RockSat-C 2012CDR

Harding Flying Bison RockSat-C 2012 Team

Critical Design Review

Harding UniversityBonnie Enix, Joshua Griffith, Will Waldron,

Edmond Wilson, David Stair28 November 2011

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RockSat-C 2012CDR

Mission Overview

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Bonnie Enix

RockSat-C 2012CDR

Mission Overview – Mission Statement

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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 2012CDR

Mission Overview – Mission Requirements

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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 2012CDR

Mission Overview – Mission Requirements

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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 2012CDR

Mission Overview – Science Questions

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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 2012CDR

Mission Overview – Benefits and Use of Results

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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 2012CDR

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

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SunAtmospheric GasesSpectrometerComputer withData Storage

I0I

RockSat-C 2012CDR

Mission Overview – Concepts

Once above Earth’s atmosphere, the spectrum of the Sun’s surfacecan be measured without interference.

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SunSpectrometerComputer withData Storage

I0

RockSat-C 2012CDR

Mission Overview – Concepts

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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 2012CDR

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 2012CDR

Mission Overview -- Concepts

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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 2012CDR

Mission Overview – Concepts

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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 2012CDR

Mission Overview – Theory

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Intensity of radiation of frequency,

Intensity of radiation incident on the sample

, after passing through sample

Absorption Cross Section at frequency, , cm2/molecule

NL

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 2012CDR

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 kmt ≈ 4.8 min

Altitude: 52 km

0 minTime

RockSat-C 2012CDR

Mission Overview – Expected Results

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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 2012CDR

Design DescriptionWill Waldron

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RockSat-C 2012CDR

Mechanical Design Elements

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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 2012CDR

Mechanical Design -- Spectrometer

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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 2012CDR

Mechanical Design Elements

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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 2012CDR

Mechanical Design Elements

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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 2012CDR

Mechanical Design Elements

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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 2012CDR

Mechanical Design Elements

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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 2012CDR

Mechanical Design Elements

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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 2012CDR

Electrical Design – Overall Schematic

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We have not completed our detailed schematic at this time.

RockSat-C 2012CDR

Electrical Design – G-Switch Circuit

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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 2012CDR

Software Design

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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 2012CDR

Software Design – Major Inputs and Outputs

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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 2012CDR

Prototyping/AnalysisJoshua Griffith

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RockSat-C 2012CDR

Prototyping Results

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Our prototyping is being carried out by exhaustive SolidWorks modeling of ourpayload.

The spectrometer has been operated and spectra of the sky have been recorded successfully

RockSat-C 2012CDR

Prototyping Results -- Mass

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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 5.97Over/Under Under 0.68

RockSat-C 2012CDR

Prototyping Results -- Power Budget

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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 2012CDR

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 teamwill 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

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RockSat-C 2012CDR

Manufacturing PlanWill Waldron

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RockSat-C 2012CDR

Manufacturing Plan

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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 2012CDR

Electrical Elements

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Items to be manufactured

Cable to connect spectrometer CCD array electronics to power and toMicroprocessor

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 2012CDR

Software Elements

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No computer code has been written at this time

We are working on learning to use the TERN Development System softwareto 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 2012CDR

Testing PlanWill Waldron

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RockSat-C 2012CDR

System Level Testing

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Tests have already been successfully carried out with the spectrometerAnd these tests will continue until we have completed a successful flightsimulation test.

The G-switch circuitry will be tested many times once the electronicsboard is fabricated.

After the software becomes somewhat operational, testing of the Instrument under a variety of sunlight/cloudy conditions will proceed untilthe 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 2012CDR

Software Testing

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Testing of the system to produce the two clock timing pulse trains requiredwill be carried out by feeding the output pins of the two DACs to a two-channeloscilloscope to evaluate the frequencies, voltages and synchronous behaviordesired.

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 theoutputs of these two transducers to an oscilloscope to make sure the signalsto be measured are actually being produced as well as what the voltageand frequency ranges are.

Then the software will be tested to see if this same data can be read in viathe two ADCs to the memory on board the microprocessor and then read outinto a spreadsheet file.

RockSat-C 2012CDR

RisksJosh Griffith

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RockSat-C 2012CDR

Risk Walk-Down

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Consequence

Entire mission fails

Entire mission fails Partial Mission failure Little 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 2012CDR

Risk Walk-Down

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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 2012CDR

User Guide ComplianceBonnie Enix

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RockSat-C 2012CDR

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

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RockSat-C 2012CDR

Sharing Logistics

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• 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 2012CDR

Project Management PlanBonnie Enix

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RockSat-C 2012CDR

Project Management – Organizational Chart

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Bonnie Enix Software &

Testing

Joshua Griffith Software &

Testing

Will Waldron Hardware & Electronics

Edmond Wilson Mentor & Logistics

David Stair Technician & Graphic Artist

RockSat-C 2012CDR

Project Management Plan

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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 SpectrometerMaking and Producing Reports ◊ ◊

RockSat-C 2012CDR

Project Management Plan

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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 2012CDR

Project Management Plan

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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

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Carry Out Vacuum Tests ◊

Carry Out Temperature Tests

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Outside Testing ◊

Mass & Center of Gravity ◊

Making And Producing Reports

◊ ◊ ◊ ◊

RockSat-C 2012CDR

Project Management Plan

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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

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Final Testing of Center of Gravity and Mass

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Making And Producing Reports

◊ ◊ ◊ ◊ ◊

RockSat-C 2012CDR

Project Management Plan

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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

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Vibration Tests and Integration at Wallops Island

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Launch Day! ◊◊◊◊◊

RockSat-C 2012CDR

Project Management – Budget

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Item Amount TotalCanister & 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 2012CDR

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 theHoliday break.

Conclusion

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