Atlantis STS-122 Status Report 2008-02-04

CBS NEWS STS-122 STATUS REPORT: 36
Posted: 11:30 AM, 2/4/08

By William Harwood
CBS News Space Analyst

SR-36 (02/04/08): Astronauts fly back to Kennedy for countdown, Thusday launch

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11:30 AM, 2/4/08, Update: Astronauts arrive for Thursday launch; weather an issue

The Atlantis astronauts flew back to the Kennedy Space Center today for the start of a new countdown to launch Thursday on a long-awaited space station assembly mission. Running two months late because of fuel sensor problems that scrubbed two launch attempts in December, the international crew landed at the Florida spaceport just after 10:30 a.m.

"We're feeling very good about this opportunity," commander Steve Frick said at the runway. "We'll keep looking at the weather, but we've very happy about the condition of Atlantis."

The countdown was scheduled to begin at 5 p.m. today with liftoff targeted for 2:45:28 p.m. Thursday. Forecasters are predicting a 60 percent chance of a delay because of rainy weather, but the odds improve to 80 percent "go" on Friday and Saturday, after a front moves through the area.

"The weather is looking good the next couple of days, but then by launch day, unfortunately, we do have a frontal boundary that's going to be coming into the area and will be affecting our weather that day," said Kathy Winters, the shuttle weather officer. "So we do have a chance of having some bad weather on launch day. ... The weather does improve, though, the following two days here at Kennedy Space Center."

The only remaining technical issue of any significance was resolved Sunday when engineers successfully coaxed a kinked Freon flex hose to retract when the shuttle's cargo bay doors were closed for flight. The flex hose, one of four that route Freon coolant to and from radiators attached to the inside of the payload bay doors, is not expected to be a problem in orbit.

"All of our systems are in good shape, our countdown work is on schedule and we have no issues to report," said NASA Test Director Charlene Blackwell-Thompson. "Atlantis is ready to go fly ... and we're all looking forward to Thursday's launch."

Atlantis, carrying the European Space Agency's Columbus research module, was originally scheduled for launch to the international space station on Dec. 6. But the flight was delayed by problems with critical engine cutoff - ECO - sensors at the base of the shuttle's huge external tank.

In the wake of a second launch scrub Dec. 9 and a Dec. 18 fueling test, engineers traced the problem to temperature-induced gaps opening up in the connector that routes signals from the sensors to the shuttle. Testing at the Marshall Space Flight Center in Huntsville, Ala., confirmed the nature of the original problem and demonstrated a new connector design, featuring soldered pins and sockets, will work as advertised.

"A lot of people have asked me is it frustrating or difficult for the crew to get so close to launch last time and then have to wait two months to try again," Frick said today. "But ... I was very happy with the way things went. The ECO sensor problem has been nagging us for quite a long time and we were actually very pleased we were able to have it re-occur a couple of times, pull the hardware out, find out what the problem really is and get a chance to fix it properly so we don't have to worry about it."

The four ECO sensors are part of a backup system intended to make sure the shuttle's main engines don't drain a tank dry after some other problem - a leak, for example, or an improper hydrogen-oxygen mixture ratio - used up propellant at faster than normal rates.

"I'm sure everyone has heard an awful lot about those sensors," Frick said, "but we really rely on them. We use virtually all of our gas just to get up to orbit for a normal mission, like 99-and-a-half percent, and we can't afford to let the engines run dry because they tend to come apart. So the ECO sensors are a critical safety system that I'm very happy we were able to fix them and feel very confident about them working.

"Our technicians here at Kennedy and all over the shuttle program - the technicians, the mechanics, the engineers - are, I think, the best there are and they've done just a tremendous job of nailing this thing down and fixing it so that we know we can go fly."

A detailed countdown timeline, the crew's flight plan, NASA's initial mission television schedule and other background are posted on the CBS News STS-122 Quick-Look page:

http://www.cbsnews.com/network/news/space/currentglance.html