Science Report
03/01/2014
Prepared by Thibaud Herriau
Helium Balloon expirement - February 26th 2014 - Science Report
This report summarizes
1. the procedure used to build the helium balloon
2. which measurement equipment was used
3. how results were extracted
4. a brie explanation of our methodology
5. Discussion of our results
6. Future opportunities for the experiment
7. The conclusions we can make concerning the experiment overall
1) DIY large-capacity helium balloons
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(For 3 balloons)
Material:
- 3 emergency blankets
- 3 small rubber pipes 3 fitting caps
- a few colsons (= plastic fixing and tightening straps)
- some tape
How to:
- Shape the emergency blankets into balloons, using as few tape as
possible, in order to minimize
their weight.
- use the colsons to attach the rubber pipes at their entrance. The pipes
are the valves that will
allow us to inflate the balloons with helium and close them afterwards
with the caps.
- attach the 3 balloons to each other with a colson, leaving enough space
to insert a rope.
The rope will allow us to attach the nacelle and keep the balloon captive.
2) The nacelle and measuring equipment
---------------------------------------
We built our nacelle using
- balsa wood (strong & light)
- glue/silicone to attach the equipment tightly
- ropes to attach the nacelle to the balloon on its upper side and to a
long (250 ft) rope on its
under side: make small holes in the balsa and tie the rope pieces.
/!\ For stability, you should at least have 3 attach points on both sides
(making a stability
plane).
On the nacelle, we attached
- an anemometer to measure the wind velocity
Ref: Winpoon® LCD Digital Wind Speed Scale Gauge Meter Anemometer Thermometer
- a multimeter measuring: altitude, temperature and humidity
Ref: GSI All-In-One Outdoor Exercise Data Handheld Monitor
- a GoPro Hero2 video camera
3) Extraction of the data
--------------------------
The video footage can be extracted as is.
To have a synchronized view of all measured meteorological data, we used
the video camera to film
the measurement devices.
We then extracted the temperature, wind velocity and humidity as a
function of the altitude by
reading the video frame by frame.
4) Planning and conditions of data acquiring
---------------------------------------------
The initial aim of this experiment was to launch the described setup
(helium balloon attached
nacelle) around 6 times during the two weeks at MDRS, depending on the
weather conditions.
Unfortunately, the amount of helium we were able to bring to the MDRS was
limited to about 800
liters (30 cubic ft).
This should theoritically allow 2 launchs with a payload of 300 grams.
We decided to do only one launch using all 30 cubic feet since 3 factors
were unfavorable:
1. MDRS is located at 1400m altitude, which means lower atmospheric pressure.
2. The temperature can reach quite high values during the day, making the
drag less effective.
3. Our payload weights 500 grams which is too much to be able to perform
two launches.
We choose the following weather conditions for the launch: no risk for
rain and not too windy.
5) Discussion
--------------
A - Data analysis
The collected data showed nothing useful unfortunately.
The altitude raised normally with the height of the nacelle, but all other
measures followed a flat
curve:
Temperature: 20 /- 1°C at every altitude
Humidity: 24% at every altitude
Wind velocity: 0.0 m/s at every altitude
That being said, a few useful points can be raised to get better results:
* Problem 1: measured wind velocity = 0.0 m/s.
Reason: We chose a sunny day with calm wind for the launch EVA. It turns
out there was no wind
during the whole EVA.
Having no wind at all is bad luck, but it should be mentionned using
helium balloons to make weather
measurements has some intrinsic limitations as strong winds don't allow
the balloon to raise
vertically.
* Problem 2: The balloon reached an altitude of 200 ft maximum.
Consequence: The difference in temperature and humidity over 200 ft isn't
big enough to be measured.
Solution: the balloon should be raised at a higher altitude (which needs
more helium and bigger
balloons).
(Note: exceeding a certain altitude, one needs administrative permissions
to launch the balloon).
* Problem 3: The density altitude of air around MDRS is high (2500m)
(Altitude: 1400m -> lower pressure & day-temperature: 25 /-10°C in February)
Consequence: Small difference of density between air and helium. Which
means we need bigger balloons
and more helium for the same upwards drag.
Solution: bigger balloons.
* Problem 4: The helium we were able to get shipped to MDRS was Walmart
helium for party balloons.
It is not of the best quality (i.e. not perfectly pure helium) and
therefore offers a smaller
drag.
Solution: Use helium bottles of better quality.
Note: the helium we used in Belgium for our test launches was top-quality
helium used in chemistry
labs.
* Problem 5: Volume and precision of the measurement equipment.
Consequence: less stable nacelle and less accurate results.
Solution: using more expensive specialized captors and record the data
with a small microprocessor,
e.g. an Arduino.
Note: This solution is more expensive than what was used.
* Problem 6: the images and videos we collected from the balloon were from
good quality but the
ropes of the setup cross the screen from corner to corner.
Avoiding this would enhance the quality of the videos.
B - SIM conditions
Although we knew a week before arriving at MDRS that we wouldn't have
enough helium to do multiple
launches, we kept this experiment as a test to see if our protocol was
doable.
We expected more workable measurements, but knew the experiment wasn't
going to be a scientific
breakthrough.
Therefore, the focus was on the fact that the experiment needed very few
ressources and had to be
performed 100% in SIM conditions. We did a test build on Earth but part of
the experiment was to
rebuild it from scratch at the MDRS, starting with its building in the lab
to the launch during EVA
and the need for an easy way to retrieve the data and analyse it back in
the Hab.
To that end, the restraint on the amount of helium was a huge pluspoint,
since it made the SIM
conditions more difficult and made us think about alternative gases that
could be used on Mars.
The SIM part of the experiment was a success.
- The balloon was easy to build, with materials usefull in many situations.
- The setup did collect the data properly
- The data was easy to retrieve
6) Future opportunities
------------------------
A big concern for this experiment is its reproductibility on Mars.
Mars' atmosphere is different from the one we have on Earth and helium
balloons will have trouble to
fly there.
Also, helium would be way too expensive to transport to Mars.
Therefore, it is important to think of alternative ways to make the
balloons raise on Mars.
Mars has a lot of rocks containing hydroxides.
Those can be processed to retrieve their oxygen content, yielding extra
hydrogen in the process.
One possible way to lift balloons would be to use that hydrogen gas.
On Earth hydrogen gas is dangerous because it explodes when reacting with
the oxygen in the air.
This wouldn't be an issue on Mars since there is no oxygen in the
atmosphere on Mars.
Conclusion
-----------
This experiment at MDRS showed some strenghts and limitations of this
method to acquire meteorogical data.
Building balloons can be done safely in SIM using only multi-purpose
materials and in small amounts.
Bringing helium to Mars is troublesome but other gases could be used
instead, such as hydrogen.
A series of issues were raised in section 5A that should be studied more
thoroughly in order to make the used methodology operational.
The balloons should be big enough to reach high altitudes and lift a
consequent payload, on a repeatable basis.