"Control, this is Endeavour," said Kittredge, still unnaturally calm.

"We have SRB sep."

There is a Glossary at the end of this book that contains many of these abbreviations.

"Roger, we see it."

"Initiating abort." Kittredge depressed the Abort push button, the rotary switch already positioned at the RTLS option.

Over her comm unit, Emma heard Jill Hewitt call out, "Emma, let's hear the checklist!"

"I've got it." Emma began to read aloud, and the sound of her own voice was as startlingly calm as Kittredge's and Hewitt's.

Anyone listening to their dialogue would never have guessed they had a catastrophe. They had assumed machine mode, their panic suppressed, every action guided by rote memory and training. onboard computers would automatically set their return course.

They were continuing downrange, still climbing to four hundred thousand feet as they dissipated fuel.

Now she felt the dizzying spin as the orbiter began its pitcharound maneuver, rolling tail over nose. The horizon, which had been upside down, suddenly righted itself as they turned back toward Kennedy, almost four hundred miles away.

"Endeavour, this is Control. Go for main engine cutoff."

"Roger," responded Kittredge. "MECO now." On the instrument panel, the three engine-status indicators suddenly flashed red. He had shut off the main engines, and in seconds, the external fuel tank would drop away into the sea.

Altitude dropping fast, thought Emma. But we're headed for home.

She gave a start. A warning buzzed, and new panel lights flashed on the console.

"Control, we've lost computer number three!" cried Hewitt. "We have lost a nav-state vector! Repeat, we've lost a nav-state vector!"