Considering all the time and trouble it takes to launch a space shuttle, you might think that a 70 percent chance of stormy weather would be good reason to reschedule.

But you would not be thinking like NASA.

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“The forecast is a forecast,” mission manager Mike Moses tells us after meteorologists make their dim projection for Atlantis’s planned liftoff at 11:26 a.m. EDT Friday.

“I only know of one way to make it a 100 percent no-go forecast, and that’s to not put propellant in the tank,” Moses said.

WATCH VIDEO: A cargo ship replenishes space station supplies just days before shuttle Discovery is due to launch.

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So, come 2 a.m., that’s probably what Moses and his team will decide to do, namely proceed with launch preparations until conditions either will or won’t cooperate for launch.

I got a different view of the process today from one of my sisters, an astrophysicist and educator, in town for the launch. Her take:

NASA’s decision-making process involves constant sweeps of information (local weather, weather at three international shuttle abort sites, conditions for air-based reconnaissance) forecasted over time (70% weather will interfere tomorrow, 60% on Saturday, 40% on Sunday), cross-correlated with myriad other factors, and extruded through a complex web of contingency requirements, boundary conditions, and constraints.

At any given moment, the resultant phase space of possibility is a complicated topology of probabilistic outcomes, none of which is excluded until and unless conditions clearly rule it out. Part of what makes today –- the day before a launch or a non-launch -– so interesting is that NASA never stops re-shaping that probabilistic topology. Every moment brings a new iteration of not-knowing.

Though wrapped in an analytical scaffolding, and though following seemingly literal production rules, the process nonetheless yields fluidity, complexity, and simultaneity. As of this afternoon, all of tomorrow’s possible conditions exist. NASA projects them all with a detachment that might make a Zen master smile. What will or won’t happen hasn’t happened -– or not –- yet, so, just as Schrodinger’s cat is both alive and dead until we open the box to find out, so, too, tomorrow’s launch is both happening and not.

Yes, this last launch has our attention riveted. We’re all waiting for it to happen. The possible not-happening, though, shows us NASA’s process, too: an object lesson in what Rilke may have meant by “Live the questions.”

Image: Shuttle Atlantis: Ready for launch — or not. Credit: NASA