The BOREALIS program is a high altitude scientific balloon program operated by the Montana Space
Consortium. In this activity students will use a model of the BOREALIS
balloon system to study buoyancy issues which help insure a successful
scientific balloon flight. Students will measure the lift capability of
their balloon. They will then mass the payload components to determine
which instruments can be included on the flight while remaining within the
mass limit. Finally, students will compete in a ``race to the ceiling''
where the last one to the top is the winner, since a longer balloon flight
allows for more collection of scientific data.
Materials
To complete this activity each team will need the following materials:
1 pre-constructed BOREALIS balloon model
(visit here
for model building instructions)
approximately 10-20 paper punch pieces or grains of rice
(NOTE: this item depends on the lift capability of the balloon used to
make the BOREALIS model. Once the model is complete, you will want it
to carry approximately 10-20 uniform objects. Experiment to determine
if the balloon system you have can lift 10-20 paper punch pieces, rice
grains or some other uniform object like popcorn kernels.)
Classroom scale with metric weight set (including milligram weights)
The BOREALIS team must measure the lift of the balloon before each
flight so that they know it will lift the payload modules and
instruments. The BOREALIS team is able to fill the balloon at the
launch site and they can make sure they fill it with enough helium to
provide the necessary lift. You can see a picture of the team members
measuring the balloon lift with a scale in the image below.
In this activity the balloon is already filled, and therefore has a
certain amount of lift. You will measure that lift and then make sure
you do not include more mass in the vehicle than the balloon can
handle.
It will be easiest to measure the balloon lift if we leave the
vehicle components attached. That way the payload capsule
boxes can hold the weights from the weight set.
To measure the lift of the balloon itself we will first measure the
mass of the vehicle components.
Take your model of the BOREALIS balloon project and have a
fellow team member hold on to the balloon so that it is not providing
any lift to the vehicle system. Place the vehicle system on a scale
and measure the mass of all the components together. Record this mass
in Box A at the bottom of the Balloon Mass Sheet.
Now release the balloon so that the system is floating. Hold
onto it just enough to keep it from floating away. Place weights into
the payload capsules until the balloon is just barely able to float
upward. Record the amount of mass you added to the capsules. Since
the vehicle must remain attached to the balloon during flight, the
amount of addition mass you were able to add is the allowable mass for
the instruments in your scientific payload. Record this mass in Box B
att eh bottom of the Balloon Mass Sheet.
Add together the mass of the vehicle (Box B) and the mass of the
additional weights you placed inside. This number is the total lift
of your balloon. Record the balloon lift in Box C on the Balloon Mass
Sheet.
Payload Instruments
In this activity we will represent the scientific instruments on your
balloon flight by small, uniform objects. We would like the balloon
model to be able to carry approximately 10 - 20 small objects. Paper
punch pieces, rice grains or popcorn kernels might be good choices,
you'll have to experiment (if your teacher has not done so already) to
determine which objects work with your balloon so that it can carry
10-20 pieces.
Once you have determined what type of small object you will be
using to represent the scientific instruments measure the mass of one
of these objects. For example, measure the mass of one paper punch
piece, or one rice grain. (Since these objects are so light, it may
be easiest to measure the mass of 100 objects, and then divide the
answer by 100 to get the mass of just one.) Record the mass of one
payload object on the Balloon Mass Sheet in column 3. The same number
should be written all the way down column 3.
Column 1 on the Balloon Mass
Sheet lists several different instruments which have been flown on the BOREALIS
balloon. You can read about these different instruments at the instrument web
site here.
Each instrument has a mass which is represented by the number of
mass units in column 2 on the Balloon Mass Sheet. Multiply the number
in column 2 by the mass of one unit (column 3) to calculate the total
mass of each particular instrument. Record the total instrument mass
in column 4.
You must now choose which instruments you would like to fly on
your balloon flight. You can choose more than one of some instruments
if you want. For instance, if you flew two thermometers one could
measure the temperature inside the capsule, while the other measured
the temperature outside the capsule. However, you must not have a
total payload weight which is larger than the allowable payload weight,
or your balloon will sink! It is best to choose a combination of
instruments which gets very close to the allowable payload weight.
This will allow your balloon to rise slowly, which will maximize your
flight time, providing a long mission in which to take data.
Once you have decided on which instruments to fly, record the
total payload weight in Box D on the Balloon Payload sheet. You may
want to calculate several possible instrument combinations on scratch
paper before deciding on your final payload.
Now fill the capsules on the balloon model with the appropriate
number of objects to represent the instruments you have chosen. For
example, place four objects in the capsule for each camera you are
flying. Place two objects inside for each thermometer and so on. Do
this for all the instruments you have chosen to fly.
The Race: Last One Wins!
Once everyone has loaded their balloon vehicles with the instruments
it is time for launch! The object is to be the last team to the
ceiling. Longer flights are able to collect more scientific data. Good
luck!
Activity Extensions
Teachers may wish to have each student, or group, write a science
proposal about the science they could do on their balloon flight. For
example, students could choose to explain what temperature
measurements might be interesting to make, and why. Such proposals
could elaborate on what type of pictures a camera payload might take
and what they might learn from such pictures.
Other students may want to research weather conditions to
determine which direction a scientific balloon might travel if
launched in their area.
