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COSGC Space Research Symposium 2009
BOWSER
Balloon Observatory for Wavelength and Spectral
Emission Readings
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Mission Premise
4.3 km above sea level
402.3km 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?
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Telescope Comparison
Ground-Based
• Capability for large primary
mirrors
• Easy to maintain
Pros
• Cannot function in bad
weather
• Cannot function during
daytime
Cons • Images subject to
atmospheric distortion
• Cannot compensate for
turbulence at wavelengths
shorter than 1200 nm.
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Orbiting
• 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 300-1200 nm
range.
Balloon-Stationed
• 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
• Easy to maintain
• May not be as stable of a
• HST cost nearly 6 billion
platform as HST
dollars
• Cannot stay at float for
• Difficult and expensive
extremely long durations of
maintenance
• Takes long time to observe one time.
celestial object
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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)
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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
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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 8th
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.
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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.
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Payload Location
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Payload Location
Payload 10
Payload 9
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Payload 12
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BOWSER Payload
360° LED Array
Multi-Angle
LED Array
Aluminum
“Isogrid”
Modified Newtonian
Telescope
Sunshade
Computer
(TS-7260)
AVR Board
DVR (DVQ19)
Compass
(HMC6343)
Photometers
Stepper Motor
Wide Angle Camera
(Canon G9)
Telescope CCD
(PC164CEX-2)
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Mission Visual
36 km
HASP Balloon
35.9 km
35.8 km
θ
35.7 km
35.6 km
• Verification of the MODTRAN model
35.5 km
• BOWSER will measure sky brightness
as a function of:
• Altitude
• Wavelength
• Angle from the Sun
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HASP Payload
35.4 km
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Mission Visual
HASP Balloon
Yaw
XYZ
Accelerations
• 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
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Pitch / Roll
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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:
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.
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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
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LEDs as Light Sensors
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LED 360 Array
• Requirements:
– 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.
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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
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Angle From the Sun Test
Looking for a relationship of wavelength-4
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Photodetector Array
•
Requirements:
– 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.
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Modified Newtonian Telescope
•
Requirements:
– Characterize sky background brightness and
faint limit of detectable stars
– Image celestial bodies and constellations
consisting of 8th 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 8th magnitude stars in
order for CCD to perform like the Star Tracker
5000.
– Affordable baffling modification constructed
under the guidance of professional Russ Melon.
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Telescope CCD
• Requirements:
– Identify constellations consisting of 8th
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.
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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.
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Disturbance Sensors
•
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
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•
Requirements:
– Characterize the pointing errors in the
balloon environment.
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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.
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CAD Drawings
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CAD Drawings
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Structural Compliance
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Questions?
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Mario Test Flight Results
Voltage data from
photometer tubes
launch
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burst
Voltage data from
LED tubes
landing
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launch
burst
landing
Mario Test Flight Results
Light intensity data
from LED tubes
Light intensity data
from photometer tubes
launch
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burst
landing
launch
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burst
landing
Mission Timeline
-2:00:00
0:00:00
~3:00:00
HASP Internal Batteries On
Ascent Observations
Float Observations
Avionics Components Checkout
Pictures 1 per 3 sec
Science Components Checkout
Video 10 sec every 3 min
Pictures change from continuous to
clusters every 30 sec
All ADS and Light Sensing
taking continuous data
10 sec of video every 5 minutes
Continuous ADS and Light sensing
1 picture every 3 sec
+1:00:00
0:00:00
Launch
+3:00:00
+2:00:00
+4:00:00
+5:00:00
KEY:
Health and Status packages
every 10 minutes on ascent
Satellite Communications
Activate Computer & AVRs
Activate Compass &
Accelerometer
Still Imaging
Video
Activate LEDs and photodiodes
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30 sec clusters every 5 minutes
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ADS and Light Sensing
Mission Timeline
18:00:00
Termination
All Instruments Shall Remain Off
~18:48:00
+14:00:00
+15:00:00
+16:00:00
Landing
All Instruments Shall Remain Off
17:30:00
Payload Shall Be Recovered By HASP
Personnel
Prepare for Termination
+17:00:00
Close sunshade
Suspend operation of all electronics
KEY:
Satellite Communications
Still Imaging
Video
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ADS and Light Sensing