OCULUS - ASR M ICHIGAN T ECHNOLOGICAL U NIVERSITY Andrew Mauragis Joshua Ehlert Lars Ramseyer SHOT II P OST- L AUNCH J UNE 13, 2010.

OCULUS - ASRMICHIGAN TECHNOLOGICAL

UNIVERSITY

Andrew MauragisJoshua EhlertLars Ramseyer

SHOT II POST-LAUNCHJUNE 13, 2010

EXPECTED RESULTS:

- H-bridge temperature increased rapidly during vacuum tests. This mission will test the thermal properties of the H-bridge in low pressure combined with low temperatures (-80 °C).

18:1

418

:1718

:2018

:2318

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:4118

:4418

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:5018

:53

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Magnetic Torquer Vacuum Test

H-Bridge 2

H-Bridge 1

Torque Rod

Picaxe 1

Resistor 3

Time of Day

Temperature (°C)

ACTUAL RESULTS:

Mean ΔT: 4.75 °C

OUTCOME:

• Partial failure of logging payload• Temperature?• Loose Connection?• Batteries?

• Data acquired does not match expected results• In vacuum chamber, component did not reach a

steady-state ΔT after 30 minutes• In payload, ΔT established almost

instantaneously, at 5 C

ANALYSIS AND CONCLUSION:

• Cause for discrepancy?• Different vessel size (small insulated box vs

open board)• Ambient temperatures vs Box temperature

• Requires additional testing:• Consistent ΔT on SHOT payload, but varying

on initial vacuum test• Short in actual test magtorquer (not in our

simulated one)• Likely heatsink h-bridges to Oculus-ASR

structure