Forty yearsago today, on the afternoon of February 20, 1962, a brilliant meteor streakedover the southeastern United States, heading for the Atlantic Ocean. This was no ordinary shooting star, but aspacecraft called Friendship 7, carrying Americas first man in orbit,John Glenn, back to Earth if he survived.Mission control had learned that Friendship 7s heat shield,Glenns only protection against the fiery passage into the atmosphere might beloose. No one, including Glenn, knew ifhe would make it home alive.

It was atension-packed finale to a triumphant day for the United States. Just five hours earlier, Glenn had soared intospace atop an Atlas booster, achieving the goal of Project Mercury to put a manin orbit, a feat the Soviet Union had achieved 10 months earlier. Everyone knew that Atlas rockets had a nastyhabit of blowing up, and Glenns successful arrival in space brought jubilationto NASAs mission control in Cape Canaveral, and to an estimated 100 millionAmericans watching on television. From Friendship7 Glenn reported, Zero-g and I feel fine, as he began his orbitaljourney.

Circling the Earth at 17,500 miles per hour, Glenn flew a path thatvaried 110 miles and a high point of 162 miles. Inside Friendship 7, Glenn took in the view, whichincluded a spectacular orbital sunrise and sunset during each ninety-minuteorbit. On the Earth below he spotteddust storms in Africa and, as he flew through an orbital night, the lights ofPerth, Australia. And he spottedmysterious glowing particles that he nicknamed fireflies hovering near thespacecraft as he emerged from darkness into sunlight.

Then the trouble came. Inmission control, at the launch site at Cape Canaveral, Florida, controllersnoticed an indication in the telemetry from Friendship 7 that thecrafts landing bag, a device designed to cushion the impact of splashdown, haddeployed. If so, it meant Friendship7s heat shield was no longer firmly attached. Controllers argued whether the signal might be erroneous; no onecould be certain.

But if it wasnt an error, what could be done to save Glenn fromincineration? Mercurys designer, engineerMax Faget, suggested leaving the crafts retrorocket package attached duringre-entry. Normally the package, whichwas attached by three straps to the base of the spacecraft, was to be castloose just before the fiery plunge. Byleaving it on, controllers hoped, the straps would hold the heat shield inplace.

Over California on his third orbit, some four and a half hours afterlift-off, Glenn fired the retrorockets, which slowed the craft with a series offirm jolts. Over Texas, Glenn got theword that he was to leave the retropackage attached. And then he waited.

As Friendship 7 slammed into the upper atmosphere Glenn saw theblack sky outside his window turn fiery orange. A glowing sheath of ionized gas surrounded the plummeting craft,blocking communications with Earth.Every so often chunks of glowing debris sped past; Glenn wondered if hewas witnessing the destruction of his heatshield. He waited for a feeling of intense heat to build up at his back,but it never came: The heatshield hadworked; the signal had turned out to be an error after all. The flaming chunks, he realized, must havebeen pieces of the retropack. Whencommunications resumed, Glenn reported, My condition is good, but that was areal fireball, boy.

And as Glenn splashed down safely in the Atlantic, it was a resoundingtriumph for NASA. The mission had beena literal baptism of fire, but now the space agency knew that humans couldsurvive and even enjoy spaceflight.And the flight left a lasting impression with those who witnessed it ontelevision, including a number of future astronauts. Some of the men who walked on the moon say Glenns flight helpedmotivate them to become astronauts. Anddecades after Glenn flew, astronauts aboard the Space Shuttle were stillthinking back to that historic mission.

I canttell you how many times the thought occurred to me while we were sitting upthere on orbit, says five-time shuttle veteran Hoot Gibson. Id be sitting over in the commanders seaton the left side of the cockpit. AndId be looking across this gigantic flight deck and looking out the forwardwindows at the Earth down there 200 miles below, and thinking to myself, Wow,we have really got it easy in this great big comfortable vehicle that we fly inspace with. Look at how much room wevegot, look how we can move around, look how capable it is. And think back to when they rode up here inthose little tiny Mercury capsules. Ialways said, Boy, we have really got it easy compared those guys that flewthose little capsules up there.

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