Tank debris seen as shuttle thunders into space
BY WILLIAM HARWOOD
STORY WRITTEN FOR CBS NEWS "SPACE PLACE" & USED WITH PERMISSION
Posted: July 4, 2006
The space shuttle Discovery and its flag-waving crew thundered into space today, putting on a spectacular Fourth of July skyshow as it rocketed away on a long-awaited mission to repair and resupply the international space station.
NASA managers warned reporters before launch that small bits of foam insulation would fall from the shuttle's external tank during launch and that they were confident nothing large enough to cause damage would hit the orbiter.
As expected, what appeared to be several small pieces of debris could be seen separating from the tank about two minutes and 47 seconds after liftoff, but it was not immediately clear whether it posed any concern or not. At that point in the ascent, Discovery was out of the thicker regions of the atmosphere, greatly reducing the threat posed by debris.
Otherwise, Discovery's thundering ascent appear picture-perfect.
Climbing smoothly away from pad 39B atop twin pillars of 5,000-degree flame and a churning cloud of dirty brown exhaust, Discovery majestically wheeled about and arced away on a trajectory up the East Coast of the United States, thrilling thousands of tourists and area residents lining area roads and beaches.
At the controls were commander Steven Lindsey, pilot Mark Kelly and flight engineer Lisa Nowak. Their crewmates are Stephanie Wilson, spacewalkers Piers Sellers and Mike Fossum and European Space Agency astronaut Thomas Reiter.
It was the first manned spaceflight ever launched on the Fourth of July, and the astronauts waved small American flags as they departed crew quarters to head for the launch pad. A few minutes later, they strapped in to await the final moments of the countdown.
"Looks like Discovery is ready, the weather is beautiful, America is ready to return the space shuttle to flight," Launch Director Mike Leinbach radioed Lindsey. "Good luck and godspeed, Discovery."
"Thank you very much, Mike. I can't think of a better place to be on the Fourth of July," Lindsey replied from the flight deck. "Tell all the folks on the Florida east coast that we hope to very soon give you an up close and personal look at the rocket's red glare."
Discovery lived up to Lindsey's promise, climbing skyward and rocketing away, visible for miles around as it roared toward orbit.
A camera mounted on the shuttle's external tank provided spectacular views of the spaceship's heat-shielded underside as Florida's east coast dropped away in the background. The ascent appeared free of foam debris from the tank until about two minutes and 47 seconds when a half-dozen seemingly small pieces of debris could be seen suddengly separating. NASA managers said before launch that foam debris shedding after about 165 seconds was of no concern because by that point, the atmosphere is so thin it cannot carry debris to a dangerous impact. The debris seen today separated around 167 seconds after launch.
The foam insulation on the tank has been a source of concern ever since the 2003 Columbia disaster and, more recently, because of foam on Discovery's tank that was officially deemed a "probable/catastrophic" risk.
Another foam problem cropped up Monday when engineers spotted a small piece of insulation on Discovery's mobile launch platform that broke away from a liquid oxygen feedline bracket after a launch delay Sunday. After a hurried analysis and photographic inspection, however, engineers convinced NASA managers the defect posed no threat to the shuttle or its crew.
Eight-and-a-half minutes after liftoff, Discovery's main engines shut down and the spacecraft coasted into space. Thirty seven minutes after that, the shuttle's twin orbital maneuvering system rockets fired, raising the low point of the orbit and putting Discovery on course to rendezvous with the international space station Thursday.
Discovery is ferrying Reiter to the station to join Expedition 13 commander Pavel Vinogradov and flight engineer Jeff Williams as a full-time crew member. Launched under a commercial contract between the European Space Agency and the Russian space agency Roscosmos, Reiter will boost crew size back to three for the first time since downsizing in the wake of the Columbia disaster.
Along with delivering Reiter to the outpost, Discovery is carrying 5,100 pounds of supplies, equipment and experiment hardware, including a laboratory freezer, a European plant biology rack and a NASA oxygen generator that eventually will help boost station crew size to six.
At least two spacewalks are planned, one to test the shuttle's robot arm and a long heat-shield inspection boom as a space crane for possible repair work in the future, and to repair a broken transporter on the station's solar array truss that must be fixed before assembly can continue.
Because Discovery's on-board fuel cell supplies were topped off Monday, the crew is expected to have enough on-board oxygen and hydrogen to generate the electricity needed for a one day mission extension. If so, Sellers and Fossum will stage a third spacewalk to test wing leading edge repair techniques.
Despite the back-to-back launch delays Saturday and Sunday, Discovery's countdown was one of the smoothest in recent memory with no problems other than concern about the weather. And as it turned out, the weather was virtually ideal, with slightly high but acceptable crosswinds at the shuttle's emergency runway.
Lindsey and Kelly will carry out a series of rocket firings over the next day and a half to find tune Discovery's approach and if all goes well, the shuttle will dock with the huge lab complex around 11 a.m. Thursday.
Throughout today's ascent, dozens of cameras and a trio of radars were trained on the shuttle and its external tank, including three on each solid-fuel booster, one on the external tank and another in the belly of the space shuttle where propellant lines enter the engine compartment.
The goal was to look for any signs of foam insulation breaking away and any possible impacts on the shuttle's heat shield. To ease the aerodynamic stress on the tank, Discovery's flight computers used a so-called low-Q profile that throttled the main engines down a bit more than normal, for slightly longer than normal, during the region of maximum aerodynamic pressure. At the same time, the trajectory was lofted slightly to get the shuttle out of the dense lower atmosphere as quickly as possible.
Discovery's last flight a year ago - the first post-Columbia mission - clearly demonstrated the unknowns that still face the shuttle program. Agency managers thought they had corrected the foam insulation problem that doomed Columbia. And in a sense, they had. The so-called bipod ramp that was the source of the foam that did in NASA's original shuttle was removed before Discovery's flight.
But during ascent, a one-pound chunk of foam broke away from a wind deflector known as a protuberance air-load - PAL - ramp, one of two on the ship's external tank. The foam ramps were in place to smooth the flow of turbulent air across two external pressurization lines and a cable try as the shuttle climbs out of the dense lower atmosphere.
NASA managers ultimately decided to remove the PAL ramps, too, before today's flight, accelerating engineering work that was already underway. The decision ultimately was supported by extensive computer modeling and wind tunnel tests showing the pressurization lines, cable tray and support brackets are tough enough to stand up to worst-case aerodynamic loads.
Discovery's launch was the first actual flight test of the design change, the most significant aerodynamic modification to the tank since shuttle flights began in 1981.
But engineers have not yet come up with a new design for the foam insulation covering the 34 brackets on the external tank that support the pressurization lines and cable tray. It was that so-called ice-frost ramp foam that poses what NASA officially classified as "probable/catastrophic" in an integrated risk matrix.
During a flight readiness review earlier this month, NASA chief engineer Chris Scolese and Bryan O'Connor, the agency's top safety manager, voted to delay Discovery's launch until the ice-frost ramp foam could be redesigned.
NASA Administrator Mike Griffin decided to press ahead, however, because everyone agreed that even in a worst-case scenario, an IFR failure would not directly threaten the crew. In the event of catastrophic impact damage, Lindsey and his crewmates could move into the space station to await rescue by another shuttle crew.
"Everyone agrees that there is no elevated risk to crew from this decision and I personally think a very minor elevated risk to the orbiter, if any," Griffin told CBS News in a pre-launch interview.
In an earlier interview, O'Connor said the threat was officially defined as a system that "is likely to cause loss of the vehicle over the life of the program," O'Connor said in an interview with CBS News. "And 'likely' doesn't mean 'assuredly.' It's interpreted as a 50-50 chance that over 100 missions this thing would take out an orbiter.
Engineers estimated there was a 1-in-75 to chance ice-frost ramp foam could damage a typical heat-shield tile and a 1-in-100 chance it could cause catastrophic impact damage to beefed up tiles around landing gear doors and other critical areas.
It will take about six days, however, to complete analysis of ground-, air- and shuttle-based cameras and instruments. Data from wing leading edge impact sensors will be downlinked later today, along with video shot by Discovery's crew as the shuttle separated from the orbiter. Footage from the booster cams will be retrieved after the spent rockets are towed back to Port Canaveral.
The astronauts plan to spend most of the day Wednesday carrying out a detailed inspection of the shuttle's nose cap and wing leading edge panels, which experience the most extreme heating - more than 3,000 degrees - during re-entry. In addition, the station astronauts will photograph Discovery's belly during final approach and additional inspections are planned after docking.