Astronauts have successfully ended the third spacewalk to install the two external facilities on Columbus, the SOLAR observatory and the European Technology Exposure Facility (EuTEF), which will require activation and a full check before starting the data collection later this month.

The third STS-122 spacewalk, which was performed by Mission Specialists Rex Walheim and Stan Love, started off at 14:07 CET, a bit ahead of the schedule, and lasted for seven hours and 25 minutes. With the help of the robotic arm controlled by Mission Specialist Leland Melvin, the two spacewalkers transferred the two facilities from Atlantis’ payload to an external platform on Columbus.

The first of the two, SOLAR, is an observatory with a two year mission of monitoring the Sun. It was installed facing zenith and with the help of a movable frame will conduct Sun observations of approximately 15 minutes per orbit, according to the ESA.

The European Technology Exposure Facility (EuTEF) will provide data and support research on materials exposure to the space environment, with nine instrument modules working simultaneously. EuTEF’s tasks will include measuring the radiation environment, measuring EuTEF’s thermal environment, studying the tribology of materials, examining material degradation, and will feature an atomic oxygen detector, an exobiological exposure facility, and an Earth observing camera, all within the 350 kg facility.

In addition to installing the two payloads, Mission Specialists Walheim and Love installed handrails on Columbus and also performed an examination of a small divot on a handrail on the Airlock that could be linked to the damaged gloves of previous spacewalks.

At the same time, the astronauts retrieved a failed control moment gyroscope that has remained outside the station ever since its malfunction and replacement in October 2006, and will be returned to Earth in Atlantis’ payload bay. Pilot Alan Pointdexter was also part of the mission, by guiding the spacewalkers from inside the station.

Now that the three spacewalks are completed, the astronauts prepare for leaving the space station and returning to Earth. The undocking will start Monday at 4:26 a.m. and the Atlantis shuttle is expected to land on Wednesday, either at Cape Canaveral or at a backup site in California, due to the broken satellite that needs to be shut down.

Image credits: NASA