An EXpedite the PRocessing of Experiments to Space Station (ExPRESS) Logistics Carrier (ELC) is an unpressurized attached payload platform for the International Space Station (ISS) that provides mechanical mounting surfaces, electrical power, and command and data handling services for Orbital Replacement Units (ORUs) 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 (CAS).[1] The P3 Truss has two such attach points called Unpressurised Cargo Carrier Attachment System (UCCAS) mechanisms, one facing zenith (space facing) called UCCAS-1, the other facing nadir (earth facing) called UCCAS-2. The S3 Truss has four similar locations called Payload Attachment System (PAS) mechanisms, two facing Zenith (PAS-1 and PAS-2), and two facing Nadir (PAS-3 and PAS-4).
The ELC are four un-pressurized attached payloads, some designed by the Brazilian Space Agency,[2] for the International Space Station (ISS) 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 (ORUs) which can be retrieved when needed.[3] Experiments are mounted on ExPRESS payload adapters (ExPA) which are about the same size as the FRAMs that hold ORUs.
Within the electrical subsystem of the ELC, the ExPRESS carrier avionics (ExPCA) 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" (FCU). The FCU runs the free open-source real-time operating system (RTOS) RTEMS and provides the computing and communication resources as an ELC Command and Data Handling (C&DH) system with the following major goals:
Manifested on ELC-2 was the first ELC-based payload, Materials for ISS Experiment (MISSE-7).[4] mounted on an ExPA.
ELC-1 and ELC-2 were transported to the International Space Station by Space Shuttle Atlantis 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 date | Mission | Shuttle | ELC |
---|---|---|---|
16 November 2009 | STS-129 (ISS ULF3) | Atlantis | ELC-1 and ELC-2 |
24 February 2011 | STS-133 (ISS ULF5) | Discovery | ELC-4 |
16 May 2011 | STS-134 (ISS ULF6) | Endeavour | ELC-3 |
ELCs 1 & 2 in the Space Shuttle Atlantis cargo bay. | |
Module statistics | |
---|---|
Part of | International Space Station |
Launch date | 11 | UTC
Launch vehicle | Space Shuttle/STS-129 |
Berthed | 11P3 truss | at
Mass | 6,280 kg (13,840 lb) |
ELC-1 is located on the P3 truss at the UCCAS-2 (nadir, earth facing) site. ELC-1 weighs approx. 13,840 lbs.[5] A FRAM is a Flight Releasable Attachment Mechanism.
ELC-1 and ELC-2 (top side views) prelaunch, with red changes on orbit.
ELC-1 underside view in the SSPF, with labels
ELC-1 keel side view on orbit
JEM Exposed Platform HTV-4
Brazilian STP-H4 Experiment package
ELCs 1 & 2 in the Space Shuttle Atlantis cargo bay. | |
Module statistics | |
---|---|
Part of | International Space Station |
Launch date | 11 | UTC
Launch vehicle | Space Shuttle/STS-129 |
Berthed | 11S3 truss | at
Mass | 6,100 kg (13,400 lb) |
ELC-2 is located on the S3 truss at the PAS-1 (zenith, space facing) site, alongside AMS-2 at PAS-2. ELC-2 weighs approx. 13,400 lbs.[5]
ELC-1 and ELC-2 (top side views) prelaunch, with red changes on orbit. Note MISSE-7/8 switch.
ELC-2 underside during its transfer into the payload canister in the SSPF
ELC-2 on the SSRMS prior to its placement on the S3 Truss
ELC-2 atop the S3 Truss
ELC-2 showing MISSE-7 and the vacated HPGT FRAM
Module statistics | |
---|---|
Part of | International Space Station |
Launch date | 05 | UTC
Launch vehicle | Space Shuttle/STS-134 |
Berthed | 05S3 truss | at
Mass | 6,361 kg (14,023 lb) |
ELC-3 is located on the P3 truss at the UCCAS-1 (zenith, space facing) site. ELC-3 weighs 14,023 lbs.[7]
ELC-3 top view
ELC-3 underside view
ELC-3 in the grasp of Endeavour's robotic arm
![]() In the Space Station Processing Facility at NASA's Kennedy Space Center in Florida, technicians perform the ELC-4, deck-to-keel mate. | |
Module statistics | |
---|---|
Part of | International Space Station |
Launch date | 02 | UTC
Launch vehicle | Space Shuttle/STS-133 |
Berthed | 02S3 truss | at
Mass | 3,735 kg (8,235 lb) |
ELC-4 is located on the S3 truss at the PAS-4 (nadir, earth facing) site, alongside ESP-3 at PAS-3. ELC-4 weighs 8,235 lbs.[13]
Heat rejection subsystem radiator (HRSR) on ELC-4
FHRC and CTC4 on the HTV-2 Exposed Platform
Mike Fossum rides on the ISS's robotic arm as he transfers the RRM to the SPDM for temporary storage
JEM Exposed Platform HTV-4
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