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Student Payload Choices

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Mechanical structure constructed from foam core board ... Telemeter video signal down to ground? LSU 09/06/05. Student Payload Experiments. 18 ... – PowerPoint PPT presentation

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Title: Student Payload Choices


1
Student Payload Choices
  • Ballooning Unit, Lecture 7

2
Your balloon payload
  • Limited to about 500 grams weight
  • Roughly a cube with 15 cm to 20 cm long sides
  • Mechanical structure constructed from foam core
    board
  • Vehicle interface is a pair of strings, separated
    by 17 cm, that pass through the payload unbroken
    and secured with spring clips.
  • Need to conduct some kind of science or
    technology experiment
  • Designed, built, tested and shown to be fully
    space worthy by May of next year.
  • Will have about 14 weeks to complete this phase.
  • 48 hours after launch you will need to have
    calibrated science results from your flight and
    present your results to an audience of
    professional scientists and engineers.

Payload mechanical interface
3
Need to begin thinking now!
  • Given the constraints, you need to think about
    and address issues throughout the academic year
  • Here we discuss some example payloads that have
    either been previously developed and flown or
    which should be feasible to develop and fly
    within the limitations of this program
  • You need to choose one of these payloads to work
    on!
  • During the current skill building phase then
  • Research the scientific background for your
    payload
  • Think about how a particular activity / concept
    applies to your payload (I guarantee that they
    ALL apply) and keep track of these in a payload
    design notebook
  • Determine who in your group has similar interest
    or complimentary skills and begin developing a
    team
  • Develop hardware / software prototypes as an
    activity extension

4
Potential Payload Topics
  • Look up experiments
  • Cosmic ray intensity
  • Cosmic ray components
  • UV transmission through atmosphere
  • IR emission
  • In-situ experiments
  • Atmosphere temperature, pressure profile
  • Atmosphere ozone profile
  • Atmosphere humidity profile
  • Atmosphere trace gas profile (more difficult)
  • Remote sensing experiments
  • Imaging the ground and/or limb
  • Multispectral (filtered) imaging of the ground
  • Technology experiments
  • Balloon payload dynamics
  • Solar cell efficiency
  • Video camera imaging (live or recorded)

5
Cosmic Ray Intensity
  • Cosmic rays are high energy nuclei that originate
    outside our solar system.
  • CR interact in Earths atmosphere producing a
    shower of particles
  • The intensity of this radiation varies with
    altitude
  • This payload would determine the radiation flux
    as a function of altitude on ascent and descent
  • Simple to implement detector system by using a
    hand-held radiation monitor
  • Most effort will be in understanding what flux
    is and doing the appropriate calibrations to
    convert your measurement to flux.

6
Cosmic Ray Components
  • Cosmic rays include electrons, protons, heavy
    nuclei (He to beyond Iron) plus interaction
    products such as neutrons, pions, muons, etc.
  • This payload would try to measure the relative
    abundances of some of these components.
  • Use multiple detector systems with different
    thresholds.
  • Geiger-Muller tube for electrons, protons
  • Plastic scintillator with a photodiode for higher
    energy deposits produced by heavy ions
  • To compare multiple detector system it will be
    critical that you can determine the correct
    flux for each detector.

7
Transmission through atmosphere
8
UV Transmission
  • UV is absorbed by ozone in the upper atmosphere
  • Payload would measure the UV intensity as a
    function of altitude and infer the vertical
    distribution of ozone
  • One or more sensors (or the appropriate
    wavelength sensitivity) would monitor UV from the
    Sun.
  • The signal from the sensor would need to be
    conditioned and converted to a digital number by
    an ADC
  • You will need to take into account rotation of
    the balloon craft
  • Calibrations of sensor and ADC will be needed to
    determine flux

9
Infrared Emission
  • Sun energy is absorbed by objects on Earth
    (ground, clouds, atmosphere) and emitted in the
    infrared wavelengths (8 15 microns), further
    astronomical objects, such as the Sun, emit
    infrared energy.
  • This payload would implement an infrared sensor
    to measure the temperature of some particular
    object.
  • The signal from the sensor will need to be
    conditioned and converted to a digital number by
    an ADC.
  • You will need to take into account rotation of
    the ballooncraft.
  • You may also need to account for temperature
    dependences in your sensor and/or electronics.
  • The trick here is to understand what your sensor
    is looking at and to have the calibrations
    necessary to convert your measurement to a
    temperature.

10
Atmospheric Structure
Typical max balloon altitude 30 km
11
Temperature, Pressure Profile
  • The temperature and pressure of the atmosphere
    varies as a function of altitude.
  • Temperature initially decreases with increasing
    altitude, then increases as UV is absorbed in the
    atmosphere.
  • Pressure decreases in an exponential manner
  • This payload would implement temperature and
    pressure sensors to measure this variation.
  • Need to understand sensor ADC range accuracy.
  • Compare with standard atmosphere model

12
The Distribution of Ozone
  • The ozone layer, located between 15 50 km
    altitude, shields the Earth from high frequency
    UV components by absorbing this radiation.
  • Payload would use a standard electrochemical
    concentration cell (ECC) to measure the ozone
    density as a function of altitude
  • Will also need to measure temp. and pressure
  • ECC is based upon an iodide iodine redox
    reaction using a potassium iodide solution, so
    you will need to keep your sensor from freezing.
  • Calibration of your sensor is essential
  • This is a more challenging experiment, but doable.

13
Absolute Humidity
  • The amount of water vapor in the stratosphere may
    be directly dependent upon interactions between
    ozone, UV and methane. There are few in-situ
    studies of humidity at high altitude and a poor
    understanding of the mechanisms that control it.
  • Payload would include humidity and temperature
    sensors to obtain the absolute concentration of
    water vapor as a function of altitude
  • May also want auxiliary measurements to look for
    possible causal relationships.
  • Include UV and/or methane sensor
  • Collaborate with another team doing UV or methane
    measurements
  • Will need to condition sensor signals and use an
    ADC to obtain digital information
  • Will need to understand sensor / ADC range and
    accuracy

14
Trace gas profiles
  • There are many other components in the atmosphere
    that could be interesting to measure as a
    function of altitude
  • Methane, Carbon Dioxide, Chlorofluorocarbon
    compounds
  • Requires an appropriate sensor that could fit
    within the balloon payload power, size and weight
    constraints
  • Likely to be temperature dependent, so will need
    to monitor temperature and calibrate sensor for
    flight conditions.
  • May need to monitor pressure to obtain absolute
    levels
  • Could collaborate with multiple teams, each
    measuring a single component.
  • This would be a challenging payload

15
High Altitude Imaging
  • Provide aerial view of ground or Earth limb from
    low to high altitude
  • ACES program has yet to achieve high quality
    images from high altitude
  • Payload would fly a digital camera and be
    automatically controlled to take a series of
    images
  • May need to include a polarizing filter to cut
    down on glare
  • Need to record images on non-volatile media to
    avoid loss during power off
  • Will need thermal-vacuum testing to assure system
    will function correctly.

16
Multi-spectral Imaging
  • Remote sensing images taken of the same area but
    in different frequency bands can be used to
    distinguish between healthy vegetation, water
    features, surface roughness and other
    characteristics.
  • Payload would include multiple cameras each of
    which would take a image through a different
    color filter. (e.g. IR, green, UV)
  • Alternate payload would have one camera and a
    wheel that would include multiple filters.
    Software would then rotate the wheel one
    increment prior to taking the image
  • Camera will need different exposure times
    depending upon which filter is used.
  • This will be a very interesting and challenging
    experiment!

17
Technical Payloads
  • Measure the dynamics of the payload through use
    of accelerometers and/or tiltmeters.
  • Form basis of an inertial position sensing system
  • Investigate use of balloon payload for ?g
    experiments
  • Measure the efficiency of various solar cells
  • Can balloon payloads be powered by solar cells?
  • Record voltage and current for each cell
  • Develop a compact video camera payload and record
    specific events during the flight
  • Main problem here is weight
  • Telemeter video signal down to ground?

18
Your Own Idea
  • You can also develop an alternative payload based
    upon your own idea.
  • However, keep in mind that your payload must have
    a relevant science / technical goal and must be
    feasible given the payload weight, power, budget
    and time constraints.
  • The payloads identified here can be developed so
    they fit within these constraints.
  • In any event you need to begin your payload
    planning now!
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