Smooth, 6.5 Hour Spacewalk To Fix ISS Ammonia Pump

The ISS crew can breathe a little easier now; the NY Times reports that the ammonia pump repair that the station has needed has now been partly completed, and in less time than expected. More work is scheduled, but, says The Times: "The astronauts, Col. Michael S. Hopkins of the Air Force and Richard A. Mastracchio, were far ahead of schedule throughout the spacewalk as they detached tubing and electrical connectors from the pump. They were able to remove the 780-pound module and move it to a temporary storage location, a task that had been scheduled for a second spacewalk on Monday. ... Colonel Hopkins and Mr. Mastracchio stepped out of an airlock at 7:01 a.m. Eastern time, and even though they accomplished more than they had set out to do, they were able to return at 12:29 p.m., an hour earlier than had been scheduled. The two encountered few complications." Ars Technica has video, too.

Comments

Overly optimistic

[PPH]

As everyone knows, all projects involve several trips to Home Depot for the odd tool or bolt that was overlooked in the initial planning stage.

Re:Excuse the pedantry...

[PNutts]

I know it's a nitpick, but isn't 7:01 a.m. - 12:29 p.m. more like 5.5 hours? I understand that they were an hour faster than planned (meaning they planned 6.5 hours) but the title seems a bit off nonetheless...

Considering the ISS orbits the earth about every 90 minutes, it was more like 3 days and an hour.

Nickpick +5

Re:I'm curious...

[cbhacking]

The heat sink in your computer would be pretty miserable at dumping waste heat into space. Terrestrial heat sinks typically heat into a fluid, such as the air that your computer's fans blow across the heat sink.

Problem: there is no air (or anything else into which heat may be transferred) in space. Radiative cooling - that is to say, releasing infrared radiation - does occur, but it is *far* slower that conductive cooling. To do that effectively, though, you want a big, hot surface area that is shadowed from all other heat sources in the region (that big fusion reactor the Earth orbits counts as "in the region" here).

To cool an artificial satellite effectively, especially a big one like ISS, you use a heat transfer system (in this case, they apparently use ammonia) to concentrate the heat into radiative cooling surfaces on the shadowed side of the station. This system definitely adds complexity, not to mention generating a bit of heat itself(entropy always increases), but without it, the side of the station facing the sun would cook, and the shadowed side wouldn't get hot enough for effective radiative cooling.