Apollo 15 Flown lunar surface EVA retractable tether

25 Jul

Flown lunar surface EVA retractable tether used on the lunar surface by Apollo 15 Lunar Module Pilot Jim Irwin. The tether, referred to by astronauts as a ‘yo-yo,’ is stamped with a part number of SEB33100291-303 and serial number SN 1025. The device measures approximately 6.25 x 2.75 x 1.5, 0.7 pounds, with remnants of its original brown strap used to attach it to Irwin’s PLSS and to carry tools during lunar surface operations. Attached to the end of the 35″ retractable cord is a replacement double-jawed spring-closing mechanism with an incorporated eyelet for attachment to the tether cord. In fine condition. Accompanied by a signed letter of authenticity from Dave Scott which reads, in part: “I hereby certify that the EVA Retractable Tether (‘Yo-yo’) included with this letter was used by Lunar Module Pilot (LMP) Jim Irwin during the lunar surface activities of Apollo 15…The purpose of the Yo-yo was to enable the astronaut to carry certain tools attached to his spacesuit and be readily available without having to carry them by hand. These include the scoop and tongs, both of which were used by Jim Irwin in sampling rocks and soil near Elbow crater on the Moon during EVA-1. This Yo-yo was also used for the Universal Hand Tool (UHT) to assist in ALSEP deployment (Boyd Bold release); however during the ALSEP deployment, this particular Yo-yo failed when the string connecting the clamp broke at its attach point on the clamp, and the clamp was lost on the Moon. We returned the Yo-yo to Earth; and subsequent disassembly after the mission showed that both the bowline and the figure-eight knot attaching the cord to the clamp had untied, thus allowing the cord to retract into the housing…After this post-mission analysis the Yo-yo was reassembled to its current configuration (however the original clamp was replaced in this assembly). An improved clinch knot was installed on large Yo-yos for subsequent missions.” As noted in the Apollo 15 Mission Report (chapter 14, 5.7), both retractable tethers failed during lunar surface operations; the Commander’s tether cord broke during the first extravehicular activity, and the tool clamp came off the end of the Lunar Module Pilot’s tether. RR Auction COA.

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Posted by on July 25, 2014 in Apollo 15


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