## Wednesday...Part 2

Hi guys;
Landing postponed 2 days in a row -- tomorrow should be it, whether it's here in FL or out at Edwards Air Force base in CA will be decided at the very last moment.

I have gotten somewhat caught up on more blog posts.

Wednesday 5/20 -- 2
Late in the day we got the word that the team scrutinizing video of the shuttle has pronounced it free of damage - so it's safe to return.

The whole subject of danger on this mission is a strange one.  Whenever I ask the astronauts about danger, I notice I speak in general terms, whereas they answer me in the language of mathematics and probability.  I tend to think of the danger as very dramatic and a big deal; they boil it down to numbers.  And they never say "danger" - they always call it "risk."

They trust experts to calculate the odds of disaster, which are expressed in a ratio like 1:200, or 1:160 (I have no idea how they arrive at these numbers).  Back in February, two satellites collided in orbit, greatly increasing increasing the amount of space debris.  That event also increased the chances of the shuttle getting destroyed during the Hubble repair mission.

Shortly after the satellite collision, Greg Johnson ("Ray Jay") the pilot, told me that the experts had recalculated the risk of "loss of crew and vehicle" due to getting hit by debris; the latest estimate was something like 1 in 160.  I was surprised; that sounded uncomfortably dangerous to me.

But to him, it was a number.  And mission planners were taking steps to change the number to make it more acceptable (I'm told they prefer to keep the risk around 1:200).  This is what they call "risk management" or "mitigating" the risk.
That's where yesterday's maneuver, the change to an elliptical-shaped orbit came from.  By spending half their time at a lower altitude (an area with a lower probability of getting hit), they can average the higher and lower risk numbers, and improve their overall risk number.

So because the numbers have changed, the mission's suddenly not as dangerous as it was before? I get it, I suppose, but this is just not a way of thinking that I'm used to.

If I were told the chances of my car blowing up the next time I turn the key are 1 in 160 - and then later I'm told they've recalculated and the number is actually 1 in 200 - I wouldn't feel that much better about starting the car tomorrow morning.  I don't really care if it's 1:160 or 1:200 - both seem too high.

I guess regardless of the numbers, I instinctively imagine what it would feel like to be that unlucky "1" in the equation.

I understand the way these people look at the danger, and they're not foolhardy.  They do all they can to turn "risk" into "science;" like a savvy player in Vegas, they study and try to manipulate probability.  And it does make sense to me intellectually when they explain it.  But it still doesn't resonate in my gut.

Maybe I'm just too much of a humanities major.