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.
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