XA/EVA Project Office Weekly Activity Report December 13, 2001
EMU Anodized Samples Testing at MSFC
The decision to use the PCU to control the ISS plasma arc discharge was based on the established design value of 40 volt for the EMU. The EMU anodized samples testing at MSFC was designed by the EMU community to develop enough confidence in the EMUÕs ability to withstand the 40 volt limit since any potential arcing on the EMU will present a catastrophic hazard to the crewmember. Preliminary analysis of the test results indicated that the EMU is capable of withstanding 40 volt in an ISS plasma environment. Additional tests will be performed to determine if a new threshold greater than 40 volts can be implemented.
Floating Potential Measurement Unit (FPMU) Design Review
EVA Project office personnel supported the Floating Potential Measurement Unit (FPMU) design review at the Space Dynamics Laboratory in Logan, Utah, December 4-5, 2001. The FPMU is scheduled to be installed by the EVA crew on STS-114/ULF-1. It will monitor the space environment to allow the EVA crewmembers to avoid potential electrical shock hazards. The EVA Project Office representative presented the EVA design and integration requirements for hardware and provided comments to the existing design regarding tether points, handholds, and pinch point hazards. A 1-g evaluation of the hardware will be conducted with the STS-114 EVA crew in January 2002 using the FPMU prototype.
Hubble Space Telescope (HST) Crew Aids and Tools (CAT) Design Certification Review (DCR)
XA participated in the CATS DCR at Goddard Space Flight Center on December 7, 2001 for Servicing Mission 3B (SM3B). 110 individual EVA tools were reviewed including 28 new designs specifically for SM3B. All CATÕs hardware is designed and built. Status was given on the ongoing certification of the CATÕs hardware. The Goddard CATÕs team expects to have all hardware certification in review for signature by December 21, 2001.
EMU Battery Charging Issues
Prior to docking for the STS-108 (UF-1) mission the ISS crew attempted to re-charge EMU batteries on board ISS in preparation for the EVA performed on December 10th. In most cases the battery charging was cutting off prior to full charge when utilizing the Battery Charger Assembly (BCA) in the ISS Joint Airlock. During the STS-108 mission a decision was made to utilize the back up EMU Middeck charger that was certified to be operated in the ISS Joint Airlock to perform charging of EMU batteries. This back up plan was successful and prior to the EVA all batteries on-orbit were either at full charge or at a charge level adequate to support a nominal EVA. The failure is believed to be related to integration issues between the charger and the EMU advanced battery. A team is quickly pursuing corrective action, which will most likely result in uploading new software to the BCAÕs on-orbit.
STS-108/UF-1 EVA
An EVA of 4:11 hr/min duration was successfully completed on STS-108/UF-1 on September 10, 2001 (Mission Flight Day 06). STS-108 Crewmembers Linda Godwin and Dan Tami, operating out of the Orbiter Airlock, successfully completed EVA tasks on ISS. Completed were two Beta Gimbal Assembly (BGA) blanket installations, an S-Band Antenna Support Assembly (SASA) blanket retrieval, and a DC Current Switching Unit (DCSU) ORU visual inspection. An attempt at locking the fourth leg of the BGA Four Bar assembly using the EVA vise grip tool was unsuccessful. Per direction from the ISS Program to the flight team, not attempted was: 1) the retrieval of EVA tools from stowage locations outside of ISS as an 8A Get Ahead task; and 2) exterior ORU photos and MMOD impact photos.
G. Allen Flynt
Manager
