SPANDEX

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SPANDEX

• FRR

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Mission Goal We aim to measure solar panel
efficiency as a function of altitude. We would
like to determine if the lower temperature and
thinner air of the upper atmosphere have an
effect on the efficiency of a PV cell. Science
Objectives We seek to determine the efficiency of
the solar cell, discover what effect varying
temperatures have on the efficiency, and to
discover if the Suns radiation in the upper
atmosphere has a different effect from the
radiation in the lower atmosphere. Technical
Objectives We will construct a well-insulated
box, voltmeter, and MPP (maximum power point)
tracker. We also want to keep the payload level
at all times.
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Background and Requirements
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Background and Requirements

• P out V2 / R
• Efficiency P out / P in
• Area of cell 106.25 cm2
• The solar cell data sheet claims that the cell
  should put out 1.55 watts at 25 degrees Celsius
  with an irradiance of 1000 W/m2 shining directly
  on it
• We expect a max of 1.84 W at -60 degrees Celsius
  with the sun at 21 degrees from its normal with
  an irradiance measurement of 1000 W/m2.
• We expect a min of 0.08 W at 80 degrees Celsius
  with an irradiance measurement of 625 W/m2 with
  the sun at 64.8 degrees from the normal on a
  cloudy day.

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Mechanical Structure
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Mechanical Structure
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Electronics
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Flight Software
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Ground Software
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Thermistors
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Thermal Test Results

• We immersed our payload in the dry ice chamber
  from 430 to 630 pm. We determined that the
  test was successful because all of the
  electronics and software were functioning when
  the box was removed from the chamber. However,
  the delay time between the relays switching
  increased during approximately the last 15
  minutes of the test. This should not be a
  problem during flight since the payload will only
  experience temperatures around -60 degrees C for
  30 minutes instead of 2 hours. The temperature
  inside the payload after the test was 10 degrees
  C. We also placed a pv cell rubber cemented to a
  piece of foam in the dry ice (-60 degrees C) as
  well as in a furnace (80 degrees C). The rubber
  cement held and the solar cell did not warp.

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Pressure Test Results

• Since the payload cannot fit in the vacuum bell
  jar, we only placed our electronics in it. We
  performed the test from 700 to 730 and we
  encountered no problems with the electronics or
  software.

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Shock Test Results

• After the pressure test, we dropped the box from
  about 10 feet. We did not include the pivot or
  solar cell because we expect these to break on
  impact. The payload landed on mulch while
  collecting nonexistent data and functioned
  properly afterwards. All components within the
  payload remained in place on impact.