Despite being more than 40 years old, images taken by five spacecraft that orbited the moon in the 1960?s are proving invaluable in planning for humankind?s return to the moon.
Between August 1966 and August 1967, NASA?s five Lunar Orbiter spacecraft returned more than 2,600 images of the moon and photographed 99 percent of the lunar surface.
This multitude of images has now been digitized, processed and made available online by the Lunar and Planetary Institute (LPI).
?We wanted to make these images available to as wide an audience as possible,? said Mike O?Dell, a programmer at the Lunar and Planetary Institute in Houston, Texas. ?Now, users can find everything in one place, searchable, with documentation and of a high enough quality to use directly or to at least identify which frames would be useful in higher detail.?
Detailed study of Lunar Orbiter images is nothing new; the primary aim of the Lunar Orbiter project was to image potential Apollo landing sites in high resolution.
In fact the first three Lunar Orbiters proved so successful at this task that the remaining two missions were devoted to mapping the entire lunar surface. During the intervening four decades, image-processing techniques have taken a giant leap and the LPI took a few small steps to ensure the Lunar Orbiter photos continue to look their best.
?We did a minimal contrast stretch and then we used software to de-stripe the images, enhancing their clarity and beauty,? O?Dell said.
Age and wisdom
While these venerable images are both fascinating and beautiful, with Japan?s Kaguya and China?s Chang?e 1 spacecraft currently in lunar orbit and NASA?s Lunar Reconnaissance Orbiter (LRO) set to lift off in late 2008, will these aging portraits remain relevant for long?
?The Lunar Orbiter missions were immensely successful,? said David Kring, a visiting scientist at the LPI. ?Those images are the baseline for existing geologic maps of most areas of the moon, including the lunar south pole, which is being examined as a lunar outpost site,? Kring told SPACE.com.
Craters at the south pole might harbor water ice, which could be used to drink and for fuel. And the polar location offers a spot with round-the-clock sunshine for gathering solar energy.
The Lunar Orbiters commonly obtained image resolutions of 500 feet and even managed resolutions of 3 feet in selected places, more than enough to hold their own against their high-tech camera-toting descendants.
Return to the moon
These high resolution images will play a major role in selecting landing sites for a return to the moon under Project Constellation and also for more immediate robotic landings. They might also be used to calculate how often the moon gets hit by meteorites, something any astronaut stood out on the lunar surface will want to know.
?Determining the size and frequency of impacting near-Earth debris is important because it will enhance our assessment of impact hazards, both on Earth and the lunar surface," Kring said. "A comparison of the Lunar Orbiter data represented on our new Lunar Orbiter Photo Gallery and future LRO images is already part of the analytical plans for the LRO mission.?
The lunar Orbiter data might also dictate what future explorers will do when we reach the moon.
?Lunar Orbiter images are also being used to evaluate outpost architecture and to design preliminary traverse routes across the lunar surface. The LRO data will augment the Lunar Orbiter data and, in small localized areas, will provide even higher-resolution coverage,? Kring said.