How Our Maxwell GPUs Debunked the Apollo 11 Conspiracy Theory [Updated with Video]

by Brian Caulfield

No, the Apollo 11 moon landing wasn’t a hoax. And we can prove it.

Rather, our game demo team already did. By using Maxwell, our new GPU architecture, to digitally rebuild one of the landing’s iconic photographs – Neil Armstrong’s shot of Buzz Aldrin clambering down the lunar module’s ladder.

Neil Armstrong’s photo of Buzz Aldrin clambering down to the moon’s surface. Above, Armstrong’s original photo.

The photo, taken 45 years ago, shows Aldrin lit against the dark shape of the lunar module behind him. It’s a good shot. Too good, conspiracy theorists claim.

Their argument: because the sun is behind the lunar module, and Aldrin is in its shadow, Aldrin must have been lit by something other than the sun. Some auxiliary light source. Maybe in a back-lot studio. Perhaps somewhere in L.A.

Pretty swiftly, our team debunked the debunkers. Their secret weapon: Maxwell, the new graphics architecture we’re introducing today. We designed Maxwell to solve some of the most complex lighting and graphics challenges in visual computing. Maxwell is at the heart of our new GeForce GTX 980 and GeForce GTX 970 GPUs, the most advanced GPUs ever made.


[Update: Want to try your hand at debunking a conspiracy? Read more about our demo, and download itand decide—for yourself.]

Thanks to Maxwell, our demo team rebuilt the scene of the moon landing in Unreal Engine 4, a game engine developed by Epic Games. They simulated how the sun’s rays, coming from behind the lander, bounced off the moon’s surface, and Armstrong’s suit, to cast light on Aldrin as he stepped off the lander.

It’s a feat that gives Mark Daly, who leads our demo team, great satisfaction.

“Men lost their lives as part of the Apollo project, so it bugs me when people say it was all a hoax,” says Daly, an NVIDIA veteran. “People risked their lives to get to the moon.”

Out of the Box

To understand our demo team’s discovery, it helps to know the workings of one of Maxwell’s key technologies – Voxel-Based Global Illumination, or VXGI. VXGI is about better representing the way light bounces from one object to another in real time.

To do that, VXGI breaks a scene’s geometry into many thousands of tiny boxes called “voxels,” or 3D pixels. Each of the six sides of each box is analyzed to determine its opacity (how transparent it is) and its emittance (how much, and what color, light it reflects from other objects in a scene).

VXGI let our demo team reconstruct the way light moved around the Apollo 11 landing site.

All these boxes help capture the way light bounces from one object to another. So, in a game, if a rocket launcher blows up a wall – or a character moves in front of a light source – the lighting in a scene will change. That’s a huge advancement.

If this kind of dynamic lighting environment sounds computing intensive, it is.

Maxwell accelerates the creation of voxels – a process known as “voxelation” – with hardware support for a technology called “multi-projection.” Multi-projection lets a Maxwell GPU process the geometry just once for each of a box’s six sides (For more on Maxwell’s technology, see “Maxwell: The Most Advanced CUDA GPU Ever Made,” on our Parallel Forall blog).

Moon Shot

Nice, in theory. But the practical advantages of VXGI became clear when we used it to analyze the iconic Apollo 11 photo.

To recreate the moon landing, the demo team collected every detail they could. They researched the rivets on the lunar lander, identified the properties of the dust coating the moon’s surface, and measured the reflectivity of the material used in the astronauts’ space suits.

It was during this research when the demo team uncovered a big clue. A video clip that showed Aldrin descending the ladder had a bright spot of light that seemed to move every time the camera did.

Picture perfect: Maxwell was able to recreate the conditions on the Moon's surface that led to NASA's iconic shot.
Our demo team used Maxwell to simulate the conditions on the Moon’s surface during the lunar landing 45 years ago, revealing how Aldrin was illuminated by light reflected from the Moon’s surface and Armstrong’s spacesuit. Above, a screenshot of their work.

“When the glow started moving, I thought, ‘Oh my gosh, that’s it,’” Daly says.

Was it an artificial light? Or – as one of NVIDIA’s senior GPU architects had suggested – was it a reflection from Armstrong’s bright white space suit? At first, Daly had dismissed the idea that Armstrong’s suit could account for some of the light illuminating Aldrin.

“You figure, ‘How much can some guy in a white suit contribute to the scene?’” Daly says.

Let There Be Light

Turns out, quite a bit. They could reproduce how that light illuminated Aldrin as he stepped onto the moon’s surface at the exact moment Armstrong snapped his photo. Inside a shot cited by Apollo 11 skeptics, Daly’s team had uncovered hidden evidence that the mission was real.

And that wasn’t the only proof they found for the landing hidden in NASA’s photos.

Another detail seized on by skeptics: photos from the landing site don’t show any stars. That’s led some to claim that the U.S. Government faked the landing and left out the stars in the scene, because it would be impossible to portray the position of the stars from the moon.

By using Maxwell our demo team was able to find them.

“The reason the stars aren’t visible is the exposures in the camera are set to capture the scene on the Moon’s surface,” Daly says. But they’re there. And our demo team was able to find them by digitally changing the exposure on the shots to reveal them. Consider this conspiracy theory debunked.

For a closer look at Maxwell’s technology, see “Maxwell: The Most Advanced CUDA GPU Ever Made,” on our Parallel Forall blog.

Editor’s note: This post has been updated with additional video content.