BOWSER Balloon Observatory for Wavelength and Spectral Emission Readings

Transcription

1 COSGC Space Research Symposium 2009 BOWSER Balloon Observatory for Wavelength and Spectral Emission Readings BOWSER 1

2 Mission Premise 4.3 km above sea level 402.3km above sea level BOWSER 2 Information gathered from Dr. Fesen & Dr. Brown Can the telescopic imaging of HST be achieved on a more affordable, balloon-stationed platform?

3 Telescope Comparison Pros Cons Ground-Based Orbiting Balloon-Stationed Capability for large primary mirrors Easy to maintain Above all of Earth s atmosphere Extremely dark sky background Diurnal functioning Extremely stable platform HST is currently the only facility that produces sharp pictures in the nm range. Very affordable compared to orbiting telescope Above 99% of Earth s atmosphere Sky background nearly as dark as HST Diurnal functioning. Can focus on multiple objects in the time it takes for HST to observe one Cannot function in bad weather Cannot function during daytime Images subject to atmospheric distortion Cannot compensate for turbulence at wavelengths shorter than 1200 nm. HST cost nearly 6 billion dollars Difficult and expensive maintenance Takes long time to observe one celestial object Easy to maintain May not be as stable of a platform as HST Cannot stay at float for extremely long durations of time. BOWSER 3

4 Mission Premise 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) BOWSER 4

5 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 km is vital BOWSER 5

6 StarTracker5000 Successfully flight tested as the orientation system on three sounding rockets. Attitude determination, mapping and imaging of stars from sounding rockets, satellites, and balloons Able to view a field of stars up to 8 th magnitude brightness Triangulates constellations to determine pointing direction. The ST5000 could be utilized as a part of a pointing system for a balloon-borne observatory. BOWSER 6

7 Mission Overview High Altitude Student Platform 2009 (HASP): BOWSER Proposal won large payload spot January 2009 Launch September 7, 2009 out of Fort Sumner, New Mexico Platform ascends on a zero pressure NASA balloon to 36 km and floats for 25 hours experiencing both day and night conditions Power, communications, and downlink is provided. BOWSER 7

8 Payload Location BOWSER BOWSER 8

9 Payload Location Payload 10 Payload 9 Payload 12 BOWSER 9

10 BOWSER Payload 360 LED Array Multi-Angle LED Array Aluminum Isogrid Modified Newtonian Telescope Computer (TS-7260) Sunshade AVR Board DVR (DVQ19) Compass (HMC6343) Stepper Motor Wide Angle Camera (Canon G9) Photometers Telescope CCD (PC164CEX-2) BOWSER 10

11 Mission Visual 36 km HASP Balloon 35.9 km θ 35.8 km 35.7 km 35.6 km Verification of the MODTRAN model BOWSER will measure sky brightness as a function of: Altitude Wavelength Angle from the Sun BOWSER 11 HASP Payload 35.5 km 35.4 km

12 Mission Visual HASP Balloon XYZ Accelerations Yaw Determine performance requirements for a balloon-stationed star tracker BOWSER will: Measure the faint limit of detectable stars Measure pointing errors in the typical balloon environment BOWSER 12 Pitch / Roll

13 Mission Overview 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 Objectives: Objective 1: Objective 2: Mission Objectives Level 0 Team BOWSER will measure the amplitude and frequency of pointing errors in the typical balloon environment. Team BOWSER will measure sky brightness diurnally as a function of altitude, wavelength, and angle from the sun. BOWSER 13

14 Mission Implementation BOWSER will define requirements for balloon-borne star trackers. BOWSER will measure the amplitude and frequency of pointing errors in the balloon environment. BOWSER will measure sky brightness as a function of altitude, wavelength, and angle from the sun. Gyroscopic Sensors Pressure Sensor Wide-Angle CCD 360 LED Array Digital Compass Accelerometer Sensors Modified Telescope CCD Multi-Angle LED Array Photodetector Array BOWSER 14

15 LEDs as Light Sensors BOWSER 15

16 Requirements: LED 360 Array Measure sky brightness as a function of altitude, wavelength, and angle from the sun Design Description: 64 LEDs will measure light in the red, orange, green and blue spectrum Reasons for Choice: LEDs do not require the use of filters in order to sense discreet wavelength ranges. The array will produce over six million altitude, angle, and wavelength-specific data points that can easily verify the MODTRAN model. BOWSER 16

17 LED Multi-Angle Array Requirements: Measure sky brightness as a function of altitude, wavelength, and angle from the sun Design Description: Array of 12 red LEDs with angles varying between 5 degrees and 60 degrees, spaced 5 degreed apart Reasons for Choice: Provides a second dimension of data to correspond with the LED 360 array BOWSER 17

18 Angle From the Sun Test Looking for a relationship of wavelength -4 BOWSER 18

19 Requirements: Photodetector Array Correspond sky background brightness to cosmic images to discover the faint limit of stars. Design Description: Filter and lens combination will break up the visible spectrum into approximately 50 nm ranges in the IR, red and orange spectrums. Photodetectors will measure sky background brightness corresponding with the imaging system. Reasons for Choice: Filters allow for smaller and more accurate filtering. Common angle allows for sky background brightness readings to be compared with telescope and wide-angle images of the sky. BOWSER 19

20 Modified Newtonian Telescope Requirements: Characterize sky background brightness and faint limit of detectable stars Image celestial bodies and constellations consisting of 8 th magnitude stars. Design Description: Orion Newtonian with a flat secondary mirror, interior baffle, and a correcting lens pair. Designed to baffle out stray light in order to view fainter stars during daytime. Reasons for Choice: Baffle design will allow for daytime identification of at least 8 th magnitude stars in order for CCD to perform like the Star Tracker Affordable baffling modification constructed under the guidance of professional Russ Melon. BOWSER 20

21 BOWSER 21

22 Telescope CCD Requirements: Identify constellations consisting of 8 th magnitude stars to verify the use of a star tracker on a balloon platform. Design Description: Stationed behind the modified Newtonian telescope. Acts like ST5000 by recording at 10fps. Reasons for Choice: Accurately simulates what a star tracker could see from the stratosphere both at night and during the day. BOWSER 22

23 Wide-Angle CCD Requirements: Identify constellations within its field of view. Correspond sky brightness readings with images to discover the faint limit of detectable stars. Design Description: Installed with a cone baffle to eliminate light at extreme angles of incidence. High resolution CCD will produce uncompressed RAW images of celestial bodies. Reasons for Choice: Adjustable features and customizable settings: Supports the Canon Hack Development Kit (CHDK), which allows the user to run automated scripts, control various optical settings, and automatically capture pictures on a timed program. Adjustable exposure time and ISO sensitivity makes this high resolution camera perfect for the low-light settings of the dark sky. BOWSER 23

24 Disturbance Sensors Requirements: Characterize the pointing errors in the balloon environment. Requirements: Characterize the pointing errors in the balloon environment. Design Description: This three axis gyroscopic device will measure the rotational rates of the platform. Design Description: Two dual-axis accelerometers will be mounted perpendicularly, allowing for three dimensional acceleration profiling. Reasons for Choice: Temperature compensated readings. Reasons for Choice: Fast reset time which allows for readings at 2500Hz BOWSER 24

25 Digital Compass Requirements: Sense orientation relative to N, S, E, W direction and angle from the sun Design Description: Determines the pointing direction of the scientific instruments Reasons for Choice: Tilt compensated, so the payload s movement does not affect headings. BOWSER 25

26 BOWSER 26 CAD Drawings

27 BOWSER 27 CAD Drawings

28 Structural Compliance BOWSER 28

29 BOWSER 29 Questions?

30 Mario Test Flight Results Voltage data from photometer tubes Voltage data from LED tubes launch burst landing launch burst landing BOWSER 30

31 Mario Test Flight Results Light intensity data from photometer tubes Light intensity data from LED tubes launch burst landing launch burst landing BOWSER 31

32 Mission Timeline -2:00:00 HASP Internal Batteries On Avionics Components Checkout Science Components Checkout Continuous ADS and Light sensing 0:00:00 Ascent Observations Pictures 1 per 3 sec Video 10 sec every 3 min All ADS and Light Sensing taking continuous data 1 picture every 3 sec ~3:00:00 Float Observations Pictures change from continuous to clusters every 30 sec 30 sec clusters every 5 minutes 10 sec of video every 5 minutes +1:00:00 +2:00:00 +3:00:00 +4:00:00 +5:00:00 0:00:00 Launch Activate Computer & AVRs Activate Compass & Accelerometer Activate LEDs and photodiodes Health and Status packages every 10 minutes on ascent KEY: Satellite Communications Still Imaging Video BOWSER 32 ADS and Light Sensing

33 Mission Timeline 18:00:00 Termination All Instruments Shall Remain Off +14:00:00 +15:00:00 ~18:48:00 Landing +16:00:00 +17:00:00 All Instruments Shall Remain Off 17:30:00 Payload Shall Be Recovered By HASP Personnel Prepare for Termination Close sunshade Suspend operation of all electronics KEY: Satellite Communications Still Imaging Video BOWSER 3333 ADS and Light Sensing