NASA Astronauts Steve Swanson and Rick Mastracchio perform a spacewalk outside the International Space Station to replace equipment. (Reuters)

There’s a spacewalk on the International Space Station starting at 9:30 a.m. Spacewalks are always delicate matters. You may recall that last summer an Italian astronaut, Luca Parmitano, nearly drowned during a spacewalk. There was a malfunction in his suit that caused water to leak throughout his helmet. Water in zero-G acts in funny ways — it’s like the blob, migrating across your head, into your ears, into your nose. Fellow astronaut Chris Hadfield told me, bluntly, “We just about killed him.”

Spacewalking is extremely tricky and innately dangerous. There are obvious dangers, such as sharp edges that can puncture the astronaut’s suit. As Hadfield points out, “The EMU [Extravehicular Mobility Unit] is a little one-person spaceship — completely self-contained. It has its own oxygen system, cooling system, communications, everything. Any safety that’s protecting you from death is in that suit. You’ve lost layers of redundancy that you had in the space station.”

Something went terribly wrong with Parmitano’s suit. Here’s a good write-up of the subsequent investigation. (“Engineers found aluminum silicate contamination clogging a line in the system, a blockage that had caused water to back up into Luca’s helmet.”)

Parmitano later blogged about what happened: “The water has also almost completely covered the front of my visor, sticking to it and obscuring my vision…. [T]he Sun sets, and my ability to see — already compromised by the water — completely vanishes, making my eyes useless; but worse than that, the water covers my nose — a really awful sensation that I make worse by my vain attempts to move the water by shaking my head. By now, the upper part of the helmet is full of water and I can’t even be sure that the next time I breathe I will fill my lungs with air and not liquid.”

With help from his fellow spacewalker Chris Cassidy, Parmitano managed to find his way back to the airlock, and once inside the station he managed to get his helmet off with the aid of his fellow astronauts. This was a very dicey situation, to say the least.

Alberto Cuadra shows us how they fixed the balky computer on the ISS.

Spacewalking is never a lark. There are elaborate instructions on what to do. For first-time spacewalkers in particular, the view can be disorienting and intimidating. This is not like doing a spacewalk in the cargo bay of the space shuttle. On the ISS, there’s nothing between you and the ground 250 miles below. Yeah, sure, take that next big step. You think astronauts never get cold feet?

NASA and its partners on the ISS have robust public information operations that tell us what’s going on, but I think officials could potentially be more direct about the extent to which space travel remains hazardous. Engineers and officials prefer to project competency and the sense that everything is always under control and every contingency has been anticipated. It’s the code of competency. Never let them see you sweat. Take emotion out of the equation (awe and wonder are allowed but never, for example, anxiety). Keep telling everyone that the situation is “nominal.”

And thus we get lulled into the sense that this is ordinary stuff, because usually it works out. And it’s simply a fact that a spacewalk going as planned is never going to be a big story. That’s the news business. I expect we won’t have any big news from today’s spacewalk, because these folks are very good at what they do. But we ought to pause for a moment and appreciate their work, out there in space, circling the planet every hour and a half.

[Here’s the link to our NASA project of 2013, “Destination Unknown." Part 2 is about the ISS, and I’ve lifted some material from that story for the purposes of this blog item.]