T-31 seconds and holding … and counting!

Posted by Mike Reynolds
on Friday, July 8, 2011

The countdown to Atlantis' liftoff was one of the most surreal space shuttle countdowns and launches I have witnessed. Despite the weather forecasters best prognostications, the weather continued to improve up to launch. The conditions were right on the edge of being no-go; the Shuttle Training Aircraft continued to make approaches to the Shuttle Landing Facility literally up to launch. The last mission director “go” for launch was for the conditions at the Shuttle Landing Facility.

After 30 years and 135 missions, residents and visitors to Florida's Space Coast see this rocket's red glare for the last time as space shuttle Atlantis roars off Launch Pad 39A at NASA's Kennedy Space Center in Florida at 11:29 a.m. EDT on July 8. // Photo by NASA/Jim Grossmann
As the countdown picked up at T-9 minutes, there was an almost electric feeling in the air. This reminded me of some historic shuttle launches like the first shuttle launch, the "Return to Space" launches of Discovery after the Challenger accident and the Columbia accident, and the shuttle/Hubble Space Telescope launch. Yet having covered many a shuttle launch, I knew that this one was not a done deal until the historic countdown clock reached T-0 and the two solid rocket boosters ignited.

We passed milestones like Auxiliary Power Unit start, one that had been problematic in past shuttle launches. As we approached the T-3 minute mark, the oxygen valves on External Tank, or ET, closed as directed and the gaseous oxygen vent hood, or the “beanie,” began to lift and move away from the ET and shuttle.

At T-31 seconds, the system goes to what is called Auto Sequence Start; the shuttle’s computers take control and monitor systems for launch. Many a launch has been scrubbed at T-31 seconds or even closer to T-0 when the computers detect a problem and hold the launch. No sooner had George Diller, the voice of Mission Control, said “go for Auto Sequence Start,” did the computers hold the launch at T-31 seconds. As soon as this happened I thought, “Oh well, a scrub for today.”

But NASA flight managers had another train of thought: Let’s fly today! They identified the problem as a computer detection of the beanie not being fully retracted. Not retracting your beanie is a bad thing; the shuttle can literally run into the gaseous oxygen vent hood, which would make for a very bad day. Flight managers quickly assessed the problem: a computer glitch. The gaseous oxygen vent hood had properly retracted, yet the computers had mis-assessed the position of the beanie. And so the count resumed at T-31 seconds. Understand that the launch window was very short, and if the managers and engineers had not done a spectacular job working and solving the problem, the launch attempt would have been scrubbed for today.

At T-6.6 seconds, the three space shuttle main engines came to life, and at T-0, the two solid rocket boosters ignited; Atlantis was on its way and the last space shuttle of an era had blasted off.

Stay tuned for photos from the day (they might be my best yet) and a reflection on the emotions of today's final space shuttle launch.

To leave a comment you must be a member of our community.
Login to your account now, or register for an account to start participating.
No one has commented yet.
Join our Community!

Our community is FREE to join. To participate you must either login or register for an account.


Receive news, sky-event information, observing tips, and more from Astronomy's weekly email newsletter. View our Privacy Policy.

Find us on Facebook