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For
the first time since the 1970s, a NASA spacecraft will get
clear pictures of Apollo relics on the Moon.
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July 11, 2005: Inside the lunar lander Challenger,
a radio loudspeaker crackled.
Houston:
"We've got you on television now. We have a good picture."
Gene
Cernan, Apollo 17 commander: "Glad to see old Rover's
still working."
"Rover,"
the moon buggy, sat outside with no one in the driver's seat,
its side-mounted TV camera fixed on Challenger. Back
in Houston and around the world, millions watched. The date
was Dec. 19, 1972, and history was about to be made.
Above:
The Apollo 17 moon buggy, circled, waits to film the departure
of its mothership, Challenger. [More]
Suddenly,
soundlessly, Challenger split in two (movie).
The base of the ship, the part with the landing pads, stayed
put. The top, the lunar module with Cernan and Jack Schmitt
inside, blasted off in a spray of gold foil. It rose, turned,
and headed off to rendezvous with the orbiter America,
the craft that would take them home again.
Those
were the last men on the Moon. After they were gone, the camera
panned back and forth. There was no one there, nothing, only
the rover, the lander and some equipment scattered around
the dusty floor of the Taurus-Littrow valley. Eventually,
Rover's battery died and the TV transmissions stopped.
That was our last good look at an Apollo landing site.
Many
people find this surprising, even disconcerting. Conspiracy
theorists have long insisted that NASA never went to the Moon.
It was all a hoax, they say, a way to win the Space Race by
trickery. The fact that Apollo landing sites have not been
photographed in detail since the early 1970s encourages their
claims.
 Right:
Apollo landing sites. [More]
And
why haven't we photographed them? There are six landing sites
scattered across the Moon. They always face Earth, always
in plain view. Surely the Hubble Space Telescope could photograph
the rovers and other things astronauts left behind. Right?
Wrong.
Not even Hubble can do it. The Moon is 384,400 km away. At
that distance, the smallest things Hubble can distinguish
are about 60 meters wide. The biggest piece of left-behind
Apollo equipment is only 9 meters across and thus smaller
than a single pixel in a Hubble image.
Better
pictures are coming. In 2008 NASA's Lunar Reconnaissance Orbiter
will carry a powerful modern camera into low orbit over the
Moon's surface. Its primary mission is not to photograph old
Apollo landing sites, but it will photograph them,
many times, providing the first recognizable images of Apollo
relics since 1972.
The
spacecraft's high-resolution camera, called "LROC,"
short for Lunar Reconnaissance Orbiter Camera, has a resolution
of about half a meter. That means that a half-meter square
on the Moon's surface would fill a single pixel in its digital
images.
Apollo
moon buggies are about 2 meters wide and 3 meters long. So
in the LROC images, those abandoned vehicles will fill about
4 by 6 pixels.
What
does a half-meter resolution picture look like? This image
of an airport on Earth has the same resolution as an LROC
image. Moon buggy-sized objects (automobiles and luggage carts)
are clear:
Above:
An example of half-meter resolution overhead photography,
the same resolution that LROC images will be. This photo of
an airport shows airplanes of various sizes as well as many
car-sized service vehicles. Notice how shadows help the objects
to stand out from the background. The LROC high-res images
will also be grayscale, but will be less grainy than the example
above thanks to its digital imaging technology. Image courtesy
MIT Digital Orthophoto Project.
"I
would say the rovers will look angular and distinct,"
says Mark Robinson, research associate professor at Northwestern
University in Evanston, Illinois, and Principal Investigator
for LROC. "We might see some shading differences on top
from seats, depending on the sun angle. Even the rovers' tracks
might be detectable in some instances."
Even
more recognizable will be the discarded lander platforms. Their
main bodies are 4 meters on a side, and so will fill an 8 by
8 pixel square in the LROC images. The four legs jutting out
from the platforms' four corners span a diameter of 9 meters.
So, from landing pad to landing pad, the landers will occupy
about 18 pixels in LROC images, more than enough to trace their
distinctive shapes.
Shadows
help, too. Long black shadows cast across gray lunar terrain
will reveal the shape of what cast them: the rovers and landers.
"During the course of its year-long mission, LROC will
image each landing site several times with the sunlight at
different angles each time," says Robinson. Comparing
the different shadows produced would allow for a more accurate
analysis of the shape of the objects.
Enough
nostalgia. LROC's main mission is about the future. According
to NASA's Vision
for Space Exploration, astronauts are returning to the
Moon no later than 2020. Lunar Reconnaissance Orbiter is a
scout. It will sample the Moon's radiation environment, search
for patches of frozen water, make laser maps of lunar terrain
and, using LROC, photograph the Moon's entire surface. By
the time astronauts return, they'll know the best places to
land and much of what awaits them.
Two
high-priority targets for LROC are the Moon's poles.
 "We're
particularly interested in the poles as a potential location
for a moon base," Robinson explains. "There are
some cratered regions near the poles that are in shadow year-round.
These places might be cold enough to harbor permanent deposits
of water ice. And nearby are high regions that are sunlit
all year. With constant sunlight for warmth and solar power,
and a potential source of water nearby, these high regions
would make an ideal location for a base." Data from LROC
will help pinpoint the best ridge or plateau for setting up
a lunar home.
Above:
Artist Pat Rawlings' concept of a polar moonbase. [More]
Once
a moonbase is established, what's the danger of it being hit
by a big meteorite? LROC will help answer that question.
"We
can compare LROC images of the Apollo landing sites with Apollo-era
photos," says Robinson. The presence or absence of fresh
craters will tell researchers something about the frequency
of meteor strikes.
LROC
will also be hunting for ancient hardened lava tubes. These
are cave-like places, hinted at in some Apollo images, where
astronauts could take shelter in case of an unexpected solar
storm. A global map of these natural storm shelters will help
astronauts plan their explorations.
No
one knows what else LROC might find. The Moon has never been
surveyed in such detail before. Surely new things await; old
abandoned spaceships are just the beginning.
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Authors: Dr. Tony
Phillips & Patrick
L. Barry | Production Editor:
Dr. Tony Phillips | Credit: Science@NASA
| More
Information |
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Lunar
Reconnaissance Orbiter --
home page from NASA's Goddard Space Flight Center
More stories about Lunar Reconnaissance
Orbiter, from Science@NASA: Prospecting
for Lunar Water, Hitchhiker's
Guide to the Moon
En
Route to Mars, the Moon -- (Science@NASA) Why colonize
the Moon before going to Mars? NASA scientists give
their reasons.
 More
history: The only images that show abandoned
Apollo hardware are a few shots taken by Apollo astronauts
themselves while in orbit around the Moon. The images
are grainy and analog. In one, the lander platform looks
like a speck, in another it looks like a bright blob
a few pixels across.
Right:
The left-behind Apollo lander platform only appears
as a tiny speck in this image taken by Apollo 17. The
lander is between the crosshairs under the label "LM".
[More]
More recent lunar orbiters, such as
the 1994 Clementine mission, carried modern, digital
cameras, more sensitive than Apollo-era devices. But
these were always lower-resolution cameras meant to
broadly survey the entire Moon instead of getting high-res
close-ups. Clementine's camera, for example, had a maximum
resolution of 25 meters per pixel -- still too coarse
to resolve the Apollo relics.
Apollo
17 Lunar Surface Journal -- read the words actually
said by Apollo astronauts while they were on the Moon.
This site is also a good source of images
and movies.
Recommended reading:
Apollo, the Epic Journey to the Moon, by David
West Reynolds, 2002, Tehabi Books. West's excellent
book inspired the introduction to our story, "Abandoned
Spaceships."
The
Great Moon Hoax -- (Science@NASA) Moon rocks and
common sense prove Apollo astronauts really did visit
the Moon.
Can
Hubble see the Apollo landing sites on the Moon?
NASA's
Vision for Space Exploration
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