The Eagle had landed, but the Earth men were forced to maintain their discipline. What followed the tense landing was nearly two hours of systems checks. Having determined that Eagle had not been damaged during the landing, Neil Armstrong and Edwin "Buzz" Aldrin were scheduled to eat a post-landing meal.

Stealing glances at the lunar surface through Eagle's triangular windows and gnawing their way through reconstituted ham, potatoes and fruitcake, the men unilaterally agreed that they did not need the scheduled five-hour rest break before suiting up to walk on the moon. To their relief, Houston concurred.

It would take another 3A hours for them to prepare for mankind's first Extra Vehicular Activity (EVA) on the moon. As Armstrong made his way down the ladder, he activated a black and white camera poised to catch his first step and transmit it to the world. His foot sank into the finely powdered soil, leaving an indelible print. "That's one small step for man, one giant leap for mankind." He took several more steps, testing his balance and the effects of the moon's gravity.

Armstrong's most immediate task was to collect a small sample of lunar soil. In the event that the EVA was suddenly cut short, he would at least have a sealed sample in the pocket of his spacesuit. Having done so, he began an external inspection of Eagle while he waited for Aldrin to join him. Eighteen minutes later, Aldrin took his first step. "Beautiful view," he said. "Magnificent desolation."

Before their television audience, Armstrong read from the plaque mounted on the strut of Eagle's landing gear:

HERE MEN FROM THE PLANET EARTH FIRST SET FOOT UPON THE MOON

JULY 1969, A.D.

WE CAME IN PEACE FOR ALL MANKIND.

After repositioning the television camera (1), the astronauts turned to the work at hand. They had only a limited amount of time on the surface to perform specific tasks. Aldrin began by deploying the solar wind composition experiment (2). It looked something like a flystrip -- a sheet of aluminum foil hanging from a pole -- but the data it gathered would help determine the composition of gases and other elements in the solar wind.

Together, the astronauts erected a small United States flag (3). They did not, as explorers on Earth had done before them, claim this new territory, this moon, in the name of their country.

Aldrin proceeded to test his moon legs by attempting to run and hop like a kangaroo, with Armstrong faithfully recording the awkward movements for posterity. This experiment was interrupted, however, by a call from President Richard M. Nixon. In a White House-to-moon call the president told the astronauts, "For every American, this is the proudest day of our lives."

Armstrong replied, "It's a great honor and privilege for us to be here representing not only the United States but men of peace of all nations."

After the call, the astronauts refocused their attention and divided up their work. Armstrong began collecting samples of soil and rock, carefully documenting the exact location from which they were removed and sealing them in vacuum-tight containers.

Aldrin activated the Passive Seismograph Experiment (PSE) (4), which would monitor and record any lunar seismic activity and detect any meteor impacts. Next, he positioned the Laser Ranging Retroreflector (5). Among other things, this device, left on the lunar surface, helped scientists obtain precise Earth-to-moon measurements by reflecting laser beams from Earth back to their point of origin.

To obtain core soil samples, Aldrin hammered short tubes into the lunar surface. As he did so, Houston reported that the vibrations were being recorded by the sensitive PSE.

Meanwhile, Armstrong had ventured off to inspect and photograph Little West Crater (6), a rough spot in the direction of the original planned landing site. Completing their work outside, the astronauts stowed most of the experiments and samples in the ascent stage of the lander. Armstrong loaded the last of the equipment as Aldrin reentered Eagle. At 1:09 a.m. EDT on July 21, 1969, Armstrong climbed aboard and closed the hatch, thus ending man's first exploration of the moon.

DID YOU KNOW . . .

Instant diet: The moon's gravita-tional pull at the surface is about one-sixth as strong as Earth's. So an astronaut and space suit that together weighed 360 pounds here weighed only 60 pounds during the moon walks.

Landing facts:

* Total time on lunar surface: 21 hours, 36 minutes

* Total time spent outside of Eagle: 2 hours, 31 minutes

* Total surface distance traveled: 3,300 feet

* Farthest point from Eagle reached: 200 feet

* Samples collected: 47.5 pounds

After circling the moon more than a dozen times at an altitude of about 68 miles, the lunar lander called Eagle separates from the Command and Service Module. An hour later, the lander's engine fires for 30 seconds, braking the craft and starting its descent to the lunar surface. The lander takes an hour to descend to an altitude below 50,000 feet. The descent engine begins a continuous 12-minute burn, taking it to touchdown. During this final phase, the lander is flying with its engine leading. Astronauts Neil Armstrong and Edwin "Buzz" Aldrin are traveling feet first and looking straight down at the lunar surface through the lander windows.

* `We're go on that alarm' -- Mission Control

4:10 p.m. EDT July 20

33,500 ft.

Five minutes into the burn, Armstrong reports "Program Alarm," the first of five alarms. This one signals a computer overload. Moments later, Houston gives Eagle the go-ahead.

* `Attitude control is good'

-- Armstrong

4:13 p.m., 5,000 ft.

A second computer overload alarm sounds. Houston gives another go-ahead. Dropping to 2,000 feet at 100 feet per second in automatic landing mode, Armstrong checks out the window and sees a large field of boulders ahead.

* `Pretty rocky area'

-- Armstrong

4:14 p.m., 600 ft.

Armstrong determines the designated landing area is too rough, takes manual control of Eagle and slows the descent.

* `Ease her down'

-- Aldrin

4:15 p.m., 300 ft.

Armstrong has found a flat space beyond Little West Crater. A radar warning light flashes. Surface dust is being blown around by Eagle's engine, hampering visibility.

* `I got a good spot'

-- Armstrong

4:16 p.m., 150 ft.

A warning light flashes, telling the astronauts they have 5 percent of their fuel remaining. Armstrong has 94 seconds, after which he must land immediately or abort.

* `Picking up some dust. . .'

-- Aldrin

4:17 p.m., 40 ft.

Visibility becomes obscured again due to the lunar dust.

* `Houston, Tranquility Base here. The Eagle has landed'

-- Armstrong

4:17:40 p.m.

The lunar module lands on the moon with approximately 45 seconds of fuel remaining.

CAPTION: Inside the Lunar Module

The Apollo lander design consisted of two major components. The lower stage, containing the engine and fuel for the descent, would remain on the surface. The lighter upper stage, containing the crew area, navigational equipment and a smaller engine, would propel the astronauts back into lunar orbit where they would rendezvous with the Command and Service Module.