On 29 November 1996, during the STS-80 mission, a planned EVA by Tammy Jernigan and Tom Jones had to be abandoned because the astronauts were unable to open the outer airlock hatch. A second EVA later in the mission was cancelled outright. What activities were planned for these EVAs?
Astronauts Tammy Jernigan and Tom Jones will perform two six- hour spacewalks during STS-80, one on Flight Day 10 and another on Day 12, to evaluate equipment and procedures that will be used during construction and maintenance of the International Space Station.
12.1 EVA Development Flight Tests (EDFT) Astronauts Tammy Jernigan and Tom Jones will perform two six- hour spacewalks during STS-80, one on Flight Day 10 and another on Day 12, to evaluate equipment and procedures that will be used during construction and maintenance of the International Space Station. The spacewalks are the fifth in a continuing series of Extravehicular Activities (EVAs) called the EVA Development Flight Tests (EDFT). This flight test series of spacewalks is designed to evaluate equipment and procedures planned for the station and to build spacewalking experience in preparation for assembly of the station. Jernigan is designated Extravehicular Crewmember 1 (EV- 1) and will be distinguished by red bands worn on the legs of her spacesuit. Jones is designated EV-2. Astronaut Story Musgrave will serve as the Intravehicular (IV) crewmember, assisting Jernigan and Jones from inside Columbia's crew cabin. STS-80 Pilot Kent Rominger also will assist with the spacewalks, controlling the robotic arm from inside the cabin. On the first spacewalk, an end-to-end demonstration of a maintenance task simulating the changing out of an International Space Station battery will be performed. A crane designed for use in moving large Orbital Replacement Units (ORUs) on the space station will be evaluated as part of the task. ORUs can be any piece of equipment that may be replaced on the station's exterior, and, for this evaluation, the simulated station battery will be moved using the crane. The evaluation should take almost three hours of the first spacewalk. Following the large-ORU evaluation, the astronauts will evaluate the crane's ability to move a small ORU, a cable caddy that previously was used during an STS-72 spacewalk. The second spacewalk will evaluate working with the simulated battery from a mobile platform designed for the end of the International Space Station's robotic arm. Both spacewalkers will evaluate working with the simulated battery from the platform, which will be attached to the end of Columbia's robotic arm, for a total of almost two hours each. The astronauts also will evaluate a variety of other work aids and tools designed for use during station operations, including a Body Restraint Tether (BRT), a type of "third hand" stabilizing bar for spacewalkers; a Multi-Use Tether (MUT), a type of stabilizing tether similar to the BRT that can be anchored to either round U.S. handrails or square Russian handrails; and a power tool designed for the station.
Detailed descriptions of the major items to be evaluated:
12.2 CRANE The 156-pound crane is 6 feet tall and has a boom that telescopes from lengths of 4 feet to 17.5 feet. It is designed to aid spacewalkers in transporting objects with a mass as great as 600 pounds to various worksites on the International Space Station's truss. The crane boom's attachment mechanism may also provide temporary stowage for large units during maintenance. The crane will be unstowed and installed to a socket along the left middle side of Columbia's cargo bay for the evaluations. The crane's boom can be extended by turning a ratchet fitting using a power tool or by using a manually operated hand crank. The crane can also be moved from side to side and up and down by hand cranks.
12.3 BATTERY ORBITAL REPLACEMENT UNIT A simulated battery for the International Space Station will be used for evaluations performed during STS-80 because the batteries will be among the most massive station ORUs. The station batteries will be mounted on the truss near the solar arrays and will provide power when the station moves into night on each orbit. The object to be used during STS-80 is not a real battery, although its size, 41 x 39 x 19 inches, and mass, about 354 pounds, closely imitate a station battery. It is also stowed in Columbia's cargo bay in fittings similar to those planned for stowing such replacement units during space station operations.
12.4 CABLE CADDY The Cable Caddy is a small carrier designed to hold about 20 feet of replacement electrical line for the space station. The operations of the Cable Caddy were flight-tested on STS-72, and on STS-80 it will be used only to simulate a small ORU for the space station. No cable will be unwound. The Cable Caddy has a mass of almost 50 pounds.
12.5 PORTABLE WORK PLATFORM The platform, a mobile EVA worksite designed for the end of the International Space Station's mechanical arm, was first flight- tested on STS-72. Similar to the platform used at the end of the Shuttle arm during past spacewalks, such as those to service the Hubble Space Telescope on STS-61, the platform offers greater movement with a swiveling foot restraint; a storage location for tools and temporary storage for large space station ORUs. The platform is composed of several components. An Articulating Portable Foot Restraint, a foot platform that can be swiveled to various orientations using two foot pedals, allows a spacewalker to reposition the platform without dismounting. A Portable Foot Restraint Work Stanchion (PFRWS) holds tools and equipment. A Temporary Equipment Restraint Aid (TERA) will hold large ORUs. Jernigan and Jones will evaluate the platform by using it mounted at the end of Columbia's mechanical arm to perform operations with the simulated station battery.
12.6 BODY RESTRAINT TETHER The Body Restraint Tether (BRT) seeks to provide the astronaut with a "third hand" to add stability while working. The tether is designed to hold a spacewalker steady when clamped to a handrail, freeing the astronaut's hands for work. It was first flown on STS- 69 and further evaluated on STS-72. The tether should provide a quick method of supplying stability for a spacewalker when a foot restraint is not available.
12.7 MULTI-USE TETHER The Multi-Use Tether (MUT) is similar to the BRT, but it has can perform a greater variety of tasks. Different end effectors can be attached to the tether to grip station ORUs, various spacewalking tools or handrails.