Construction of Balloon Mapping Equipment

Introduction

Our geospatial fields methods class will be conducting an exciting balloon mapping project this semester.  The project is composed of two different aspects, with the first being a balloon being launched above campus with a camera in continuous shot mode taking aerial images to then be mosaicked together to create a map.  The second aspect is a high altitude balloon launch, HABL for short, which consists of a balloon being launched into space with a camera taking a video of its travels.  This report will document the preparations and construction of materials for these projects.  Some very basic instructions with came with the balloon kit, so other websites were looked at to get a better understanding of the projects.
Here is the link to the website that our balloon kit was purchased from: http://publiclaboratory.org/wiki/balloon-mapping-kit
These two sites also had information on launching balloons:
http://archive.publiclaboratory.org/download/Grassroots_Mapping_English_2_0.pdf
http://the-rocketman.com/recovery.html

Methodology
Behind every successful field outing is a lot of preparation and planning.  To prepare for our balloon mapping projects, there were many tasks that needed to be accomplished.  These included: construction of mapping and HABL rigs, weighing of mapping and HABL rigs, parachute testing, creation of a method for implementing continuous shot on cameras, and testing of tracking device.  The class consists of about 20 students, and individuals were able to work on whichever aspect of the planning and construction they were most interested in.  This flexibility also allowed people to walk between the different projects that people were working on and get a good sense of what was going on in each phase of the construction.

Mapping Balloon
Two different groups worked on prototypes for the low altitude mapping rig.  The basic concept was to hang a camera from string in some sort of a plastic container.  The plastic container would have a portion cut out with the camera facing out in that direction.  The first prototype utilized a plastic jug with the bottom portion of it cut off.  The camera was then hung facing down with string as shown in Figure 2.

Figure 1. Side view of low altitude mapping rig prototype.

Figure 2. Bottom view of low altitude mapping rig prototype.

The second design is shown in Figure 3.  Here, a two liter bottle of soda is used to house the camera, which is secured to the bottle using zip ties.  The bottle is laid sideways, with a rectangle cut out of the bottom for a clear view for the camera.

Figure 3. "Hindenberg" prototype.

HABL
Since the HABL will be launched into space, the design is much more complicated.  A basic diagram can be seen in Figure 4.  Our design will use a styrofoam container generally used for minnows to house the camera and tracking device.  Connected to the payload is the parachute, which will deploy when the balloon pops.  Due to decreasing pressure in the atmosphere, the balloon will continue to expand until it pops.  Finally, the balloon can be seen on top.

Figure 4. Diagram of HABL rig.

As mentioned before, a styrofoam container used to hold minnows will be used to house the camera.  A small hole was cut into the bottom of the container for the camera to look out of (Figure 5).

Figure 5. Small hole for camera view.

The camera will be fastened to the bottom of the container using plastic zip ties.  High altitudes have very cold temperatures which can present issues to the electronic equipment.  In response to this, the HABL rig will have several handwarmers to keep the camera and tracking device from getting too cold.  To keep camera and handwarmers secure, a round piece of insulation was cut out to be placed on top (Figure 6).

Figure 6. Cutting the round insulation piece.

Weighing of Materials for Rigs

Determining the weight of materials used to construct the rigs is key to our project.  The helium balloon that will be used to lift the rigs can only support two pounds.  Therefore, it was important to know the weight of materials used, as well as the final weight of each payload.  One group of students was in charge of weighing and recording these weights (Figure 7).  Figures 8-11 show some of the materials used in construction.

Figure 7. Weighing materials for construction.

Figure 8. Zip ties.

Figure 9. Handwarmers.

Figure 10. Carabineer that will be used to connect the rope.

Figure 11. Rope that will be used to connect the payload, parachute, and balloon.

The following is a list of materials and their weight.

Balloon Mapping Weight Chart
Item	Weight
Balloon (Orange)	315.5 g
Balloon (Red)	322.25 g
Black rubber ring (~1 inch)	8.25 g
Camera (Biggest, black)	392.17 g
Carabineer (blue with key ring)	4.79 g
Carabineer (silver with loop)	26.71 g
Coke Bottle (2 liters, empty, whole with cap)	50.86 g
Coke Bottle (Top, Label "1")	18.6 g
Coke Bottle (Top, Label "2")	12.5 g
Handwarmers (2 in package)	54.37 g
Jif Peanut Butter (No cap, empty, whole)	48.6 g
Memory card (16 gb)	2.16 g
Memory card (32 gb)	2 g
Minno Thermo with lid and rope	75.85 g
Mt. Dew (2 liters, empty, whole with cap)	52.08 g
Orange Camera (No memory card)	185.77 g
Parachute (blue and orange)	144.7 g
Pink Rope (1 meter)	1.15 g
Rainex Bottle (Empty, whole with cap)	141.36 g
Rope (150 ft.)	416.51 g
Rubber band (black, midrange)	2.8 g
Rubber band (blue, thin, medium)	2.37 g
Rubber band (Extra small, orange)	1.14 g
Rubber band (long, tan, thin)	4.7 g
Rubber band (long, white, wide)	14.4 g
Rubber band (short, white, wide)	5.69 g
Rubber band (thin, white)	3.5 g
Silver Camera (No memory card)	187.5 g
Styrofoam (Pink, 1.5 by 19 by 17.5 in)	200.3 g
Yellow Cord with buckle	106.5 g
Zip Tie (Black)	1.5 g
Zip Tie (long, multicolored)	1.16 g
Zip Tie (Short, multicolored)	.31 g
7 Packs of Handwarmers	379.86 g
Cut Styrofoam+Minno Thermo	102.12 g
Green Bottle (With cannon, grey "Hindenburg")	239.69 g
Total Pay Load for High Altitude	944.34 g = Approx. 2.08 lbs

Parachute Testing

Another objective of our planning process was to test the parachute that would be bringing our rigs back safely to the ground.  To do this, a water bottle was filled up so that it weighed two pounds.  It was then put into the minnow bucket and attached to the parachute (Figure 8).

Figure 12.  Parachute testing rig.

The parachute was then dropped from a window on the fourth floor of the science building to the ground.  The rig was dropped three times from the fourth floor, and even though the parachute was not slowing the descent as much as we hoped, the minnow bucket did a good job of absorbing the impact from the ground.  Here is a video that was filmed from the ground of the rig being dropped.

Continuous Shot Method for Cameras
It was determined that the HABL would have the camera in video mode, while the low altitude balloon's camera would be in continuous shot mode for better quality images that would be used in the mapping process.  A test was performed to see which method used up more storage space.  A video was taken for 20 seconds, and then continuous shot mode was used for 20 seconds, with the camera taking a picture every second.  When comparing the file spaces, it was found that the continuous shot mode used up a considerable more amount of file storage.  In order for a camera to be in continuous shot mode, the button for taking a picture must be held down.  To accomplish this during the flight of the balloon, a rubber band will be put around the camera to hold the button down (Figures 9, 10).

Figure 13. Orange rubber band wrapped around camera to hold the button down.

Figure 14. View of how the camera will be hung in the low altitude balloon rig.

Testing of Tracking Device
A tracking device is necessary in these rigs because winds could blow them many miles.  Our class obtained a small GPS tracking device that can be tracked using an iPad.  The device was tested by some classmates taking a walk outside with it around campus, while others watched their path on the iPad.

Discussion
This project provided our class with a lot of issues that we needed to discuss and solve.  We were not given a specific set of instructions, so we had to consult resources and use our creativity to construct the two different balloon rigs.  This also led to a lot of collaboration between the whole class.  People had to communicate what part of this planning, testing, and construction process they were going to be involved in, as well as ideas they might have had.  This planning day should help us immensely when it comes to actually launching our balloons.  Only a few last minute tweeks to the designs should have to be made.  It also gives us confidence that all of our equipment works properly.  Hopefully, all of this preparation will make the launching of the balloons a success.  I believe that both aspects of this balloon project will prove to be very exciting and interesting.  This is a great opportunity to be involved in a cool scientific project that hopefully produces good results.

Conclusion
As you can see, our class did a lot of work in preparation for the balloon mapping projects that we will be participating in.  In this preparation, we constructed two prototypes for the low altitude balloon mapping project, constructed the HABL, weighed all of the construction materials to ensure the balloon would be able to support the weight, tested the parachute, and developed a method for keeping the camera in continuous shot mode.  The balloons will be launched towards the end of the semester when the weather is nicer.  The results of this project will be uploaded then.