IRA FULTON SCHOOL OF ENGINEERING© Devils Cube

Spectrometer

10

Spectrometer

Parameter

Edmond Optics

1000 2000nm

InGaAs NIR

NIR Quest 256-

2.5Argus 1000

Mass [g] 650 1180 230

Volume [cc] 1020.6 940.7 180

Power [W] 12 15 6.2

Range [nm] 1000 - 2000 900 - 2500 1000 - 2400

Spectral Resolution

[nm]8 9.5 12

No of bands 128 128 100

No of pixels 256 Pixel Array 256 Pixel Array 256 Pixel Array

Integration Time 20 µs to 10 s 1-400 ms 0.5µs to 4.1s

INTERPLANETARY CUBESAT DESIGN

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0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

EDMOND OPTICS NIR QUEST ARGUS 1000

Edmond Optics NIR Quest Argus 1000

Power consumption[Whr] 3 3.75 1.55

Data per exposure[kb] 4.096 4.096 3.328

Spectrometer Power Consumption & Data Generation

Power consumption[Whr] Data per exposure[kb]

Spectrometer

INTERPLANETARY CUBESAT DESIGN

IRA FULTON SCHOOL OF ENGINEERING© Devils Cube

Visual Spectrum Camera

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Cameras

ParametersCIRES - E2V Malin ECAM-C50

Teledyne Dalsa

Genie

Mass [g]Sensor system 70 256 196

Lens system 240 100 460

Volume [cc]Sensor system 50.92 199.1 129.7

Lens system 103.5 269.7 367.2

Power [W] 1.5 2.5 4.5

Pixel Density [MP] 1.3 5 12

Fly-bySR [m/pixel] 1.8 1.8 1.8

Max WD [m] 6912.00 14310.00 22118.40

Nom CaseSR [m/pixel] 2083.33 1006.29 651.04

WD [m] 8000.00 8000.00 8000.00

Best CaseSR [m/pixel] 1302.08 628.93 406.90

WD [m] 5000.00 5000.00 5000.00

WD: Working distance SR: Spatial resolution

INTERPLANETARY CUBESAT DESIGN

IRA FULTON SCHOOL OF ENGINEERING© Devils Cube

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0

5

10

15

20

25

30

35

40

CIRES - E2V MALIN ECAM-C50 TELEDYNE DALSA GENIE

CIRES - E2V Malin ECAM-C50 Teledyne Dalsa Genie

Power Consumption[Whr] 0.375 0.625 2.375

size of single image[MB] 3.75 14.74 36

Camera Power Generation and Data Generation

Power Consumption[Whr] size of single image[MB]

Visual Spectrum Camera

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Recommendations

Camera

description

Weight

age

Spectrometer Visual Spectrum Camera

Edmond

OpticsNIR Quest

Argus

1000

CIRES -

E2V

Malin

ECAM-C50

Teledyne

Dalsa

Genie

Mass 15% 3 1 5 5 4 3

Volume 15% 1 2 5 5 3 4

Power &

Operating

temperature

10% 2 1 3 5 4 3

Spectral

resolution15% 4 3 1 2 4 5

Performance 45% 4 4.56 4.33 4.22 3.67 1.78

Space heritage Aerospace Aerospace Yes Leo Yes No

Total 100% 64% 61% 78% 84% 74% 58%

The performance is a function of spectral range , integration time , SNR & QE and image size for spectral and lens

mass & vol , shutter speed , SNR& QE and image size for the camera

INTERPLANETARY CUBESAT DESIGN

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ArchitectureSpectrometer

Visual Spectrum camera

INTERPLANETARY CUBESAT DESIGN

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Modifications

1. Improvement of spectral resolution: Larger pixel array

2. Improvement of spectral range : different diffraction grating

3. Reduction of the volume : use commercially available lens

INTERPLANETARY CUBESAT DESIGN

IRA FULTON SCHOOL OF ENGINEERING© Devils Cube

17INTERPLANETARY CUBESAT DESIGN

IRA FULTON SCHOOL OF ENGINEERING© Devils Cube

Single CubeSat Limitations

• Volume constraint : Volume availability for science payload is limited (less than 1U)

• Power constraint : Unable to operate science payloads and communication system simultaneously

• Low data transmission

o Small antenna and low power

o Nominal transmission rate (7.8kbps)

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IRA FULTON SCHOOL OF ENGINEERING© Devils Cube

Benefits of CubeSat Network

• Volume o Better quality science instrument

o Multiple Spectrometers to cover the required spectrum

• Power o Reduction in power requirement

o Simultaneous subsystem operation capability

• Data transmission rate

o Extra power for transmitter

o Larger antennas

19

www.nasa.gov

INTERPLANETARY CUBESAT DESIGN

IRA FULTON SCHOOL OF ENGINEERING© Devils Cube

Maximization of Science Data

• Spectrometer o Cover complete spectrum: UV,VIS, IR & Xray

o Investigation for more mineral compositions

o Improved mineral classification capability

• Visual camerao More information and improved interpretation capability

o Stereo vision-lead to 3D map

o Enhancement of features

• Stability Data o Inter-CubeSat communication, S band ranging

o Improved accuracy

o Analogues to GRAIL and GRACE

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IRA FULTON SCHOOL OF ENGINEERING© Devils Cube

CubeSat Network Vs Hayabusa I

Instrument Hayabusa I CubeSat Network

SpectrometerNIR: range (700-2100 nm)

XRF:0.7 - IO KeV

Spectrometer network

can obtain more spectral

data (362-3920nm)

Visual Spectral

Camera

Multiband Came

Resolution -70cm at 7kmResolution -62cm at 5km

LIDARRange: 50m-50km

1-m resolution-

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IRA FULTON SCHOOL OF ENGINEERING© Devils Cube

Cubesat Network Architecture

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IRA FULTON SCHOOL OF ENGINEERING© Devils Cube

Cubesat ModificationsCubesat I & Cubesat II

• Visual spectrum camera on both CubeSats

• UV-VIS spectrometer on CubeSat I

• IR spectrometer on CubeSat II

• S-band antenna and transponder for inter-CubeSat communication and data transmission to relay CubeSats

Cubesat III & communication relay sat

• X-ray spectrometer on CubeSat III

• No science payload on communication relay sat

• S-band antenna and transponder for inter CubeSat communication

• X band antenna and transponder for communication with Earth

23INTERPLANETARY CUBESAT DESIGN

IRA FULTON SCHOOL OF ENGINEERING© Devils Cube

24INTERPLANETARY CUBESAT DESIGN

IRA FULTON SCHOOL OF ENGINEERING© Devils Cube

1. Collect a representative sample of spectral data from Phobos’ with 100 bands and 300m resolution

2. Image 1/3rd of Phobos’ surface at a minimum resolution of 1.8 m/ pixel

3. Observe the stability of the L1 Lagrange Point

Mission Objectives

25INTERPLANETARY CUBESAT DESIGN

IRA FULTON SCHOOL OF ENGINEERING© Devils Cube

• 6U CubeSat

• Spectral and Visible Sensor Array

• Deployable Solar Panels

oHawk MMG Gimballed Deployable

• Deployable X-Band Antenna

o ISARA JPL

• Dual Propulsion Systems

oAerojet Green Monopropellant

oBusek Electrospray

System Architecture

26

www.planetarysystemscorp.com/

http://www.mmadesignllc.com/

INTERPLANETARY CUBESAT DESIGN

IRA FULTON SCHOOL OF ENGINEERING© Devils Cube

System Design

27INTERPLANETARY CUBESAT DESIGN

IRA FULTON SCHOOL OF ENGINEERING© Devils Cube

• Deploy from Launch Vehicle

o Systems check, telemetry check and initial burn

• Cruise Phase (208 Days)

o Idle payload and propulsion with limited communication

• Mars Capture (270 days)

o 22 min impulsive burn over 90 min to reduce 870 m/s

o Aero-braking for 135 days to steadily circularize orbit

o EP thrust for 135 days to reach Home orbit ~200km from Phobos

Concept of Operations

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Mission Operations (547 days)

◦ Weekly schedule allotting 4 hour window of DSN

communication per week

◦ Depart Home orbit and approach Phobos to get data

◦ Collect 5 visible and 5 spectral images within 15 km

◦ Return to Home orbit and transmit data

◦ Transmit 5 spectral and 5 thumbnails of visible

images

◦ Select best 2 thumbnails and transmit cropped

lossless visible image data

Concept of Operations

INTERPLANETARY CUBESAT DESIGN

IRA FULTON SCHOOL OF ENGINEERING© Devils Cube

Budgets / Feasibility

Mass, Volume and Power Budget

SubsystemMass [kg]

(Max 14)

Volume [cc]

(Max 7000)

Power [W]

(Max Capture 44)

Chassis 1.000 7000

Power 2.110 700 0.7

Communication 2.440 508 12.9

ADCS 0.850 500 3.0

Propulsion 3.897 3080 15.0

Payload 0.586 591 2.65

Thermal 0.061 60 0.5

Total / Margin 10.944 / 21.8% 5439 / 32.0% 34.75 / 22.8%

30INTERPLANETARY CUBESAT DESIGN

IRA FULTON SCHOOL OF ENGINEERING© Devils Cube

Programmatic Risks

Key Challenges

• Test failures

• Quality rejections

• On time delivery

• Cost variations

• Supplier availability

• Mission obsolescence

Risks and Challenges

31INTERPLANETARY CUBESAT DESIGN

IRA FULTON SCHOOL OF ENGINEERING© Devils Cube

• Unable to capture into Mars orbit

oDe-scope tertiary objective and accomplish both primary and secondary objectives with a fly-by

• Unable to achieve mass/volume budget

o De-scope secondary objective and accomplish both primary and tertiary

o Remove Malin eCam-C50 from Payload

o Reduction in mass of 0.356 kg – Improves Margin by 4%

o Reduction in volume of 411 cc – Improves Margin by 5%

De-scope Considerations

32INTERPLANETARY CUBESAT DESIGN

IRA FULTON SCHOOL OF ENGINEERING© Devils Cube

33INTERPLANETARY CUBESAT DESIGN

IRA FULTON SCHOOL OF ENGINEERING© Devils Cube

Top Level Requirements

• Compliance with NASA 6U CubeSat standards

• Spectral data in range of 1000 nm to 2400 nm at 100m x 100 m spatial resolution

• Capture 33.3% of Phobos surface at 1.8 m pixel resolution

• Comply with the NASA General Environmental Verification Standard

34INTERPLANETARY CUBESAT DESIGN

IRA FULTON SCHOOL OF ENGINEERING© Devils Cube

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Instrument Down Selection Approach

INTERPLANETARY CUBESAT DESIGN

IRA FULTON SCHOOL OF ENGINEERING© Devils Cube

• Science Data Collection

• Data transfer rate

• DSN availability

• Unexpected Communication black outs

• Transit Time (7 months ) and time to achieve phobos orbit

(9 months)

36

Parameters Affecting Mission Duration

INTERPLANETARY CUBESAT DESIGN

IRA FULTON SCHOOL OF ENGINEERING© Devils Cube

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Instrument Down Selection Approach

Communications

ScienceTime Best Case Nominal Case

Best

(Co-orbit @ 5 km)Data transfer 12 months 32 months

Mission time 28 months 48 months

Nominal

(Co-orbit @ 8 km)Data transfer 5 months 12 months

Mission time 21 months 28 months

Worst

(Fly By @ 14 km)Data transfer 1.5 months 3.6 months

Mission time 17.5 months 19.6 months

Mission time varies between 17.5 to 28 months based on above conditions

INTERPLANETARY CUBESAT DESIGN

IRA FULTON SCHOOL OF ENGINEERING© Devils Cube

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Risk Assessment

Vibrations EMI interferences Radiation Temperature Variations Space Debris Impact

Hardware failures such as bit error ,chip error

Software Malfunctions Outgassing of material Degradation of Material

Strength

Effect on the cube sat reliability

Inaccurate of science data

Reduction in Mission Life

Complete Mission Failure

Use of off the shelf components which have good space heritage

Redundant subsystems

Allocating task to alternative subsystem

Ground testing of software and hardware

INTERPLANETARY CUBESAT DESIGN

IRA FULTON SCHOOL OF ENGINEERING© Devils Cube

39

Risk Assessment - Design

Complete Mission

Failure

Crtical Reduction of

Misision Life leading

to reduction in the

performance of the

components

Reduction in

Accuracy of

science data

Effects the

performance of the

other subsystems

leading to mission

failure in the long

run

Frequent

(Highest Probability of

occurrence )

Radiation effecting

onboard Comps

Unexpected short

duration

communication losses

ModerateADCS pointing

inaccuracy due to

External EMI

Solar Panel Failure due

to external impact or

bending loads

Faulty orientation

of antenna

Antenna

Deployment/Solar

panel deployment

Failure due to gimbal

failure

Occasional Propulsion System

Ignition Failure

1.External EMI

interfernce with EPS

and Controllers

2. Active Thermal

system Malfunction

Components

Outgassing

leading camera

lens fogging

Reduction in bolted

joint pretension due

to Creep

Remote

Structural failures due

to Vibration 2. Impact

by Space Debris

Camera Startup

failure

Uneven thermal

Expansion of

structure

Severity of

Risk

Risk

Occurrence

Probability

INTERPLANETARY CUBESAT DESIGN

IRA FULTON SCHOOL OF ENGINEERING© Devils Cube

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System Configuration Comparison

Subsystem Configuration-1 Configuration-2 Configuration-3

Battery

Capacity>120 W h 120 W h 120 W h

Antenna X– Band X-Band X-Band & UHF

PayloadCamera & Point

SpectrometerOnly Spectrometer

Point Spectrometer &

Camera

Pros and Cons

• Longer

Communications

• Lots of Science

Data

• Basic Model

• No High

Resolution

Cameras

• Better

Communications

during orbit

insertion

• Lots of science

data

• More mass and

less data

INTERPLANETARY CUBESAT DESIGN

IRA FULTON SCHOOL OF ENGINEERING© Devils Cube

41INTERPLANETARY CUBESAT DESIGN

IRA FULTON SCHOOL OF ENGINEERING© Devils Cube

System Requirements

Computer

● Plug and play architecture

● Space heritage

● Low active mode power consumption

● USART, SPI, I2C interfacing support

● Health check and autonomous fault repair

● Signature check algorithm

● Use of CCDS standards

Telecom

● X-band communication

● DSN compatibility (<-190 dB)

● EIRP > 22 dB

● Turnaround ratio (880/749)

42INTERPLANETARY CUBESAT DESIGN

IRA FULTON SCHOOL OF ENGINEERING© Devils Cube

Components

Iris X-band Transponder

http://www.clyde-

space.com/cubesat_shop/obdh/

pumpkin_cubesat_obc/pumpkin_motherboard

MSP 430

Pumpkin Motherboard

https://store.ti.com/cc3100boost-

cc31xxemuboost-exp430f5529lp.aspx

https://store.ti.com/cc3100boost-

cc31xxemuboost-exp430f5529lp.aspx

High Gain Reflectarray

http://mstl.atl.calpoly.edu/~bklofas/Pres

entations/DevelopersWorkshop2015/Kle

sh_MarCO.pdf

43INTERPLANETARY CUBESAT DESIGN

IRA FULTON SCHOOL OF ENGINEERING© Devils Cube

Computer System Architecture

MSP430

SD Card

4 GB

Voltage

Regulator

RAM

512 B

ADC

10-bit

Clock

16 MHz

Flash

16 KB

Watchdog

15-bit

5 V

I2C

To EPS

USCI

(SPI and

USART)

To

Transponder/

ADCS/

Propulsion

To other

subsystems

44INTERPLANETARY CUBESAT DESIGN

IRA FULTON SCHOOL OF ENGINEERING© Devils Cube

Functional Flow and Pseudo Code

1. Establish

Communication Link

3. Control trajectory

2. Get T&T and

science data

1. Main system

check

3. Power system

check

2. Housekeeping

system check

4. Communication

link check

6. Science data

capture

5. Trajectory

check

Pseudo CodeFFBD

45INTERPLANETARY CUBESAT DESIGN

IRA FULTON SCHOOL OF ENGINEERING© Devils Cube

Antenna Analysis

Efficiency Gain (dB)Number of

deployableGain (dB)

55% 30.35 1 31.69

75% 31.69 2 34.7

46INTERPLANETARY CUBESAT DESIGN

IRA FULTON SCHOOL OF ENGINEERING© Devils Cube

Link and Data Budget

Table 1 : Storage requirements (in MB)

Table 2 : Achievable data rates (in bps)

Figure 1: Data accumulation plot for best-best case

Comms

Science

Best Worst

Best 766.48 3802.9

Nominal 309.54 1503.5

Worst 103.18 471.68

Spectrometer 0.332

Range

Gain

Closest Nominal Farthest

Best 19679.43 9782.92 3885.43

Nominal 12302.78 7815.12 2700.46

Worst 6860.08 4942.85 901.76

47INTERPLANETARY CUBESAT DESIGN

IRA FULTON SCHOOL OF ENGINEERING© Devils Cube

Results

● Hardware and software requirements have been fulfilled

● Communication link can be established

● 200 MB of data margin

Results and Recommendations

Recommendations

● Use of Ka band

● Use DSN for longer time

● Get better EIRP

● Use of LDPC code

48INTERPLANETARY CUBESAT DESIGN

IRA FULTON SCHOOL OF ENGINEERING© Devils Cube

Propulsion & Mission Trajectory

49INTERPLANETARY CUBESAT DESIGN

IRA FULTON SCHOOL OF ENGINEERING© Devils Cube

Planetary Capture

50

∆𝑉 = 𝑉∞2 + 2

𝜇

𝑅𝑚 + 𝑎𝑙𝑡− 2

𝜇

𝑅𝑚 + 𝑎𝑙𝑡−𝜇

𝑎

𝑎 =𝑅𝑚 + 𝑎𝑙𝑡 + 𝑅𝑆𝑂𝐼

2

Lowest Energy Capture

Periapsis : 120 km altitude

Apoapsis : 576,000 km

Eccentricity ~ 1

Capture ∆V

Time of flight : 207 days

V∞ = 2/438 km/s

∆Vcap = 569.2 m/s

Aerobraking ∆V = 4.3 m/s

INTERPLANETARY CUBESAT DESIGN

IRA FULTON SCHOOL OF ENGINEERING© Devils Cube

Capture Propulsion System Trade Study

Planetary Capture

51

Propulsion System Specific

Impulse

Propellant

Mass

Fraction

Propellant

Mass

Propellant

Volume

HYDROS

Bipropellant

300 s 0.176 1.794 kg 1794 cm3

Busek Green

Monopropellant

220 s 0.232 2.365 kg 1577 cm3

Aerojet Green

Monopropellant

250s 0.212 2.112 kg 1405 cm3

INTERPLANETARY CUBESAT DESIGN

IRA FULTON SCHOOL OF ENGINEERING© Devils Cube

Capture Propulsion System Trade Study

Planetary Capture

52

Propulsion System Propellant

Mass

Propellant

Volume

Thrust System

MassSystem

Volume

HYDROS

Bipropellant

1.794 kg 1794

cm3

0.8 N 1.2 kg 1000 cm3

Busek Green

Monopropellant

2.365 kg 1577

cm3

0.5 N 1.5 kg 500 cm3

Aerojet Green

Monopropellant

2.112 kg 1405

cm3

4 N 1.3 kg 1100 cm3

INTERPLANETARY CUBESAT DESIGN

IRA FULTON SCHOOL OF ENGINEERING© Devils Cube

Planetary Capture

53

Thrusting Schedule◦ ∆Vcap = 569.2 𝑚 𝑠

◦ 𝑚 = 0.0016 𝑘𝑔𝑠

◦ Thrust = 4 N◦ Optimal Maneuver at 120km

Required Thrusting Time◦ 22 Minutes*

◦ Finite Burns Increase ∆V◦ 1.5 Hours < 9000 km◦ ∆Vmax = 870 𝑚 𝑠 +40%

◦ 4 Hours < 23000 km◦ ∆Vmax = 1190 𝑚 𝑠 +80%

◦ Thermal Dependence

INTERPLANETARY CUBESAT DESIGN

IRA FULTON SCHOOL OF ENGINEERING© Devils Cube

Initial Conditions

• Periapsis : 120km Altitude

• Apoapsis : 576,000 km

Procedure

◦ Raise Periapsis to ≈ 150km

◦ LOGIC passes through mars atmosphere

If Periapsis < 120 km

Raise Periapsis to ≈ 150km

Elseif Apoapsis < Phobos

Raise Periapsis to ≈ 300km

End Aerobraking

Aerobraking

54

Aerobraking

∆V: 350 m/s

Approx Time : 4.5 Months

INTERPLANETARY CUBESAT DESIGN

IRA FULTON SCHOOL OF ENGINEERING© Devils Cube

Initial Conditions: • Periapsis : 300 km Altitude• Apoapsis : 9300 km

Final Conditions:• Periapsis : 9234 km• Apoapsis : 9517 km

Phobos Co-Orbit

55

Impulsive ∆V: 285 𝑚 𝑠Low Thrust ≈ 385 𝑚 𝑠

Low Thrust Transfer Time:≈ 4.5 months

Propulsion

System

Specific

Impulse

Propellant

Mass

Fraction

Propellant

Mass

Propellant

Volume

System

Volume

Busek

Electrospray

2300 s 0.0177 0.175 kg 175 cm3 300 cm3

Busek Pulsed

Plasma

536 s 0.071 0.703kg 231 cm3 330 cm3

Aerojet Green

Monopropellant

250 s 0.109 1.08 kg 720 cm3 N/A

INTERPLANETARY CUBESAT DESIGN

IRA FULTON SCHOOL OF ENGINEERING© Devils Cube

Mission Trajectory

56INTERPLANETARY CUBESAT DESIGN

IRA FULTON SCHOOL OF ENGINEERING© Devils Cube

57INTERPLANETARY CUBESAT DESIGN

IRA FULTON SCHOOL OF ENGINEERING© Devils Cube

• Orbit around Mars while staying close to Phobos for long time

• Requirements

o Not crash into Phobos

o Stay in close range

• Optimal Condition

o Stay as close as possible for long time to make maneuvers to perform science mission

Home Orbit

58

Orbital Parameter

Semi-major axis 9378 km

Eccentricity 0.0073

Inclination 1.22 degree

Min. Distance 35.1 km

Max. Distance 233.1 km

Results from Analysis with STK

• Inclination is relative to Mars’s Equatorial Plane

• Inclination of Phobos is 1.075 deg

INTERPLANETARY CUBESAT DESIGN

IRA FULTON SCHOOL OF ENGINEERING© Devils Cube

59

Distance to Phobos surface in a day

Orbit path in Phobos’ fixed frame

In a day

Orbit path in phobos’ fixed frame

In a month without maneuvers

INTERPLANETARY CUBESAT DESIGN

IRA FULTON SCHOOL OF ENGINEERING© Devils Cube

ADCS Trade Study

60

Product Pointing

Accuracy

Slew

Rate*

Volume Mass Power

XACT ± 0.007 deg 4.3 deg/s 10 x 10 x 5 cm 0.85 kg 2W (steady)

3W (max)

MAI-400 ± 0.05 deg 2.7 deg/s 10 x 10 x 5.59

cm

0.635 kg 4W (steady)

8.5W (max)

MAI-200 < ± 0.05 deg 2.7 deg/s 10 x 10 x 7.87

cm

0.907 kg 5.5W(steady)

13.7 W (max)

XACT has the best performance in almost all categories.

*Moment of inertia was estimated as 0.2 kg-m2 for 6U Cube Sat to calculate the slew rate

INTERPLANETARY CUBESAT DESIGN

IRA FULTON SCHOOL OF ENGINEERING© Devils Cube

On the Transfer Orbit to Mars

o No Camera Pointing is required

o Antenna Pointing to Earth

(4 hours per week)

o Solar Panel Orientation to Sun

(as much as possible)

o Thrust Vector Control

(as reaching to Mars)

Pointing Schedule

61

Pointing Schedule on the Transfer Orbit to Mars

INTERPLANETARY CUBESAT DESIGN

IRA FULTON SCHOOL OF ENGINEERING© Devils Cube

Co-Orbit with Phobos

• Communication

4 hours every week

• Power Charging

Whenever possible, the maximum

surface of solar panel should be

facing to the Sun.

Pointing Schedule

62

Angle profiles to the important

directions from the direction vector

of CubeSat on the orbit in a day

INTERPLANETARY CUBESAT DESIGN

IRA FULTON SCHOOL OF ENGINEERING© Devils Cube

Considerations

63

Considerations for Orbit

• Maneuver Schedule

oTo cover wide range of the surface

• Delta V consumption

o In order to perform maneuvers to collect

enough science data

Considerations for Pointing

• External torque

o Solar pressure

o Gravitational torque

o Torque from rotating solar panels

• Momentum damping requirement

o Use of thruster for damping

INTERPLANETARY CUBESAT DESIGN

IRA FULTON SCHOOL OF ENGINEERING© Devils Cube

64INTERPLANETARY CUBESAT DESIGN

IRA FULTON SCHOOL OF ENGINEERING© Devils Cube

Keep Alive Power Requirements

65

Power Budget for Keep Alive Configuration

System Subsystem Power Survival (W) Power Active (W)

Comms Antenna (X-Band) 0 0

Transponder 1 1

CPU/OBC 0.01 0.01

Subtotal 1.01 1.01

Power Photovoltaics 0 0

Battery 0.1 0.2

EPS 0.1 0.1

Subtotal 0.2 0.3

Thermal MLI 0 0

Heaters 5 1

Subtotal 5 1

ADCS Sealed Unit 0.85 1.5

Subtotal 0.85 1.5

Propulsion Electrospray 0.5 5

Thruster 0.5 0.5

Subtotal 1 5.5

Payload Camera + Lens 1.75 2.5

Spectrometer 0.9 6.3

Subtotal 2.65 8.8

Total 10.71 18.11

INTERPLANETARY CUBESAT DESIGN

IRA FULTON SCHOOL OF ENGINEERING© Devils Cube

Power Schedule

66

• Communications are ON for 4 hours, once a week (Peak Power)

• Thermal, constant at maximum

• Payload 3x a day, for 30 minutes duration each time

• Propulsion 1x per day, for one hour

• ADCS working at constant operational level

INTERPLANETARY CUBESAT DESIGN

IRA FULTON SCHOOL OF ENGINEERING© Devils Cube

Power Architecture

67

• Peak Power Tracking:

o Longer mission durations

o Solar array can be decoupled

(simper array designs)

• Centralized Architecture:

o Distributes all voltages rails

from one location

o Fewer regulators required

INTERPLANETARY CUBESAT DESIGN

IRA FULTON SCHOOL OF ENGINEERING© Devils Cube

Solar Insolation Model

68

Date May 7 2021 Jun 2 2021 Feb 7 2022

Eclipsetime

(average)38 min 25 min 53 min

Duration of eclipses for orbit next to Phobos

INTERPLANETARY CUBESAT DESIGN

IRA FULTON SCHOOL OF ENGINEERING© Devils Cube

Power System State

69

• Li-ion batteries (120 Whr) – DoD 31.9% :

o 1% discharge per day, 90% EPS efficiency

o Communications are ON for 4 hours, once a week

o Thermal, constant at maximum (5 W)

o Payload 3x a day, for 30 minutes duration each time (2.65 W idle/8.8 W peak)

o Propulsion 1x per day, for one hour (1 W idle/5 W active)

o ADCS working at constant operational level (1.5 W)

INTERPLANETARY CUBESAT DESIGN

IRA FULTON SCHOOL OF ENGINEERING© Devils Cube

Power System State

70INTERPLANETARY CUBESAT DESIGN

IRA FULTON SCHOOL OF ENGINEERING© Devils Cube

Energy Capability of the Batteries

Component Model Voltage (V) Capacity (Ah) Energy (Wh)

BatteryGS NanoPower

BPXUp to 29.6 V 2.6 154

Power Configurations

71

Energy Available to Charge the Batteries

Component Model Efficiency Energy (W)

Deployable Solar

Panels

Hawk Solar Arrays -

MMA30% 22

Electrical Power System

Component Part Number EfficiencyPower Consumption

(W)

EPS Blue Canyon Tech EPS 85% <0.1

o Li-ion batteries

o Autonomous heater system

o Can be configured for nominal voltages ranging up to 29.6 V

o Sun tracked continuous high power

o 140 W/Kg

o Modular and scalable to 100 W peak power and 50 W

OAP

o Charge and distribution fault protection

o Space heritage

INTERPLANETARY CUBESAT DESIGN

IRA FULTON SCHOOL OF ENGINEERING© Devils Cube

72INTERPLANETARY CUBESAT DESIGN

IRA FULTON SCHOOL OF ENGINEERING© Devils Cube

• Ensure System is warm and temperature doesn’t drop below 253K

• Ensure subsystems temperature is within the operating limits

• Transient Thermal Environment

• Radiation is the main mode of heat transfer

Objectives & Challenges

73© Devils Cube INTERPLANETARY CUBESAT DESIGN

IRA FULTON SCHOOL OF ENGINEERING© Devils Cube

Transient Thermal Environment

• Variations in Solar flux, Mars IR, over a number of days considered

• Exact values of AU found using Wolframalpha

• Eclipse period during one orbit found using STK

Spacecraft Thermal Control Handbook Volume 1: Fundamental Technologies David G. Gilmore

74

Perihelion Aphelion Mean

Direct Solar (W/m2) 717 493 589

Mars Albedo 0.29 0.29 0.29

Maximum IR (W/m2) 470 315 390

Minimum IR (W/m2) 30 30 30

AU 1.381 1.666 1.5235

INTERPLANETARY CUBESAT DESIGN

IRA FULTON SCHOOL OF ENGINEERING© Devils Cube

Heat

Load(W/m2)

Q incident

(W/m2) Emittance Absorptivity

Q Absorbed

(W/m2)

Solar Flux 638.9407 0.55 0.35 223.629245

Mars Albedo 191.6822 0.55 0.35 67.08877

Phobos Albedo 44.7259 0.55 0.35 15.654065

Mars IR 425.9474 0.55 0.35 234.27107

Total Maximum 540.64315

75

Heat

Load(W/m2)

Q incident

(W/m2) Emittance Absorptivity

Q Absorbed

(W/m2)

Solar Flux 492.6368 0.55 0.35 172.42288

Mars Albedo 147.4846 0.55 0.35 51.61961

Phobos Albedo 34.4846 0.55 0.35 12.06961

Mars IR 315.5439 0.55 0.35 173.549145

Total Minimum 409.661245

Transient Thermal Environment

INTERPLANETARY CUBESAT DESIGN

IRA FULTON SCHOOL OF ENGINEERING© Devils Cube

• SOLAR LOAD=1367.5/AU2

76

Transient Thermal Environment

INTERPLANETARY CUBESAT DESIGN

IRA FULTON SCHOOL OF ENGINEERING© Devils Cube

• Thermal modelling done using ANSYS steady-state thermal and transient thermal

• Assumptions:

o Approximate geometric shapes

o Ignored effects of mountings

o Ignored effect of solar panels and antennas

o Geometry scaled to 1/4th actual size

o Actual battery dimensions

Thermal Modelling

77INTERPLANETARY CUBESAT DESIGN

IRA FULTON SCHOOL OF ENGINEERING© Devils Cube

Keep Alive Power

• Value found to be 12W

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IRA FULTON SCHOOL OF ENGINEERING© Devils Cube

From Earth to Mars

• 207 days required to travel from LEO to Mars orbit

• Steady state analysis

• Patch heaters (0.5 W) & ADCS switched on

79INTERPLANETARY CUBESAT DESIGN

IRA FULTON SCHOOL OF ENGINEERING© Devils Cube

Critical Subsystem

Battery

• Operating temperature in the range of -15o C to 75o C

• Prolonged exposure to freezing temperatures affect charge transport and cause electrode damage

• Steady state simulations performed

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IRA FULTON SCHOOL OF ENGINEERING© Devils Cube

Thermal Sub-System Requirements

81

Characteristic Description Characteristic Description

External MLI Single Aluminized

Kapton (eight

layers of 1 mill. )

Heaters Kapton

Resistance Patch

Heaters

Emissivity

Absorptivity

0.55

0.35-0.51

Quantity Four

Max. Weight 11.4 g Power 0.5 W each

Internal MLI Single Aluminized

Kapton (One

Layer of 0.5 mill.)

Controlling

Mechanism

Tayco Solid State

Controller

Emissivity

Absorptivity

0.03

0.14

Density 0.0019 g/cm2

Component to be

covered

Propulsion

system(Except

Nozzle)

INTERPLANETARY CUBESAT DESIGN

IRA FULTON SCHOOL OF ENGINEERING© Devils Cube

Mitigation Strategies

• MLI has very good space heritage

• Heaters at risk of failure

• Turn on batteries to maintain temperature in case of heaters failure

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IRA FULTON SCHOOL OF ENGINEERING© Devils Cube

83

A “Devils Cube” CubeSat

INTERPLANETARY CUBESAT DESIGN

IRA FULTON SCHOOL OF ENGINEERING© Devils Cube