NASA re-creates the Apollo 8 Earthrise using Lunar Reconnaissance Orbiter data
Posted by Andrew Chaikin
2013/12/20 02:20 CST
If there's one thing I've learned after decades of studying the first human voyages to another world, it's that there is always more to discover about Apollo. Case in point: The Apollo 8 Earthrise photo that became one of the iconic images of the 20th century. I thought I knew everything there was to know about that photograph and how it was made—until last spring, when I got an email from NASA’s Ernie Wright of the Goddard Space Flight Center's Scientific Visualization Studio. Ernie had done some remarkable detective work comparing the astronauts' onboard mission photography with new topographic maps from the Lunar Reconnaissance Orbiter, which has been orbiting the moon since 2009. The superb accuracy of the LRO data makes it possible, for the first time, to know exactly where Apollo 8 was over the moon when the astronauts first saw the Earth rising above the moon's barren horizon.
More important, it tells what the spacecraft's orientation was at every moment. The result, shown in NASA's new video re-creation of the event, reveals that—much to my surprise—Apollo 8 had its nose pointed at the moon and was rotating about its long axis at the moment the Earth appeared. The timing of this roll maneuver, performed by mission commander Frank Borman as dictated by the flight plan, was just right to cause the rising Earth to become visible to Bill Anders—first in his side window, then in his rendezvous window (and then the center hatch window, which is where crewmate Jim Lovell saw it). I'd always known that the spacecraft's onboard voice tapes documented the fact that Anders was the one who first saw the rising Earth. But Ernie Wright's "space forensics" work shows, for the first time, why Anders alone had that initial view and was able to record the event using the camera he was already holding—a Hasselblad outfitted with a 250-mm telephoto lens—with three pictures, a black-and-white image followed by two color ones. And there was one more surprising detail that Ernie alerted me to: You can actually hear the Hasselblad's shutter and motorized film advance on the tape (and on the new video), as Anders snaps these historic photographs. That allowed Ernie to pin down the exact moment at which each image was taken.
The chance to see the Earthrise exactly as the astronauts saw it makes this Apollo 8 anniversary a very special one. Even though 45 years have passed since that incredible event, it has lost none of its power. It's the moment when we began to fully comprehend the words of the great space visionary Konstantin Tsiolkovsky: "The Earth is the cradle of humanity, but one cannot live in the cradle forever."