NASA Podcasts

Shuttle Era: Launch Weather Forecasting
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Mike Leinbach, Shuttle Launch Director: There are so many things that can keep a shuttle on the ground, weather being one of them. It's one of the more visible ones to the public, of course.

Narrator: Weather is often the difference between "go" and "no go" when a space shuttle is ready to lift off from NASA's Kennedy Space Center in Florida.

The task of tracking the weather and determining whether or not it's safe for a shuttle to launch falls to the Launch Weather Officer.

It's a service provided by the U.S. Air Force 45th Weather Squadron, based at nearby Cape Canaveral Air Force Station.

Kathy Winters, Shuttle Launch Weather Officer: Well it's a very tropical environment here in Florida. We have the sea breeze that occurs, we have the river breezes that occur. Anytime we get some low-level convergence and we have enough moisture, we can develop showers and thunderstorms, particularly in the summer time. And so, working the weather, you want to really be able to nail it down, but there's a lot of times where there's a lot of iffy situations. And so that's where it's really challenging.

Narrator: Space shuttle launches are governed by a complex set of weather rules, called "launch commit criteria," designed to keep the shuttle and astronauts safe.

There are limits for rain, lightning, clouds and winds. And if any one of the rules is violated, that's a "no-go."

Winters: It may look good out here, but we actually could be red. And so I know a lot of people think, "It wasn't that bad!" But it's violating our launch commit criteria and we have a safety issue. So we have to call it.

Narrator: The team can only begin filling the shuttle's 15-story external fuel tank if weather permits -- and of course, conditions must be favorable at the launch pad at liftoff.

They also need good conditions for a landing, in case the shuttle develops a problem during flight and must come back to land at Kennedy -- an unlikely, last-resort emergency landing option called a Return to Launch Site abort.

Winters relies on several forecasting tools including radars, satellite imagery, weather balloons and other data sources.

Winters: The location of the radar is off to the west, as opposed to the south. So our new radar being off to the left allows us to pick up the sea breeze a lot better, particularly now because we have Doppler capability with this radar.

Narrator: Conditions can change quickly, so the launch team often will go ahead with a countdown -- despite a gloomy forecast -- just to be ready in case the weather changes for the better.

Leinbach: I recall one mission where we decided to tank and go for launch with only 5 percent chance of launching that day, and indeed, we launched. And so that's a case where we got lucky, probably. There've been other cases where we had, you know, about an 80 percent "go" for launch, and then we end up scrubbing for weather. More often than not, we'll give it a shot.

Narrator: The team has weathered some memorable days -- one of which took place in August 2006, when Hurricane Ernesto threatened Kennedy Space Center as shuttle Atlantis waited on the launch pad.

Leinbach: Hurricanes and a shuttle on the launch pad are incompatible, as you might imagine. And so we have very strict criteria to roll the vehicle back to the VAB in the event of a threatening hurricane.

Narrator: Space shuttle Atlantis began the long, slow roll from the launch pad to the safety of the Vehicle Assembly Building in advance of the storm.

But when the shuttle was only a third of the way through the six-hour move, Leinbach learned Ernesto had not strengthened -- and he sent the shuttle back to the launch pad.

Leinbach: And we went back to the pad, the storm passed about 50 miles offshore, got a little bit of rain and some wind, but no big deal -- and we were able to launch about seven or eight days later.

Winters: It was just so unique. It was very challenging. At the time I probably wouldn't have called it my favorite, but now, looking back, it's one of our favorite stories to talk about.

Narrator: Winters is part of a team of about 40 people supporting launch at the 45th Weather Squadron.

That's in addition to personnel at Johnson Space Center's Spaceflight Meteorology Group in Houston, the Marshall Space Flight Center in Huntsville, and the weather office here at Kennedy.

But the working relationship between the launch director and launch weather officer is critical.

Leinbach: We do a daily weather tag-up every day. Monday through Friday, every day, for about 10, 15 minutes. Doing a daily with her is really helpful, not only for the people processing the vehicle at the pad, but it builds that relationship between she and I that is very critical on launch day.

Leinbach: Range weather.

Winters: Weather has no constraints for launch.

Leinbach: Thank you, Kathy.

Winters: There's been times we've been in tough situations and I think Mike can tell just from the sound of my voice what I'm feeling, what I'm thinking about a particular situation. So he knows if I'm getting more concerned about something just by the tone of my voice.

Narrator: NASA will never control the weather, but a talented team and strict safely guidelines will always help protect the nation's spacecraft... and crews.
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