When the space shuttle Challenger exploded during its launch into crystalline skies over Cape Canaveral on Jan. 28, 1986, the loss of seven crew members and an icon of US technological prowess was a national tragedy.
Saturday morning's loss of the shuttle Columbia and its seven astronauts nearly 17 years to the day after the Challenger accident was a tragedy of global proportions.
The international makeup of the crew, the condolences pouring in from capitals around the world, and the aging - and now-dwindling - fleet of orbiters, which serve as key strands in the lifeline between Earth and the International Space Station, highlight how closely many countries with space-faring aspirations have hitched their hopes to the National Aeronautics and Space Administration.
Those links will now be tested. The stark images showing Columbia's lone contrail slowly splitting into many are likely to rekindle debates within the US and within its partner countries over the value of putting humans in space. The loss certainly will shine a spotlight on NASA's oft repeated commitment to safety and the willingness of the president and Congress to fund that commitment. And it is likely to reinvigorate efforts to build a replacement for the shuttles, which have become the DC-3s of spaceflight - an obsolete design that nevertheless has performed remarkably well.
Yet the global commitment to human spaceflight is slowly expanding. China selected its first astronaut early last month and is planning to send him into orbit, perhaps by the end of the year.
"We may see some politicians arguing that we shouldn't be sending people in to space," says Ray Williamson, a professor at George Washington University's Space Policy Institute in Washington. "But we're just as likely to see people saying that while this is a terrible tragedy, Columbia demonstrates that we're all in this together. We saw this happen after 9/11, when people said, 'this just strengthens our resolve to overcome these issues.' "
Much will depend on how long NASA takes to find and fix the problem that brought an otherwise flawless shuttle mission to a tragic close. The shuttle broke up 207,135 feet over Texas as it was traveling at 18 times the speed of sound, showering debris over two states.
Yesterday, NASA administrator Sean O'Keefe named a seven-member intergovernmental panel to conduct an inquiry into the disaster. The panel will be headed by (ret.) Adm. Harold Gehman Jr., who spearheaded the investigation into the bombing of the U.S.S. Cole in Yemen in 2000. Congress is also planning its own set of probes, and the White House is considering an investigative commission, too.
Even though 9/11 remains fresh in memory and an Israeli Air Force colonel was one of the mission specialists, Mr. O'Keefe stressed that, on the basis of information so far, "we have no indication that the mishap was caused by anything or anyone on the ground."
Early speculation about what went wrong is focusing on the left wing of the spacecraft. During lift-off, a piece of foam insulation from the shuttle's main fuel tank broke off and struck the wing, perhaps damaging some of the heat-resistant tiles that protect the shuttle from a fiery reentry. Flight controllers got their first inklings that something was wrong when unrelated sensors on the left wing began failing over a seven-minute period just prior to losing all contact with Columbia. The crew was acknowledging the appearance of a failure alarm on its instrument panel when the orbiter's transmission fell silent.
Columbia's flight was the second in the past three missions where foam insulation from the tank broke off during launch and struck some part of the spacecraft, according to shuttle program manager Ron Dittemore. During the first incident, which involved the shuttle Atlantis in October, the foam struck the skirt of one of the solid-rocket boosters, causing "superficial damage."
"Two occurrences in the last three flights says that something has changed" in the way the tanks are being assembled, he continues, but after engineers analyzed the problem, "there was no alarm from a safety standpoint."
Given that the foam struck the left wing and the sensor failures occurred there, beginning with the flaps at the rear and working forward to the landing gear and hydraulic systems, "we can't discount that there might be a connection," he says, although at this point the evidence falls short of a smoking gun. Key evidence - still and video images the astronauts take of the main fuel tank when it separates from the orbiter - were destroyed along with the shuttle.
Investigators are, however, combing the Texas and Louisiana countrysides for debris from spacecraft. They've also impounded data the shuttle was sending on its systems' performance.
If lost heat-resistant tiles should emerge as the most likely cause, Dittemore acknowledges nothing could have been done after launch. The shuttles' design does not allow for in-orbit tile repair.
Although concerns about possible changes in the way the fuel tank is prepared raise memories of Challenger and its flawed solid-rocket boosters, some aerospace engineers suggest that significant differences separate the Challenger incident from Saturday's tragedy.
"Challenger resulted from a fundamental design flaw and bad decisions," Jim Oberg, a former engineer with the shuttle program, told ABC News over the weekend. "We've flown reentries 100 times, and we know how it works. I don't see a design flaw, so I don't see us taking three years to get the shuttles flying again."
Yet Columbia's loss once again focuses attention on NASA's commitment to safe operations. During the past few years, the agency's Aerospace Safety Advisory Panel (ASAP) and the General Accounting Office have reiterated their concern that budget cuts and layoffs have undercut the reservoir of expertise and high morale that once characterized operations.
In addition, while the ASAP credits the agency for close attention to safety on any given flight, NASA displays no strategy for the long-term safety upgrades that will help keep the shuttles flying for another 20 years. The panel traces the problem to tight budgets and the trade-off between planning for long-term improvements while pursuing the so-far fruitless quest for a launch vehicle to replace the shuttle.
That may be changing. This week, NASA was set to unveil its FY 2004 budget, which reportedly included long-term safety upgrades for the orbiters. The agency was also seeking money to replace aging equipment at the Kennedy Space Center, and was reinvigorating its quest for a shuttle replacement.
"Every time something like this happens, there are changes and improvements at NASA," says Brian Chase, executive director of the National Space Society, an advocacy group in Washington. The Columbia loss "will raise the awareness of the need to maintain our space infrastructure and to develop a new launch capability."