1. BOWSER 1 COSGC Space Research Symposium 2010 BOWSER Balloon Observatory for Wavelength and Spectral Emission Readings

2. BOWSER 2 4.3 km above sea level402.3km above sea level Information gathered from Dr. Fesen & Dr. Brown Can the telescopic imaging of HST be achieved on a more affordable, balloon-stationed platform? Mission Premise

3. BOWSER 3 Problems a balloon-borne observatory faces: Optical Disturbances: o Bright Sky Background = Decreased Stellar Magnitude Limit Difficult to Orient Platform Mechanical Disturbances: o Pointing Errors Balloon Movements (Pitch, Roll, Yaw) High-frequency disturbances (on board motors) Mission Premise

4. BOWSER 4 MODTRAN Displays sky background as a function of wavelength, altitude, and angle from the sun Indicates the ideal orientation for daytime observations from the stratosphere Theoretically, the model predicts an adequate reduction in sky brightness in the stratosphere Proving the accuracy of brightness at 35-40 km is vital

5. BOWSER 5 Mission Overview High Altitude Student Platform 2009 (HASP): – BOWSER Proposal won large payload spot January 2009 – Launched September 11, 2009 out of Fort Sumner, New Mexico – Platform ascended on a zero pressure NASA balloon to 36 km and flew for 16 hours experiencing both day and night conditions – Power, communications, and downlink were provided.

6. BOWSER 6 Mission Visual HASP Balloon HASP Payload Verification of the MODTRAN model BOWSER will measure sky brightness as a function of: Altitude Wavelength Angle from the Sun θ 36 km 35.9 km 35.8 km 35.7 km 35.6 km 35.5 km 35.4 km

7. BOWSER 7 Mission Statement: Mission Science Goal Team BOWSER is working towards the eventual goal of supporting the diffraction-limited performance of balloon-borne telescopes. This mission focuses on the specific problem of compensating for mechanical and optical disturbances: BOWSER will measure the amplitude and frequency of disturbances in the typical balloon environment and characterize the stratospheric sky brightness in order to determine the performance requirements for balloon-borne star trackers. Mission Overview Mission Objectives: Mission Objectives Level 0 Objective 1:Team BOWSER will measure the amplitude and frequency of pointing errors in the typical balloon environment. Objective 2:Team BOWSER will measure sky brightness diurnally as a function of altitude, wavelength, and angle from the sun.

8. BOWSER 8 Current data What Has Been Done to the LEDs

9. BOWSER 9 LED Placement For LEDs 1-4, these are where red, orange, and yellow are divided LEDs 5-9 are divided similarly

10. BOWSER 10 Raw Red LED Data Area enlarged in next slide

11. BOWSER 11 Sky Brightness Notice that BOWSER spins in different directions as the peak colors build and descend opposite to each other. This graph is only looking from hours 12.2 to 13.8 of flight. Between the hours of12.8 and 13.6, the straps which connected The balloon to the payload enter the field of view of The LED array. Area enlarged in next slide

12. BOWSER 12 Enlarged Red LED event

13. BOWSER 13 Raw Orange LED Data Area enlarged in the next slide

14. BOWSER 14 Enlarged Orange LED Event

15. BOWSER 15 Raw Yellow LED Data Area enlarged in the next slide

16. BOWSER 16 Enlarged Yellow LED Event

17. BOWSER 17 Movies Current Data Continued…

18. BOWSER 18 Talk about all three tests and at what facility they will be conducted Introduction to Testing

19. BOWSER 19 Goal: – Determine if a small sample of LEDs makes a valid test article to represent the characteristic trends of the entire population of flight LEDs. Assumptions: – It does not matter if the intensity of the light is measured in or because the goal is only to determine if the trend of the sample falls within a valid standard deviation range. – The sun’s intensity remains constant during a single trial. Phase 1

20. BOWSER 20 Phase 2 Goal: – Correct for the non-linear regime of an LED’s response with respect to changes in optical power. Assumptions: – An LED’s response to intensity is the same across all wavelengths.

21. BOWSER 21 Phase 3 Goal: – Produce PSD graphs for each set of three LEDs for a given intensity Assumptions: – The solar intensity does not change between trials – The response of the diode is not a function of the shape of the solar emission spectrum

22. BOWSER 22 Phase 3

23. BOWSER 23 Talk about how the model is going to be implemented from the tests What can we say about the intensity of the sky background with respect to our three parameters (altitude, wavelength and angle from the sun)? Altitude = not much incase we get lucky Wavelength = limited to the sections of the spectrum as seen by the LEDs Angle from the sun = should be able to say a lot at our float altitude Slides on the Model

24. BOWSER 24 Once the LEDs have been tested, flight data can be converted into a model Consists of sky brightness as a function of: – Altitude – Wavelength – Angle from the sun Goal is to validate MODTRAN as fully as possible Implementation

25. BOWSER 25 Expected behavior: – Discrete wavelengths absorbed more at sea level – Effect drops off with altitude – General increase in brightness Altitude

26. BOWSER 26 Model development: – Brightness is integrated over the wavelength range of each set of LEDs. – Difference between actual area and ideal area (no absorption) reveals amount of absorption. – Overlap of three different ranges allow rough estimate of the depth of major divots. Potential setbacks/solutions: – Data must be taken for the same intensity (i.e. must be pointed at the sun) – Must get lucky to have numerous viable data points – May be able to combine with angle from the sun model to increase amount of data Altitude

27. BOWSER 27 Expected behavior: – Wavelength will drop off similarly to a perfect blackbody. – Deviations will occur due to atmospheric absorption. Wavelength

28. BOWSER 28 Model development: – All data is gathered from constant altitude (During float, 120,000 ft) and direct incidence of the sun. – Brightness is integrated over the wavelength range of each set of LEDs. – Area shows total intensity of those three bandwidths. Potential setbacks/solutions: – Lack of resolution: can only identify three ranges. Wavelength

29. BOWSER 29 Expected behavior: – Intensity will drop off exponentially – Predicted drop-off is λ -4 Angle from the Sun

30. BOWSER 30 Model development: – All data is gathered from constant altitude (During float, 120,000 ft). – Angle from the sun is determined by compass data. – Brightness is integrated over the wavelength range of each set of LEDs for various angles. – Decrease in total brightness averaged over the wavelength range, relation with λ determined. Potential setbacks/solutions: – Cannot compare with exact wavelength values, relation with λ is estimated.

31. BOWSER 31 Questions?

32. BOWSER 32 Angle From the Sun Test Looking for a relationship of wavelength -4