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Scientific Research in a Gas Balloon

by Lunar_Lander
Tags: balloon, research, scientific
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Aug12-09, 04:22 AM
P: 38

I was shown these forums by a friend who studies Astrophysics and he suggested me that I could present my little science project here. I hope that this area is OK for that, because I assume that my project is not as advanced (i.e. that it already delivered results), that it could go into "Independent Research".

Since I was about 12, I read quite a good amount of material on research balloons (it was started when I found a Adventures book in my village's library, which had an account on Prof. Piccard's stratosphere flight in 1931). With time, I collected more and more material, mostly on the stratosphere flights in the USA and the USSR in the 1930s, but later also about the open-basket flights of the 19th and early 20th century. Most of the information I have is about the flights of James Glaisher in the UK in 1862-66, with some more info about French flights from 1804 (by Gay-Lussac), 1850 (Barral and Bixio) and from 1870-78 (Tissandier brothers and others).

Another German book from 1900 that I own, discusses all these flights, and also 75 flights made in Germany in the time span 1888-99. This research later continued until 1934.

During reading this book and especially the description and the criticism on Glaisher's flights, I thought about the fact that nowadays there are only unmanned research balloons that ascend well into the stratosphere. I then thought that it might be worth it to try and conduct an ascent with a standard gas balloon, taking modern versions of the instruments that had been taken up by Glaisher and others. So I contacted a gas balloon pilot, and he said that a flight in his 650m3 balloon would cost 800 USD, and one in his 1050m3 balloon would be 1400 USD, when he and I would be the only persons in the balloon. I thought that it would be a really cheap price for a science project and started designing a scientific program for the flights (I still hope to find a sponsor, who is maybe willing to pay several flights, maybe up to five of them. I'll explain the reasons for that later).

My program is based mostly on what had been done by Glaisher and the other balloonists, with some additions of Barral and Bixio's program.
First in the list are the four normal meteorological measurements:
barometric pressure
temperature of the air
humidity of the air
direction and velocity of the wind

All these had been measured in the past with instruments containing mercury, which always had been a danger to the balloon crew and environment. Thus I still don't know whether to take a mercurial barometer or rather an electronic pressure sensor. As for the temperature and humidity, I would use the installation introducted on the German flights: Two timber bars support an aspirated psychrometer to hang 1.6 meters away from the basket. This and the aspiration would eliminate solar heating and would give the true numbers for temperature and humidity. (Glaisher had put all of his apparatus on a board which he placed across the basket, where the board then obviously was heated by the sun, influencing all of his thermometers)
I would double check the observations with an electrical thermometer, also aspirated, and humidity with a stock building store hygrometer, because then you could compare the performance of the two methods (in my tests I have run, I found the hygrometer to be up to 10% off from that what the psychrometer said).
The wind could be easily determined from the velocity and direction of the balloon, as the balloon moves as fast as the wind. Only that I would use GPS instead of navigational fixes, which might not be available at all, if there are clouds obscuring the Earth.

Next up are electrical and magnetic measurements, for which I would take either an electrometer with a long metal wire suspended from it (as it was done "back then"), or a modern electrofieldmeter. For the magnetic measurements I would use a Hall-Probe or observe the duration of several oscillations of a magnetic needle. You see again, that this would be a perfect opportunity to "Cross-Check" the "old" and the "new" method, but I would say that the apparatus you need for that work is a bit bulky and heavy, so it might be only possible to take the new instruments (which I would prefer as some kind of "Standard").

Then, there is the measurement of the incoming solar radiation. Here I would like to repeat an experiment Barral and Bixio did: They mounted three identical thermometers on a polished metal board. Then they coated the bulb of one of the thermometers with silver, and blackened the bulb of the third thermometer, and left the second unchanged. Unfortunately the blackened bulb thermometer broke during launch, leaving them only with the normal and the silver thermometer. In addition to this I would take an actinometer or a similar electronic device. (To come back to Glaisher: From the second year of his work on, he had an actinometer on-board, and also a blackened-bulb thermometer on one flight. It was astonishing for him to find that the difference between the blackened and the normal dry thermometer was zero all the time, whereas the actinometer showed a significant solar input. Also an error that was induced by is observation board)

I also would like to follow Glaisher by taking up a spectroscope and pointing it at the sky, Earth and the sun. I have found instructions on how to build a spectroscope with employing a CD, maybe I will make one of these or lend myself a spectroscope from my school (they already said that I may use some of the apparatus they have).

To conclude the physical experiments, there is the VLF-3 receiver from the Inspire Inc. ( group, who have shown interest in measuring VLF waves from a free flying balloon. Also, I would like to take an instrument to measure incoming particle radiation, a Geiger Counter for example.

These would be all physical experiments. I have thought about an Aitken dust counter, a balloon gas thermometer or a luxmeter, but I don't want to stretch the program too far. Maybe these two are good for a later flight.

Then I have some chemical experiments. First up is the collection of air samples at different altitudes, where I hope that I could have them analyzed at the University here (for which I have to ask). Then an apparatus to determine CO2 gravimetrically (by aspirating air through tubes filled with KOH and weighing them before and after. Finally Ozone measurements both with air analysis tubes calibrated for O3 and ozone papers like Glaisher had used them (starch papers coated with KI solution).

Finally I would like to do some biological measurements, though I think that I would need professional assistance for that. I think about having a bacteria collector of some kind (either on-board like it was done in Munich in 1904 or one that is dropped on a parachute like on the Explorer II in 1935), and maybe some plant samples and insects to study the influences the flight had on them.

These would be my experimental program. As for the statement that I would like to do more then one flight: I think that several flights would have the advantage to gather more data, and to build Flight 2 on the experiences of Flight 1 (which could be improving or even omitting experiments which were too awkward to handle, etc.)

I would welcome any discussion about the project, because I think that the forum here is a great international platform with many interested people who have experiences that I do not have !
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