Last Tuesday, while the president prepared to tell us why we must go to war, the scientists onboard the space shuttle Columbia put aside their work to remember in silence the seven astronauts who had died exactly 17 years before on the Challenger. They paid tribute as well to the three men who were killed when Apollo 1 burned on its launch pad 19 years and one day before Challenger exploded.

Yesterday, American flags again fell to half-staff. The president scooted back to Washington from Camp David. With a slight catch in our breath, we asked whether this might have been the work of terrorists, because after 9/11, we believe they are capable of just about anything.

And now we learn who these seven astronauts were, and we are proud of them -- but only in retrospect, because before we woke up yesterday morning to several trails of vapor where there should have been one, we had no idea that they were even in space. Routine shuttle launches and landings aren't news anymore, haven't been for many years now.

The shuttle, the unglamorous space bus that is the most visible remaining activity of NASA, the agency that once supremely captured the American imagination, had become humdrum by the mid-'80s. I was sitting in the newsroom of the Miami Herald on the crystalline morning in January of 1986 when the Challenger exploded into those horribly beautiful plumes of fire and smoke; my newspaper's representative at Cape Canaveral that day was our schools reporter, because the only thing about that launch that elicited public interest was the presence onboard of Christa McAuliffe, the New Hampshire high school social studies teacher who went along for the ride.

And now there are dozens of Christa McAuliffe Elementary Schools, including one in Germantown, and Christa McAuliffe's two children are adults, who sat somewhere yesterday seeing it all over again. And my friend Ellen, who watched the Challenger light up the sky in all the wrong ways and then spent the next few hours trying to tell me what she'd seen, trying to turn that ghastly experience into words of meaning for a newspaper story, left the news business, in good part because she did not want to be someone whose job it was to see horrible things and convert them into marketable prose.

Space is a frontier of possibility. It is adventure for a planet that is running low on terrestrial mysteries. Yet space exploration seems corny, dated, a naive dream, an extravagance. One year ago, Sen. Bill Nelson of Florida, who had flown on the shuttle just weeks earlier in 1986, warned that "we're starving NASA's shuttle budget -- and thus greatly increasing the chance of a catastrophic loss. I wonder if the lessons of Challenger are fading."

NASA, which put men on the moon and sent spacecraft to most of our solar system's planets, has been reduced to surfing eBay and Yahoo for replacement parts for its 1980s computers.

We have little room for space and the future when we are under attack by visitors from the medieval world, terrorists whose culture, passed over by progress, yearns for the deep past.

In times of strain and fear, people cling to simple stories, elevate instant death to something full of grace and seek the possibility of a painless transition to a better place.

On TV yesterday, we were assured almost from the start that the astronauts had died instantly, which was exactly what NASA told us in 1986 and in 1967. It took a lawsuit by Betty Grissom, widow of Apollo 1 astronaut Gus Grissom, before the government admitted that instant death was a story NASA put out to ease the pain of the families; the Apollo astronauts had lived through a long minute of agony before they ran out of air. Similarly, the official story about the Challenger was that the astronauts had not suffered; weeks later, when their remains were discovered at the bottom of the sea, the story became much muddier.

When the flight deck tape recorder was recovered from the Atlantic, we learned that someone on board the Challenger had said "Uh-oh" after the bright flash.

Even if we ignore them until disaster strikes, astronauts connect us to dreams of freedom. Less than a month ago, an armed German man commandeered a small plane and threatened to fly it into a skyscraper in Frankfurt. After he was talked down to a safe landing, he said he planned his suicide mission to force the world to recall his idol, Judith Resnik, who died on the Challenger and who in 1984 had become the first Jew in space.

Yesterday, the first Israeli in space died. Ilan Ramon, it turns out, was one of eight F-16 pilots who bombed Iraq's nuclear reactor in 1981. Now Iraq again poses a threat to this world, and this man who left those immediate dangers behind and went in search of a wider world is gone.

And as we head into a war that's supposed to forestall doom on Earth, maybe we, too, will follow Ramon and look upward to infinite space, a place so big it must contain just a bit of hope.