RockSat-C 2012 CDR Harding Flying Bison RockSat-C 2012 Team Critical Design Review Harding...
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RockSat-C 2012
CDR
Harding Flying Bison RockSat-C 2012 Team
Critical Design Review
Harding UniversityBonnie Enix, Joshua Griffith, Will Waldron,
Edmond Wilson, David Stair
28 November 2011
1
RockSat-C 2012
CDR
Mission Overview
2
Bonnie Enix
RockSat-C 2012
CDR
Mission Overview – Mission Statement
3
Design, build, test and fly a spectrometer that will measure visible and near-infrared spectra of gases in Earth’s atmosphere at lower altitudes and the Sun’s irradiance at high altitudes
Tabulate and interpret spectra and create a technical report summarizing the results obtained and conclusions reached
RockSat-C 2012
CDR
Mission Overview – Mission Requirements
4
Requirements
1. An optical port is mandatory
2. An adequate, stable and reliable power supply
3. A robust, responsive G-Switch
4. A sensitive, rugged spectrometer operating in the 200 – 1000 nm wavelength range
5. A photodiode sensitive to the same wavelengths as the spectrometer
6. A microprocessor with two programmable clocks, high speed analog to digital converters, and memory to store the acquired spectra
RockSat-C 2012
CDR
Mission Overview – Mission Requirements
5
Requirements - continued
7. Power distribution board to allocate the correct voltages and currents to each device requiring power
8. Signal conditioning board to insure the electrical inputs and outputs between the sensors and the microprocessor match in terms of voltage ranges, currents and impedances
9. Software program to operate the payload
10. Mounting hardware for the payload that will withstand the g-forces imposed during testing and flight and will not interfere with the Frostburg State University payload
RockSat-C 2012
CDR
Mission Overview – Science Questions
6
Science questions to be answered:
1. What atoms and molecules can be identified in the spectra acquired by our spectrometer during the flight?
2. What are the concentrations of these substances?
3. Can the lineshapes of the oxygen and water spectra be used to reveal the altitude, temperature and number density of each gas?
4. Is this spectrometer system accurate, sensitive, useful and robust enough to be deployed on future Solar System missions?
RockSat-C 2012
CDR
Mission Overview – Benefits and Use of Results
7
This project fits into a larger program to build a suite of spectrometersto be deployed on a mobile robotic vehicle on the surface of Mars
The spectrometers will be used to detect, measure, and pinpoint thelocation of biomarker gases on Mars (if they exist) and to gain newinformation about the atmosphere of Mars to evaluate regions ofhabitability for human exploration
Successful completion of this mission will provide a heritage for thespectrometer as we move up the TRL ladder seeking approval for inclusion of this instrument on a future Solar System mission
A comprehensive technical report will be created and an oral summaryprepared for presentation at a technical meeting
RockSat-C 2012
CDR
Mission Overview – Concepts
With the spectrometer located inside the Earth’s atmosphere, the Sun’s light can be used as the optical light source in obtaining transmission spectra of Earth’s atmosphere
8
SunAtmospheric GasesSpectrometerComputer withData Storage
I0I
RockSat-C 2012
CDR
Mission Overview – Concepts
Once above Earth’s atmosphere, the spectrum of the Sun’s surface
can be measured without interference.
9
SunSpectrometerComputer withData Storage
I0
RockSat-C 2012
CDR
Mission Overview – Concepts
10
The spectrometer measures atmospheric spectrum through optical portin rocket airframe using Sunlight as the source. Any gases that absorbradiation in the 200 to 1100 nm range will contribute to the acquired spectra.
RockSat-C 2012
CDR
Mission Overview – Concepts
Percent of atmosphere below rocket as a function of flight time.The flight will be above the atmosphere for about half the flight.
RockSat-C 2012
CDR
Mission Overview -- Concepts
12
We can definitely measurewater and oxygen!
Spectrum of Earth’s atmosphere at sea level over a 10 km path. Water (green) and oxygen (blue) dominate the atmospheric spectrum in the region of 200 to 1080 nm -- the range of our instrument. Spectrum created from HITRAN 2008 Database and HITRAN-PC software.
RockSat-C 2012
CDR
Mission Overview – Concepts
13
Spectrum of Earth’s atmosphere at 297 ft. above sea level measured with flight spectrometer. Water and oxygen peaks are clearly visible. Blue trace made with spectrometer pointed to bright clear sky away from Sun. Red trace made with instrument pointed directly at the Sun
oxygen
water
RockSat-C 2012
CDR
Mission Overview – Theory
14
Intensity of radiation of frequency,
Intensity of radiation incident on the sample
, after passing through sample
Absorption Cross Section at frequency, , cm2/molecule
N
L
Transmittance of light through a sample obeys the Beer-Lambert Law
Sample path length
Number of absorbing molecules per volume
SampleI (ν)
I0(ν)
I (ν)
I0(ν)Spectrometer
RockSat-C 2012
CDR
Mission Overview – Concept of Operations
t ≈ 1.3 min
Altitude: 75 km
t ≈ 15 min
Splash Down
t ≈ 1.7 min
Altitude: 95 km
G switch triggered -- All systems on -- Begin data collection
t ≈ 4.0 min
Altitude: 95 kmApogee
t ≈ 2.8 min
Altitude: ≈115 km
End of Orion Burn
Rocket above atmosphere
t ≈ 4.5 min
Altitude: 75 km
Altitude
t ≈ 5.5 min
Chute DeploysWhen G-switch activates payload, spectra will be measured at a frequency of 2.0 Hz producing 1200 spectra in 10 minutes
Rocket re-enters
atmosphere
t ≈ 0.6 min
Altitude: 52 km
t ≈ 4.8 min
Altitude: 52 km
0 min
Time
RockSat-C 2012
CDR
Mission Overview – Expected Results
16
G-Switch will function properly to turn on electronics
Batteries will be sufficient to power the payload for 20 minutes
Instrument will perform well and at least 100 useable spectra will be recorded, 50 in the atmosphere and 50 above the atmosphere
Concentrations of water vapor and oxygen will be measured as a function of altitude
Ozone will be measured at higher altitudes
Other atmospheric pollutant gases may be detected
RockSat-C 2012
CDR
Design DescriptionWill Waldron
17
RockSat-C 2012
CDR
Mechanical Design Elements
18
SolidWorks rendering of spectrometer payload mounted in tophalf of canister using optical port to right of wire-way as viewed from top or bottom of rocket.
Photodiode on topLight gathering lens on bottom
Spectrometer
G- Switch
Microcomputer
Electronics board
RockSat-C 2012
CDR
Mechanical Design -- Spectrometer
19
Light enters spectrometer through fiber optic cable in the front of the instrument,goes through a slit and strikes the round mirror facing front. From there the light isdirected to the diffraction grating (mounted on hemi-cylinder) which diffracts the light onto the collimating mirror on the left of the instrument and then to a CCDarray detector. A plastic filter in front of the CCD array removes unwanted spectral orders
RockSat-C 2012
CDR
Mechanical Design Elements
20
Cut away portion of payload diagram showing spectrometer mounted on main mounting plate and with cover removed from spectrometer. Fiber optic cable also removed. Spectrometer has no moving parts and is mounted in a sturdy aluminumoptical bench.
RockSat-C 2012
CDR
Mechanical Design Elements
21
Spectrometer payload occupies exactly half the vertical space of the canister.In order to mount all the components, two aluminum mounting plates are required.One-half inch stainless steel standoffs are used to secure the payload to the topof the canister using 8-32 stainless steel socket head cap screws.
RockSat-C 2012
CDR
Mechanical Design Elements
22
View of 1/8 inch thick top mounting plate with components.Electronics board is mounted under the microprocessor board.
TERN Model EL Microprocessor with2 gigabyte compact flash memory
G-Switch
Battery compartmentholding five 9-volt alkaline batteries
RockSat-C 2012
CDR
Mechanical Design Elements
23
Side view of payload showing positioning of spectrometer with attached fiber optic cable. Fiber optic cable is terminated with light collecting lens aimed atrocket viewport. Photodiode is mounted above light collecting lens. Batteries,G-switch, microprocessor and electronics board mounted on secondary plate.
RockSat-C 2012
CDR
Mechanical Design Elements
24
The only change since PDR is the decision to leave off the accelerometers from the payload.
The purpose of the accelerometers was to provide accurate knowledge of the rocket view port direction at each instance
of the rocket flight.
It was realized that obtaining this information would require time and effort beyond our time budget.
The same information can be obtained from the flight dataWFF will record during flight.
Changes since PDR:
RockSat-C 2012
CDR
Electrical Design – Overall Schematic
25
We have not completed our detailed schematic at this time.
RockSat-C 2012
CDR
Electrical Design – G-Switch Circuit
26
We have decided to use the RockOn workshop G-switch circuit. We have studied the schematic for it and are makinginroads into exactly how it works.
RockSat-C 2012
CDR
Software Design
27
The program starts with a power-on reset onmicroprocessor.
The initial real time clock reading is taken andstored to determine the length of time for thedata collection.
Begin iterations by storing the real time clock,photodiode reading and 2048 pixels of theCCD Linear Array.
RockSat-C 2012
CDR
Software Design – Major Inputs and Outputs
28
Timing diagram for spectrometer operation. Top two traces show timing relationsfor the two clocks that clock the data out of the spectrometer. Bottom trace is the2048 pixel data output for one complete spectrum. Two DACs are need for clockingand two ADCs are required to read the spectrometer and photodiode sensors foreach clock cycle.
RockSat-C 2012
CDR
Prototyping/AnalysisJoshua Griffith
29
RockSat-C 2012
CDR
Prototyping Results
30
Our prototyping is being carried out by exhaustive SolidWorks modeling of our
payload.
The spectrometer has been operated and spectra of the sky have been recorded successfully
RockSat-C 2012
CDR
Prototyping Results -- Mass
31
Mass BudgetSubsystem Total Mass (lbf)
Main Al Plate 1.57Secondary Al Plate 0.37Spectrometer 2.37Batteries 0.50Battery holder 0.34Microprocessor 0.15Electronics Board 0.20Fiber Optic Cable 0.13Standoffs 0.34
Total 5.97
Over/Under Under 0.68
RockSat-C 2012
CDR
Prototyping Results -- Power Budget
32
Power BudgetSubsystem Voltage (V) Current (A) Time On (min) Amp-Hours
Microprocessor 9 0.250 15 0.063CCD Array 5 0.010 15 0.003Photodiode 0 0 15 0.00
Total (A*hr): 0.063Over/Under Under 0.937
RockSat-C 2012
CDR
Prototyping Results
Mass, volume and power analysis
The total allowed mass for a canister including its payload is 20.0 lbf.
The canister has a mass of about 6.7 lbf.
If the remaining mass is divided equally between two teams, each team
will have 6.65 lbf.
Our payload has a mass of 5.97 lbf.
We have ample room for mounting our instrument and power supply in the volume allocated (1/2 canister)
Our energy requirements can be amply met with several 9 VDC batteries. Our current consumption is 260 mA. One 9 VDC battery would last 1.25 h at this drain rate
33
RockSat-C 2012
CDR
Manufacturing PlanWill Waldron
34
RockSat-C 2012
CDR
Manufacturing Plan
35
Items to be constructed:
9 in. x 0.25 inch circular aluminum plate
9 in x 0.125 inch circular aluminum plate
G-switch brackett
Battery holder for 5 9-volt batteries
All other items have already been acquired
Manufacturing of the above four items will be done in January/February
RockSat-C 2012
CDR
Electrical Elements
36
Items to be manufactured
Cable to connect spectrometer CCD array electronics to power and to
Microprocessor
Connections between battery stack, G-switch, WFF RBF wires,
Microprocessor and spectrometer
G-switch circuit
All items to needed for electrical circuits are in place
Manufacturing of these items will take place in January/February
RockSat-C 2012
CDR
Software Elements
37
No computer code has been written at this time
We are working on learning to use the TERN Development System software
to carry out analog to digital and digital to analog conversion and data
storage and retrieval.
It is estimated that most of January – April 2012 will be needed to perfect the
software.
RockSat-C 2012
CDR
Testing PlanWill Waldron
38
RockSat-C 2012
CDR
System Level Testing
39
Tests have already been successfully carried out with the spectrometer
And these tests will continue until we have completed a successful flight
simulation test.
The G-switch circuitry will be tested many times once the electronics
board is fabricated.
After the software becomes somewhat operational, testing of the
Instrument under a variety of sunlight/cloudy conditions will proceed until
the instrument can respond satisfactorily to a wide range of sky conditions.
Power supply testing will be carried out to insure the instrument has an
adequate amount of current/voltage capability plus a reserve.
RockSat-C 2012
CDR
Software Testing
40
Testing of the system to produce the two clock timing pulse trains required
will be carried out by feeding the output pins of the two DACs to a two-channel
oscilloscope to evaluate the frequencies, voltages and synchronous behavior
desired.
Testing of the system to acquire the voltages produced by the two sensors,
the photodiode and the CCD array, will be carried out by first feeding the
outputs of these two transducers to an oscilloscope to make sure the signals
to be measured are actually being produced as well as what the voltage
and frequency ranges are.
Then the software will be tested to see if this same data can be read in via
the two ADCs to the memory on board the microprocessor and then read out
into a spreadsheet file.
RockSat-C 2012
CDR
RisksJosh Griffith
41
RockSat-C 2012
CDR
Risk Walk-Down
42
Consequence
Entire mission fails
Entire mission fails Partial Mission failureLittle to no data collected
Once above clouds, measurements will
be successful
G-Switch doesn’t activate electronics
Batteries drain before end of flight
Microcontroller has malfunction
Sunlight too low due to cloud cover
Possibility
RockSat-C 2012
CDR
Risk Walk-Down
43
Risks:• G-switch malfunction• Batteries drain early• Microprocessor not started• Cloud cover to thick• Sun too low on horizon
Mitigation:
• Testing the system with manytrials is the only reasonableway to minimize failure
RockSat-C 2012
CDR
User Guide ComplianceBonnie Enix
44
RockSat-C 2012
CDR
User Guide Compliance
• Mass of payload plus canister is 13.4 lbf
• CG within 1”x1”x1” envelope? – Information not available yet
• Batteries? 5 9-Volt Alkaline, non rechargeable batteries
• One optical port required
• G-switch activation at time of launch is the method chosen
45
RockSat-C 2012
CDR
Sharing Logistics
46
• We are sharing our canister with Frostburg State University • Plan for collaboration
We communicate by e-mail and RockSat-C website
We will send a copy of our CDR to Frostburg and request a copy oftheir CDR
• We plan to joining our payload to Frostburg’s with stainless steel standoffs.
grandpmr.com
RockSat-C 2012
CDR
Project Management PlanBonnie Enix
47
RockSat-C 2012
CDR
Project Management – Organizational Chart
48
Bonnie Enix Software &
Testing
Joshua Griffith Software &
Testing
Will Waldron Hardware & Electronics
Edmond Wilson Mentor & Logistics
David Stair Technician & Graphic Artist
RockSat-C 2012
CDR
Project Management Plan
49
Task – February 2012 Week 1 Week 2 Week 3 Week 4
G-Switch Implementation ◊
Compression Testing of Plates & Standoffs
◊
Power Distribution System ◊
Constructing 2 Aluminum Plates ◊
Interfacing Controller to Spectrometer
Making and Producing Reports ◊ ◊
RockSat-C 2012
CDR
Project Management Plan
50
Task – March 2012 Week 1
Week 2
Week 3
Week 4
Week 5
Construction of Brackets & Fixtures to go on mounting plates
◊
Spring Break
Assembling Payload Mechanical
Spring Break
◊
Interfacing Controller to Spectrometer
Spring Break
◊
Reporting and Making Reports
Spring Break
◊
RockSat-C 2012
CDR
Project Management Plan
51
Task – April 2012 Week 1
Week 2
Week 3
Week 4
Week 5
Testing Fully Integrated System In Laboratory
◊
Using Atmosphere Models To Predict Results
◊
Carry Out Vacuum Tests ◊
Carry Out Temperature Tests
◊
Outside Testing ◊
Mass & Center of Gravity ◊
Making And Producing Reports
◊ ◊ ◊ ◊
RockSat-C 2012
CDR
Project Management Plan
52
Task – May 2012 Week 1
Week 2
Week 3
Week 4
Week 5
Day in the Life Testing #1 ◊
Day in the Life Testing #2 ◊
Outside Testing of Payload ◊
Final Testing of Electrical Shorts
◊
Final Testing of Center of Gravity and Mass
◊
Making And Producing Reports
◊ ◊ ◊ ◊ ◊
RockSat-C 2012
CDR
Project Management Plan
53
Task – June 2012 Week 1
Week 2
Week 3
Week 4
Week 5
Final Inspections, Integration and Testing
◊
Making And Producing Reports
◊ ◊
Travel to Wallops Island ◊
Visual Inspections at Wallops Island
◊
Vibration Tests and Integration at Wallops Island
◊
Launch Day! ◊◊◊◊◊
RockSat-C 2012
CDR
Project Management – Budget
54
Item Amount Total
Canister & Fees 7000 7000
Travel & lodging for launch week 1800/person 7200
Student Fellowship 8 weeks at 40 hr/wk
4000/student 12000
Materials & Components 1500 1500
Total $27,700
RockSat-C 2012
CDR
We believe we have a good workable plan.
Our mentor has two years of experience in this program.
We are looking forward to progressing rapidly starting at the beginning of
the spring semester.
We will be working on software familiarization and construction over the
Holiday break.
Conclusion
55