ARISSat-1 Control Panel and Safety Circuitry Jerry Zdenek

April 3, 2010ARISSat-1 CDR2 Introduction Provides the Control of the Satellite and indicate Satellite Status Scope –Requirements –Design –Safety Considerations –Verification –Operations

April 3, 2010ARISSat-1 CDR3 Requirements Compliant with all ISS safety requirements Provide an interface that an Astronaut or Cosmonaut 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

April 3, 2010ARISSat-1 CDR4 Design Provide all timer functions required –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 / Cosmonauts on Suitsat-1 Measure control panel temperature

Control Panel ARISSat-1

April 3, 2010ARISSat-1 CDR6 Control Panel Front Flight labels are slightly different

April 3, 2010ARISSat-1 CDR7 Control Panel Assembly Flight units will have wires strain relieved

April 3, 2010ARISSat-1 CDR8 Control Panel Flight Labeling

April 3, 2010ARISSat-1 CDR9 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

April 3, 2010ARISSat-1 CDR10 LED Brightness Must balance two conflicting requirements –Minimize power usage –Good visibility to personnel, 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

April 3, 2010ARISSat-1 CDR11 Schematic – Timer Control

April 3, 2010ARISSat-1 CDR12 Schematic – Status LEDs

April 3, 2010ARISSat-1 CDR13 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 and MIL-DTL-3950

April 3, 2010ARISSat-1 CDR14 Safety Considerations Access to switches –Metal Finger guards provided so that only one switch is activated at a time

April 3, 2010ARISSat-1 CDR15 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!

Safety Interlocks ARISSat-1

April 3, 2010ARISSat-1 CDR17 Hazards RF Transmission Battery Overcharging

April 3, 2010ARISSat-1 CDR18 Safety Interlocks

April 3, 2010ARISSat-1 CDR19 Start up Timeline

April 3, 2010ARISSat-1 CDR20 RF Transmission Hazard Three Interlocks –Battery Relay / Solar Panel Relay Prevents any 28V Power from powering supplies –Timer 1 / 8V Switching Supply –Timer 2 / Push to talk

April 3, 2010ARISSat-1 CDR21 RF Transmission Interlocks

April 3, 2010ARISSat-1 CDR22 Battery Overcharging Hazard Three Interlocks –Battery Relay –Solar Panel Relay –MPPT

April 3, 2010ARISSat-1 CDR23 Battery Overcharging Interlocks

Inter Connect Board ARISSat-1

April 3, 2010ARISSat-1 CDR25 Inter Connect Board Connects all PCB assemblies in the IHU stack to the outside world Provides Safety Circuitry Scope –Requirements –Design –Safety Considerations –Operations –Verification –Status

April 3, 2010ARISSat-1 CDR26 Stack

April 3, 2010ARISSat-1 CDR27 Stack SDX IHU PSU ICB CMD DEC

April 3, 2010ARISSat-1 CDR28 Interface Connectors

April 3, 2010ARISSat-1 CDR29 Safety Considerations ICB is critical and integral to electrical safety on the satellite –Isolates Battery –MPPT Isolation Relays –Prevents charging hazards –Inhibits RF transmission –Times events after switch changes to allow Satellite to move away from personnel Connectors that provide power are sockets, not pins

April 3, 2010ARISSat-1 CDR30 Safety Schematics Relays

April 3, 2010ARISSat-1 CDR31 Safety Timers Power

April 3, 2010ARISSat-1 CDR32 Interlock 2 Operator turns on Timer 1 Switch –Timer 1 begins counting –Timer 1 Counting LED starts blinking –~20 seconds later, IHU powers up Takes a picture –7.5 minutes later, 8V switcher is enabled Provides power to RF transmitter

April 3, 2010ARISSat-1 CDR33 Control Panel Timer 1 Switch Interface

April 3, 2010ARISSat-1 CDR34 Timer 1 Schematic

April 3, 2010ARISSat-1 CDR35 IHU Reset PSU 5V Switcher ICB

April 3, 2010ARISSat-1 CDR36 RF Power Inhibit (Timer1) ICB PSU 8V Switcher

April 3, 2010ARISSat-1 CDR37 Interlock 3 Operator turns on Timer 2 Switch –Timer 2 begins oscillating Does not start counting time until Timer 1 is complete –Timer 2 Enabled LED starts blinking –RF Push to Talk is still disabled Upon expiration of Timer 2 (~7.5 minutes) –MPPTs connected to 28V Bus –RF Push to talk is enabled

April 3, 2010ARISSat-1 CDR38 Control Panel Timer 2 Switch Interface

April 3, 2010ARISSat-1 CDR39 Timer 2 Schematic

April 3, 2010ARISSat-1 CDR40 Push To Talk Inhibit (Timer2) Control Panel Transmitter ICB

April 3, 2010ARISSat-1 CDR41 Command Decoder Reset Command Decoder can drive a signal high to force the Satellite to reset Upon driving this line high –PSU +5V Switcher is shut down for ~20 seconds Kills power to the IHU and SDX Kills the microprocessor running on the PSU Kills the Command Decoder –PSU will cycle the RF power on restart

April 3, 2010ARISSat-1 CDR42 Command Decoder Interface

April 3, 2010ARISSat-1 CDR43 Control Panel LED interface

April 3, 2010ARISSat-1 CDR44 Verification Operating with both low and high voltage inputs Ran system at real time speed multiple times –Video Taped one run to verify specified timings Measured current with system off