1. Skillz That Killz Team 3 Final Presentation
Jocelyn Mulkey
Kaitlyn Zimmitti
Jess Davidoff
Travis Dowdy
Taylor Smith
Hunter Hoopes
December 1, 2009

2. Mission Overview Mission Statement:
To determine if solar cells generate more energy at higher altitudes.
To determine if solar cells would produce enough energy to power a future BalloonSat mission.
We expected to prove that it is possible to power BalloonSats solely with solar energy.

3. Design Overview
We used 12 solar cells in series in an array, a current sensor, a Zener diode, two 30,000 Ohm resistors, and a signal line between resistors to connect the circuit to AVR board. Our structure was a rectangular prism.

4. Functional Block Diagram
2 x 9V
BATTERIES
SOLAR PANELS X 12
Wired in Series
Current Sensor
G-Switch
RBF
Zener Diode
AVR
HOBO
Voltage Divider
3 x 9V BATTERIES
Heater
2GB MEMORY
Camera
2 x AA BATTERIES

5. Differences in Proposal and Final Product
No multiplexer
Instead we used a current sensor, diode, and resistors
Changed structure from cube to rectangular prism
12 solar panels on top instead of one on each side of structure

6. Results and Analysis
Our actual results were not what we expected. We expected voltage to decrease as the satellite fell back to Earth, but it did not do so. However, the solar array did create enough energy to power the BalloonSat.
Our flight went well and as expected except that our pressure sensor and temperature sensor were shorted and as a result our data from those sensors were skewed.

7. Pictures from Flight

8. Failure Analysis
Testing after flight showed that the pressure sensor and temperature sensor were partially shorted together, which explains why the trends of both data sets are similar. Because of this failure, the data from both sensors is unreliable.
The tests we performed in order to determine the cause of the failure were:
Measuring voltage across partially shorted circuit
Correctly circuiting both sensors
Shorting both sensors together completely
We found that the values of the sensors during flight were between the full short values and accurate data points.

9. Conclusions
We were able to conclude that although power did not increase as altitude increased, it would be possible to power a BalloonSat during a clear day if the sun was high in the sky because the power produced by the solar array leveled at about 7 volts.

10. Lessons Learned If we could have done this differently, we would have:
Made our deadlines earlier.
Communicated within the team better.
Taken more care in retrieving data after testing and been more organized with it.
Done more testing.
To get different results, we would have:
Made sure testing data was correct in order to make sure all sensors were working.

11. Ready to Fly Again
Payload should be stored carefully, with nothing on top of it, at room temperature. Batteries should be used within 6 months.
Payload would be activated by installing new batteries and re-arming the payload, then flipping the power switch and the G-switch.
In order to repair the satellite and make it flight-ready again, we fixed the circuit so that the temperature and pressure sensor were no longer partially shorted together.

12. How design meets requirement
Requirements Matrix
Requirement
How design meets requirement
1. Assemble BalloonSat in order to advance our understanding of solar energy up to an altitude of 30 kilometers for under $100 by 11/07/2009.
Satellite was completed on time and team members paid for extra costs over $100.
2. Determine altitude using data from the pressure sensor.
The pressure sensor did not give accurate data during flight. However, EOSS recorded altitude through the flight and this data was used instead of determining altitude from the pressure sensor.
3. Establish if BalloonSat can be powered solely by solar energy.
It was determined that the solar array produce enough energy to power a BalloonSat during a sunny day.
4. The BalloonSat shall not have an internal temperature of less than -10 degrees Celsius.
Heater system and insulation ensured that all hardware was protected during flight by providing adequate heat.
5. The BalloonSat shall have a weight of less than 850 grams.
Total weight of BalloonSat, not including HOBO, was 839 grams.

13. Money and Weight Budget
Item
Proposed Cost (including shipping)
Actual Cost (including shipping)
Weight
AVR Microcontroller and batteries $0
150 g
Heater System and batteries
$9.66
100 g
Foam Core
108 g
Insulation
25 g
Switches (2)
20 g
Flight String Tube
Canon Digital Camera
220 g
HOBO
30 g
Monocrystalline Solar Cells (12)
$59.40
$69.40
84 g
Zener Diode (2)
$15.20
5 g
Current Sensor
<1 g
.1 ohm Resistor
$2.29
Breakout Board
$5.19
Resistors (7)
2 g
Velcro
1 g
Aluminum Tape
Hot glue
Extra Wire
10 g
Test Batteries (5x9V and 1xCR1220 )
$15.22
$26.40
N/A
Dry Ice
$20.00
$21.95
TOTAL
$ (Cost over $100 covered by team members)
$ (Cost over $100 covered by team members)
Total of known: 817 g
Actual Weight : 869 g

14. Message to Next Semester
This class is hard and it should be about a 10 credit class. You will sacrifice a lot of sleep this semester. Be prepared to be stressed and worried about your experiment. That being said, it’s also a class that teaches you a lot about working with a team and using your resources. Don’t be afraid to ask questions! Most people don’t know what they’re doing right away; usually it’s alright to have no idea what you’re doing, as long as you work hard to figure it out. You’re very likely going to worry about your grade, but don’t. Worry more about using this class as a learning experience. It’s hard to mess up your grade if you go to class. But definitely always be working on the project. Don’t wait to make deadlines, no matter how much time you think you have! Everything takes longer than you think it will. You’re not done after launch! There is a lot to analyzing data and preparing the final report, no matter how simple it sounds. Also, make sure your team communicates well. Communication is critical to having a successful project. If your team is having problems, address them early. Have meetings frequently and make sure everyone is caught up with the project. Make sure more than one person knows how the components of your satellite work and that everyone is involved. Take advantage of the people in SpaceGrant who know what they’re doing. Most of them will be more than willing to help you.