1.0 Mission Overview

1.1 Mission Statement:

The balloon satellite, AIRSat – Atmospheric Infrared Research Satellite - will ascend to a maximum altitude of approximately 100,000 feet and will use a vinyl tubing to collect the air samples upon descent. At the launch site there will be ground level gas in the tubing (Fig. 1.1). On the ascent of the flight, the ground level gas in the tube will evacuate due to the near vacuum conditions until the maximum altitude of the flight is reached ( Fig.1.2). However, there will still be a trace amount of residual ground level gas within the tube that will be spread throughout the entire length of the tube. Then, as the “satellite” descends, the tube will begin filling up with air until it lands (see Fig. 1.3). The air entering the tube will compress the gound level gas (red in Fig.s 1.1-1.3) and as the satellite continues to descend, air entering the tube will continue to compress all the air within the tube.

Fig. 1.1

Presitation Pic 2

Fig 1.2

Presitation Pic 2

Fig 1.3

After retrieving the AIRSat and returning to the chemistry lab in Trinidad, we will analyze the air that has been collected using a Thermo Scientific Fourier Transform Infrared (iS10) spectrometer. Each sample analyzed will be 64 cc plug of air (noodle) for which we will determine the concentrations of the greenhouse gases carbon dioxide (CO₂) and methane (CH₄). AIRSat will also take measurements of internal and external temperature, air pressure, and relative humidity. These data are used in our gas model (see Section 3 below and Appendix A) to determine the altitude for each air sample (noodle of gas collected). Thus a CO₂ concentration versus altitude and CH4 versus altitude may be created. These results may be used to aid in the calibration of atmospheric models that need greenhouse gas concentrations as inputs.

1.2 Mission Objectives:

1) Construct a balloon satellite that will hold altitudinal air samples from a height of 100,000 feet.

2) Transport air samples from Deer Trail, CO to Trinidad, CO and analyze the air samples using an iS10 FT-IR spectrometer.

3) Collect data from onboard sensors needed for air sample analysis.

4) Discover new ways to improve research that involves taking air samples via balloon satellites.

5) Use our data to aid research for organizations such as NOAA.

1.3 Mission Background:

Global climate change models need accurate concentration values for greenhouse gases such as carbon dioxide, water vapor, methane, and nitrous oxide. Numerous Aircore experiments have been launched by balloons since 2005, but none using plastic tubing. Team Panacea has decided to embark on a mission to analyze and quantify certain greenhouse gases and determine its relationship with altitude using lightweight plastic tubing rather than metallic tubing. By constructing the AIRSat, the team explores a low-cost method of using vinyl tubing for capturing atmospheric gas samples and focuses on the concentrations of methaneand carbon dioxide.

1.4 Mission Expectations:

We expected that our balloon satellite will capture enough air samples from the atmosphere throughout its descent that we will be able to accurately measure the concentration of the greenhouse gases, carbon dioxide and methane, as a function of altitude. Data that is collected from onboard sensors will be used to aid in the process of analyzing air samples.

2.0 Requirements Flow Down

The following objective requirements and system requirements are derived from the mission statement and its mission objectives. These requirements detail the specifications of our AIRSat including hardware, software, and design needs.

2.1 Objective Requirements:

Level	Objective	Requirement
0	O.1	Team Panacea has constructed the AIRSat, a balloon satellite that will be launched on January 16, 2010. This device will be attached to a high altitude latex balloon reaching nearly 100,000 feet in altitude. This device shall not exceed 3.00 kg in mass. The cost of materials not including those provided by STEM grant has not exceeded $2200. The design is in compliance with ACCESS guidelines.
0	O.2	The instruments of the spacecraft shall remain intact and functional during the approximate 90 minute ascent and 45 minute descent. It will also have to endure the impact of landing.
0	O.3	AIRSat will measure the quantity of the greenhouse gases, methane and carbon dioxide, in the atmosphere as a function of altitude. It has two HOBO data loggers onboard to acquire the data for interior and exterior temperature, pressure readings, and relative humidity. The data loggers will record and store all the data to use for analysis. Altitude will be determined using the data retrieved from the transponder EOSS beacon attached to the launch vehicle. A Fourier Transform Infrared (FT-IR) spectrometer funded through STEM will be utilized for analysis of gas samples.
0	O.4	The internal temperature of the box shall not reach below -30°C. An internal heater has been installed to ensure this objective.
0	O.5	The AIRSat has been built in a manner that allows attachment to the balloon launch vehicle via a thin rope through the center of the payload, which will also connect with the other schools’ satellites.
0	O.6	A means of knowing how many air samples will be collected in conjunction with the diffusing mixing that will occur amongst the samples once they are collected has been modeled.
0	O.7	Control samples have been acquired to determine the quantity of carbon dioxide and methane within the atmosphere.
1	1.1	The mass and budget has been divided among all the components of the box. The AIRSat has been completed and successfully tested by January 14, 2010. The AIRSat shall remain completely intact and reusable after its impact to the Earth. All ACCESS template requirements shall be met as stated in the design document and the construction of the balloon satellite.
1	1.2	The container of the AIRSat is cylindrical in shape and made out of foam core and reflective aluminum bubble wrap insulation. It shall be capable of withstanding the forces experienced during flight and landing so that it can fly again. The box shall be tethered to the balloon launch vehicle via a thin rope as mentioned previously and shall not interfere with the other devices onboard the payload. There are two compartments to this cylindrical payload. The outermost partition comprises approximately 100 meters of coiled vinyl tubing, which can endure severe impact at very cold temperatures and will be the means in which Team Panacea will retrieve the air samples for our mission. One end is closed off while the other end will be open to allow air to enter upon descent. The tubing also aids in structural support for the inner compartment. This compartment consists of a pressure sensor and a resistance heater that will ensure the temperature does not fall below -30ºC allowing the balloon satellite’s electronic devices to endure the cold environment. Both are be powered by three nine-volt batteries. The pressure sensor is connected to a HOBO data logger to collect and store barometric. This HOBO data logger also obtains internal temperature readings. The other HOBO data logger gathers relative humidity and external temperature via a temperature probe.
1	1.3	Ascent and descent rates of the payload during flight will be computed with GPS data provided by the EOSS transponder beacon.
1	1.4	An Excel spreadsheet has been set up to allow for input data from the HOBO data loggers and the transponder EOSS beacon, which will determine the quantity of samples obtained. It will also allow Team Panacea to determine what each gas sample corresponds to in terms of altitude and location within the vinyl tubing. Any diffusing mixing that will occur will be determined as a function of time using this spreadsheet model.
1	1.5	17-liter containers of 300 ppm, 350 ppm, and 392 ppm of carbon dioxide and 9.6 ppm of methane have been used as calibration methods for the FT-IR spectrometer. This will allow a comparison to made with a known quantity of gas to determine the unknown amount present in the air samples contained within the tubing.
1	1.6	All data and results collected have been be taken into account and made into appropriate graphs and spreadsheets.

3.0 Design

3.1 Mission Specifications:

AIRSat is constructed from foam core and vinyl tubing which which will provide strength to the design without adding much to the weight constraint of 3.00 kg. Foam core has been proven to be very sturdy and workable. These qualities make it easy to repair and modify the balloon satellite. AIRSat is constructed using a cylindrical design. The cylinder will be built based on the coiled tubing, with electronics in the core region, surrounded by foam core, then the tubing coil, and finally a reflective aluminum bubble wrap insulation, which will provide both thermal and structural protection. AIRSat is wrapped in aluminum tape along all edges to strengthen weak seams. The temperature of the electronics chamber shall remain above -30ºC, while the tubing temperature will remain above the brittle point for the tubing material (-40ºC). Furthermore, there are three nine-volt batteries that will power ceramic resisters which will be the source of heat within the AIRSat. This resistance heater is located closest to the batteries and other devices such as the two HOBO data recorders to keep the most critical science equipment functioning throughout the flight.

The key components for the mission onboard the AIRSat are a gas pressure sensor, temperature sensor, and a 181-foot coil of 3/16” inner diameter tubing to collect atmospheric gas samples upon the descent of the balloon satellite. The tubing is plugged on one end with hot glue, and the other end will be open to the outside environment. The tube shall be nearly evacuated at maximum altitude, and will then fill on descent. When the team reaches the landing location, we shall use a clamp to close off the open end of the tubing in order to keep the collected gas as undisturbed as possible.

A spreadsheet model of the gas in the tube was created using the data from the July 2009 launch. This was used to determine the tubing length and diameter to optimize the altitude resolution. A new spreadsheet based off this preliminary model used our January launch data to obtain information that was essential for our mission. (Refer to Appendix A).

The analysis works as follows: the 64-cc glass cell has two valves in it. One valve is connected to the vinyl tubing with the air samples with the opposite end of the tubing open. The other valve is connected to the vacuum pump. The cell is initially evacuated with the air sample tubing valve shut off. A background sample is taken of the evacuated cell using the iS10. Next, the vacuum pump valve is closed while the tubing valve is simultaneously opened to allow the first “noodle” of air to fill the cell. The evacuated cell will draw exactly 64-cc of air into it. Once this first sample is analyzed, the tubing valve is closed and the cell is evacuated again. We repeat the process for all subsequent samples. We perform the exact same procedure for the purchased standards (300ppm, 350ppm, 392 ppm CO₂, and 9.6ppm CH₄) to produce a calibration method.

Upon the AIRSat team’s arrival back to Trinidad, the gas samples shall be analyzed as soon as possible to limit any further diffusion amongst the gas quantities obtained from various sections of the atmosphere.

When we analyze the samples using the iS-10 we start by using an argon flush-gas to rid the chamber of any background CO₂. The chamber and laser beam path must be CO₂ free because the background from the room would dominate the sample signal. We have the iS-10 resolution set to 0.5 cm^-1 because that is the finest resolution it is capable of and provides the most accuracy, though it takes the longest amount of time to scan. The machine is set to take 32 scans of each sample. This number of scans lowers the amount of noise (compared to signal) but increasing the number of scans would only increase the amount of time we have to spend analyzing a single sample. Figure 3.1 shows a typical background spectrum when the device has been flushed with argon for at least 30 minutes.

Figure 3.1

. bckgnd

This background is subtracted from each sample signal yielding a result that depends only on the sample, at least in theory. Figure 3.2 is this net signal from our first sample from AIRSat. The the dominant feature of the CO₂ signal is indicated; this occurs in the 2300 cm^-1 range.

Figure 3.2

Given this graph, we can analyze only what gases are present using the Search feature of the Omnic software that comes with the iS10 spectrometer. This matches the pattern against a library of patterns and suggests possible chemicals in the sample. For all of our samples, CO₂ and water are indicated, but nothing else. Next, to determine how much CO₂is in this sample we need to create a “method.” A method takes spectra from at least two calibration gases and fits them to a line (signal strength versus know concentration). We used three (3) different reference gas samples obtained from MESA gas supplier. These were 300, 350, and 392 ppm CO₂ (+/- 0.3 ppm) and 9.6 ppm CH₄. The computer measures the area under the curve of the CO₂ spike between 2307.5 and 2378 cm-1 (see Figure 3.3) and uses that as the signal strength.

Figure 3.3

AreaUnderLine

We analyzed each 64 cc batch of gas from the AIRSat and recorded the fit results (see Table 9.1).

3.2 RFP Compliance

The design of AIRSat complies with all requirements as set forth in the Request for Proposal. The AIRSat contains a gas-sampling tubing system plus a pressure, temperature, humidity recording HOBOs. The AIRSat contains all the mandatory flight equipment. In order to comply with the RFP, the AIRSat is designed in a manner which is not harmful to anyone, it is also designed so that it can be reused after flight. The exterior of the AIRSat shall contain an American Flag as well as team name and contact information as mandated. The mass of the AIRSat as a function of its design shall not exceed 3.00 kg. Even if not explicitly stated in this section appropriate steps have been taken to ensure that the AIRSat shall fulfill all requirements listed in the Request for Proposal.

3.3 Design Drawings:

3.4 Requirements and Limitations:

The structure of our satellite is required to have mass less than 3.00 kg. The structure is comprised of two separate cylindrical compartments. The inner partition includes the electrical devices and components in a heated environment. The heat shall be provided via a resistance heater powered by three nine-volt batteries, which are also located in this compartment. The tubing is coiled around in the outer compartment. The tubing will help provide much of the structural support of the satellite. This is then wrapped with reflective aluminum bubble wrap insulation to provide both a good R-value and protection upon landing for the tubing.

The tubing required for the project is able to withstand the cold, harsh environment and impact at landing while not exceeding the AIRSat payload weight constraint. It also retains enough gas molecules to analyze without allowing much diffusion. This is the reason a 3/16” diameter tubing is required. The weight constraint of 3.00 kg allowed us to use 183 feet of tubing. One end shall be open to collect the air molecules while the other shall be plugged with hot glue. At landing, a clamp shall be used on the open end to preserve the integrity of our samples.

The data required for our mission are pressure and temperature. To obtain this data, two HOBO sensors shall be utilized. One will analyze humidity, temperature, light intensity, and external temperature of the tubing. The other shall attain the pressure readings as the payload goes through various layers of the atmosphere and internal temperature. These devices are placed in the inner, heated compartment so as to not result in their malfunctioning which would greatly affect the outcome of our mission.

3.6 Functional Block Diagram:

3.7 System Interface:

The two HOBOs shall be programmed to take data readings simultaneously every ten seconds during the flight; these will record internal temperature, external temperature of the tubing, relative humidity, plus pressure, and thus for each atmospheric level.

4.0 Management

4.1 Organization Chart:

Team Panacea’s organization chart was designed based on personal skills. There is an individual in charge of a certain duty with an assistant, but everyone is involved in all aspects of the project.

Text Box: BOB PHILBIN

Project Leader

Text Box: JUDY MACLAREN

Support

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POSITION	RESPONSIBILITIES
Project Leader	Responsible for budget management and team organization.
Mission Specialist	Responsible for design, construction and management of the AIRSat
Electronics Engineer	Responsible for wiring and programming of the AIRSat.
Testing Coordinator	Responsible for all testing of the AIRSat to ensure its ability to survive flight and landing
FT-IR Scientist	Responsible for gas sampling system and testing.
Structure and Thermal Engineer	Responsible for the construction and testing of the AIRSat.
Support	Moral Support, witness and chemistry guru.

4.1 Schedule:

Due Date	Milestone	Completed or Comments
07-11-2009	ACCESS training workshop and launch	Completed
09-09-2009	Student/team recruitment complete	Completed
09-16-2009	Top three missions/experiments selected	Completed
09-23-2009	Final mission/experiment selected	Completed
10-14-2009	Design Document Rev A/B complete and submitted to Chris	Completed
10-30-2009	Critical Design Review (Rev C) completed	Completed
11-02-2009	FT-IR detection system working and team trained on FT-IR	Completed
11-10-2009	AIRSat complete and final adjustments	Completed
11-18-2009	Initial experiment and payload results completed	Completed
12-09-2009	First full mission simulation test completed	Completed
12-16-2009	Second full mission simulation test completed	Completed
01-11-2010	Launch Readiness Review with all teams and JPL complete (via phone)	Completed
01-14-2010	Pre-Launch Inspection in Trinidad	Completed
01-15-2010	Final Launch Readiness Review with all teams in Boulder, Colorado	Completed
01-16-2010	LAUNCH at 6:50 AM in Windsor, Colorado	Completed
01-16-2010	FT-IR gas analysis in Trinidad	Completed
01-29-2010	Final reports and final presentations complete	Completed
02-05-2010	Presentations at JPL (Pasadena, CA)	In Progress

5.0 Budget.

The budget is separated into two parts. The first part is the equipment we use to analyze the air samples. The second part is equipment used to build the AIRSat.

Component	Mass	Part #	Company Contact Inf	Price	Purchased by	Vendor Name
Lab Equipment:
Spectrometer	-	iS10	Bill Mohar	$19,000.00	USDA grant	Thermo Electron North America
100ml gas cell	-		18006485456	$ 711.00	STEM grant	Thermo Electron North America
NaCl windows	-	7000-316	bill.mohar@thermalfisher.com	$ 169.00	STEM grant	Thermo Electron North America
KBr windows	-	7000-452		$ 218.00	STEM grant	Thermo Electron North America
Consulting (~2 hr)	-		Pieter.Tans@noaa.gov	-	NOAA	Dr. P. Tans
Consult (~.5 hr)	-		DanielOh@SLSensors.com	-	Searchlight Sensors	Dr. D. Oh
Argon tank	-		Vernon.Paulsen@trinidadstate.edu	$ 100.00	COSGC	TSJC welding
Sub total				$20,198.00
AIRSat Equipment:
PVC Tube	2385gms	42161300	Phil Rico 17198469211	$ 50.00	COSGC	Trinidad Builders Supply
valves, glue, etc.	20gms		Phil Rico 17198469211	$ 15.00	COSGC	Trinidad Builders Supply
Structure (foam board)	210gms	W950069		$ 13.00	COSGC	Wal-Mart
Insulation	50gms		Phil Rico 17198469211	$ 25.00	COSGC	Trinidad Builders Supply
2 HOBO	92gms (46g *2)	U12-012	Christopher Koehler Koehler@Colorado.edu	$ 260.00	Donation	Space Grant
Heater	15gms		Christopher Koehler Koehler@Colorado.edu	$ 25.00	Donation	Space Grant
9V Batteries (3)	140gms (46g *3)			$ 30.00	COSGC	Wal-Mart
Wiring	5g		Christopher Koehler Koehler@Colorado.edu	$ 5.00	Donation	Space Grant
Subtotal				$ 423.00
Total	2937gms.			$20,621.00

6.0 Test Plan and Results

6.1 Test Plan:

The testing of the AIRSat was separated into structural testing and scientific testing. Testing structural integrity occupied our team’s highest priority level because the science mission would not have worked without a robust experimental platform. The AIRSat had to be capable of withstanding the forces experienced during launch as well as forces acting on the structure throughout the flight. The most difficult tests on the structure occurred when the balloon had burst and when the AIRSat landed. To ensure that the AIRSat survived these situations on launch day, our team has subjected the AIRSat to simulations for each of the events mentioned above.

The only way to ensure that the science subsystems performed as intended was to test them in conditions as close to those experienced during the flight. Thorough testing was the only way to prepare for problems that could occur during the actual mission. By testing each stage of the flight our team determined and fixed any potential problems that could prevent a successful mission on launch day.

The first test on the structure simulated the most extreme forces acting on the AIRSat during flight, especially those occurring at burst. The whip test involved swinging the structure with simulated flight masses by a line (approximately 1 m) running through its central tube. This test replicated the gravitational and tension forces acting on the structure as it twists and spins during the flight. To test the AIRSat’s structural integrity during the landing, we conducted two separate tests. The first of these tests simulated the blunt force experienced as the AIRSat hit the ground. We dropped the AIRSat from approximately seven meters onto a hard surface twice. Team Panacea also performed a worst case scenario of an extremely hard landing by dropping it from seven meters onto concrete. The second landing simulation tested the AIRSat’s structural integrity in the event that the parachute continues to drag the balloon string along the ground. Stairs replicated the forces experienced during this event well. Our team rolled the AIRSat down a two-story flight of stairs with mass simulators.

The modified “cooler” test was a cold impact test, and it was undoubtedly the most important test for our project. The reason for this is because the tubing becomes brittle at low temperatures and the AIRSat will be subjected to an extremely cold environment. We took our fully functional and integrated flight payload and cooled it to a temperature simulating that of launch day by placing it in a Styrofoam cooler with 7 to 10 pounds of dry ice. The dry ice was uniformly distributed within the cooler. A non-conductive material, Styrofoam, was placed in the center. The payload was then activated and placed onto the non-conductive material, and the lid was then closed. We checked that all the devices functioned properly and the tubing remained intact with no cracks. We used the HOBO data logger to obtain the temperature reading that the payload experienced on the exterior and interior while in the cooler.

Team Panacea has also done a mission simulation over the full range of pressure using the published values of equilibrium vapor pressure of water in a vacuum chamber. This did not work as expected to give an absolute pressure calibration because the water vapor was not always in equilibrium, so the pressure was not in sync with the theoretical pressure as determined from the water temperature.

While thorough testing was a top priority for our mission, we failed to conduct one test that turned out to be critical. We conducted many gas analyses on the tubing, including how it adsorbed methane and carbon dioxide, but we failed to consider the effect of the Drierite on these gasses. We assumed that it would only adsorb water, its design purpose, but never tested its methane or carbon dioxide uptake or outgassing. After the launch, we did experiment with the Drierite and discovered that when palced in an enclosure, the CO₂ concentration rises to about double the atmosphere value, i.e., about 630 ppm rather than 400ppm (see Fig 6.1).

Fig. 6.1 Vernier LabQuest with [CO2] measurement in air-filled 200ml container, at 3.5 hr, 8 gm of fresh Drierite was added to the container.

6.2 Pressure Testing

Team Panacea calibrated the onboard pressure sensor using a two-step procedure. An vacuum apparatus was set up with a pre-calibrated Vernier pressure sensor that was spliced into our uncalibrated sensor to obtain voltage readings from the uncalibrated sensor. The pressure and voltage readings from each of these devices were recorded by the LabQuest. The pressure was brought to 0 Torr with the vacuum pump and allowed to slowly leak back to room pressure (613.3 Torr as determined by a mercury barometer, which is our primary standard). This was done every second for 900 seconds. Once the data was put into a spreadsheet, the first step of the procedure was to correct the LabQuest Vernier pressure sensor readings to that of the barometer readings (see Fig. 6.2).

Fig 6.2

This corrected LabQuest pressure was then correlated against the AIRSat pressure sensor (see Fig 6.3 for the linear fit)

Fig 6.3

The resulting equation results in pressure from sensor voltage output (P = 1675.8*V -21 Torr). Our gas model spreadsheet converts raw voltage values from the HOBO to absolute pressure values in Torr using this formula.

7.0 Expected Results

Given that AIRSat uses 55.0 meters of vinyl tubing, we expect to collect just over fifteen (15.3) 64cc samples as predicted by our spreadsheet model (based on the ideal gas law and the data retrieved from the flight – see Appendix A). We rely on the near-vacuum conditions at 100,000 feet (roughly 130 Torr) to evacuate the tubing and leave only a small amount of ground level gas in the tube. The air samples are collected on descent, the tube closed off upon recovery, and analyzed using the FT-IR spectrometer immediately upon arrival back in Trinidad. The FT-IR spectrometer is located at the Trinidad State Junior College campus in Trinidad, Colorado, which is 14 miles north of the New Mexico border. The trip from the landing site to Trinidad is expected to take about four hours. Due to the small diameter of the tube, the molecular diffusion along the tube should not adversely affect the altitude resolution provided the sample is analyzed within 16 hours of air sampling.

Once the quantities of carbon dioxide and methane were determined with our FT-IR analysis, we made a profile of these atmospheric greenhouse gases in relation to certain altitudes or levels of the atmosphere. We then used the residual gas that was acquired at launch to serve as an indicator of any contamination by plasticizers or other impurities that may arise. This has been analyzed by comparing the aforementioned sample to our last sample taken at ground level upon landing. Team Panacea has also collected ground level gas using extra tubing that was not launched as a control.

We tried to anticipate all possible mission complications. First, there were a wide array of issues that could have occurred from the simplest electronic device malfunction to analyses determined via the FT-IR spectrometer with its sensitive laser light. There were also many other things that could go awry in real life as compared to results that spreadsheet models have computed; nonetheless we had an optimistic attitude about the AIRSat project. We proceeded forward and expected to obtain data that will be useful for determining atmospheric greenhouse gas concentrations versus altitude. We also hope that our project serves as a guide for other groups

to follow in gathering information pertinent to the science of climate change.

8.0 Launch and Recovery

AIRSat launched from Deer Trail, Colorado at 7:25 a.m. MST on the January 16, 2010. The organization Edge Of Space Sciences organized the launch, obtained permission from the FAA, supplied the balloon, and provided the tracked hardware and software. After recovery, we drove immediately back to Trinidad were we ran the gas from the AIRSat through the iS10. This was complete late afternoon the same day.

The day before the launch we pumped on the AIRSat tube with a vacuum pump for three hours. This was to rid the tube of any gases that may be attached to its walls and dry out the tube of any access moisture. At the launch site we opened our tubing to let the air in and turned on our electronics, EOSS took care of the rest. When we found our payloads we couldn’t get to them because EOSS could not contact the owner of the land. We didn’t want to go on the land without permission so we had to let our payload sit there for several hours. We found that AIRSat was in perfect condition. All the payloads landed in a grassy field spread out in a straight line; we could not have asked for a more perfect landing.

After a four hour drive we reached Trinidad and immediately began running samples through the iS10 gas analyzer to limit the diffusive mixing that occurs. Figure 8.1 shows the result of computing the diffusive mixing expected for different amounts of time (measured from landing to analysis). The diffusive mixing approaches 0.5 noodle length (~1.7m), i.e., the i^th sample has mixed to about halfway into the (i+1)^th and (i-1)^th samples and vice versa. Landing was 9:30 a.m. and we ran the first gas sample into the iS10 at 4:20 pm, at about 7 hours. The final sample ran at 5:20 p.m., so 8 hours was the maximum time any gas sat in the tube. This means that sample resolution error corresponds to about 0.2 noodles.

Figure 8.1

9.0 Results, Analysis, and Conclusions

The structure of the AIRSat remained intact throughout the entire mission and is able to withstand future launches. Moreover, all electrical devices and instrumentation performed as expected. There was no failure in either of these categories. The temperature within the heated inner compartment ranged from 15.1ºC to 20.3ºC. This fulfilled our requirement of being above -30 ºC to keep all the devices working properly. The data comparing the external temperature (that is, the outside of the tubing) and the internal temperature are shown in Figure 9.1.

Fig. 9.1

Using the altitude data from EOSS plus the pressure and temperature data from our onboard data loggers we built a “tubing gas” model (see Appendix A). The spreadsheet predicts the details associated with each sample (or “noodle”) of gas. It also predicts the amount of diffusive mixing between noodles.

Using the spreadsheet model, Figure 9.2 was constructed showing cell number (or noodle number) versus altitude. This graph verifies our predictions that the noodles near that descended would give more precise as it descended back to Earth. We figured this would be the case since air is more concentrated near the ground and the air at burst is less dense; subsequently the samples taken at higher altitudes consist of a broader spectrum of the atmosphere, and those lower cover a smaller section of the atmosphere.

Fig. 9.2

Red=Residual ground gas

The analysis with the FT-IR spectrometer gave us the following data for each of the 15 noodles for carbon dioxide concentrations:

Table 9.1

cell number (noodle)	Altitude Range (km)	AIRSat Meas. [CO2] (+/-10 ppm)	NOAA AirCore [CO2] (+/- 0.3 ppm)	AIRSat Meas. [CH4] (ppm)	NOAA Aircraft [CH4] (+/- 0.005 ppm)
1	20 to 24	779	372	1.5
2	16 to 20	775	374	1.9
3	13 to 16	783	377	-0.4
4	11 to 13	769	378	1.5
5	10 to 11	741	382	-0.1
6	9 to 10	736	384	-1.9
7	8 to 9	722	385	0.7
8	7 to 8	708	383	0.6	1.76
9	6 to 7	704	382	3.8	1.76
10	5 to 6	679	382	-2.1	1.78
11	4.5 to 5	602	382	-1.2	1.77
12	4 to 4.5	571	383	-0.3	1.75
13	3 to 4	549	384	-0.9	1.74
14	2.5 to 3	530	386	2.7	1.78
15	2 to 2.5	533	389	2.9	1.77

The data retrieved from NOAA’s AirCore experiments reveals that our data is high by about a factor of two. At first, we thgouth this might be a problem with the Thermo iS10 FT-IR spectrometer, since we are all quite new to using it.

Once we inserted our flight data into our spreadsheet model (Appendix A), the results are self-consistent. The spreadsheet predicts that the first cell corresponds to altitudes from burst, at 24000 m down to 20000 m, the second cell from there down to 14000 m, and so forth as summarized in Figure 9.2 and Table 9.1. The topmost cell, however, actually consists of residual gas from ground level (because the tube was open on the ground and not all this gas evacuates the tube during ascent). The spreadsheet model predicts that the first 56% of the first noodle consists of ground-level gas, which was measured to be 533ppm in the 15^th noodle. The first noodle was measured at 641ppm, so the uppermost gas must be at 779ppm (from the weighted average, 0.56*533+(1-0.56)*H = 641 implies H=779). This value is consistent with the value measured in the second cell, 775ppm, so we feel confident in the iS10’s analyses.

While these data seem to be self-consistent, the carbon dioxide concentrations are still 100% too high compared to the NOAA data¹, which is accurate to less than 1 ppm. We considered the possibility that because the flight took place downwind of the Denver metropolitan area, the carbon dioxide concentrations might reflect this large carbon dioxide source, Dr. Tans¹ had stated that the mixing time for ground level gas with 20km altitudes is on the order of decades, so should expect nearer 370 ppm, since that’s what carbon dioxide concentrations were in the 1980s, not 800 ppm at that altitude. Furthermore, it does not seem likely that the emissions from Denver could double the carbon dioxide concentration.

A second possible explanation occurred to us when we accidently discovered that the CO₂ concentration in a wooden cabinet was 1500ppm; we think this is due to respiration of the wood, i.e., carbons are being oxidized and producing CO₂. The Drierite (CaSO₄) we used apparently is outgassing CO₂; we suspect this because it has an organic indicator embedded in it to visually alert the user to when ; the organics in the indicator are reacting with atmospheric oxygen to produce CO₂. We tested this after the launch and found that this is true (see Figure 6.1– [CO₂] vs time from Vernier CO₂ sensor in closed bottle with crushed Drierite).

The results for methane (CH₄) contain several values that do not coincide with NOAA’s Aircraft program². In fact, our spectrometer shows negative concentrations in addition to values that vastly exceed NOAA’s mean concentrations of 1.76 ppm. AIRSat methane concentrations lumped together yield 0.58+/-0.65 ppm. This error bar is larger than the measurment, showing that our spectrometer signal is dominated by noise due to the very low concentrations within the atmosphere. Evidently, it also reveals that the FT-IR’s sensitivity to methane is inadequate for these measurements.

Although Team Panacea did not successfully measure what we had expected, we did identify some interesting surface chemistry. While this may be classified as a mission failure, it did allow us to learn about infrared gas analysis, greenhouse gases, calibrations, a deeper appreciation for the ideal gas law, and especially to never assume that a given component will do just one thing (law of unintended consequences). We had very positive results regarding design and hardware; all of the electronic components worked perfectly and the payload’s structural performance was more than adequate.

10.0 Ready for Flight

The AIRSat had a good structure that did not suffer any damage when it came back from the atmosphere. We are able to send it back any moment. The batteries are the only component that need to be replaced. The AIRSat needs to be activated by programming the two HOBO data loggers and the switch needs to be turned on just before launch to make the heater work. Before the next flight, however, the desiccant needs to be replaced with a dessicant that does not outgas CO₂.

11.0 Benefits to NASA

Team Panacea believes that our experiment was beneficial to NASA by exploring the option of using a light weight tubing for AirCore experiments. We elected to use a light weight vinyl tubing instead of a metal tubing. By doing this, we reduced cost and gained additional length, allowing more gas samples and thus finer altitude resolution.

The effectiveness of the tubing has been an overall success. The tubing endured rigorous testing and performed as expected during flight. NASA will be able to reduce atmospheric research costs because weight is a significant cost factor in sending equipment to space. We believe that if NASA were to develop a rover that had the capabilities to analyze gas on an alien planet, then lightweight tubing could be used to collect and store the gas until the rover can conveniently analyze the samples. By using lightweight tubing, costs would be significantly less than if stainless steel tubing were to be used.

Team Panacea also believes that a better understanding of the adsorption and desorption of CO2 from materials like our dessicant would contribute two ways: one is the effort to sequester CO2 from the atmosphere to reduce global warming and the second is for manned missions where the astronauts’ air supply needs to be “scrubbed,” i.e., CO2. concentration reduced (think Apollo 13).

12.0 Potential Follow-on Work:

Air Sat is a project that could be followed up in future missions. Even though we did not get the results we expected, all of the functions of the satellite worked properly for the entire flight. If future teams were to continue the AIRSat project, the following should be considered before launching the satellite again:

1) Determine precisely how the desiccant adsorbs and desorbs CO₂.

2) Find a desiccant that will not affect the CO₂ concentrations in the tubing.

3) Learn all the capabilities of the FT-IR and how to operate it fully. Perhaps buy a longer gas cell for increased precision.

4) Run every conceivable test and simulation that may cause errors.

13.0 Lessons Learned

Team Panacea has been very grateful to have this opportunity to participate in the creation of AIRSat through COSGC. We are pleased with the overall outcome of the project and are focused on further progress with this type of research. Studying for this project we have gained extensive knowledge regarding the study of greenhouse gasses and their effects on our environment. We have studied the behaviors of these gasses in order to better understand how this experiment compares to similar studies.

During our visit to Boulder, we were able to visit NOAA (National Oceanic and Atmospheric Administration) and received a guided tour from Dr.s Pieter Tans, Anna Karion, and Colm Sweeny. We also visited NCAR (The National Center for Atmospheric Research). These tours gave us more insight regarding the science of AirCore experiments. We would like to extend our sincere appreciation for the help Dr.s Tans, Karion, and Sweeny gave us.

Although we are satisfied with the overall outcome of the AIRSat launch, however there was one detail that was overlooked as previously mentioned in Section 6.0. By using the organic compound Drierite to remove moisture from the air, we contaminated our samples. This excess CO₂ gas has proven to be problematic in determining the actual values of CO₂during analysis. For future applications, we have learned that an inorganic Drierite is ideal for this sort of application.

14.0 Message to Next Year:

Team Panacea has gained valuable knowledge that could not be achieved any other way than from experience. Most of the functions that we expected the satellite to perform operated as planned. If possible we would have changed the desiccant used. We would also have learned how to completely operate the FT-IR spectrometer to analyze the air samples. Also, we should have run more tests that would have been able to identify the problems that we discovered after the analysis. Our main message to next year will undoubtedly have to be to never assume anything.

APPENDIX A: Tubing Gas Model (Spreadsheet – this has a macro in it that does the least squares fit)

The first of the spreadsheet’s columns is the time, which is used to correlate EOSS data with AirSat HOBO data. Each row is separated by 30s because this is the resolution of the EOSS flight data. The second column is the altitude from this EOSS GPS flight beacon data file (see www.eoss.org/ansrecap/ar_160/recap149.htm). Next is the temperature of the outermost section of the tubing, which is inside a ½ cm of bubble-wrap. Its temperature is higher than the outside air, but the captured cold air quickly equilibrates with the warmer tubing. This value was chosen rather than the slightly higher (5 to 10 °C) temperature inside the container, because the tubing is insulated from the heated instrumentation compartment. If time permitted, we would build a thermal model to determine a better, average tubing temperature. The next column is the absolute pressure inside the AirSat, which equals the exterior pressure because the AirSat is not airtight. There is a 1cm² hole near the internal temperature/relative humidity sensor on one of the onboard HOBO U-12 data loggers.

The next columns are “change” columns, i.e., they indicate the change in a parameter during each 30s interval. The first change column is the compression length, dL, of the column of gas in the tube due to the drop in altitude (increase in pressure), which causes the N resident molecules to shrink (the temperature effect is also computed). This column shows that the gas decreases in length anywhere from 3cm (the last 30s before landing) to 11m (the second 30s interval after burst). Because the tubing length is fixed, this reduction of gas length causes additional atmospheric gas from that altiude to enter the open end of the tube. The number of molecules entering the tube during each 30s interval is computed. The length of the corresponding cumulative column of air for each 30s at ground level pressure is computed and labelled “L@gnd.” This value divided by the length of a “noodle” of gas (~3.59m), gives the number of cells (each cell is 64cc because that is the volume of our FT-IR sample cell). Samples between 0.0 and 0.99 cell are in the first FT-IR sample, those between 1.00 and 1.99 are in the second FT-IR sample, and so on. The results of the CO₂ concentration measurements were then manually entered into the last column and allow us to plot CO₂ concentration versus altitude. The tube is 55.0 m long, so there are 55.0/3.59 = 15.3 noodles (or tube volume, 980cc, divided by 64 cc test cell is 15.3 cells). The last column are values of [CO2] from NOAA. The first several rows of the table follow:

t (s)	T (K)	Alt (m)	P (Pa)	N	dL(m)	dN	L @ gnd	#cells	CO2	CO2
4322	264	23728	2712	7.3E+20			2.00	0.56	779
4352	264	23428	2838	7.6E+20	-2.52	3.4E+19	2.09	0.58	779
4382	263	22627	3469	9.4E+20	-11.16	1.7E+20	2.57	0.71	779
4412	262	21703	4102	1.1E+21	-9.40	1.7E+20	3.04	0.85	779
4442	261	20866	4606	1.3E+21	-6.58	1.4E+20	3.43	0.96	779
4472	260	20093	4858	1.3E+21	-3.12	7.3E+19	3.63	1.01	779	374
4502	260	19309	5741	1.6E+21	-9.34	2.5E+20	4.31	1.20	779
4532	259	18481	6245	1.7E+21	-4.79	1.4E+20	4.70	1.31	779
4562	258	17747	6750	1.9E+21	-4.42	1.4E+20	5.09	1.42	779
4592	258	17128	7509	2.1E+21	-6.00	2.1E+20	5.68	1.58	775	377

References:

¹ Interview with Dr. Pieter Tans, Colm Sweeny, and Anna Karion, Jan 15 at NOAA

² NOAA Aircraft Program, www.esrl.noaa.gov/gmd/publications/annrpt25/2_7.pdf retrieved 26-Jan-2010.

Revision	Description	Date
A	Conceptual Design Review	10/12/2009
B	Preliminary Design Review	10/12/2009
C	Critical Design Review	1/15/2010
D	Analysis and Final Report	1/28/2010