Astronauts Conducting STS-118’s Fourth Spacewalk

Image: Mission Specialist Dave Williams emerges from the hatch at the beginning of STS-118’s fourth spacewalk. Image: NASA TV

Mission Specialist Dave Williams and Flight Engineer Clay Anderson are working outside the International Space Station. The spacewalk kicked off at 9:17 a.m. EDT and is scheduled to wrap up about 1:47 pm.

The orbital duo’s scheduled tasks for the shortened spacewalk include the installation an External Wireless Instrumentation System antenna, installation of a stand for the shuttle’s robotic arm extension boom and retrieval two containers of the Materials ISS Experiment.

Mission Specialist Tracy Caldwell is the spacewalk coordinator, a role that she has for all four STS-118 spacewalks.

Overnight, mission managers decided to shorten the originally planned 6.5-hour spacewalk to 4.5 hours so that the crew can close hatches between the station and shuttle at the end of the day today. That plan preserves the option to have Endeavour undock from the station on Sunday and prepare for a landing on Tuesday. The earlier landing is being considered in the event Hurricane Dean threatens the Houston area. It could allow an opportunity for the shuttle to land before Mission Control, Houston, would be shut down in preparation for a storm.

However, managers will review the forecast for Dean and mission activities this afternoon during their daily meeting and assess whether they will continue to pursue a possible early undocking and landing.