Hubble Space Telescope

(HST) Archive System

NASA Langley Research Center
Hampton, Virginia

Returned Hardware

Tools and Crew Aids
The Hubble Space Telescope was designed to be serviced on-orbit by astronauts conducting EVA's. Most of the tool complement used on the first servicing mission were designed and developed prior to the launch of the HST in April, 1990.

After the first servicing mission, the astronaut crew detailed their experiences with the serving mission tools in their debriefing. In addition, the EVA Section of the Mission Operations Directorate (MOD) authored the STS-61 EVA Post-Flight Report in order to capture the knowledge gained from the servicing mission relative to mission operations. Based on this knowledge, MOD developed a set of recommendations for future mission successes.

The HST servicing mission required many HST-specific tools and crew aids. These included: the short and long 7/16 inch adjustable extensions, the fuse tether (commonly known as the fish stringer), multi-setting torque limiter, portable grapple fixture, and the fastener retention tools (commonly known as hairpins). Additional, less unique tools used were the push-button portable foot restraint (PFR) and articulating sockets, retractable tethers, high-speed power tool with rotary impact driver, and the large hook mini-work station end effector.

The adjustable extensions proved valuable because they enabled the astronauts to perform different HST tasks without having to use larger, bulkier hardware that could have caused a snag hazard. The fuse tether served as a device to transport the P15 and P16 fuses to the worksite as well as one to assist in the handling of multiple tools and tool caddies that were to be installed on the MFR. The multi-setting torque limiter reportedly functioned well. The portable grapple fixture was not needed during the mission, although it would have allowed the solar arrays to be jettisoned via the RMS. The fastener retention tools were used to capture the non-captive fasteners on the DF-224 computer and SADE.

The push-button PFR and articulating socket represent improvements to existing designs. The retractable tethers operated with excellent results, and are regarded as a major advancement in EVA tethers. The high-speed power tool and rotary impact driver added to the tool complement later in the development process; while they were not needed on this mission, they provide a good capability to free a stuck fastener. The EVA crew generally preferred the large hook as the end effector on the mini-work station, instead of the normal end effector.

The tools and crew aids manifested on the first servicing mission totalled approximately 200. They were tracked via a tool list that was placed under configuration control approximately six months before launch. The configuration control provided a means to define stowage requirements, responsible organizations, schedules for completion, delivery dates, and inventories of flight and training units.

During the crew debrief, several operating problems were noted with regard to the tools. These included:

• The small power driver could use a speed control.
• Power tools create RFI on the astronauts' helmet radios but the interference was tolerable.
• The power tool batteries can go dead without warning.

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