The EXpedite the PRocessing of Experiments to Space Station (EXPRESS) Logistics Carrier (ELC) is a platform designed to support external payloads mounted to the International Space Station (ISS) starboard and port trusses with either deep space or Earth views.Facility Manager(s)
Goddard Space Flight Center, Greenbelt, MD, United States
National Aeronautics and Space Administration (NASA)Expeditions Assigned
33/34Previous ISS Missions
The EXpedite the PRocessing of Experiments to the Space Station (EXPRESS) Logistics Carrier (ELC) is carried in the space shuttle cargo bay to the International Space Station (ISS). Five ELCs will be delivered to the ISS before the space shuttle's retirement in 2010; four ELCs will be attached to starboard truss 3 (S3), and one ELC will be attached to port truss 3 (P3). When the ELC is attached to the S3 and P3 sites, a variety of views—toward the zenith (deep space) or nadir (Earth) with a combination of ram (forward) and wake (aft) pointing—allow many viewing opportunities.
Each ELC can accommodate 12 Flight Releasable Attachment Mechanism (FRAM)-based cargos, including two payload attach sites with full avionics accommodation. The mass capacity for an ELC is 4,445 kg (9,800 lb) with a volume of 30 m3.
The ISS provides power to the ELCs through two 3-kW, 120-Vdc feeds at the ISS-to-ELC interface. The ELC power distribution module converts the 120-Vdc power to 120-Vdc and 28-Vdc power. Both power voltages are provided to each payload attach site by separate buses. The 120-Vdc power is also provided to other cargo attach sites. After ELC installation, it may take up to 4 hours for the power to be connected. At the ISS-to-ELC interface, there are two types of data ports: the High-Rate Data Link (HRDL) and the Low-Rate Data Link (LRDL). The HRDL uses fiber optics to provide ISS-to-ELC communication. At the interface between the ELC avionics module and the payload interface, there are three data ports: HRDL, LRDL, and Medium-Rate Data Link (MRDL, Ethernet). For uplink MRDL, Ethernet is used; the ELC avionics module will convert the MRDL signal from HRDL interface and deliver it to each payload attach site. The transmission rate between the ELC avionics module and the payload attach site is no higher than 10 Mbps. Downlink MRDL and HRDL signals will be transmitted from payload attach site to the ELC avionics module by separated buses. The ELC avionics module will combine these two signals for transmission to the ISS using the HRDL interface. The HRDL rate for downlink service to the ground is no higher than 95 Mbps (megabits per second). The LRDL is used for a two-way data and command link between the ELC and each payload attach site via the ELC avionics module at maximum rate of 1 Mbps. External camera ports are also available for the ELC payloads. At least 14 camera port locations along the trusses can be used for payload observation.