Once again, almost 17 years to the day after the loss of space shuttle Challenger, this time on the eve of war, the nation looked on in horror as a space shuttle orbiter broke up on television, over and over and over again.

Once again, we mourn the loss of seven brave and talented men and women, a crew that this time not only "looked like America," but looked like the planet itself, at least that nobler part of it that resides on every continent.

Kalpana Chawla wasn't born an American--she was from India--but she became one, and a citizen that any rational nation would be proud to call its own. Israeli payload specialist Ilan Ramon was the son of the survivors of Auschwitz.. In light of our current adversaries, he should be considered not just an Israeli hero, but a world hero, because he flew on the mission that destroyed the Osirak reactor in 1981, almost certainly preventing Saddam Hussein from acquiring nuclear weapons before the first Gulf War.

Col. Ramon wanted to take a Holocaust artifact with him on his journey into space, and had taken with him haunting space art drawn by a 14-year-old boy imprisoned in Auschwitz during the second world war. The artwork had survived incineration in a crematorium, but didn't survive the fiery entry of an ill-fated space vehicle. It will have to be replaced in the museum whence it came with a print and a memorial plaque to explain to future generations the absence of the original.

Fortunately, despite the fact that they can no longer view the evanescent carbon molecules on which the moonscape was originally etched, because of modern technology, people will continue to be able to appreciate the young artist's vision. The medium is truly not the message.

The rest of the crew, Comdr. Rick Husband, pilot William McCool, and mission specialists Laurel Clark, David Brown and Michael Anderson, native-born Americans all, were exemplars of dedication and competence whom our nation thankfully seems to produce in such generous abundance and attract from other parts of the world. We should grieve for all of their loved ones and families, but not for them--they died doing what they loved after what was the peak experience of their lives.

Thankfully, this time the event wasn't watched live by millions of schoolchildren, with a teacher on board, as the Challenger disaster was. Spaceflight has become so seemingly (if not truly) routine that few television stations cover it any more, except when it becomes news by dint of its failure, as it did  Saturday (though it, like most NASA missions, did carry some schoolchildrens' experiments, and those children will be devastated).

Three other factors will make it easier to bear than the first shuttle catastrophe, and hopefully allow us to return to shuttle operations much more quickly than the last time.

First, it isn't the first. Because of the Challenger tragedy, as a nation we became somewhat inured to the idea that things can go wrong with space shuttles 17 years ago.

Second, we are now a nation at war, and less than a year and a half ago watched our mightiest skyscrapers fall, killing thousands of our fellow citizens. We aren't more callous now, but it's fair to say that, as we send thousands of our brave men and women off to an unknown fate on the other side of the globe, we have a different perspective than we did at the time of the 1986 Challenger disaster.

Third, we have many more successful flights under our belt than we did in 1986, and this will probably end up looking more like an anomaly than a fundamental design flaw.

So what did go wrong?

It may be days, weeks or months before we can say for certain, but one likely candidate is a failure of the thermal protection system, the tiles that shield the metal airframe of the orbiter from the fiery heat of entering the earth's atmosphere at 17,000 miles per hour.

The tiles on the shuttle that keep separate the hot plasma from the structure are fragile and the failure of one can result in the failure of many others. Such a failure can cascade, perhaps across the leading, or hottest, portion of the wing. Without the protection of these insulating barriers, the aluminum structure can quickly heat, first to the point that it loses its rigidity, then to the point of actually melting, and then to burning itself.

Long before this would happen, however, the loss of support from the side that suffered the breakdown would result in an inability to control the vehicle. Once a vehicle, like a shuttle orbiter, deviates even slightly from its optimal attitude in the hurricane of hypersonic flight, it will quickly break up and burn. So quickly that, in fact, it was probably merciful to its inhabitants.

We don't know yet if this was the cause, but as data accumulates, it appears more and more likely. Regardless, we do know from the multiple videos that we saw this weekend that the breakup was swift and fiery, and undoubtedly fatal.

What does it mean for the future of the space program?

Ironically, Monday was the day that NASA's new budget was to be revealed, presumably including the addition of funds for a new nuclear reactor program for use in space. This event puts into question all of NASA's current planning, including budgets for whatever new plans might emerge from the investigations.

But consider that in 1986, there was no critical requirement to fly shuttles. No important experiment wouldn't occur, no elections would be lost, if we didn't fly. So, for almost three years, we didn't fly.

In 2003, we have a space station in orbit with three crew aboard, and plans to rotate them indefinitely. Even with ramped-up support from the Russians, we cannot afford not to fly the shuttle for almost three years. But Saturday, we lost a quarter of our total shuttle fleet, a component that cannot be practically replaced. We can support the station with a three-orbiter fleet, particularly since Columbia was not generally used for space station missions, but another such event will mean the loss of a third of the remaining fleet.

NASA has long been considering backups for the shuttle, and its eventual replacement. Saturday's events mean that they have to pursue that goal with even more promptness and seriousness. I can't predict what policy will come out of Saturday's tragedy, though I have some thoughts as to what it should be. I do know that, in the wake of another space-policy wakeup call, whatever they thought on Friday would be announced Monday, will (as was President Reagan's delayed State of the Union address in 1986) have to be utterly revised, even as we continue to mourn the loss of seven American heros.


Rand Simberg is a recovering aerospace engineer and a consultant in space commercialization, space tourism and Internet security. He offers occasionally biting commentary about infinity and beyond at his Web log, Transterrestrial Musings.

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