Shuttle lands safely in Fla.

Hubble mission is weighed

Safety improvements might allow resumption of night launches

September 22, 2006|By Michael Cabbage and Robyn Shelton | Michael Cabbage and Robyn Shelton,Orlando Sentinel

CAPE CANAVERAL, Fla. -- NASA will spend the next month considering a possible service call to the Hubble Space Telescope after shuttle Atlantis safely glided home yesterday through starry pre-dawn skies.

The shuttle's six astronauts ended a four-year hiatus in the construction of the International Space Station by installing a new set of solar arrays that eventually will double the outpost's power supply. But Atlantis' flight could have an equally important impact on future shuttle operations beginning with the next scheduled launch to the station in December.

Minimal debris shedding during liftoff from Atlantis' external fuel tank means NASA likely will authorize the resumption of night launches before the next mission. Engineers also are growing more confident in their ability to assess the health of the shuttle's heat shield from photos and inspection data.

The tank's performance and the improved inspections make a mission to service Hubble a growing possibility. A decision on the flight is expected in late-October.

"Hubble is one of the great observatories. It has revealed fundamental things about the universe of which we had no idea and would have had no idea without that mission," NASA administrator Michael Griffin said. "If we can do it [a servicing flight] safely, we want to do it."

The daylight launch requirement has hamstrung NASA by severely limiting flight opportunities since the rule was adopted after the 2003 Columbia accident.

The requirement was put in place to allow better photography of liftoff so NASA could monitor the performance of the shuttle's redesigned tank. The goal was to make sure large, potentially damaging pieces of foam insulation weren't breaking off the tank's exterior and hitting the shuttle - the scenario that doomed Columbia.

The tank performed well during Atlantis' launch, making two consecutive flights with no dangerous debris shedding. Had damage been detected, NASA would have had the option of sheltering the shuttle crew on the station until a rescue flight was dispatched.

The post-Columbia safety improvements and the need for more launch opportunities are expected to lead shuttle managers to end the self-imposed restriction.

"The team overall does feel extremely confident about launching at night," said John Shannon, deputy manager of NASA's shuttle program. "Launching at night does not impact the safety of the crew because we're going to do the full inspection just like we did on this flight."

In the days immediately after Atlantis' launch, engineers assessed the health of the shuttle's heat shield in record time from data collected by a sensor-laden, 50-foot boom and photos taken in orbit.

Two other boom surveys were done later in the mission. All went quickly and smoothly.

That wasn't the case in 2005, when the boom first was used to inspect the shuttle in flight.

Then, analysts were unsure exactly what to make of some scars on shuttle Discovery's protective heat tiles and pieces of ceramic cloth that protruded from between heat-resistant tiles on the orbiter's belly. Now, engineers have data from earlier flights for comparison as well as experience in interpreting what they see.

As a result, the inspections are proving to be an increasingly effective and reliable tool.

"This is just standard work now," Shannon said last week. "From a process standpoint, we're not surprised by any of these things and we know what to do to analyze it."

All these factors likely will play a role in NASA's decision whether to launch a servicing flight to Hubble in early 2008. The orbital observatory has reshaped humankind's understanding of the universe, but needs maintenance to extend its life.

The mission has been hotly debated since the Columbia accident because Hubble flies in a different orbit than the station. That means astronauts would not be able to take refuge at the outpost if their ship suffered irreparable damage during liftoff. It also appears unlikely NASA would be able to launch a rescue flight if something went wrong.

However, the tank's improved performance and the ability to confidently detect heat shield damage clearly will weigh in favor of servicing Hubble. NASA also continues to work on techniques for repairing small areas of heat shield damage in orbit.

Michael Cabbage and Robyn Shelton write for the Orlando Sentinel.

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