Goddard Team Develops New Carriers for ISS
In a partnership that exemplifies the One NASA theme, Goddard Space Flight Center engineers teamed up with the External Payloads Group at Johnson Space Center and the ISS Payload Ground Processing support team at Kennedy Space Center to create the ExPRESS Logistics Carrier (ELC) Project.
The ELC is an un-pressurized attached payload project 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. ("ExPRESS" stands for Expedite the Processing of Experiments to the Space Station.)
Based at Goddard, this newly formed project designed, built and tested five unpressurized aluminum carriers and six avionics packages for bringing spare hardware and science to 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. 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 also capable of carrying 10,000 lbs. to orbit and will also serve as parking fixtures for spare ISS hardware which can be retrieved when needed.
Tackling Challenges Head On
In addition to an aggressive production schedule and nearly 800 ISS requirements, the newly formed ELC Project successfully tackled a multitude of issues that included technical challenges, limited funding, mass optimization, ongoing ISS operations, and the need to accommodate multiple payloads and science experiments on the same platform.
It took more than 100 engineers from Goddard, Johnson, Marshall and Kennedy Space Centers working together over a three-year period to complete this multi-million dollar project.
“Prior to Goddard’s involvement, Brazil’s efforts to design the avionics for the combined carrier proved too costly and bulky to implement,” said ELC Project Manager Kevin Carmack at Goddard. “Our experts solved the avionics issue by incorporating new technology including high data rate processing into the solution.”
Engineers from the Hubble Space Telescope (HST) Carriers Development Office at Goddard formed a large segment of this new organization, developing the unique ELC design, which incorporates elements of both types of science and spare hardware pallets. The mechanical challenge was to create the most efficient aluminum design ever flown in order to optimize the payload capability of the structure. The large platform needed to be extremely flat and the 250 holes had to be precisely drilled to allow engineers at KSC to integrate heavy payloads. Due of its prior expertise in building the cargo carriers for Hubble Space Telescope servicing missions, Goddard served as the overall designer, integrator and manufacturer for the ELCs.
Adhering to an aggressive delivery schedule due to the pending shut down of the Shuttle program in 2010, engineers from Goddard and Johnson started design activities in early 2006. But as work on the ELC began, the integrated team quickly found themselves tackling a host of other challenges such as cultural barriers, which included differences in design philosophy, test programs, quality oversight and methods of systems verification.
The distance between Centers and across time zones also proved challenging when scheduling meetings and communicating issues or ideas. Foreign ISS customers, particularly Russia and Germany, presented language barriers as well as distance issues. According to Carmack, the Goddard ELC team viewed these issues as an opportunity to expand relationships, forging stronger partnerships in the process.
The ELC Project engineers at Goddard fabricated the platforms, relying on expertise gleaned from many years of work on space shuttle hardware for missions such as Solar Maximum, Gamma Ray Observatory, Upper Atmosphere Research Satellite, as well as five highly successful Hubble Space Telescope servicing missions. They also assembled and integrated its components and provided the necessary test facilities, mechanical / electrical ground support equipment, and flight avionics.
The Center’s contributions seamlessly interfaced with Johnson’s government-furnished equipment for Shuttle and ISS electrical interfaces, structural grappling, and test facilities such as the Neutral Buoyancy Lab and Kennedy’s mechanical ground support equipment for ground handling and launch site integration of the payloads and experiments. Goddard also worked very closely with Marshall Space Flight Center for implementation of their software development and pre-launch verification and checkout.
Furthering NASA’s Goals
Goddard’s ELC Project demonstrates the One NASA theme of making decisions for the common good through its inclusive, participatory philosophy.
“Team members from three Centers served on the Joint Review Board for major milestone reviews, implementing decisions that required cross-Center participation,” said Carmack.
By distributing work among the core competencies of each Center, the ELC Project exemplified how NASA Centers can effectively work together, particularly in the areas of systems engineering, safety, on-orbit operations, reliability and project management.
Four ELCs will be delivered to the ISS before the scheduled retirement of the space shuttle. Two ELCs will be attached to the ISS on the starboard truss 3 and two ELCs will be attached to the port truss via the space shuttle’s robotic arm.
ELCs #1 and #2 will fly aboard the Space Shuttle Atlantis STS-129 mission slated for November 16. ELC #3 will fly aboard the Space Shuttle Endeavour on STS-134 mission in July 2010, while ELC #4 will be carried to the ISS aboard the Space Shuttle Discovery on STS-133 mission in September 2010. ELC #5 will serve as a spare.
For more information about this unique new carrier, go to: NASA ELC mission page
NASA's Goddard Space Flight Center