In the Moon's Sea of Tranquillity the lunar lander Eagle stands squarely on its spindly legs.
The legs have been designed to shorten on impact but Eagle has touched down gently so they are still extended, and the craft's outside ladder ends a metre above the ground.
Astronauts Armstrong and Aldrin will soon be down that ladder, watched live on television by up to a fifth of humanity.
This day, July 21 1969, in Australia - will fulfil the work of 400,000 people.
The astronauts are scheduled to sleep now but they want to skip the nap and get outside.
Houston gives the go-ahead just after 8am eastern Australian time and the astronauts start donning their spacesuits.
CSIRO's Parkes telescope is scheduled to receive the television pictures of the moonwalk but the Moon has not yet risen for Australia, so if the astronauts walk early the pictures will come through NASA's Goldstone station in California.
Honeysuckle locks on
At 8.45am Prime Minister John Gorton makes a surprise visit to the Honeysuckle Creek tracking station and stays for an hour.
After he leaves the station staff tip Honeysuckle's dish to the horizon, wait for the Moon to rise at 11:15am and then lock on to Eagle's signal.
The astronauts are still fastening and checking connections in their life support systems and after that they have to slowly depressurise the cabin.
This all takes about six hours, pushing the moonwalk closer to the original timetable.
At last the hatch opens and Armstrong begins to inch backwards out of the craft.
First footstep
The Parkes telescope is tipped over, waiting for the Moon to rise into its field of view.
Suddenly the wind picks up and two powerful gusts hit the telescope, slamming the dish back against its drive system.
The telescope tower shudders and sways and the wind alarm rings in the control room.
Such wind could damage the dish, even pull it off the tower.
At any other time the telescope would be stowed immediately but director John Bolton decides to keep going.
The wind slackens just as the Moon comes into view but doesn't die down completely.
Parkes will end up operating outside its safety limits for the entire moonwalk.
On Eagle Armstrong starts to climb down the ladder, pausing to lower an external tray that holds a small TV camera.
At first viewers see a picture coming from Goldstone - a jumble of black and white with little detail.
Honeysuckle and Parkes are also getting pictures, Parkes through its secondary feed as the Moon has not yet risen into its main beam.
The Australian stations send their signals to Sydney where a NASA controller chooses between them and forwards his choice to Houston.
Houston picks either the Australian signal or Goldstone's to send to the world - except for Australia, which gets signals straight from Sydney.
Armstrong reaches the bottom of the ladder and takes the last big step down onto one of Eagle's footpads.
He jumps back on the ladder to check he can get up again then returns to the footpad.
Houston switches from Goldstone's picture to Honeysuckle's.
"I'm going to step off the LM [lunar module] now," Armstrong announces, then carefully lifts his left foot and sets it on the Moon's soil.
"That's one small step for [a] man, one giant leap for mankind."
It is 12:56:20pm eastern Australian time.
"Commander on the Moon!!!!" Honeysuckle Operations Supervisor John Saxon writes excitedly in his logbook, noting the time to the second; station staff have been running an office sweep on when the first step will be.
Armstrong inspects Eagle, takes photos and scoops up the first sample of lunar soil.
Around nine minutes into the broadcast the Moon rises into Parkes' main beam and the Sydney controller passes the Parkes picture to Houston.
"Beautiful picture, thank you," Houston says. It will stick with Parkes for the rest of the moonwalk.
For almost three hours Parkes staffer Neil Mason will drive the telescope to keep it pointed at the Moon, not allowed to even glance at the television pictures lest the wind pick up again and affect the telescope's reception.
Citizens of Earth
Soon Aldrin will climb down the ladder and note the "magnificent desolation".
The world will see him dash around like a hyperactive ghost then hop like a kangaroo to try out movements in the Moon's weak gravity.
The world will watch as Aldrin sets up experiments, including a matchbox-sized dust detector created by Australian physicist Brian O'Brien, the astronauts plant the US flag and President Nixon speaks with them from the White House.
But for those first minutes the world sees just one man, anonymous in his spacesuit and helmet, representing humanity.
Moscow television doesn't carry the moonwalk but Soviet cosmonauts watch it from a military reception centre.
When they see Armstrong step onto the Moon - achieving the victory that might have been theirs - they applaud.
"Everyone forgot that we were all citizens of different countries on Earth," one of them, Aleksei Leonov, writes later.
"That moment really united the human race."
- One Giant Leap is a joint initiative with CSIRO, Australia's national science agency, to celebrate the 50th anniversary of the moon landing.
