Space MonkeysFinal Presentation

Michael Bartek, Jacob Blakely, Katelynn Finn, Katie Fletcher, Lance Markovchick, Michael

Skeen, Thomas Snow

12-02-08

Fall 2008 R

ev D

12-02-08

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 OverviewDigital 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 BatteryMotor 1

Motor 2

Functional Block Diagram Pt 2

Results and AnalysisDigital 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 -3.85 °C at 8:00am

• External Temperature: Minimum -69.16 °C at 7:40am

• External temperature at launch site was about -8°C

Internal Temperature Graph

External Temperature Graph

Relative Humidity

• 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 DownDetail

The BalloonSat shall ascend to an altitude of 30 km on November 15. The BalloonSat shall record internal and external temperatures in degrees Celsius throughout the flight. The attitude of the BalloonSat shall be controlled so that the BalloonSat does not spin on the flight string. The attitude of the BalloonSat shall be measured relative to the camera in degrees off of magnetic north. Pictures shall be taken of the environment outside the BalloonSat throughout the flight. The inside of the BalloonSat shall be kept above a temperature of 0¡ Celsius The acceleration of the BalloonSat shall be recorded in all three axes by an accelerometer to evaluate the success of the attitude and control system The BalloonSat shall not exceed 1000 grams in total. The BalloonSat shall be constructed with a budget of 150 dollars.

The BalloonSat shall attach to a helium balloon by interfacing to the 2.4m Dacron flight string. The BalloonSat will contain and protect all subsystems so that they are not damaged and can be flown again. A Hobo Data Logger shall record the temperature inside and outside the BalloonSat. A Digital Compass shall be used to record the orientation of the camera on the BalloonSat relative to magnetic

Momentum wheels shall be constructed to resist any spinning motion of the BalloonSat. A mass budget and a monetary budget shall be created. A digital camera shall be flown on the BalloonSat. A system of heaters and insulation shall be used to maintain an internal temperature above 0¡ Celsius. An accelerometer shall be flown on the BalloonSat. The BalloonSat shall contain its own power for the entire flight. All tests, design changes, and construction shall be completed prior to November 15 launch date

The BalloonSat structure shall consist of foam core. All components shall be secured down in the box so not to be damaged during flight/landing. In the middle of the box shall be a PVC tube allowing the flight string to pass through the center of the box. On bottom of the tube a ball bearing shall be placed allowing the box to rotate freely perpendicular to the flight string. The BallonSat shall bear the U.S.A. flag and contact information on the outside of the box. The HOBO data logger will use internal and external temperature sensors to measure the temperature inside and outside the BalloonSat A heating circuit shall be used. A space blanket shall be used in addition to the provided insulation

Appendix- Requirements Flow Down

A 3cm by 3cm Plexiglas window shall allow the camera to take pictures of the outside environment from within the BalloonSat. Momentum wheels shall be constructed and attached to the BalloonSat

A Digital Compass shall be calibrated to measure the orientation of the BalloonSat A Basic Stamp II module shall control the digital compass and store its data A Canon A570IS Digital camera shall be flown. A HOBO accelerometer shall be flown to verify the success of the digital compass

Appendix - Cost SummaryPart Part number Vendor Cost

Hitachi HM55B Compass Module 29123 Parallax $36.59

Small DC Electric Motor (2)#GWSPKMOT-1006 Advantage Hobby

$12.49

16 K byte EEPROM COM-00525 SparkFun $5.28

Mylar BlanketN/A N/A

Provided

Ball Bearing Kit7748 VXB Ball Bearings $13.93

Ball Bearing N/A McGuckin Hardware $7.56

Small Washers N/A McGuckin Hardware $1.00

Digital camera and 1GB memory cardN/A N/A

Provided

HOBO data logger with internal and external temperature sensors

N/A N/A

Provided

HeaterN/A N/A

Provided

SwitchesN/A N/A

Provided

Foam CoreN/A N/A

Provided

Batteries (9V and AA)N/A N/A

Provided

Aluminum tapeN/A N/A

Provided

Hot GlueN/A N/A

Provided

InsulationN/A N/A

Provided

Plastic tubeN/A N/A

Provided

Basic Stamp II module and carrier board N/A N/A Provided

Total

$106.85

Monetary Budget:

Appendix - Mass SummaryItem Mass

Camera 220g

HOBO 35g

Basic Stamp II with Carrier Board and Digital Compass

33g

Accelerometer 17g

Heater circuit (no batteries) 17g

(4) 9V Lithium batteries 136g

(1) 9V Alkaline Battery 46g

Foam Core and internal structure 213g

Ball Bearing 1g

(2) Small DC Electric Motor w/ washers

239g

(4) Switches 20g

Total 967g (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?