Tuesday, March 10, 2015

EVAs prepare ISS for changes

Is there any job better than this?

In the last month, American astronauts aboard the International SPace Station have conducted three spacewalks preparing the ISS for future module changes. With the expansion of commercial programs to include manned ferry missions from Earth to the ISS, some of the modules on the station need to be moved in order to provide better docking positions. The current placement of the modules benefitted the docking of the US space shuttles, but as only one shuttle docked at a time, the new arrangement must allow for the docking of multiple spacecraft. In each manned flight, the craft must be useable as emergency escape vessels. That means there would be no time in an emergency to use the robotic arm for positioning and cable hookups, the way that it's done now with robotic cargo ships.

Astronaut Barry Wilmore connects cables on the Harmony module.

The first of the series of three spacewalks by Expedition 42 took place on February 21. Astronauts Barry Wilmore and Terry Virts spent 6 hours and 41 minutes outside in space, during which they rerouted cables on the US-built Harmony module and the Pressurized Mating Adapter 2. Designated EVA-29, the spacewalk was successful and the astronauts prepared for the next step.

Astronaut Terry Virts rides the robotic arm into position.

The second spacewalk, EVA-30 took places days later on February 25th. The main goal was to rout power cables and prepare the PMA-2 for installation later this year of mating adapters, which will be delivered by the Dragon spacecraft. The astronauts got ahead of the schedule, and used the extra time to start preparations for the next spacewalk. However, during the spacewalk, Terry Virts encountered a problem - water was leaking into his space helmet. Engineers noticed it during the beginning of the EVA as Virts left the airlock, but since it was very small (not anywhere near the amount of water that endangered astronaut Luca Parmitano in 2013) they continued the EVA and kept a close watch on the problem. Virts was able to detect some of the water leak by the end of the spacewalk, but managed to complete the EVA and return inside without any problem.

Astronaut Wilmore during the recent EVA. You can see part of a docked Soyuz spacecraft in the upper right of the image.

EVA-31 took place on March 1st. The objective this time was to install new antennas for the new C2V2 communications system and connect more wiring. The new comms system will be used for astronauts in docking spacecraft to talk with station crewmembers and ground controllers, and is an advanced system compared to the shuttle-era High Frequency setup. The antennas and about 400 feet of cabling were installed in 5 hours and 38 minutes - over an hour earlier than had been planned. Great job of planning and executing their tasks enabled them to return early. There was also no further problem with water in Virts' helmet.

You can read detailed accounts of the spacewalks, with more pictures, on the pages at NASA Spaceflight.com at:

With the successful conclusion of the three EVAs, Expedition 42 gets ready to conclude. Tuesday March 10th will see a change of command ceremony as Barry Wilmore (USA), Alexander Samokutyaev (Russia) and Elena Serova ( Russia) prepare to leave the ISS and return to Earth.

It's not all work on the ISS. Here, astronaut Terry Virts and ESA astronaut Samantha Cristoforetti play with their food before eating a snack.

A moment of reflection. Samantha Cristoforetti (ESA) pays tribute to the passing of legendary Star Trek actor Leonard Nimoy by making the Vulcan hand gesture for "Live Long and Prosper." She is wearing her Star Trek shirt pin which she brought aboard the station, of course not knowing that Nimoy would pass away during her stay. Now there's a Star Trek fan.

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