process, according to Duggan. The water system literally had bugs growing in it. Filters were replaced and valves redesigned. “All regenerative life control systems, in general, have been more complicated than we envisioned—not at a component level, but at a system level,” Cothran said. One of the bigger lessons learned was finding the proper lubricant for the gears that hold the station together. Engineers originally went with a solid lubricant, such as gold and other soft metals, deciding that grease wouldn’t work. The gold failed and gear bearings were destroyed and had to be replaced. Grease, as it turned out, works the best in a vacuum, Cothran said. The space station, launched during the time of dial-up modems, has made steady software and hardware upgrades as the technology has changed. The station started out with Intel 386 class processors on board; it now has Pentium class processors. Efforts are being made to double the data speed rate of 300 megabits per second. Overall, the performance of the space station’s computers and other electronics has been positive. “I’m surprised that the radiation environment has not been more disabling,” said Boeing manager Clemen. “The electronics we put up there have performed remarkably well.” Mark Mulqueen, Boeing’s ISS program manager, said the future of the International Space Station could be determined by the availability of alternative future commercial space platforms in low Earth orbit, which would allow the continued discovery of science and research in a zero-gravity environment. The International Space Station already is assisting in preparations for a manned mission to Mars. Studies are being conducted on the long-term skeletal effects on humans in space well ahead of the two- to three-year future journey to Mars. In addition to testing critical systems, answers must be found for the effects of zero gravity on our muscular skeletal tissue and bone densities. The space station is a crucial stepping stone to deep-space exploration, Mulqueen noted. “Low Earth orbiting laboratories can still thrive for medical or pharmaceutical research, or even become a future vacation destination, depending on commercial markets and costs to operate and maintain,” Mulqueen said. Other space stations, such as Mir and Skylab, were purposely destroyed by burning up in Earth’s atmosphere once their systems had worn out and usefulness had come to an end. Barring the unknown, the International Space Station could postpone that fate for decades, suggested John Vollmer, Boeing’s ISS chief engineer. “As long as we’re willing to continue to upgrade and sustain the station,” Vollmer explained, “the design of it by nature will allow us to continue operation for a very long time.” • DANIEL.W.RALEY@BOEING.COM MARCH 2016 | 23
Frontiers March 2016 Issue
To see the actual publication please follow the link above