With a second shuttle on standby for possible rescue duty, the shuttle Atlantis blasted off Monday on a high-stakes five-spacewalk mission to resuscitate the aging Hubble Space Telescope--a fifth and final housecall to give the hobbled satellite a new lease on life.
With its three main engines roaring at full throttle, Atlantis' twin solid-fuel boosters ignited with a ground-shaking roar at 2:01:56 p.m. EDT, instantly pushing the winged spacecraft skyward atop a churning cloud of exhaust.
At the moment of liftoff, the Hubble Space Telescope was soaring high above central Florida in its 350-mile-high orbit, streaking through space at 5 miles per second. But it will take Atlantis two days to catch up with the observatory to kick off the long-awaited repairs.
Quickly climbing above its launch gantry, Atlantis wheeled about and arced away to the east over the Atlantic Ocean, leaving a trail of smoke in its wake as it rocketed through a partly cloudy sky. Other than an instrumentation glitch moments after liftoff, the launching was picture perfect.
At the controls aboard Atlantis were commander Scott Altman, pilot Gregory C. Johnson and flight engineer Megan McArthur. They were joined by spacewalkers John Grunsfeld, Michael Massimino, Andrew Feustel and Michael Good. It will be the second Hubble visit in a row for Altman and Massimino and the third for Grunsfeld. The rest are shuttle rookies.
The Hubble mission is the only flight on NASA's post-Columbia manifest that does not go to the International Space Station. Because Hubble and the space station are in different orbits, Altman and his crewmates cannot seek safe haven aboard the lab complex if any major problems prevent a safe re-entry.
In addition, at Hubble's higher altitude the risk of a catastrophic impact with space debris is greater, on average 1 in 229 compared to less than 1 in 300 or better for a typical station mission. As a result, the shuttle Endeavour is poised atop launch pad 39B, on stand-by for possible rescue duty if needed. Over the next four days, engineers will get Endeavour ready for the start of a three-day countdown and then stand by as Atlantis' mission proceeds.
If any ascent-related heat-shield damage is spotted, Endeavour could, in theory, be ready for launch by next Monday. If impact damage from space debris is seen toward the end of the mission, Endeavour could be launched on three days' notice.
While it will take several days to complete an initial inspection of Atlantis' heat shield, there were no obvious debris strikes or other problems visible in television views downlinked from a camera on the side of the shuttle's external tank during the critical first two minutes of flight.
NASA managers are confident Endeavour won't be needed, thanks to post-Columbia improvements that have greatly reduced foam shedding from the shuttle's external tank and development of repair techniques that can fix the sort of damage that might be reasonably expected. Endeavour is on stand-by for the remote possibility of Columbia-class damage.
"There are very small odds we would, in fact, have a problem on ascent for which the remedy would be a launch on need shuttle, a rescue shuttle," said former NASA Administrator Mike Griffin, the man who approved the Hubble servicing mission. "But against the very small probability that it could occur, we will carry that rescue option in the manifest...The safety of our crew conducting this mission will be as much as we can possibly do."
Griffin's predecessor, Sean O'Keefe, canceled the final Hubble servicing mission in 2004 because of post-Columbia safety concerns. O'Keefe told CBS News Monday he did not regret the decision, based on the state of post-Columbia safety upgrades at the time, but added he was "thrilled and delighted" the mission had been reinstated.
"Absolutely no regrets whatsoever, in January of '04, but extraordinary pride in the colleagues here at NASA who really put an awful lot of determination, persistence, talent and technical expertise to bear to make this day possible," he said.
Launch originally was scheduled for last October 14, but just three weeks before takeoff, a critical circuit in the telescope's science instrument data system malfunctioned. To restore full redundancy, NASA managers decided to delay the servicing mission to give engineers time to check out and certify a flight spare that had been used for ground testing. The replacement computer was delivered to the Kennedy Space Center on March 30 and launched aboard Atlantis.
Hoping to extend Hubble's life well into the next decade, the four spacewalkers, working in two-man teams, plan five back-to-back excursions to install six new stabilizing gyroscopes, six new nickel-hydrogen battery packs, the new data computer, and two new instruments, the $126 million Wide Field Camera 3 and the $81 million Cosmic Origins Spectrograph. Like all modern Hubble instruments, both are equipped with corrective optics to counteract the spherical aberration that prevents Hubble's 94.5-inch mirror from achieving a sharp focus.
The Atlantis astronauts also will attempt to repair two other instruments: the Space Telescope Imaging Spectrograph, which suffered a power supply failure in 2004, and the Advanced Camera for Surveys, which broke down in 2007. Neither instrument was designed to be serviced in orbit, but determined engineers devised custom tools and an ingenious plan for the spacewalkers to bypass the failed electronics.
If the instrument repairs go well, the astronauts will install an upgraded fine guidance sensor during the final spacewalk. If the astronauts have problems with the repair work, the guidance sensor task likely will be deleted to give the crew more time to complete at least one of the repairs.
Either way, the astronauts plan to install new insulation and a grapple fixture that will permit attachment of a rocket motor or even NASA's new Orion manned spacecraft in the future to drive Hubble out of orbit when it is no longer able to do science.
"On Servicing Mission 4, we're going to give Hubble another extreme makeover," said Program Manager Preston Burch. "This makeover will be the best one yet because we will outfit Hubble with the most powerful and advanced imaging and spectrographic instruments available and we will extend Hubble's operating lifetime for five additional years."
Without Servicing Mission 4, engineers believe Hubble would be hard pressed to survive past 2010. But if the Atlantis astronauts are successful, they will leave behind an essentially new telescope, one that is equipped with a full suite of five operational scientific instruments for the first time since launch in 1990. And with new gyros and batteries, Hubble has a good chance of remaining fully operational long enough to work in concert with its eventual replacement, the James Webb Space Telescope.
"There's not much margin for error," Burch said Sunday. "We'll need flawless execution from our astronaut team and we'll also need flawless performance from all of our hardware. But we have done extensive testing, extensive training and we're highly confident that we're going to have another successful mission like the ones we've had before."
NASA has spent about $10 billion on the Hubble Space Telescope to date, making it one of the most expensive science projects in history. The cost of the Atlantis mission and the two new instruments totals $887 million.
Asked whether it made sense to spend more money on a 20-year-old space telescope, Griffin said it makes all the sense in the world.
"After we get done with it, it's not an old telescope," he told CBS News in a recent interview. "Every subsystem that needs refurbishment is being refurbished and it's getting a new complement of instruments. So the only part of it that's old is the optical metering structure and the glass. And the glass doesn't care. When they're done, it really is not an old telescope, it's a new telescope."
"So the question you want to ask yourself when you look at the value proposition, if for the cost of this shuttle flight--and bear in mind, most of the instrument costs and all that were already paid for--plus the team that we've been carrying, and it's about a $10-million-a-month team, if for whatever all that adds up to you could get yourself a new telescope in space, would you think that would be worthwhile? And I think most people, most astronomers, would say yes."