mission overview - university of colorado boulder · web viewa dedicated 6ah battery will power the...

Colorado Space Grant Consortium

GATEWAY TO SPACE FALL 2010

DESIGN DOCUMENT

Team µ-

Written by: Henry Shennan, Jennifer Nill, Graham Risch, Chelsea Donaldson,

and Jonathan Lumpkin

4 December 2010Revision D

Gateway to Space ASEN/ASTR 2500 Fall 2010

Revision Log

Revision Description DateA/B Conceptual and Preliminary Design Review 10.5.2010C Critical Design Review 11.2.2010D Analysis and Final Report 12.4.2010

Table of Contents

1.0 Mission Overview...............................................................................................................32.0 Requirements Flow Down..................................................................................................33.0 Design.................................................................................................................................44.0 Management.......................................................................................................................85.0 Budget...............................................................................................................................106.0 Test Plan and Results........................................................................................................117.0 Expected Results...............................................................................................................168.0 Launch and Recovery.......................................................................................................169.0 Results and Analysis.........................................................................................................1810.0 Ready for Flight..............................................................................................................2111.0 Conclusions and Lessons Learned..................................................................................2212.0 Message to Next semester..............................................................................................23

of 31 December 4, 2010Rev D


1.0 Mission Overview 1.1 Mission Statement

Team Muon will examine the “dayglow effect” by observing light frequencies at spectral line emission of 557.7nm, which will limit the detection of light strictly to the “dayglow effect.” We will compare the data we obtain with measurements altitude in order to analyze how and if the intensity of the dayglow effect observed correlates with altitude. We expect that the dayglow effect will be the most intense at higher altitudes, because of the higher oxygen concentrations on the ozone layer.1.2 Mission Background

After initial experiments with muon detection using a single photomultiplier tube with a scintillator plate it was determined that, as a result of dark current processes within the apparatus, the signal to noise ratio of a scintillator plate and photomultiplier tube was far too small, to produce reliable data given the constraints posed by an airborne platform. Thus, it was decided to use a photomultiplier tube to look at other low-intensity light sources in the upper atmosphere. While redesigning our experiment with the photomultiplier tube we discovered that the only way to make it work would result in our SAT being about 400 grams overweight. We therefore substituted our photomultiplier tube for a light intensity to frequency IC, which solved our weight problem while still performing the same function.

A delicate balance must be reached in the discrimination filters leading to the sensor; the sensor must not be oversaturated with light, but must be supplied with enough light to allow for accurate detection with a reasonable time of integration. We only need to measure a slim portion of the light spectrum, so we will use a spectral line filter that will discriminate incoming radiation to a 10nm bandpass centered at 557.7nm. This will limit our observations to the dayglow effect produced by oxygen in the mid to upper atmosphere.

Dayglow is produced when molecular oxygen in the atmosphere is excited by fluorescent and resonant processes which emit photons in the form of light. The light produced by this phenomenon interferes with weak signals of visible light sent by distant objects. This is the reason that telescopes on earth are not nearly as sensitive as satellite based telescopes like the Hubble. This spectral line is centered at 557.7 nm, and the air glow phenomenon is caused by energy from the sun striking oxygen particles, which then emit a spectral glow as their valence electrons move. The brightest region of airglow is an approximately 10 mile thick zone at an altitude of about 60 miles source: http://www.albany.edu/faculty/rgk/atm101/airglow.htm

However, the effects can still be measured throughout the lower atmosphere. Airglow occurs due to many elements in the atmosphere, mainly nitrogen, sodium, hydroxyl atoms and oxygen. Being that oxygen is the most prevalent contributor to airglow as well as having the brightest spectral emission, it was logical to measure light intensity from that wavelength.



Air glow as observed from spaceSpecific tests must be conducted in order to calibrate the scientific instruments on

board, including an ambient light test to confirm the isolation of the Light to Frequency Converter from errant signal sources and a known source test to characterize the noise level and sensitivity of the system.



2.0 Requirements Flow DownLevel # Detail From Compliant?Basic RequirementsO 1 The Satellite shall be launched to a height of

30km and be recovered after landing on November 6

MS Yes

O 2 The BalloonSat shall have a maximum mass of 850 grams.

MS Yes mass-830g

O 3 Budget is 300$ MS Yes

O 4 The balloonsat shall take internal and external temperature readings

MS Yes with Hobo

O 5 The ballonsat shall carry a camera that will take pictures every 20 seconds.

MS Yes

O 6 The internal temperature shall not dip below -10 degrees Celsius

MS No-internal temp was below -10

O 7 The satellite shall carry a photomultiplier tube and filters to measure oxygen light emissions

MS No-a light frequency converter was used instead

Level 1System RequirementsS 1 The Balloonsat shall be attached to a weather

balloon and have a hole through which the flight string will pass.

O1 Yes

S 2 The Balloonsat must be insulated and heated sufficiently enough to ensure the functionality of the payload.

O4/O6 Yes-all equipment functioned properly

S 4 The balloonsat shall not leak light so that only a certain wavelength is measured

O7 Yes

S 5 A HOBO data logger shall record internal and external temperature of the balloonsat

O4 Yes

S 6 A mass budget and a monetary budget shall be created.

O2,O3 Yes

S 7 A Canon A570IS Digital camera shall be flown. O5 YesS 8 The BalloonSat shall carry enough power to

operate for a specified period of time during the flight.

O1 Yes

S 9 The balloon sat shall carry all necessary O7 Yes



experimental equipmentLevel 2Subsystem RequirementsSS 1 The BalloonSat shall be constructed of foam core

and aluminum tapeS3 Yes

SS 2 Payload must be secured so damage does not occur during flight/landing

S3 Yes

SS 3 The photomultiplier tube shall be filtered by an optical lens in addition to a neutral density film to prevent oversaturation and misreadings

S9 Yes-with the PMT replaced by light to frequency converter

SS 4 A heating circuit shall be used with three 9V batteries.

S2 Yes

SS 5 The balloonsat shall be insulated with insulation foam

S2 Yes

SS 6 A magnifying circuit shall be used to amplify power for the PMT

S8 No

SS 9 An Arduino shall be flown to collect and store data from PMT

S9 Yes-however, the sensitivity was too high and data was unusable.

3.0 Design3.2.1 Satellite Structure

The craft itself will consist of a cubic solid with dimensions 15cm to a side assembled out of 5mm foam-core board as shown in figure 3.3. A rectangular section along the craft’s bottom surface of dimensions 15cm by 5cm by 5cm will be un-insulated and open to the outside air, whereas the remaining larger section will be insulated with 7mm plastic foam and will contain all of the craft’s electronics. The two sections will be separated by an insulated foam-core divider and bridged by the 8 power and data wires to the photomultiplier tube. The insulated section of the spacecraft will be heated with a resistive heating element consisting of 3 9V batteries and 4 4Ω ceramic resistors in series in order to keep the internal temperature above --10°C. The craft will be assembled following the procedure described in the Gateway to Space lecture of 9 September 2010, whereby a 90° groove is cut into the foam-core and hot glue is used to cement the interior of the joint while aluminum tape reinforces the outer edge.



This method of construction has several advantages in that it is durable, relatively simple, and low-weight when compared to alternatives such as aluminum. Finally, a central bushing will be run through the center of the craft to accommodate a 2.4mm braided Dacron tether line. The line will be fastened to the craft by two figure-8 knots in the line that butt up against non-abrasive bushings at either end of the center tube.3.2.2 Detector Subsystem

The detector subsystem will consist of a light to frequency integrated circuit (Taos TSL235R) assembled in a light-tight housing with a bandpass filter. The IC converts the incident light intensity measured by an integrated photodiode array into a variable pulse count, which can be recorded by an Arduino and later converted back into an intensity value. A dedicated 6Ah battery will power the assembly for the duration of the experiment, and will be regulated by a 5V DC/DC converter prior to the Arduino and a 0.1uF capacitor at the Arduino’s 5V output. A 25.3mm diameter spectral line filter described in the introduction (and characterized below) will be assembled in the light-tight tube that leads to the aperture of the light to frequency converter (figure 3.1). The spectral line filter has a 10nm half-power bandpass centered at 560nm with -3dB points at 554nm and 464nm. Light entering the apparatus will first be filtered and attenuated by the filter, and then detected and amplified by the light to frequency IC, which will send output to be recorded by the Arduino microcontroller onto the 4GB microSD card through its shield sitting atop the Arduino board.

Figure 3.1: Light Detection Assembly



Figure 3.2: 560nm Filter Bandpass

(Image from Newport Optics Corp.)3.2.3 Secondary Data Collection Devices

In order to fulfill its secondary mission objectives, the craft will also include a Canon A570IS digital camera which will take photographs out of a portal in the side of the spacecraft in 15 second intervals. The camera will have its own onboard power source of two AA lithium batteries and its own onboard memory to store captured photographs. The camera will be activated prior to launch by a switch on one of the exterior sides of the spacecraft. The remainder of the secondary mission objectives will be accomplished using a HOBO data logger. The HOBO will be located within the insulated, heated portion of the craft, and will record the internal temperature and humidity of that portion of the craft. The extendable second temperature probe of the HOBO will be routed to the exterior of the craft, and will record the ambient temperature adjacent to the craft. The HOBO will be activated prior to launch, and will remain active until the craft is recovered.



3.3.1 Functional Block DiagramsFigure 3.3: Functional Block Diagram of the Flight Component


Arduino Duemilanove Flash ROM

Light to Frequency IC and Assembly

MicroSD Shield

HOBO data logger(interior/exterior temperature sensors and interior humidity sensor)

Resistive Heater

Canon A570IS camera (includes onboard power, data storage, and timing firmware)

9V batteries

External switch

Data extraction via USB

External switch


3.3.2 Design DrawingsFigures 3.4,5: Flight Component Design

3.5 Discussion of Requirements Met



The light to frequency circuit has passed both life and functional tests to ensure that it will operate as designed for the duration of the mission, satisfying the payload objectives set forth in section 2. The aerial component of our mission has been designed to ascend to the specified altitude of 30-40km and return safely without endangering any of the other payloads. The spacecraft will carry enough batteries to power instruments for the entire 90m duration of the flight.

The total mass of the craft with payload is 830g (with a mass allowance of 10g to account for measurement inaccuracy and final changes and launch preparations, for details please see section 5), which satisfies the 850g limit set by the requirements in the RFP. Our design includes the HOBO, Canon camera, internal heater, and temperature sensors mandated by the requirements, and satisfies the requirement that the craft be constructed of foam-core board. Our budget does include a $25.00 lump sum for spare parts and other unanticipated expenses and still meets the requirement that the total budget be under $300 (for details, please see section 5). The craft is designed to be reusable, and will include identification and an American flag on an exterior surface. Finally, onboard heaters will ensure that the internal temperature of the craft remains above -10C and a central PVC tube with rubber bushings will ensure that the tether is not damaged during the mission.

4.0 ManagementThe team responsible for the completion of this project will be organized in such a

way as to ensure that no one individual is wholly responsible for any given subsystem. This organizational structure makes it much less likely that any subsystem will fail to be completed, and also provides a means by which mistakes can be caught easily and early while reinforcing team structure. Due to his prior experience with light detectors in particular, and electronics in general, Henry will be leading the design, construction, and testing of the mission payload. The construction of the satellite structure (box, wiring, etc.) will be led by Jon with the assistance of the rest of the team throughout the build. Testing was led by Chelsea and Graham and every other team member assisted with separate tests in order that at least 3 people were present for every individual test. Programming will be done by Jen and Henry with a team overview to confirm that it performs to the level necessary for mission success.

The design documents are assigned by section to each person with at least one other person reviewing the writer’s work to ensure cohesiveness and thoroughness. Chelsea is responsible for the presentations with the assistance of the rest of the team. All other vital tasks have been spread between members with a reviewer and/or partner for each task to maintain efficiency while ensuring that all tasks are completed correctly and on-time by preventing any subsystem from relying entirely on the input from any single team member.



Figure 4.1: Team Structure(red arrows and items indicate shared responsibility; testing duties are shared among all team members)


Henry ShennanTeam Leader

Experiment design, construction, and

Testing, Programming

Chelsea DonaldsonTeam Leader

Systems IntegrationExperiment Construction,

TestingTesting

Graham RischBudget Management and

Structures, Testing

Jennifer NillSecondary ObjectivesTesting, Programming

Jonathan LumpkinMicrocontroller Programming,

Structures


Figure 4.2: Project Schedule

28/10/2010 Structural Testing (Whip, Drop Test- again)

29/10/2010 PMT Calibration30/10/2010 HOBO Testing and Data

Collection30/10/2010 Arduino Programming30/10/2010 Cold Test & HOBO Test

(during cold test)31/10/2010 Arduino Maintenance11/01/2010 Light Leak Test11/02/2010 Launch Readiness

Review Presentations11/02/2010 DD revision C due 07:00

11/04/2010 Mission Life Test11/05/2010 Weigh-in and aerial

component turn-in11/06/2010 Data Collection

11/08/2010 Begin data analysis

11/07/2010 Team Meeting 9

11/14/2010 Team Meeting 10

11/30/2010 Final team presentation to the class

12/04/2010 ITLL design expo 09:00-16:00

12/04/2010 DD revision D due

12/21/2010 World Ends

Figure 4.3: Team Member InformationName Contact InformationHenry Shennan 303-564-7575



[email protected] Nill 303-241-7143

[email protected] Lumpkin 970-669-8776

[email protected] Donaldson 970-331-6409

[email protected] Risch 678-463-1374

Graham [email protected]

5.0 Budget The management of the team’s budget will be split between Henry Shennan and

Graham Risch. Shennan will be responsible for the budgets as they concern the main mission. Risch will be responsible for the budgets as they apply to the remainder of the mission, and will have supervisory capacity over Shennan for this and matters concerning the budget. Both Risch and Shennan will meet a minimum of 3 times over the course of the project to make sure that both the weight and the cost of the project fall within the bounds specified in the mission requirements.

As detailed in Figure 5, the cost of our experiment is expected to be, which, allows for a margin of $27.35 for unexpected part failures and other unplanned expenses to remain below the maximum cost of $300.00 specified in the requirements.

Figure 5: Parts Budget

A note on part codes (column 1): P: primary systems, S: secondary systems,



L: Light Detector A: Auxiliary/Structure, T: testingPart Description Manufacturer Supplier Dimensions Weight CostS1 A570IS camera and accessories Canon GTS 45x75x90mm 228g N/AS2 HOBO data logger Onset Inc. GTS 68x48x19mm 30g N/AS3 Switches (3) Unknown GTS 10x20x10mm 15g N/AP1 Arduino Duemilanove Arduino Sparkfun 70x53x6mm 35g $21.65P2 Light to Frequency IC Taos Semi. Sparkfun 10x5x3mm 3g $5.95P3 Arduino MicroSD shield Arduino Sparkfun 70x50x2mm 10g $14.95P4 4GB MicroSD card Kingston Shennan 10x9x1mm 3g DonatedP5 6000mAh lithium battery generic Shennan 30x4x75mm 90g DonatedL2 560nm bandpass filter Newport

OpticsCASA-APS 25mm dia.,

5mm long20g Donated

L3 Photographer’s light paper generic Shennan 1m3 2g N/AL4 Filter and L/F IC mount N/A (PVC

stock)Shennan 25mm dia,

30mm long<5g $0.60†

A1 Foam Board unknown GTS 4mm, 1.3m3 65g N/AA2 Foam Insulation unknown GTS 6mm, 0.8m3 75g N/AA3 Heating circuit, excl. batteries unknown GTS 10x50x50mm 55g N/AA4 10 9V batteries (3 flight, 7

testing)Duracell McGuckin’s 48x25x15 46g ea.

(184g flight)

$30.00†

T CO2 (s) (temperature testing) N/A Safeway’s N/A N/A $5.00†

X Parts not used in final craft (including PMT, electronics, etc)

Various Various N/A N/A $230.10

Totals (including sunk costs from prior experimentation) 830g $272.65

†Cost shouldered by team, not included in monetary budget

6.0 Test Plan and Results6.1 Testing Overview

The first round of testing on the aerial component will consist of tests on all of the individual components to ensure that they function properly. Components will be tested according to their manufacturer’s instructions, and will be tested in conditions consistent with what they will experience during the mission.

The second round of testing will be conducted on the subsystems. The external structure of the craft will be tested for integrity by first conducting drop tests from a height of 20m, and then by being spun on a 1m cord at a minimum of 50rpm. Those tests will only consist of the structure with representative weights replacing onboard instruments.

If any single component or subsystem fails a test we will evaluate the problem, fix the problem, and prove it is fixed by retesting. The final round of testing will be tests on the entire craft complete with electronics. These tests will include, at minimum, a temperature test to simulate temperatures down to -30°C, and a full mission simulation.

6.2 Descriptions of Specific TestsKinetic Testing



In the presence of at least two team members observing the proper safety procedures as outlined in section 3.6, a structural clone of the aerial component (the final structure with metal masses representing different parts of the payload in different locations) will be subjected to three separate tests: a drop from 20m, a roll down a staircase consisting of 15 steps each 10cm in height, and a spin test consisting of 1 minute rotating at 50rpm at the end of a 1m tether.

The drop test shall be conducted with at least 5 random orientations of the aerial component each consisting of at least two trials. No initial velocity is to be imparted onto the craft. Multiple structural clones may be required. This test will be considered a success if and only if the structure maintains its shape and protects a payload representative of the fragility of the most delicate components of the actual payload. The test was conducted off of the South face of the ITLL from the overlooking balcony at a height of approximately 15m. The spacecraft suffered structural damage to one corner, but overall was fairly intact. The results of this test showed us that our structure was very sound and required no improvements.

The roll test is to be conducted at least 3 times. A tether will be attached to the structural clone in order to prevent damage to persons or property in the surrounding areas, but must be sufficiently long and slack as to not have any influence on the motion of the craft. The criteria for success are the same in this test as in the drop test. The test was conducted and proved successful, with minimal structural damage to the craft. Two of the craft’s corners were depressed by 1-3cm, and a 5cm long gash in the outer paper covering of the foamcore was observed on one side. These damages were deemed cosmetic, however, and did not affect the structural integrity of the craft.

The spin test will be conducted by attaching the structural clone to the end of a 1m rope representative of the tether to be used in the launching of the mission. The craft will be attached to the rope in the same manner that the actual craft will be attached to the tether; this test is as much of a test of the attachment mechanisms as it is of the ability of the craft to survive large accelerations. The structural clone will be spun at a minimum of 50rpm for at least two minutes, and will then be inspected for damage. The same criteria for success that applied in the drop test and in the roll test apply here as well. The craft survived the spin test with no apparent damage.Temperature Test

The entire aerial component will be tested at multiple temperatures prior to launch. The first temperature test will specifically concern the section of the craft designed to be insulated from the cold during the mission. The craft will be placed inside a 10 gallon styrofoam cooler on small stilts to prevent heat transfer by conduction and to prevent direct contact with the dry ice. The resistive heater and all other electronic components will be turned on for the duration of the test. The HOBO will be used to monitor the temperature inside the insulated portion of the craft and to monitor the temperature of the exterior of the craft within the cooler. Dry ice will be used to reduce the ambient air temperature inside the cooler to the temperatures required for the test to take place.



Figure 6.1: Temperature Testing Results:

0.003.00

6.009.00

12.0015.00

18.0021.00

24.0027.00

30.0033.00

36.0039.00

42.00

-30

-20

-10

0

10

20

30

Interior and Exterior Temperatures vs. Time Elapsed for the 1st Cold Test Conducted on 1 November 2010

ExternalInternal

Time Elapsed (min)

Tem

pera

ture

(°C)

As shown by figure 6.1, our temperature test was successful in that the internal temperature of the craft was maintained at or above -10°C with external temperatures reaching -20°C. The onboard heaters failed during this test because the batteries got too cold to provide power to the heater before the heater could successfully begin warming the SAT. Therefore on launch day we will start the heater ten minutes prior to launch so that it will have sufficient time to warm up the inside and stay running throughout flight.Light Test

We have to test how much light is transmitted through our bandpass filter. If too much light gets through it will over saturate our light to frequency IC and burn it out. Therefore we will do multiple tests to ensure that the main part of our experiment will not be compromised. First we will test to make sure the green filter is working properly by running the mission payload in two environments; a totally dark environment and an environment with varying light intensity. As figure 6.1 demonstrates, the output of the IC remains constant at a level slightly above the preset base level of 300pps (pulses per second; “equivalent” to an irradiance value of 3 uW/cm2) under no illumination. The count is not zero due to the programming of the IC; the sensor switches to maximum intensity under no illumination (note the initial spikes upon powerup) and “bottoms out” at the 300pps value. The fact that it lays 10-12pps above the 300pps base level may indicate a light leak during testing, or may just indicate noise within the detector system. Prior to launch, the routine which allows for variable sensitivity will be removed from the code in order to produce reliable flight data.



Figure 6.1: Light to Frequency IC under no illumination

1 7 14 20 26 32 39 45 51 57 64 70 76 82 89 95 101 107 114 1202.5

3

3.5

4

4.5

5

Test of the Light Intensity to Frequency IC Under No Illumination

Trial 1 Trial 2 Trial 3

Time Elapsed (s)

Irrad

ianc

e (m

W/c

m2)

The second test shows the response pattern produced when a varying light source is introduced (a lamp moving back and forth near the sensor). Note that the period of the variable illumination is roughly 60s, which is demonstrated clearly in figure 6.2, confirming that the light to frequency IC is functional.



Figure 6.2: Light to Frequency IC under variable illumination

0 200 400 600 800 1000 1200 14000

1

2

3

4

5

6 Test of the Light to Frequency IC with a Variable Light Source

Time Elapsed (s)

Irrad

ianc

e (m

W/c

m2)

These light tests will double as our mission life test as we are under an extreme time constraint and the these tests, when combined with the prior cold test, are sufficient to validate the functionality of all of the subsystems.HOBO Test

To make sure that our HOBO works we will connect it to a computer and “launch” it. After launch we will put the external probe into a scenario in which it will experience hot and cold temperatures, and then we will reconnect the HOBO to the computer and analyze the data to make sure the sensors work and the HOBO is functional. We confirmed that functionality during both the temperature tests on the satellite as a whole, and during the temperature dependence tests on the light-to-frequency module.



6.3 Safety ObservationsWhile constructing and testing this satellite we will observe proper safety

precautions as outlined by Professor Koehler and as described on the ITLL safety sheet. Work with soldering irons will take place in a well-ventilated area and diligence will be exercised to prevent burns and solder overflow and sputtering. During construction of the electronic subsystems ESD precautions will be observed; all members working on the microcontroller, sensors, and magnetometer will be required to wear antistatic bracelets properly connected to a common ground. In addition, wiring of key electronic components will be checked at least twice prior to the application of current in order to both safeguard the electronics and prevent accidents due to component malfunction and/or failure. Finally, both the drop and whip tests will be conducted in broad daylight under favorable weather conditions, and by at least two people: one to conduct the test, and the second to spot him or her. Both team members will be required to wear helmets for the duration of the tests. Finally, any tests involving dry ice will be conducted with the use of gloves and safety glasses to prevent contact burns and injuries due to fragmentation of the dry ice, and will be conducted in a space with proper ventilation.

7.0 Expected Results

At the conclusion of data collection and data extraction, the spectral irradiance recorded from the detector will be compared to oxygen concentration measurements obtained from another group. These data will be plotted against altitude data obtained from the GPS transceiver located on the lift vehicle. By examining how oxygen concentration and spectral line intensity correlate to each other and to altitude, we hope to gain a better understanding of what conditions allow the dayglow phenomena to occur.

We expect our data to show an increase in light intensity at the 557.7 nm band as we increase in altitude. This is because dayglow only occurs at high altitudes and therefore as we get higher we will observe a greater fraction of the dayglow effect occurring. To extract our data from the craft we will remove our SD card from the Arduino and simply upload the data to our computer as a text file. We will have two sets of data; the square wave emitted by the sensor and the number of counts per second recorded from the sensor (our frequency measurement). We can convert the frequency impulse data into irradiance and plot a graph of irradiance vs. time. By then comparing this graph to the altitude vs. time graph we can relate the spectral irradiance to altitude during our flight.

8.0 Launch and Recovery8.1 Expectations for Launch and Craft Recovery

All of our teammates will leave campus at 4:45 am on November 6, 2010 in order to arrive at the Windsor launch site by 6:00AM. Before launch we will inspect out satellite to observe that all the systems are still functioning and begin running our mission 20 minutes prior to launch in order to provide baseline data from the ground to compare to data collected while the craft is airborne. Henry will be responsible for holding and releasing the balloon satellite during the launch itself. Our whole team will then convoy



behind Professor Koehler to the recovery site, where we will first perform a visual inspection of our craft (assuming it can be located). If it is structurally intact, we will deactivate all onboard systems (the heater, Arduino, photomultiplier, and camera), and remove the HOBO and onboard memory (in both the camera and the Arduino) for processing. The data collected will then be ferried from the HOBO and the memory chips to a laptop computer.8.2 Data Extraction

After recovery of the aerial component, data recorded in the flash ROM of the microSD card attached to the Arduino microcontroller will be downloaded from that device as a text file using a USB cable to a laptop computer running Microsoft Excel and analyzed along with data collected from the HOBO using Onset’s HOBOware software and the data collected from the ground component of the mission.8.3 Data Analysis

At the conclusion of data collection and data extraction, the light intensity measurements from the detector will be scaled to a baseline value (the noise level) using the data collected about the characteristics of the instrument during calibration, by taking the difference between the two measurements. This adjusted intensity figure will be plotted against altitude data obtained from the GPS transceiver located on the lift vehicle. When combined with data regarding atmospheric O2 concentrations from other groups, this dataset may be used to examine how gaseous concentrations and altitude affect the incidence and prevalence of the airglow effect.8.4 An Account of Launch and Recovery

During launch day on November 6, 2010 our team left very close to our expected departure time of 4:45 and we arrived at the launch site before 6:00 in Winsor as planned. We then waited for the rest of the class to arrive. Once everyone had arrived we attached our payload to the Dacron line, secured it, and placed it on a tarp to be prepared for launch. At 7:20:00 we turned on our Arduino microcontroller to collect data before launch. At exactly 7:46:33 we began our mission by launching the balloon, which had an initial ascent rate of 405 meters per minute that slowed as the balloon reached higher altitudes. After launch we waited at the launch sight for approximately 20 minutes while we obtained a projected flight path. We then traveled east along highway 392 for approximately 20 miles to our observing area for burst, which happened at approximately 10:11:03 and descended initially at a rate of about 610 meters per minute and gradually slowed to a rate of approximately 290 meters per minute right before touchdown. The touchdown location was 40.40758 degrees latitude -104.4941 degrees longitude. Once we got the go-ahead we went onto the private property where our payload had landed and retrieved our satellite. At approximately 11:28 we arrived at our payload and turned off the switches to the Arduino, heater, and camera (which we observed to still be working at the time). We examined our payload and found no physical damage to either the foam core or the exposed hardware which included the camera lens and the hobo external port. After launch, during data collection we observed that the camera, hobo, and Arduino microcontroller all collected data for the time period that we expected it to and fortunately none of our hardware was damaged. 9.0 Results and Analysis 9.1 Results



After recovering the craft, both the data from the light detector and the HOBO data were offloaded to a laptop and analyzed in Microsoft Excel. We began our analysis by examining the sensor data collected by the HOBO logger.

We found that while our craft was well insulated, it failed to maintain an internal temperature of above -20C, instead dropping to -25C both times the craft passed though the tropopause. Despite the fact that we technically failed this requirement, all of the onboard instruments, including the camera, functioned continually throughout the mission. We addressed this problem after flight by increasing the craft’s insulation and performing a second cold test, as described in section 10. The relative humidity data collected indicates that condensation was never a serious problem during the flight itself; it peaked after landing as condensed and frozen water from the flight was released back into the craft as it warmed back up on the ground.

Figure 9.1: Internal and External Temperature Data from the Flight



6:00:00 6:39:00 7:18:00 7:57:00 8:36:00 9:15:00 9:54:00 10:33:0011:12:0011:51:0012:30:00-80

-60

-40

-20

0

20

40

Internal and External Temperatures During Flight: 6 November 2010

Internal Temperature External Temperature

Time

Tem

pera

ture

(°C)

Figure 9.2: Relative Humidity Data from the Flight


Tropopause on ascent

Tropopause on descent

Maximum Altitude and Burst

Stratosphere

Troposphere, ascent

Troposphere, descent

LandingLaunch

Internal and External Temperature and Flight Data vs Time


We next analyzed the data taken by the light to frequency converter during the flight. As the pulse count was directly proportional to the irradiance measured by the sensor, we simply used the conversion provided by the manufacturer of the chip to convert from pulse count to irradiance (100ppm is equivalent to 1mW/cm2). Our results are shown in figure 9.3. We next compared our irradiance data to the temperature, relative humidity, and altitude datasets.

According to Joseph W. Chamberlain in his book Physics of the Aurora and Airglow, the observed phenomenon is “critically dependent on relative humidity”. The higher the relative humidity, the less easily light propagates through the atmosphere. Consequently, the measured light intensity will be lower when moisture condensation is encountered during data collection. This inverse relationship can be observed early on in the flight; as relative humidity increases, the irradiance decreases proportionately. This trend later fails to apply; especially notable is the change once the balloon satellite has risen above cloud range.

Further supporting this conclusion is a report from the Department of Electrical and Computer Engineering, Ben-Gurion University of the Negev, Beer-Sheva, Israel. A technique for active measurement of atmospheric transmittance using an imaging system claims that “The relative part of water vapor and other particulates affect the electrooptical characteristics of the atmosphere.”

Although in other research humidity affects airglow, we found there to be no evident correlation and no causative link with relative humidity (the sensor was in an airtight capsule, our altitude was much lower, and the data show no significant trends), and found that any correlation to temperature was unlikely. We later confirmed there to


Launch

LandingNote the inverse relationship


be no relationship between temperature and irradiance in post flight testing (see section 9.2).

We did find a correlation between irradiance and altitude, as shown in figure 9.4. An initial drop in irradiance corresponds to the passage of the payload through cloud layers in the upper troposphere (evidence of this cloud cover was supplied by photos taken by the onboard camera), after which the value for irradiance levels out until landing, at which point it experiences a sudden drop (probably due to the orientation of the sensor) and then a slow tapering off as cloud cover returned that afternoon. The sharp drop in the irradiance trend at landing is logical. If the sensor is being dragged through dirt and debris, observed light intensity will be significantly lower.

Another significant point in the data is that the plateau in irradiance occurs right as the balloon crosses into the ozone layer. Further research has not provided and link between the data and ozone, but it is still an interesting fact to note.

We were unable to find any evidence for or against the presence of airglow at any altitude, as our sensor was overwhelmed by background light due to a fault in our design. Our bandpass filter, with a relatively wide bandwidth of 10nm, was unable to successfully differentiate between spectral line emissions and background light (such a differentiation would be characterized by spectral peaks in the irradiance data). In order to successfully detect airglow, we would need a filtered detector with a much narrower bandwidth (on the order of 0.1nm or smaller), and a second detector with a bandpass appropriately outside of the band of interest (557.7±0.1nm) to act as a reference level. Additionally, a more accurate experiment would go much higher in the atmosphere.

Figure 9.3: Raw Light Intensity Data



7:20:13 7:44:01 8:07:49 8:31:37 8:55:25 9:19:13 9:43:01 10:06:49 10:30:37 10:54:254.4

4.6

4.8

5

5.2

5.4

5.6

5.8

6

6.2

Sensor Data Collected During the Flight

Time Elapsed (min)

Irrad

ianc

e (m

W/c

m2)

Launch

Cloud cover

Landing

Figure 9.4: Light Intensity Data as it relates to Altitude


Approximate Maximum Cloud Altitude

Irradiance

Dip in data attributed to clouds

Ozone

Burst

Note the sharp drop


9.2 Post Flight TestingIn order to either verify or refute the hypothesis that temperature had an effect on

the frequency readings, we conducted a test where the sensor was placed in dry ice and then removed and allowed to warm to room temperature while under constant illumination (the HOBO datalogger was used to measure temperature). We found that variations in temperature do not have a significant effect on the measured frequency of a source of constant luminance. (Results of the test are shown in figure 9.5).

Figure 9.5: Independence of Light Intensity Measurements from Temperature

1 88 175 262 349 436 523 610 697 784 871 958 1045113212190

1

2

3

4

5

6

7

-15

-10

-5

0

5

10

15

20

25

Temperature Independence of the Light to Frequency IC

Irradiance Temperature

Time Elapsed (s)

Irra

dian

ce (m

W/c

m2)

Tem

per-

atur

e (°C

)

10.0 Ready for FlightThe post launch analysis of the craft shows no damage to the exterior structure.

After running tests on the sensors it was determined that the light intensity to frequency IC did not burn out from possible oversaturation during the flight and as such remains



functional. Since the internal temperature dropped below -20° Celsius during the mission we added more insulation, including internal foam to reduce the volume to be heated and three layers of thermal foil on the exterior of the craft. The graph below shows internal and external temperature readings during a second cold test using dry ice.

This second test does not fit common trends, and it has been determined that the consistency of internal temperature is due to gross overinsulation as well as heater failure and mistesting. Only one side of the box was cold, and the internal temperature remained at room temperature, meaning the cold test wasn’t working, but neither was the heater.

20:00:0020:13:0020:26:0020:39:0020:52:0021:05:0021:18:0021:31:0021:44:0021:57:00-80

-60

-40

-20

0

20

40Temperature Test with Improved Insulation:

29 November 2010

Internal Temperature External Temperature

Time (2h total duration)

Tem

pera

ture

(°C)

Figure 10.1: Temperature values during a second cold test after modifications to the craft’s insulation. (Please note: it is possible that the heater was not activated for the course of this test, which explains the lack of an increase in the internal temperature of the craft).

The memory cards in the camera and in the Arduino have been erased and reformatted so that they will be ready for the next flight and all connections have been double checked to make sure they are all still functional; the batteries have also been removed so that they will not be drained over time. The craft should be stored in such a way as to avoid extremes in temperature and humidity and in a place that won’t scratch the lens. After removing the batteries there are no internal components that will not last 6 months when stored properly. Before launch the HOBO datalogger must be configured to start at the time of launch. In order to activate the craft’s other electronics, including the heater, camera, and Arduino microcontroller, the batteries discussed above will have to be replaced inside the craft and the exterior switches switched to their on positions (or toggled, in the case of the camera)

11.0 Conclusions and Lessons LearnedAfter this seemingly long semester, our team has learned a lot about introductory

engineering such as systems, mechanical and electrical components, as well as teamwork.



Through various mistakes and even failures sometimes throughout the term, we have come to understand not only how easy it is to mess up but also how valuable it is to learn from those mistakes. We had many issues during the semester regarding the choice of our project, which subsequently cost us almost half of the semester. Besides not wholly agreeing on ideas as a team, we should have asked more questions and gotten more help in the beginning and this could have allowed us to avoid such time losses much earlier on. Also, we didn’t anticipate many of the problems we ran into until it was too late and simple proactive thinking measures may have helped us in this area as well.

As for our data collection, we obtained very little information from our actual experiment of looking for the presence of airglow in the atmosphere for many reasons. Among those reasons, we had programmed the sensitivity of our sensor to be too high and this is why we believe we saw most of our data to be saturated and unusable for drawing definitive conclusions. This could have been helped with more testing prior to launch but as we ran out of time, we had overlooked this variable. Looking back on the rest of our data, we tried to make correlations between the unsaturated data from our experiment and the flight temperatures, relative humidity, altitude etc. to attempt to explain our results. Nothing seemed to match or be the cause of what we saw in the mission data, although a plausible explanation may be found by comparing those data to the altitude of the craft (please see section 10). We were unable to meet our mission requirement comparing our data to oxygen levels from the flight because On Cloud 9’s experiment failed and they were unable to obtain any data for us to compare to.

On the topic of teamwork, there were times when there were definite clashes of personalities, work styles and communication especially, all of which taught us valuable lessons about working with people from different backgrounds. There was almost a breaking point between team members but with the entire semester’s work at stake, we were able to overcome certain barriers and come together to finish the project. The biggest hurdle was communication between members and dealing with how to compromise how we each operate inside and outside of the classroom was the biggest learning experience overall.

12.0 Message to Next semesterWhen entering this class in the beginning of the semester, there are definitely

some tips and advice that would prove beneficial to your success throughout the semester because this class is not like most other college courses. It involves more work outside of class than any other I have taken and it would be the best idea to get as much help as you can as soon as any problems come up to make the most out of your time. It may seem like a few months is sufficient for the amount of work given but it is not if you don’t spend that time efficiently. Time will fly by faster than you know it and the last thing you want is to wait until the last week to figure everything out. Even if you think you are working at a good pace and keeping on track, you probably aren’t because the most work you have to do will pop up out of nowhere when a problem you haven’t foreseen arises and you only have a certain amount of time to determine what is causing issues and fix it.

Another key point that seems obvious but can really cause problems is the choice of your project. There are many reasons why this could make or break you, first of all because if not all of your team members like the idea, they won’t be inspired or



motivated enough to give it their all throughout the term. Also, if not everyone understands the project and how to analyze the results you will get in the end, you will have A LOT more work to do, especially after launch. This not only wastes time but it also causes more dissonance within the project and team, even if no one realizes or speaks of it openly. You don’t need to choose something everyone already knows about or understands completely, this is a learning experience and you should choose something you’re interested in finding more about but that is also reasonable. Which brings me to my next point that you need to choose a project that is challenging but that is attainable in the short amount of time you are given. Critically analyze what you want to accomplish, any issues that could arise and if it can be done. Our team find out way too late that there were obstacles that we could not get over within the semester leading us to change our project multiple times losing us a lot of time, motivation and confidence in our idea. Do not make this mistake because it could be the difference of having fun with the project and just trying to finish to have something done. If you do find a good idea, go with it and enjoy the process of learning from mistakes and fixing problems as the come up.

Lastly, and maybe most importantly, make a conscious effort to understand you team members and let them understand you to act as a cohesive team. Try to figure out each other’s strengths and weaknesses early on so you can play each other’s strengths but also help each other where there are weaknesses. Communication is another factor that can either make or break your team’s success because the odds are that you will be put on a team that is comprised of very different individuals from very different backgrounds. It is inevitable that personalities clash at times but it is how you deal with these situations that really matters. Respecting everyone should be the first and foremost rule, even if you don’t necessarily get along with someone, be respectful of them as a person no matter what. Do not take anything to personally or try to offend others personally or there will be major tension and feelings can be hurt. Also realize that others may not be as experienced in some areas and that you just need to help each other and allow them to try and learn more. The distribution of work between team members needs to be as equal as possible and done as a team, not individually so everyone understands what is going on. These should be understood going into the project because there are always slackers and there may be overachievers who, in the long run, can both contribute negatively to your team if they don’t allow equal work to be done across the board. You also need to be able to take responsibility for things you have messed up on and be able to contribute more to your team if this happens because sometimes, special circumstances may arise but you still need to be there for your team.

Along with these things, one of my best pieces of advice would be to set norms for the team at the very beginning. These involve things like types of communication (phone, email, etc.), when/where to meet for team meetings, etc. Make it clear that you consider being late or missing a meeting to be unacceptable, that you need to be anticipate phone calls at certain times if a team member needs you for help on certain parts of the project, etc. Also, if a team member is not present for work that needs to be done, do your best to get in touch with them as they may not know about it or may have extenuating circumstances that you don’t know of. These types of things will eliminate excuses and hopefully save time that could be easily wasted.



Overall, this is a great learning opportunity and a chance to have a lot of fun doing a really amazing project that not many people get to do. Don’t take it for granted and don’t think it’s not a big deal because as you will find out, it will become a huge part of your semester and college career as a whole.


mission overview - university of colorado boulder · web viewa dedicated 6ah battery will power the...

Documents