NASA is still perplexed over the parachute failure that damaged its new Ares I-X test rocket during its October test launch, but otherwise the debut flight went well, mission managers said.

The $445 million suborbital Ares I-X rocket, NASA's first prototype of the vehicle it plans to carry humans to orbit after the space shuttles retire, blasted off Oct. 28 from the Kennedy Space Center in Florida. It soared eastward into the sky, peaked at about 28 miles altitude, then the solid-rocket first stage separated from its dummy second stage and dropped into the ocean as planned.

But two of three parachutes failed to deploy to soften the spent first stage's splashdown into the ocean as planned. Consequently, the booster hit the water harder than expected, causing a huge dent and other damage. Ultimately, since the parts aren't intended to be reused, mission managers said the malfunction wasn't a major problem and they were able to gather all the data they needed.

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"We're still investigating what happened there and why," said Marshall Smith, chief of the System Engineering and Integration Office for the Ares I-X mission, during a Thursday news conference.

Mission managers suspect that the chutes began to deploy earlier than planned, and thus took on more force than they were designed for, resulting in their failure.

Gathering data

The towering 327-foot Ares I-X rocket was loaded with more than 700 onboard sensors to gather data about the booster's trajectory and performance.

Among the promising signs revealed in the report were the fact that the rocket shook and rolled much less than some models predicted, which had originally been a concern for the Ares I design concept. Additionally, early visuals raised some fears that the first and second stages might have hit each other, or "re-contacted," after separation, but detailed analysis revealed that they didn't.

"First stage separation was entirely nominal," Smith said. "We're pretty confident there's no re-contact issues."

Additionally, three connectors failed to detach during the separation of two pieces of the segment connecting the first and second stages. This was somewhat expected though, and the two pieces separated anyway, ripping the connectors, because of the strong force pulling them apart.

"It didn't really matter," said Bob Ess, Ares I-X mission manager. "We did asses this possible failure scenario before launch."

Puzzling measurements

Another odd finding was the measurement of the structural damping, which is basically how much the structure of the rocket is able to resist vibrations, during the test launch. The booster experienced about 20 percent less damping than models had predicted.

"I can't tell you whether it's bad or good — it just doesn't match," Smith said.

The engineers plan to investigate that issue and others as they continue to review the data, which is still in preliminary stages of analysis. Almost all the data was recovered from the rocket when teams retrieved the stage from the ocean, though for some reason the data at the end of the flight wasn't recorded properly to the disk. But mission managers said they had other versions of that data and were more concerned with the ascent than descent anyway.

"We've got loads of that data, so were not super concerned with getting that," Smith said.

NASA is also beginning to plan the next Ares I flight test, which is currently targeted for 2012.