I believe that the reason why CO2 did not drop was because of the gas chamber.
Since we did not take away any CO2 or put any in while it was testing, wouldn't that mean that the mV would not change at all? I could be wrong because I don't know how the gas chamber worked. (As in how it creates the pressure) Because if it does suck the air out of the glass jar there could be a drop in CO2 since it is getting sucked out.
I believe that the reason why CO2 did not drop was because of the gas chamber.
Since we did not take away any CO2 or put any in while it was testing, wouldn't that mean that the mV would not change at all? I could be wrong because I don't know how the gas chamber worked. (As in how it creates the pressure) Because if it does suck the air out of the glass jar there could be a drop in CO2 since it is getting sucked out.
Dylan,
An interesting hypothesis. But we must consider two things:
1) The vacuum pump sucked all the air out of the bell jar and so CO2 concentration decreased. Do you agree or disagree?
2) If you read Dr. Allen's discussion on partial pressure versus parts per million it seems that air pressure affects the CO2 mV reading. As altitude increase, even if CO2 concentration stays the same, the changing pressure affects the CO2 mV reading. How and why?
Dr. Allen and Sylvie, is what I've explained to Dylan accurate? Could you help clarify?
The concept and theory behind answer to #2 is important to understand Dylan, because we could falsely conclude that CO2 concentration increased (or decreased) with altitude when what really happened was that the CO2 sensor responded to the change in pressure as altitude increased!!
To "prove" this point look at yesterday's graph. Did the humidity (purple graph line) really change when the altitude (yellow line) increased because the pressure in the bell jar changed...? And why didn't CO2 mV (light ble line) change at all? I'm eager to read your, and your teammates' (including Dr. Allen's and Sylvie's) thoughts and comments.
Dylan, I think you are right, in a way. As the vacuum pump works, it sucks out molecules without regard to whether they are N2 or O2 or CO2 or whatever. The proportion of those molecules stays the same as the pressure drops--There is just less of everything. So if the MG811 sensor does in fact respond to parts-per-million, then you would expect zero change in reading as the vacuum pump works. That is the result. Does that mean the sensor responded to ppm?
In the real ASP-2 flight, there might be a small change in CO2 ppm concentration with altitude because of the effect of gravity and chemical reactions going on in the atmosphere. That is different from a vacuum jar.
On the other hand, I was expecting the sensor to respond as much to partial pressure as to ppm. Here are the response equations from the MG811 data sheet:
See that last term in the equation, involving P(CO2)? That definitely says "partial pressure", not "parts-per-million". There are good reasons from physical chemistry that you would expect a response to partial pressure. The two units of measurement become inter-convertible when you are talking about a constant pressure, like standard pressure of 1013.25 millibar.
Here is the graph from the MG811 data sheet again, one that you have already see many times.
See, the x axis is definitely in units of ppm, and the conditions on the left include temperature and %RH and O2 concentration, but not pressure. But I think it probably should have said something like, "P=1013.25 mbar" as one of the conditions.
One thing I want you all to take away from this is 1) look at data sheets carefully and 2) look at data sheets critically. Read between the lines, challenge your assumptions.
Now, remember all our talk early on about interpolation and extrapolation? When you put this sensor in a vacuum, or in a depleted CO2 environment, you are going below the limit of CO2 concentration that is plotted on the graph. Extrapolation. You are testing what happens. Reaching into the unknown. Do you see all the other lines for other gases that are flat at 320 mV? Its as though that 320mV level is kind of a limit, and no matter what, maybe that is as low as the sensor can go. Did we talk about how extrapolation is more "dangerous" than "interpolation"? The only way to see is to test it, and that "characterization" is what you are doing.
The lack of response in the CO2 reading could mean 1) it does in fact respond to ppm, not pp, or 2) it simple does not respond at low gas pressures and extrapolation is unjustified. What do you think?
When you say that when we test it in the gas chamber, it simulates altitude increase. Isn't that for just pressure? It is not inserting more or less chemicals that correspond to the altitude, it just simulates the altitude treasure wise. Am I wrong?
When you say that when we test it in the gas chamber, it simulates altitude increase. Isn't that for just pressure? It is not inserting more or less chemicals that correspond to the altitude, it just simulates the altitude treasure wise. Am I wrong?
Dylan,
No, we didn't insert any more gases into the vacuum chamber (the large glass 'bell jar' that we used on Sunday.) The change in pressure as we evacuated (sucked out) the gases simulated a change in altitude because, as altitude increases, air pressure changes. Does air pressure increase or decrease as altitude increases?
Dr. Allen makes a good point and poses a good question: did we decrease the concentration of gases (especially CO2) as we evacuated the air? No. There was just less of CO2 (N2 and O2), but at the same concentration. The question he posed that we still have to answer is: Is the CO2 sensor responding to a change in air pressure (it appears that it didn't), to a change in CO2 (it does outside the vacuum chamber, or both? Ultimately we need to know the answers so we can accurately and correctly interpret the data we get. We don;t want to falsely conclude that CO2 concentration increased (or decreased) when what really appened was the sensor detected and recorded a change in air pressure as the altitude changes.
I like one of Dr. Allen's parting comments: "Challenge your assumptions!" That what scientist do, and we still need answers to the questions above. Justin, Sean, Mike, Andrew (Sylvie?), what do you guys think? How do we make sense of the data we're getting from the vacuum chamber, then how do we apply that knowledge to our flights... in just 3-1/2 weeks~! Let's stick with it until we understand what's going on and then have the "right" answers. We are, in fact, characterizing the Parallax CO2 sensors! We're doing real science, not theoretical work or make-believe stuff. You are doing the work of scientists. :rolleyes:
Below is a calibration procedure for a hand-held 'Pasco' module and sensor I have in the science lab that measures CO2 in ppm.
QUESTIONS:
1) How can we use this procedure to help calibrate the CO2 sensor on the ASP?
2) What helpful information does the procedure give us that we can apply to the ASP?
3) What could we do with the hand-held Pasco module and the ASP side-by-side; how could that help us?
=======================================
Calibration Procedure for the Pasco Carbon Dioxide Sensor
1. Go outside and collect a sample of fresh air (CO2 in typical atmospheric conditions is around 400 ppm).
2. Insert the sensor assembly and probe into the upright sampling bottle. Be sure the stopper fits snugly into the neck of the bottle.
3. Bring the sensor/bottle assembly inside and connect it to the interface. Ensure the interface is turned on and connected to a computer.
4. On the top of the Carbon Dioxide Sensor, move the range switch button to the 10K range position.
5. In the software setup window, double click on the CO2 Sensor icon (to open the Sensor Properties dialog); then click on the Measurement tab, and select the 10K concentration range.
6. In the software, open a display and click the Start button to observe the carbon dioxide reading. Wait at least 90 seconds for the reading to stabilize.
7. Press the Calibrate button on the sensor and hold for 3 seconds. The green light will stay on to indicate calibration has begun.
8. Wait approximately one minute. When the green light flashes again, calibration is finished.
I like one of Dr. Allen's parting comments: "Challenge your assumptions!" That what scientist do, and we still need answers to the questions above. Justin, Sean, Mike, Andrew (Sylvie?), what do you guys think? How do we make sense of the data we're getting from the vacuum chamber, then how do we apply that knowledge to our flights...
I'm again going to sit tight for now while Dr. Allen helps you to figure this out, unless something leaps out at me. This is definitely his area. But I'm still paying close attention.
I'll be out of town on Thursday and half of Friday, attending the NASA Wisconsin Space Grant Consortium annual meeting. This year's presentations will focus on asteroids and our missions to them.
As an aside, last Thursday night I had the best star-gazing night of my life. I was out far from the city, seeing "All's Well that Ends Well" at a beautiful outdoor theatre in central Wisconsin, and afterwards, found a darksky spot out there and set up my little 3" "goto" refractor, and was able to see three galaxies, probably 6 globular clusters and 4 open clusters, 3 or 4 gaseous nebulae, and of course Jupiter. All the while with my naked eyes I got to watch meteors from the Perseid shower, which peaked the night before but was still going strong for the first hour at least that I was out there. If you have dark skies, and any interest in astronomy, you can get a nice little scope for only a couple of hundred dollars that will really take you places.
You're very much on the right track with that calibration procedure.
Suppose you have two measuring cups, and both have marks that go from 1 to 10. You fill the first one with water up to the 10 mark. Then you pour it into the second cup, but you see that it only comes up to the 8 mark. Can you find a formula that lets you convert from one unit of measurement to the other? Example: the second cup is full to the 4 mark, and you pour the water into the first cup. What mark does it come up to there?
This is like any problem of units conversion, such as cups to liters. Sometimes the marks on the cups have the same units, so you just have to say "units-cup1" and "units-cup2" to distinguish them. Even though the units are arbitrary, it is the same idea. It takes a calibration to go from cup1 units to cup2 units. If you have a quart measuring cup and a liter measuring cup, the calibration has already been done for you at a factory somewhere.
Now suppose one cup is full of stuff to the 2.5 Volt mark, where as a second cup is full to the 2.1 Volt mark with the same amount of stuff. What is the conversion factor? Got it? Okay, how about this: Stuff fills the second cup to the 1.5 Volt level, how high would it be in the first cup? Yes, cups are not Volts, but it is the same idea.
Challenge your assumptions. Do you have to make any assumptions in the above story?
Sylvie, I envy you the good viewing and am gladdened to hear about those wonderful objects you saw. It was cold and overcast here in the Bay area for the Perseids. Anyway, it is always too bright with city lights here for good viewing. We did have a bright night sky in the mountains a couple of weeks ago. A number of years ago I was backpacking in the crater of Mt. Haleakala on Maui for the Perseids, and the scene like a moonscape was worth the trip.
1) How can we use this procedure to help calibrate the CO2 sensor on the ASP?
-Could this procedure work on the ASP-2?
2) What helpful information does the procedure give us that we can apply to the ASP?
-Is it that CO2 concentration in typical atmospheric conditions is around 400 ppm?
3) What could we do with the hand-held Pasco module and the ASP side-by-side; how could that help us?
-We could compare the two different numbers and see if we can find the equation that is similar in all of the numbers.
"1) How can we use this procedure to help calibrate the CO2 sensor on the ASP?"
A. The steps may be similar for calibrating the Pasco module as for the CO2 sensor on the ASP. There might be a range that both have to be set to (steps 4 and 5).
2) What helpful information does the procedure give us that we can apply to the ASP?
A. Like Sean said the typical atmospheric conditions are around 400 ppm. In steps 4 and 5 we know there's a range. Could this be similar to the ASP?
3) What could we do with the hand-held Pasco module and the ASP side-by-side; how could that help us?"
A. With each of them running (and if I'm reading Dr. Allen's examples right) then we could find an equation that applies to both of them. We could also find an equation in the numbers for the ppm for both like Sean said.
What could we do with the hand-held Pasco module and the ASP side-by-side; how could that help us?"
A. With each of them running (and if I'm reading Dr. Allen's examples right)... we could find an equation that applies to both of them. We could also find an equation in the numbers for the ppm for both like Sean said.
Justin
Justin, Sean, and Dr. Allen,
You're all three thinking on the same wavelength; maybe some day Sean and Justin you can follow in Dr. Allen's footsteps. I agree that we could run the two sensors side by side and then calculate a conversion factor from the Pasco CO2 sensor that we could apply to the ASP's CO2 sensor. This is assuming altitude doesn't affect the CO2 sensor's mV data, like what happened in the vacuum chamber. This is a big assumption to make though... seems like it might even violate the laws of physics (see Nernst's equation and the Faraday constant that Dr. Allen mentioned above.) Or maybe you're treading on cutting-edge research with NASICON materials... That would be cool!
I propose that we run the two sensors side by side in closed container with ambient air (the air around us) to get a baseline data point. Then we'll put them in the sealed vacuum chamber, still side-by side, and measure CO2 on the Pasco sensor. We can correlate that with the ASP's CO2 sensor millivoltage. We could do that at different pressure altitudes in the vacuum chamber (4,000 feet = 100 psi. 8,000 feet =200 psi, 12,000 psi =3,000 feet, etc.)
What's are everyone's thoughts on this idea? **Rocketeers, please don't agree with me to "make me happy" (I'm already happy!) or just to get the project done. Think, talk, and then we'll plan.
Good teamwork Justin, Sean, and Dr. Allen!
==================================
So Sylvie, did you see any Perseids at all? It was too cloudy here. Globular clusters are nice, but... the Perseids,Gemenids, the Lyrids, and (Brrrrr!) the Leonids can be stellar. We have a 12" Schmidt-CAssegrain at the school that I'm sorry to say gets little use (along with its CCD camera.) Too many irons, too much fire, too little time!
How about go the other direction too with the Pasco? Put both sensors in a big plastic bag and rebreath the air in the bag a few times (but don't overdo it!). Record and report the data! And/or put both sensors in a terrarium day and night to see if plants really do exchange O2 and CO2 in photosythesis.
Do you know what the operating principle of the Pasco sensor? Many CO2 sensors use the NDIR technique. Does the Pasco use that technique? Is it a different method from the MG811? Rocketeers, google NDIR. How does it work?
It seems to me that having a second, presumably already calibrated sensor (the Pasco) makes all of the earlier stuff about finding a couple of datapoints moot (you know, my comment about running the ASP in helium and so on). If you can run the two side by side, you've got all the calibration points you want.
Now you're not going to find one equation that applies to both sensors, I don't think. Each sensor will have a different equation, and in fact, I think we've learned that each of the different Parallax CO2 sensors is different enough to require its own equation. But you'll get the data you need to find the equation for the one you wind up using. I think things are really rolling now.
==================
I did see about 12 Perseids, including about 4 really good ones. No fireballs, but good bright streaks.
I don't have dark skys here at home, though with the 3" scope I CAN see the Orion Nebula from my balcony (in fact, it's rising right about now). I can get to decent skies in about a 45 minute drive, though, and I'm starting to find the good spots to set up.
NDIR stands for, "non-dispersive infrared absorbance. The sensor that has an infrared lamp located somewhere on the front of the device. Most molecules can absorb infrared light, but only at certain times. It depends on how much of the certain chemical is concentrated at one point. (If the chemical is not densely populated in the certain area, it won't absorb the infrared light) The sensor will examine how much infrared light was absorbed by gases by looking at the CO2's wavelength. The sensor will know the properties of CO2 and how it reacts to infrared light so it is able to pick it out of a crowed of other gases. Therefor, if there is allot of CO2 in a specific area, the sensor will experience a different wavelength, and then be able to tell how much CO2 is present.
I understand that they are both not of a reliable source, .edu, .gov, .org, but they where the best sources that, "Looked like they new what they where doing".
What exactly do you mean by. "...in a closed container..."?
What I mean is, put both the Pasco CO2 sensor and the ASP in a closed, sealed container like the vacuum jar (or anything big enough to hold them both that we can put a lid on.) That way the CO2 concentration would stay same for both sensors.
Like Sylvie and Dr. Allen said, the ASP would measure CO2 in millivolts (mV) while the Pasco sensor measures CO2 in parts per million (ppm.) Then we would make a "comparison chart" (on Excel, etc.) showing how many ppm = how many mV. We'd start at ambient (room) conditions then figure out a way to change the CO2 concentration. Maybe we could put "dry ice" (which is frozen carbon dioxide) in the vacuum chamber to get a higher concentration, or something like that. Then we would connect the data points (dots) on the graph to make a graph similar to the one we've used all along. We would calculate the constant for this graph using the slope intercept formula and simply multiply the constant by the ASP's millivoltage to get ppm.
Like Dr. Allen explained before, this is called "characterizing" the sensor. It gives us a unquie constant for the sensor we will use in the flights.
Sylvie and Dr. Allen, am I on track here? Does this seem correct? If not, please feel free to correct me and certainly add your thoughts and comments.
Good answers, Dylan. Each element or molecule can absorb or give off light at very specific wavelengths. It is not an understatement to say that a lot of science and engineering is done by shining light on or through things or by looking at natural light sources or absorbers. Emission and absorption lines are what allow us to figure out the elements and molecules that are present in distant galaxies. The "lines" are very narrow spectral (color) bands that have to do with the electron energy shells of the atoms. In NDIR, there is some method of selecting only the very narrow line that is characteristic of carbon dioxide. Usually it is a specialized optical interference filter that cancels out everything but the one line.
It is great to have a calibraton standard. That changes everything. Otherwise we have only the fact that atmospheric concentration is near 400ppm. We could do interesting things with that. But it will be great to have a few more points to determine a scale factor. It will not be quite as simple as y=ax+b (linear equation), because remember the sensor is nonlinear in its dependence of mV on ppm. But calibration points will be an immense help to fix the curve.
Are you going to be testing the sensors and the Pasco sensor? Or are you still waiting for our input?
I'm glad you asked this - I am wondering how this is going. It seems like you have what you need in order to move forward, but you have very little time to do so.
Dr. Allen can correct me here, but it seems to me that you need to:
1) make sure your ASP2 is working properly, in that it responds to all of the things it is meant to measure, and correctly logs them to the USB drive.
2) put the ASP2 into a closed environment with the Pasco, and get a good collection of datapoints on both sensors, spread across the full range of CO2 concentrations that you expect to see on the flight.
3) Do the math: knowing then what you know about the voltage put out by the CO2 sensor and how it varies with the CO2 concentration reported by the Pasco sensor, find an equation relating that voltage to that concentration.
Test it repeatedly, and put together those checklists and the like that Mr. Kibler asked for a few posts ago.
Now, in theory steps 2 and 3 can be done after the flight - if you collect good voltage data AND the sensor survives the flight, you can do the calibration stuff after the flight (though I might ask Dr. Allen if the sensor will be changed by the flight).
But I think you have only about three weeks until you need to be ready to fly, right? You're right, Dylan, to ask whether or not something is expected of you right now. You can't afford to be wasting days with miscommunication.
==========================
Today I was at the Space Grant Consortium conference, and saw some presentations by college students doing work very similar to yours. The high altitude balloon payload crew had projects that really reminded me of yours, and in fact they used several Basic Stamps to collect and record data. Once you guys get to high school and college you might want to look into contests and scholarships offered by your state's Space Grant Consortium.
Are you going to be testing the sensors and the Pasco sensor? Or are you still waiting for our input?
Dylan,
The answers to your questions are, "yes", and "yes". Chris and I just finished calibrating the Pasco CO2 sensor and it's ready to go. To calibrate it we first had to let the sensor warm up (90 seconds), collect a CO2 sample in the sealed "catch jar", then run the sensor inside the jar for another 90 seconds. Ambient CO2 concentration (at ground level, 25 Celsius and 61% humidity) was 398-402 ppm.
What should I (or rather, we) do now...?
I can bring the Pasco CO2 sensor to Pat's Peak tomorrow when we help with Chili Fest if anyone wants. But then, don't we need a "game plan", a scientific procedure to follow? So, what should I we do with the Pasco CO2 sensor and the ASP-2 now? :idea:
HINT #1: Read Dr. Allen's excellent explanation about the physics of how the Pasco CO2 sensor works... a bit differently than the ASP's CO2 sensor. Thanks Dr. Allen!
(BIG) HINT #2: Read Sylvie's post just above.Thanks Sylvie!
After you read these two posts, guide me through a step-by-step procedure. What do we do first, second, third, etc.?
We could, and should meet and do this as a team. But with school starting on Monday (Chili Fest tomorrow, and the Goffstown Rotary presentation Tuesday morning), our "lab time" is limited. Do you want your CO2 reading to be in "ppm" or "mV" when you make your presentation to scientists and professors the day after you launch? Let's think, plan and work now, before we run out of time and have a zillion other things to do at the same time on launch day.
... Once you guys get to high school and college you might want to look into contests and scholarships offered by your state's Space Grant Consortium.
Sylvie,
Thanks for encouraging the Rocketeers onward and upward by reminding them about the scholarships-- and many, many other opportunities-- that await them if they continue along the Path of Excellence they've chosen to forge and follow!
Thanks for encouraging the Rocketeers onward and upward by reminding them about the scholarships-- and many, many other opportunities-- that await them if they continue along the Path of Excellence they've chosen to forge and follow!
============================
Is that you in the sailplane ?!
Yup, that's me in the sailplane, at Dillingham Field on Oahu back in 2005, just before taking off for some aerobatics. I didn't look quite the same color when I got back to the ground.
Re. the scholarships, I'm kinda frustrated that I've got access to all of this money that my students could be getting their hands on - but I can't find students who are interested in space sciences or technology. I am dead certain that I could get them scholarships and great internships, but none of them are interested. You wouldn't believe the great things these undergraduates get to do, working internships at the NASA Research centers, flying in the "Vomit Comet" with their experiments, and lots of other really cool things that I would have killed to have been able to do. I hope your students take advantage of them. I'm told that our Space Grant Consortium is one of the best (heck, I get to work with a woman who runs one of the Mars rovers...), but I'm sure there's the same kinds of opportunities out there.
After reading your post Sylvie, I just HAD to respond.
During my senior or before that year in high school, during the summer for ten or nine weeks, I wanted to take an internship at NASA in California. Not really, but I would kill for an internship at NASA, even if I had to pay for an apartment for the entire summer by myself! I have no idea what students would be turning that down! I mean, if I am qualified as one of your students, i'm always available :P.
After reading your post Sylvie, I just HAD to respond.
During my senior or before... I would kill for an internship at NASA. :P.
Dylan,
First, thanks so much for coming to Chili Fest and helping out in the rain. You don't know how much the Rotarians enjoyed seeing you and your teammates there, and how much they appreciated your help.
Regarding a NASA high school internship, now's the time to start looking. Simply "google" 'NASA high school internships" (or something similar.) You will be surprised :hop: how many internships and scholarships are available to you already. Keep in mind that each internship has certain criteria (age, grade in school, etc.) and that they have deadline application dates. Apply sooner rather than later and let me know how I can help out.
After reading your post Sylvie, I just HAD to respond.
"... I would kill for an internship at NASA even if I had to pay for an apartment for the entire summer by myself!" :P.
Dylan and Rocketeers,
For internship information, read below. There's a link at the bottom of this page but there are many, many other internships available. This one is at NASA's Jet Propulsion Lab (JPL) in California. The stipend ("allowance") you get is $3,000.
JPL SpaceSHIP (Summer High School Internship Program) - Program Overview
The Jet Propulsion Laboratory Summer High School Internship Program (JPL SpaceSHIP) is an 8-week internship designed for high school students, age 16 or older, who have demonstrated a strong interest in and aptitude for science, technology, engineering and/or mathematics (STEM). One of JPL SpaceSHIP's objectives is to encourage pre-college students who have been traditionally underrepresented in STEM fields to consider such fields for their careers.
Students participating in JPL SpaceSHIP are provided an opportunity to do introductory research, work in a technical environment, and expand their computer skills under the guidance of NASA's science, engineering, and technical professionals. Here are some examples of past projects SpaceSHIP students worked on:
Developed strategies for social media web sites: YouTube, Facebook, Twitter- JPL missions and projects want to be part of social media too. Students worked with a variety of projects to create plans for connecting with the public on social media sites.
Worked with databases and software: Several students tested and evaluated database systems. Another student helped develop procedures for software testing.
Evaluated and updated data and computer models: Some students analyzed and classified science data. Others updated models for a future spacecraft's flight path.
Participants will also have an opportunity to develop and prepare written technical reports and abstracts, make a formal final presentation, interact with students from diverse cultural backgrounds and participate in numerous enrichment activities while earning a stipend for the internship.
Located in Pasadena, California, JPL is the leading NASA Center for robotic exploration of the solar system. More information about JPL can be found at http://www.jpl.nasa.gov.
Eligibility Requirements
Students must be U.S. citizens
All participants must be at least 16 years old at the time of participation (June 28, 2010)
With the exception of the letters of recommendation, this application must be completed by the student and represent the student's own work
Student's home address must lie within a 50 mile radius of JPL's Oak Grove facility (4800 Oak Grove Drive, Pasadena, CA 91109-8009)
All applicants must have a 3.0 GPA or above based on a 4.0 scale
Student application must provide evidence of interest in and aptitude for science, technology, engineering and/or mathematics
Finalists will be interviewed prior to selection. Selected students are responsible for their own transportation to and from JPL and if under the age of 18, must provide a work permit.
Program Duration
8 weeks
June 28 - August 20, 2010
Student participation is required for the entire duration of the internship
Stipend $3,000 per internship (taxable)
Sorry everybody for the gap in our conversation. We had a rotary to present to today and had to really rush to prepare for it since at the last moment, Mr. Kibler discovered he could not make it.
Sorry everybody for the gap in our conversation. We had a rotary to present to today and had to really rush to prepare for it since at the last moment, Mr. Kibler discovered he could not make it.
Rocketeers,
EXCELLENT JOB at the Rotary presentation today! :jumpin:
You obviously "wow-ed" them and they rewarded your efforts accordingly. Well done! I'm eager to hear all the details. I'm please to see that you were confident, and comfortable, in making a major presentation without me there. Good leadership and excellent teamwork!
Dylan,
Did you have a chance to read through the information and links about student internships at NASA (in the post above)? If not, then you should.
It is only for college students so I will still look for one for when I am in high school. The one you sent me a link to seems to need me to live within 50 miles of the area it is taking place.
*after looking through high school internships*
I have just seen, WAY to much programs and what not at too many different flight centers. This will defiantly be something I will need help on.
P.S. When are we going to test the PASCO and the CO2 sensor? If we are, are we going to each write our own procedures? I feel as if September is creeping up way to fast for us to finish in time.
"When are we going to test the PASCO and the CO2 sensor? ...are we going to each write our own procedures? I feel as if September is creeping up way too fast."
I'm waiting for the team to work together and write one procedure, then e-mail it to me so that Chris and I can test it. But he's running short on time too. He leaves for college down in DC right after I get off school this Friday (12-13 hour drive.)
See Sylvie and Dr. Allen's posts on the last page. They explain how to write the procedure. You're right: we are running out of time and we only have one team practice left. It's on Sunday, Sept. 12th just two days before we leave. Everything-- like the procedure--will need to be done long before then because we're packing up that day! :shocked:
Comments
I believe that the reason why CO2 did not drop was because of the gas chamber.
Since we did not take away any CO2 or put any in while it was testing, wouldn't that mean that the mV would not change at all? I could be wrong because I don't know how the gas chamber worked. (As in how it creates the pressure) Because if it does suck the air out of the glass jar there could be a drop in CO2 since it is getting sucked out.
Dylan,
An interesting hypothesis. But we must consider two things:
1) The vacuum pump sucked all the air out of the bell jar and so CO2 concentration decreased. Do you agree or disagree?
2) If you read Dr. Allen's discussion on partial pressure versus parts per million it seems that air pressure affects the CO2 mV reading. As altitude increase, even if CO2 concentration stays the same, the changing pressure affects the CO2 mV reading. How and why?
Dr. Allen and Sylvie, is what I've explained to Dylan accurate? Could you help clarify?
The concept and theory behind answer to #2 is important to understand Dylan, because we could falsely conclude that CO2 concentration increased (or decreased) with altitude when what really happened was that the CO2 sensor responded to the change in pressure as altitude increased!!
To "prove" this point look at yesterday's graph. Did the humidity (purple graph line) really change when the altitude (yellow line) increased because the pressure in the bell jar changed...? And why didn't CO2 mV (light ble line) change at all? I'm eager to read your, and your teammates' (including Dr. Allen's and Sylvie's) thoughts and comments.
Mr. Kibler
In the real ASP-2 flight, there might be a small change in CO2 ppm concentration with altitude because of the effect of gravity and chemical reactions going on in the atmosphere. That is different from a vacuum jar.
On the other hand, I was expecting the sensor to respond as much to partial pressure as to ppm. Here are the response equations from the MG811 data sheet:
See that last term in the equation, involving P(CO2)? That definitely says "partial pressure", not "parts-per-million". There are good reasons from physical chemistry that you would expect a response to partial pressure. The two units of measurement become inter-convertible when you are talking about a constant pressure, like standard pressure of 1013.25 millibar.
Here is the graph from the MG811 data sheet again, one that you have already see many times.
See, the x axis is definitely in units of ppm, and the conditions on the left include temperature and %RH and O2 concentration, but not pressure. But I think it probably should have said something like, "P=1013.25 mbar" as one of the conditions.
One thing I want you all to take away from this is 1) look at data sheets carefully and 2) look at data sheets critically. Read between the lines, challenge your assumptions.
Now, remember all our talk early on about interpolation and extrapolation? When you put this sensor in a vacuum, or in a depleted CO2 environment, you are going below the limit of CO2 concentration that is plotted on the graph. Extrapolation. You are testing what happens. Reaching into the unknown. Do you see all the other lines for other gases that are flat at 320 mV? Its as though that 320mV level is kind of a limit, and no matter what, maybe that is as low as the sensor can go. Did we talk about how extrapolation is more "dangerous" than "interpolation"? The only way to see is to test it, and that "characterization" is what you are doing.
The lack of response in the CO2 reading could mean 1) it does in fact respond to ppm, not pp, or 2) it simple does not respond at low gas pressures and extrapolation is unjustified. What do you think?
When you say that when we test it in the gas chamber, it simulates altitude increase. Isn't that for just pressure? It is not inserting more or less chemicals that correspond to the altitude, it just simulates the altitude treasure wise. Am I wrong?
Dylan,
No, we didn't insert any more gases into the vacuum chamber (the large glass 'bell jar' that we used on Sunday.) The change in pressure as we evacuated (sucked out) the gases simulated a change in altitude because, as altitude increases, air pressure changes. Does air pressure increase or decrease as altitude increases?
Dr. Allen makes a good point and poses a good question: did we decrease the concentration of gases (especially CO2) as we evacuated the air? No. There was just less of CO2 (N2 and O2), but at the same concentration. The question he posed that we still have to answer is: Is the CO2 sensor responding to a change in air pressure (it appears that it didn't), to a change in CO2 (it does outside the vacuum chamber, or both? Ultimately we need to know the answers so we can accurately and correctly interpret the data we get. We don;t want to falsely conclude that CO2 concentration increased (or decreased) when what really appened was the sensor detected and recorded a change in air pressure as the altitude changes.
I like one of Dr. Allen's parting comments: "Challenge your assumptions!" That what scientist do, and we still need answers to the questions above. Justin, Sean, Mike, Andrew (Sylvie?), what do you guys think? How do we make sense of the data we're getting from the vacuum chamber, then how do we apply that knowledge to our flights... in just 3-1/2 weeks~! Let's stick with it until we understand what's going on and then have the "right" answers. We are, in fact, characterizing the Parallax CO2 sensors! We're doing real science, not theoretical work or make-believe stuff. You are doing the work of scientists. :rolleyes:
Mr. Kibler
Below is a calibration procedure for a hand-held 'Pasco' module and sensor I have in the science lab that measures CO2 in ppm.
QUESTIONS:
1) How can we use this procedure to help calibrate the CO2 sensor on the ASP?
2) What helpful information does the procedure give us that we can apply to the ASP?
3) What could we do with the hand-held Pasco module and the ASP side-by-side; how could that help us?
=======================================
Calibration Procedure for the Pasco Carbon Dioxide Sensor
1. Go outside and collect a sample of fresh air (CO2 in typical atmospheric conditions is around 400 ppm).
2. Insert the sensor assembly and probe into the upright sampling bottle. Be sure the stopper fits snugly into the neck of the bottle.
3. Bring the sensor/bottle assembly inside and connect it to the interface. Ensure the interface is turned on and connected to a computer.
4. On the top of the Carbon Dioxide Sensor, move the range switch button to the 10K range position.
5. In the software setup window, double click on the CO2 Sensor icon (to open the Sensor Properties dialog); then click on the Measurement tab, and select the 10K concentration range.
6. In the software, open a display and click the Start button to observe the carbon dioxide reading. Wait at least 90 seconds for the reading to stabilize.
7. Press the Calibrate button on the sensor and hold for 3 seconds. The green light will stay on to indicate calibration has begun.
8. Wait approximately one minute. When the green light flashes again, calibration is finished.
Mr. Kibler
I'm again going to sit tight for now while Dr. Allen helps you to figure this out, unless something leaps out at me. This is definitely his area. But I'm still paying close attention.
I'll be out of town on Thursday and half of Friday, attending the NASA Wisconsin Space Grant Consortium annual meeting. This year's presentations will focus on asteroids and our missions to them.
As an aside, last Thursday night I had the best star-gazing night of my life. I was out far from the city, seeing "All's Well that Ends Well" at a beautiful outdoor theatre in central Wisconsin, and afterwards, found a darksky spot out there and set up my little 3" "goto" refractor, and was able to see three galaxies, probably 6 globular clusters and 4 open clusters, 3 or 4 gaseous nebulae, and of course Jupiter. All the while with my naked eyes I got to watch meteors from the Perseid shower, which peaked the night before but was still going strong for the first hour at least that I was out there. If you have dark skies, and any interest in astronomy, you can get a nice little scope for only a couple of hundred dollars that will really take you places.
Suppose you have two measuring cups, and both have marks that go from 1 to 10. You fill the first one with water up to the 10 mark. Then you pour it into the second cup, but you see that it only comes up to the 8 mark. Can you find a formula that lets you convert from one unit of measurement to the other? Example: the second cup is full to the 4 mark, and you pour the water into the first cup. What mark does it come up to there?
This is like any problem of units conversion, such as cups to liters. Sometimes the marks on the cups have the same units, so you just have to say "units-cup1" and "units-cup2" to distinguish them. Even though the units are arbitrary, it is the same idea. It takes a calibration to go from cup1 units to cup2 units. If you have a quart measuring cup and a liter measuring cup, the calibration has already been done for you at a factory somewhere.
Now suppose one cup is full of stuff to the 2.5 Volt mark, where as a second cup is full to the 2.1 Volt mark with the same amount of stuff. What is the conversion factor? Got it? Okay, how about this: Stuff fills the second cup to the 1.5 Volt level, how high would it be in the first cup? Yes, cups are not Volts, but it is the same idea.
Challenge your assumptions. Do you have to make any assumptions in the above story?
Sylvie, I envy you the good viewing and am gladdened to hear about those wonderful objects you saw. It was cold and overcast here in the Bay area for the Perseids. Anyway, it is always too bright with city lights here for good viewing. We did have a bright night sky in the mountains a couple of weeks ago. A number of years ago I was backpacking in the crater of Mt. Haleakala on Maui for the Perseids, and the scene like a moonscape was worth the trip.
Here are my answers to your recent questions:
1) How can we use this procedure to help calibrate the CO2 sensor on the ASP?
-Could this procedure work on the ASP-2?
2) What helpful information does the procedure give us that we can apply to the ASP?
-Is it that CO2 concentration in typical atmospheric conditions is around 400 ppm?
3) What could we do with the hand-held Pasco module and the ASP side-by-side; how could that help us?
-We could compare the two different numbers and see if we can find the equation that is similar in all of the numbers.
Sean
Here are my answers to your questions:
"1) How can we use this procedure to help calibrate the CO2 sensor on the ASP?"
A. The steps may be similar for calibrating the Pasco module as for the CO2 sensor on the ASP. There might be a range that both have to be set to (steps 4 and 5).
2) What helpful information does the procedure give us that we can apply to the ASP?
A. Like Sean said the typical atmospheric conditions are around 400 ppm. In steps 4 and 5 we know there's a range. Could this be similar to the ASP?
3) What could we do with the hand-held Pasco module and the ASP side-by-side; how could that help us?"
A. With each of them running (and if I'm reading Dr. Allen's examples right) then we could find an equation that applies to both of them. We could also find an equation in the numbers for the ppm for both like Sean said.
Justin
Justin, Sean, and Dr. Allen,
You're all three thinking on the same wavelength; maybe some day Sean and Justin you can follow in Dr. Allen's footsteps. I agree that we could run the two sensors side by side and then calculate a conversion factor from the Pasco CO2 sensor that we could apply to the ASP's CO2 sensor. This is assuming altitude doesn't affect the CO2 sensor's mV data, like what happened in the vacuum chamber. This is a big assumption to make though... seems like it might even violate the laws of physics (see Nernst's equation and the Faraday constant that Dr. Allen mentioned above.) Or maybe you're treading on cutting-edge research with NASICON materials... That would be cool!
I propose that we run the two sensors side by side in closed container with ambient air (the air around us) to get a baseline data point. Then we'll put them in the sealed vacuum chamber, still side-by side, and measure CO2 on the Pasco sensor. We can correlate that with the ASP's CO2 sensor millivoltage. We could do that at different pressure altitudes in the vacuum chamber (4,000 feet = 100 psi. 8,000 feet =200 psi, 12,000 psi =3,000 feet, etc.)
What's are everyone's thoughts on this idea? **Rocketeers, please don't agree with me to "make me happy" (I'm already happy!) or just to get the project done. Think, talk, and then we'll plan.
Good teamwork Justin, Sean, and Dr. Allen!
==================================
So Sylvie, did you see any Perseids at all? It was too cloudy here. Globular clusters are nice, but... the Perseids,Gemenids, the Lyrids, and (Brrrrr!) the Leonids can be stellar. We have a 12" Schmidt-CAssegrain at the school that I'm sorry to say gets little use (along with its CCD camera.) Too many irons, too much fire, too little time!
"I've seen it rainin' fire in the sky",
Mark
Do you know what the operating principle of the Pasco sensor? Many CO2 sensors use the NDIR technique. Does the Pasco use that technique? Is it a different method from the MG811? Rocketeers, google NDIR. How does it work?
Now you're not going to find one equation that applies to both sensors, I don't think. Each sensor will have a different equation, and in fact, I think we've learned that each of the different Parallax CO2 sensors is different enough to require its own equation. But you'll get the data you need to find the equation for the one you wind up using. I think things are really rolling now.
==================
I did see about 12 Perseids, including about 4 really good ones. No fireballs, but good bright streaks.
I don't have dark skys here at home, though with the 3" scope I CAN see the Orion Nebula from my balcony (in fact, it's rising right about now). I can get to decent skies in about a 45 minute drive, though, and I'm starting to find the good spots to set up.
I got my sources from both.
http://www.intl-lighttech.com/applications/light-source-apps/ndir-gas-sensor/ndir-gas-sensor-index
and
http://www.raesystems.com/~raedocs/App_Tech_Notes/Tech_Notes/TN-169_NDIR_CO2_Theory.pdf
I understand that they are both not of a reliable source, .edu, .gov, .org, but they where the best sources that, "Looked like they new what they where doing".
Good research, and an excellent answer! That's helpful information to know and understand.
I got a hand-held shortwave receiver for the project and it reads out the longitude and latitude for the ASP transmitter beautifully.
Keep up the good work. You have a bright future ahead of you.
Mr. Kibler
What exactly do you mean by. "...in a closed container..."?
What I mean is, put both the Pasco CO2 sensor and the ASP in a closed, sealed container like the vacuum jar (or anything big enough to hold them both that we can put a lid on.) That way the CO2 concentration would stay same for both sensors.
Like Sylvie and Dr. Allen said, the ASP would measure CO2 in millivolts (mV) while the Pasco sensor measures CO2 in parts per million (ppm.) Then we would make a "comparison chart" (on Excel, etc.) showing how many ppm = how many mV. We'd start at ambient (room) conditions then figure out a way to change the CO2 concentration. Maybe we could put "dry ice" (which is frozen carbon dioxide) in the vacuum chamber to get a higher concentration, or something like that. Then we would connect the data points (dots) on the graph to make a graph similar to the one we've used all along. We would calculate the constant for this graph using the slope intercept formula and simply multiply the constant by the ASP's millivoltage to get ppm.
Like Dr. Allen explained before, this is called "characterizing" the sensor. It gives us a unquie constant for the sensor we will use in the flights.
Sylvie and Dr. Allen, am I on track here? Does this seem correct? If not, please feel free to correct me and certainly add your thoughts and comments.
Another good question Dylan!
Almost there,
Mr. Kibler
It is great to have a calibraton standard. That changes everything. Otherwise we have only the fact that atmospheric concentration is near 400ppm. We could do interesting things with that. But it will be great to have a few more points to determine a scale factor. It will not be quite as simple as y=ax+b (linear equation), because remember the sensor is nonlinear in its dependence of mV on ppm. But calibration points will be an immense help to fix the curve.
Exactly. A well calibrated standard is
Are you going to be testing the sensors and the Pasco sensor? Or are you still waiting for our input?
I'm glad you asked this - I am wondering how this is going. It seems like you have what you need in order to move forward, but you have very little time to do so.
Dr. Allen can correct me here, but it seems to me that you need to:
1) make sure your ASP2 is working properly, in that it responds to all of the things it is meant to measure, and correctly logs them to the USB drive.
2) put the ASP2 into a closed environment with the Pasco, and get a good collection of datapoints on both sensors, spread across the full range of CO2 concentrations that you expect to see on the flight.
3) Do the math: knowing then what you know about the voltage put out by the CO2 sensor and how it varies with the CO2 concentration reported by the Pasco sensor, find an equation relating that voltage to that concentration.
Test it repeatedly, and put together those checklists and the like that Mr. Kibler asked for a few posts ago.
Now, in theory steps 2 and 3 can be done after the flight - if you collect good voltage data AND the sensor survives the flight, you can do the calibration stuff after the flight (though I might ask Dr. Allen if the sensor will be changed by the flight).
But I think you have only about three weeks until you need to be ready to fly, right? You're right, Dylan, to ask whether or not something is expected of you right now. You can't afford to be wasting days with miscommunication.
==========================
Today I was at the Space Grant Consortium conference, and saw some presentations by college students doing work very similar to yours. The high altitude balloon payload crew had projects that really reminded me of yours, and in fact they used several Basic Stamps to collect and record data. Once you guys get to high school and college you might want to look into contests and scholarships offered by your state's Space Grant Consortium.
Dylan,
The answers to your questions are, "yes", and "yes". Chris and I just finished calibrating the Pasco CO2 sensor and it's ready to go. To calibrate it we first had to let the sensor warm up (90 seconds), collect a CO2 sample in the sealed "catch jar", then run the sensor inside the jar for another 90 seconds. Ambient CO2 concentration (at ground level, 25 Celsius and 61% humidity) was 398-402 ppm.
What should I (or rather, we) do now...?
I can bring the Pasco CO2 sensor to Pat's Peak tomorrow when we help with Chili Fest if anyone wants. But then, don't we need a "game plan", a scientific procedure to follow? So, what should I we do with the Pasco CO2 sensor and the ASP-2 now? :idea:
HINT #1: Read Dr. Allen's excellent explanation about the physics of how the Pasco CO2 sensor works... a bit differently than the ASP's CO2 sensor. Thanks Dr. Allen!
(BIG) HINT #2: Read Sylvie's post just above. Thanks Sylvie!
After you read these two posts, guide me through a step-by-step procedure. What do we do first, second, third, etc.?
We could, and should meet and do this as a team. But with school starting on Monday (Chili Fest tomorrow, and the Goffstown Rotary presentation Tuesday morning), our "lab time" is limited. Do you want your CO2 reading to be in "ppm" or "mV" when you make your presentation to scientists and professors the day after you launch? Let's think, plan and work now, before we run out of time and have a zillion other things to do at the same time on launch day.
Standing by,
Mr. Kibler
Sylvie,
Thanks for encouraging the Rocketeers onward and upward by reminding them about the scholarships-- and many, many other opportunities-- that await them if they continue along the Path of Excellence they've chosen to forge and follow!
============================
Is that you in the sailplane ?!
Mark
Yup, that's me in the sailplane, at Dillingham Field on Oahu back in 2005, just before taking off for some aerobatics. I didn't look quite the same color when I got back to the ground.
Re. the scholarships, I'm kinda frustrated that I've got access to all of this money that my students could be getting their hands on - but I can't find students who are interested in space sciences or technology. I am dead certain that I could get them scholarships and great internships, but none of them are interested. You wouldn't believe the great things these undergraduates get to do, working internships at the NASA Research centers, flying in the "Vomit Comet" with their experiments, and lots of other really cool things that I would have killed to have been able to do. I hope your students take advantage of them. I'm told that our Space Grant Consortium is one of the best (heck, I get to work with a woman who runs one of the Mars rovers...), but I'm sure there's the same kinds of opportunities out there.
During my senior or before that year in high school, during the summer for ten or nine weeks, I wanted to take an internship at NASA in California. Not really, but I would kill for an internship at NASA, even if I had to pay for an apartment for the entire summer by myself! I have no idea what students would be turning that down! I mean, if I am qualified as one of your students, i'm always available :P.
Dylan,
First, thanks so much for coming to Chili Fest and helping out in the rain. You don't know how much the Rotarians enjoyed seeing you and your teammates there, and how much they appreciated your help.
Regarding a NASA high school internship, now's the time to start looking. Simply "google" 'NASA high school internships" (or something similar.) You will be surprised :hop: how many internships and scholarships are available to you already. Keep in mind that each internship has certain criteria (age, grade in school, etc.) and that they have deadline application dates. Apply sooner rather than later and let me know how I can help out.
Still drying out,
Mr. Kibler
Dylan and Rocketeers,
For internship information, read below. There's a link at the bottom of this page but there are many, many other internships available. This one is at NASA's Jet Propulsion Lab (JPL) in California. The stipend ("allowance") you get is $3,000.
JPL SpaceSHIP (Summer High School Internship Program) - Program Overview
The Jet Propulsion Laboratory Summer High School Internship Program (JPL SpaceSHIP) is an 8-week internship designed for high school students, age 16 or older, who have demonstrated a strong interest in and aptitude for science, technology, engineering and/or mathematics (STEM). One of JPL SpaceSHIP's objectives is to encourage pre-college students who have been traditionally underrepresented in STEM fields to consider such fields for their careers.
Students participating in JPL SpaceSHIP are provided an opportunity to do introductory research, work in a technical environment, and expand their computer skills under the guidance of NASA's science, engineering, and technical professionals. Here are some examples of past projects SpaceSHIP students worked on:
Developed strategies for social media web sites: YouTube, Facebook, Twitter- JPL missions and projects want to be part of social media too. Students worked with a variety of projects to create plans for connecting with the public on social media sites.
Worked with databases and software: Several students tested and evaluated database systems. Another student helped develop procedures for software testing.
Evaluated and updated data and computer models: Some students analyzed and classified science data. Others updated models for a future spacecraft's flight path.
Participants will also have an opportunity to develop and prepare written technical reports and abstracts, make a formal final presentation, interact with students from diverse cultural backgrounds and participate in numerous enrichment activities while earning a stipend for the internship.
Located in Pasadena, California, JPL is the leading NASA Center for robotic exploration of the solar system. More information about JPL can be found at http://www.jpl.nasa.gov.
Eligibility Requirements
Students must be U.S. citizens
All participants must be at least 16 years old at the time of participation (June 28, 2010)
With the exception of the letters of recommendation, this application must be completed by the student and represent the student's own work
Student's home address must lie within a 50 mile radius of JPL's Oak Grove facility (4800 Oak Grove Drive, Pasadena, CA 91109-8009)
All applicants must have a 3.0 GPA or above based on a 4.0 scale
Student application must provide evidence of interest in and aptitude for science, technology, engineering and/or mathematics
Finalists will be interviewed prior to selection. Selected students are responsible for their own transportation to and from JPL and if under the age of 18, must provide a work permit.
Program Duration
8 weeks
June 28 - August 20, 2010
Student participation is required for the entire duration of the internship
Stipend $3,000 per internship (taxable)
http://jplspaceship.jpl.nasa.gov/
Aim high,
Mr. Kibler
Rocketeers,
EXCELLENT JOB at the Rotary presentation today! :jumpin:
You obviously "wow-ed" them and they rewarded your efforts accordingly. Well done! I'm eager to hear all the details. I'm please to see that you were confident, and comfortable, in making a major presentation without me there. Good leadership and excellent teamwork!
Dylan,
Did you have a chance to read through the information and links about student internships at NASA (in the post above)? If not, then you should.
Mr. Kibler
http://www.nasa.gov/offices/education/programs/descriptions/Marshall_Robotics_Academy.html
It is only for college students so I will still look for one for when I am in high school. The one you sent me a link to seems to need me to live within 50 miles of the area it is taking place.
*after looking through high school internships*
I have just seen, WAY to much programs and what not at too many different flight centers. This will defiantly be something I will need help on.
P.S. When are we going to test the PASCO and the CO2 sensor? If we are, are we going to each write our own procedures? I feel as if September is creeping up way to fast for us to finish in time.
"When are we going to test the PASCO and the CO2 sensor? ...are we going to each write our own procedures? I feel as if September is creeping up way too fast."
I'm waiting for the team to work together and write one procedure, then e-mail it to me so that Chris and I can test it. But he's running short on time too. He leaves for college down in DC right after I get off school this Friday (12-13 hour drive.)
See Sylvie and Dr. Allen's posts on the last page. They explain how to write the procedure. You're right: we are running out of time and we only have one team practice left. It's on Sunday, Sept. 12th just two days before we leave. Everything-- like the procedure--will need to be done long before then because we're packing up that day! :shocked:
Mr. Kibler