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Feb 15, 2010 ARISSat-1 CDR 2
Introduction• Provides the Control of the Satellite and
indicate Satellite Status• Scope
– Requirements– Design– Safety Considerations– Verification– Operations– Status
Feb 15, 2010 ARISSat-1 CDR 3
Requirements
• Compliant with all ISS safety requirements
• Provide an interface that an Astronaut in a pressure suit can control the satellite
• Indicate status of the Satellite
• Allow the system to be quickly shut down in case of a problem
Feb 15, 2010 ARISSat-1 CDR 4
Design• Provide all timer functions equivalent to Suitsat-1
– One Power switch with LED status– Two Timer switches with LED status
• Same mechanical switch layout as Suitsat-1• Additional LEDs for Operational and Safety
Verification• Solve LED visibility problem reported by
Astronauts• Measure control panel temperature
Feb 15, 2010 ARISSat-1 CDR 5
Control Panel Front
Feb 15, 2010 ARISSat-1 CDR 6
Control Panel Assembly
• Flight units will have wires strain relieved
Feb 15, 2010 ARISSat-1 CDR 7
Design
• Interface Box– Switches and LEDs only– Nearly completely passive assembly
• Control circuitry on ICB
• Safety functions managed by ICB
• LED Brightness circuitry within Control Panel
Feb 15, 2010 ARISSat-1 CDR 8
LED Brightness
• Must balance two conflicting requirements– Minimize power usage– Good visibility to Astronauts, factoring in sun
visor
• Solution: two different brightness modes– LEDs always on dimly (room visible) – If the first timer has not expired, run extra
current through the LEDs for brightness– Using very high efficiency LEDs
Feb 15, 2010 ARISSat-1 CDR 9
Schematic – Timer Control
Feb 15, 2010 ARISSat-1 CDR 10
Schematic – Status LEDs
Feb 15, 2010 ARISSat-1 CDR 11
Safety Considerations
• Activation Switches – False activation due to switch contamination
could create a safety hazard– Using APEM 12000X778 Switches to insure
safety– Switches are designed for high-rel
applications and is QPL certified to MIL-DTL-83731 and MIL-DTL-3950
Feb 15, 2010 ARISSat-1 CDR 12
Safety Considerations
• Access to switches– Metal Finger guards provided so that only one
switch is activated at a time
Feb 15, 2010 ARISSat-1 CDR 13
Verification• Improved design over Suitsat-1
– Switches are now operating with 50% design margin on wetting current
– Suitsat-1 was operating outside spec
• Operating with both low and high voltage inputs• In use during development testing of other
systems• Ran system at real time speed multiple times
– Video Taped one run to verify specified timings
Feb 15, 2010 ARISSat-1 CDR 14
Operations• Integral with ICB Safety Circuitry
– Further details in ICB design review
• To Deploy:– Turn on 28V Power switch
• Verify LEDs in correct state
– Turn on Timer 1 Switch• Verify LEDs in correct state
– Turn on Timer 2 State• Verify LEDs in correct state
• Launch the satellite!
Feb 15, 2010 ARISSat-1 CDR 15
Status• Design and Documentation Complete• Electrical Testing complete• Positioning of Thermistor inside box not
defined yet• Switch set up the same as Suitsat-1, so no
operational problems expected• Quantity of LEDs has been brought up as
a training / ease of use issue• Just need to assemble flight units!