A countdown suspended five days by a failed engine computer advanced without a hitch Monday toward a Tuesday launch of space shuttle Atlantis with the Jupiter-bound Galileo probe.
The countdown was resumed at 12:01 a.m. when the traditional call to stations summoned workers to their posts in the control center and on the launch pad."We see nothing standing up and going to bite us," NASA test director Al Sofge said Monday after workers had completed early tasks, including checks of the guidance system and preparations for fueling the spaceship.
Liftoff of Atlantis and its crew of five astronauts was set for a 26-minute period starting at 12:57 p.m. Tuesday. That's when Earth and Jupiter will be aligned properly for Galileo to orbit the giant planet in 1995 after a six-year voyage.
The weather outlook was improving with forecasters increasing from 70 to 80 percent the chance that conditions will be good at launch time.
Shuttle managers on Sunday gave the go-ahead to restart the countdown after assessing the readiness of the shuttle and replacing the bad computer that forced a postponement of the launch, scheduled originally for last Thursday.
"We retested the computer and everything looks fine," test director Mike Leinbach told reporters.
Astronaut Donald Williams, who commands Atlantis' crew, praised technicians who worked around the clock for four days to make the computer swap, saying they "did a super job."
Launch preparations were taking place under the tightest security ever for a shuttle flight because of threats from anti-nuclear activists opposed to a launch carrying 49.4 pounds of radioactive plutonium-238.
The main Galileo craft will enter an orbit around the planet, and its cameras and 10 scientific instruments will gather information on temperatures, magnetic fields, radiation, cloud characteristics and gravity.
Galileo also will study Jupiter for clues to the formation of the solar system. Many scientists believe the planet still holds much of the material, in the original state, from which the sun and planets formed 4.6 billion years ago.