The subsystems that enable experiment operations are described below: 

Rack Interface Controller (RIC) image

Rack Interface Controller (RIC) (20 MHZ Motorola Processor)

  • Command and control interface for rack subsystems and payloads
  • Collects health and status (H&S) from subsystems and subrack payloads
  • Packages H&S for on-board use and downlink
  • Uses H&S to make decisions (like Thermal Shutdown)


EXPRESS Memory Unit (EMU) image

EXPRESS Memory Unit (EMU)

  • The EMU is a solid state memory device (320 MB) that is used for:
  • System software files
  • Configuration files


Payload Ethernet Hub/Bridge (PEHB) image

Payload Ethernet Hub/Bridge (PEHB)

  • Ethernet interface to payloads
  • Supports payload-to-payload communication through Internal (LAN 0) /External Local Area Network (LAN) 1/2 bridging
  • Command and data interface to EXPRESS laptop
  • Payload interface to ISS LAN 1/2 for Medium Rate Link (MRL) Telemetry downlink


EXPRESS Laptop Computer image

ELC: EXPRESS Laptop Computer

  • Dedicated to EXPRESS rack operations
  • Crew can view rack displays
  • Crew can command rack and payloads
  • Payload can have applications installed
  • Lenovo T61p


EXPRESS Rack Thermal System image

EXPRESS Rack Thermal System

  • Moderate Temperature Loop (MTL)
  • Rack Smoke Detector
  • Avionics Air Assembly (AAA)
  • Rack Thermal Shut-Down


Avionics Air Assembly (AAA) image
Avionics Air Assembly (AAA)     
  • Avionics air cooling provides up to 1200 W of payload heat rejection into the Moderate Temperature cooling Loop (MTL).
  • 6.8 kg/hr (15 lb/hr) air flow (nominal) to each Middeck Locker position
  • Residual air available to ISIS drawer locations (at the rear of the locations)

Moderate Temperature Loop (MTL)

  • Coldplate cooling for rack subsystems
  • Two connections for payload use (supply and return) provide 45.5 kg/hr (100 lbs/hr) each (front panel QD interface)
  • EXPRESS rack in operation requires 45.5 kg/hr (100 lbs/hr)

Three Ways Payloads are Cooled

  • Cabin Heat Load - Front Breather (500w)
  • AAA - Rear Breather (1200 w total)
  • MTL - 2 payload connections at 45.5kg/hr (100 lbs) each


Solid State Power Controller Module (SSPCM) image

Solid State Power Controller Module (SSPCM)

  • Provides 120 VDC output to:
    • RIC, AAA, PEHB, Area Smoke Detector
  • Converts 120 VDC to 28 V for:
    • Each payload position, EMU, Laptop power port
    • Payload Data Interfaces
      *Analog Inputs  *Bi-directional Discretes
      2 each MDL                  3 each MDL
      1 each ISIS Drawer        2 each ISIS Drawer
      * Use is Payload Developer defined