Space Monkeys Final Presentation Michael Bartek, Jacob Blakely, Katelynn Finn, Katie Fletcher, Lance Markovchick, Michael Skeen, Thomas Snow Fall 2008 Rev D

Mission Overview The BalloonSat Curious George shall ascend to 30 km while using an Attitude Determination system to measure the horizontal orientation of the on-board camera Secondarily, momentum wheels shall control the position of the BalloonSat to stabilize a digital camera in a fixed direction An accelerometer shall be included onboard the BalloonSat to check the data taken by the digital compass

Mission Overview Continued The Space Monkeys team is sending a BalloonSat to altitude to employ simple and inexpensive components for an Attitude Determination and Control subsystem The main mission is to use the attitude and control systems to record the orientation and direction of the camera throughout the flight

Design Overview Design Overview (60 – 120 seconds) –Should be shown with pictures of actual hardware –Include your Functional Block Diagram –Walk everyone through HOW your BalloonSat worked –Discuss differences from your proposal and your final product Digital Compass: It took readings of what direction the BalloonSat was facing during the flight. Camera: The camera took pictures throughout the flight every twenty seconds. Electric Motors: They acted to stabilize the spinning of the BalloonSat Heater: The heater kept the internal temperature of the BalloonSat above -4 degrees Celsius. Accelerometer: It was used to verify the electric motors and measure the movement of the BalloonSat. HOBO: During the flight, the HOBO took internal and external temperature readings. Basic Stamp: It controlled the compass and the timing of the readings. It stored the data taken.

Changes from Proposal The structure was halved in height (20 cm to 10 cm) Accelerometer added HOBO and heater moved to top of BalloonSat No Plexiglas for camera Basic Stamp Carrier Board added

Functional Block Diagram Switch Battery Motor 1 Motor 2

Functional Block Diagram Pt 2

Results and Analysis Digital Compass The compass recorded readings for 4340 seconds (72 minutes, 20 seconds) worth of flight. Readings were taken every 20 seconds The compass and camera were not completely synchronized so compass readings do not match up with the pictures. The timing would need to be recalibrated to synchronize the compass and camera and get the precise direction that the camera is facing. The compass was correctly calibrated and showed that the satellite did not stop rotating Momentum wheels were more effective at higher altitude where there was less atmosphere

N Digital Compass Readings From lift off to approximately 70 minutes into launch Distance from the origin represents the duration of the flight in terms of seconds

Motor Analysis The motors did not resist changes in angular momentum as strong as originally thought. The satellite spun with a varying rate throughout most of the flight With higher RPM’s and/or a higher spinning mass, the momentum wheels would have produced better results. Also, using a microcontroller to control the power input to the momentum wheels would make them more effective when linked to the digital compass readings We cannot determine exactly when the motors ran out of battery power from the compass or accelerometer data, so we cannot determine the motors’ relative effectiveness compared to not having them

HOBO Analysis Internal Temperature: Minimum value °C at 8:00am External Temperature: Minimum °C at 7:40am External temperature at launch site was about -8°C

Internal Temperature Graph

External Temperature Graph

Relative Humidity 29.2% at launch 24.5% at 7:32am 62.3% at 7:38am 42.9% at 7:45am 62.7% at 8:46am There was an increase in humidity as the balloon traveled through the tropopause into the stratosphere. This caused condensation and obscured the pictures taken by the camera for about 30 minutes, a little under 100 pictures.

Relative Humidity Graph Explains condensation on camera lens

Accelerometer No useful data other than it showed that the momentum wheels were working, same type of quick oscillations recorded in cold test

Images Camera images were not obscured by the BalloonSat About 100 pictures were obscured by condensation

Failure Analysis The battery exploded under the heater Possible combination of –Heat –Low pressure –Possible manufacturers defect Contributed to weakened battery casing The heater is moved away from the batteries so they will not overheat Compass and camera weren’t synchronized Fixed by getting fine tuning the exact intervals of the camera and compass

Conclusions The momentum wheels might have been more effective at a higher altitude, but also less atmosphere That electric motors being used as momentum wheels are not very effective when they are constantly running A digital compass is an acceptable device to use to determine attitude of high altitude observatories It would be better to control the power input to the momentum wheels to turn the BalloonSat to the desired heading using a microcontroller

Lessons Learned We believe that we could have tested the BalloonSat more thoroughly if we had time, particularly involving the heater Next time, we would increase the frequency of the digital compass readings We would also look into the necessary code and apparatus to control the power source to the momentum wheels, and how to link that to the digital compass readings We would also have worked on reducing condensation on the camera, possibly by installing another lens in the BalloonSat in front of the camera and adding a chemical to the outside such as Rain-X to repel moisture

Ready to fly again… Damaged insulation was replaced, available batteries replaced Should be stored in dry place that is safe from anything hitting the box and causing structural damage The switches should be taped into the “OFF” position so that the batteries are not depleted in storage

Ready to fly again… All systems verified to still be functional Thread ball bering onto flight string between know and payload Heater turned on 30 minutes before flight Camera turned on 10 minutes before flight Digital compass turned on to synch with camera 2 minutes before flight Electric motors turned on just before flight to save battery

Appendix - Requirements Flow Down

Appendix - Cost Summary Mass summary and cost summary (show but only discuss if time) PartPart numberVendorCost Hitachi HM55B Compass Module 29123Parallax $36.59 Small DC Electric Motor (2) #GWSPKMOT-1006Advantage Hobby $ K byte EEPROM COM-00525SparkFun $5.28 Mylar Blanket N/A Provided Ball Bearing Kit7748VXB Ball Bearings $13.93 Ball Bearing N/AMcGuckin Hardware $7.56 Small Washers N/AMcGuckin Hardware $1.00 Digital camera and 1GB memory card N/A Provided HOBO data logger with internal and external temperature sensors N/A Provided Heater N/A Provided Switches N/A Provided Foam Core N/A Provided Batteries (9V and AA) N/A Provided Aluminum tape N/A Provided Hot Glue N/A Provided Insulation N/A Provided Plastic tube N/A Provided Basic Stamp II module and carrier board N/A Provided Total $ Monetary Budget:

Appendix - Mass Summary ItemMass Camera220g HOBO35g Basic Stamp II with Carrier Board and Digital Compass 33g Accelerometer17g Heater circuit (no batteries)17g (4) 9V Lithium batteries136g (1) 9V Alkaline Battery46g Foam Core and internal structure213g Ball Bearing1g (2) Small DC Electric Motor w/ washers 239g (4) Switches20g Total967g (33g margin)

Appendix - Message to Next Semester Make sure that you leave enough time for adequate time for testing Have a schedule and stick to it Get to know your team mates Do not make the mission unnecessarily complicated

Questions?