Astronauts Aim To Finish Battery Swap In Final Spacewalk

Two Atlantis astronauts will venture outside the International Space Station Friday on an excursion aimed at replacing decade-old batteries that have outlived their warranty.

Twelve $3.6 million batteries were launched along with a port-side central truss segment in late 2000. Six of those batteries were swapped out on the STS-127 mission last July. Four were changed out Wednesday during the second of three spacewalks planned during shuttle Atlantis' mission to the station. The remaining two batteries are to be removed and replaces during Friday's planned 6.5-hour excursion.

Here’s a look at the day in space:

1:50 a.m.: Shuttle and station crews wake.

2:25 a.m.: Spacewalk preps resume.

6:05 a.m.: Station robot arm moves cargo carrier into place for spacewalk.

6:45 a.m.: Mission specialists Garrett Reisman and Mike Good begin spacewalk.

7:55 a.m.: Battery removal begins.

10:40 a.m.: Old batteries stowed on cargo carrier.

11:15 a.m.: Spacewalkers clean up work site, gather tools.

11:30 a.m.: Spacewalkers retrieve power-and-data grapple fixture. (Time permitting).

11:35 a.m.: Station arm moves cargo carrier to outpost’s mobile rail cart.

1:15 p.m.: Spacewalk ends.

4:50 p.m.: Station crew sleeps.

5:20 p.m.: Shuttle crew sleeps.