ExPRESS Logistics Carrier


An EXpedite the PRocessing of Experiments to Space Station Logistics Carrier''' is an unpressurized attached payload platform for the International Space Station that provides mechanical mounting surfaces, electrical power, and command and data handling services for Orbital Replacement Units as well as science experiments on the ISS. The ELCs were developed primarily at the Goddard Space Flight Center in Greenbelt, Maryland, with support from JSC, KSC, and MSFC. ELC was formerly called "Express Pallet" and is the unpressurized counterpart to the pressurized ExPRESS Rack. An ELC provides scientists with a platform and infrastructure to deploy experiments in the vacuum of space without requiring a separate dedicated Earth-orbiting satellite.
ELCs interface directly with the ISS integrated truss common attach system. The P3 Truss has two such attach points called Unpressurised Cargo Carrier Attachment System mechanisms, one facing zenith called UCCAS-1, the other facing nadir called UCCAS-2. The S3 Truss has four similar locations called Payload Attachment System mechanisms, two facing Zenith, and two facing Nadir.

Description

The ELC are four un-pressurized attached payloads, some designed by the Brazilian Space Agency, for the International Space Station that provides mechanical mounting surfaces, electrical power, and command and data handling services for science experiments on the ISS. The ELCs have a deck size of about 14 feet by 16 feet and spans the width of the space shuttle's payload bay. They are made of steel, coated with UV paint. Each one is capable of providing scientists with a platform and infrastructure to deploy experiments in the vacuum of space without requiring a separate dedicated Earth-orbiting satellite. Each carrier is capable of carrying 9,800 lbs. to orbit and will also serve as parking fixtures for spare ISS hardware which can be retrieved when needed. Experiments are mounted on ExPRESS payload adapters which are about the same size as the FRAMs that hold ORUs.

Electrical subsystem ExPRESS carrier avionics (ExPCA)

Within the electrical subsystem of the ELC, the ExPRESS carrier avionics provides electrical power distribution to experiments, and data interfaces to the ISS. Within the ExPCA, the ColdFire-based flight computer, software, and related electronics comprise its "flight controller unit". The FCU runs the free open-source real-time operating system RTEMS and provides the computing and communication resources as an ELC Command and Data Handling system with the following major goals:
Manifested on ELC-2 was the first ELC-based payload, Materials for ISS Experiment. mounted on an ExPA.

ELC launch schedule

ELC-1 and ELC-2 were transported to the International Space Station by on mission STS-129 in November 2009. ELC-4 launched on mission STS-133 Discovery on 24 February 2011 and was installed on the station on 27 February. ELC-3 launched on mission STS-134 Endeavour on 16 May 2011 and was installed on the station on 18 May.
The Alpha Magnetic Spectrometer occupies the mounting location intended for ELC-5 on the ISS truss.
Launch dateMissionShuttleELC
16 November 2009STS-129 AtlantisELC-1 and ELC-2
24 February 2011STS-133 DiscoveryELC-4
16 May 2011STS-134 EndeavourELC-3

Locations and components

ELC-1

ELC-1 is located on the P3 truss at the UCCAS-2 site. ELC-1 weighs approx. 13,840 lbs. A FRAM is a Flight Releasable Attachment Mechanism.

ELC-2

ELC-2 is located on the S3 truss at the PAS-1 site, alongside AMS-2 at PAS-2. ELC-2 weighs approx. 13,400 lbs.

ELC-3

ELC-3 is located on the P3 truss at the UCCAS-1 site. ELC-3 weighs 14,023 lbs.

ELC-4

ELC-4 is located on the S3 truss at the PAS-4 site, alongside ESP-3 at PAS-3. ELC-4 weighs 8,235 lbs.