Beyond the Moon To Mars
Man Or Machine?
|Dr. Andrew Chaikin, book cover photograph. Banner image of Moon-Mars occultation, copyright, andrewchaikin.com.
Parts 1 * 2 * 3
NASA Research Park (NRP) launched a new Exploration Lecture Series at NASA Ames Research Center, to feature top researchers and academics, who will examine new technologies for human and robot-based exploration, as well as on-going and planned space exploration missions. The first lecture, "The Moon, Mars and Beyond," featured Dr. Andrew Chaikin, author of "A Man on the Moon: The Triumphant Story of the Apollo Space Program." The book was the basis for Tom Hanks' HBO miniseries "From the Earth to the Moon," which won an Emmy for best miniseries in 1998.
Chaikin has authored and edited several popular books about space, including "The New Solar System," "Air and Space: The National Air and Space Museum Story of Flight," "Apollo: An Eyewitness Account," and " Full Moon," a collection of Apollo photography. Chaikin's most recent book, "SPACE: A History of Space Exploration in Photographs," was published in 2002 by Carlton Books.
|Moon occulting Venus, the morning star, taken by the lunar probe, Clementine.
A graduate of Brown University, Chaikin served as executive editor for space and science at Space.com until 2001 and was editor of Sky and Telescope magazine for many years. Chaikin is currently a commentator for National Public Radio's Morning Edition program.
During Dr. Chaikin's public lecture, he described the Moon-Mars exploration as 'exciting and tremendously challenging'. His lecture featured a spectacularly symbolic image that he photographed from central Florida during last year's closest approach between Mars and Earth--the nearest such view towards our sister planet seen in recorded history. Using a Celestron Nexstar 11-inch telescope and a webcam, Chaikin captured an occultation of Mars by our own Moon in silhouette. Six months later, the blue-ribbon Presidential Commission studying transits to the Moon, Mars and beyond formed with the same image in mind: How best to hopscotch humans safely to the moon first, followed by the challenging trek to Mars?
Chaikin's perspective is unique since he had unparalleled access to the 23 living astronauts who pioneered the Apollo exploration of the Moon. Chaikin noted that humans left the moon for the last time, thirty-one years ago. While posing the question, What can we learn from the Apollo astronauts about going back to the moon and onwards to Mars in the coming decades?, Chaikin recalled a story told to him by Bob Gilruth, a key mission planner at the Johnson Space Center during Apollo. Gilruth was walking on the beach while a full moon was out. He looked up to the light-grey, shining disk and said, "Someday, they're going to want to go back to the moon, and they'll realize how difficult it is."
|Opportunity's size dominates crater. "This is a picture of the vehicle," said Malin, referring to a bright spot. "One thing to note is how big it is relative to the crater. It fills the size of the crater." Click image for larger view.
What martian scenery will greet the first human visitor? Chaikin noted that "Mars is a geological wonder, with canyons as long as the continental United States. With big volcanoes, sucha as the largest in our solar system--Olympus--which towers three times higher than Mount Everest."
Unlike the moon, Mars has winds. Mars has exposed ice seen glinting with sunlight. Even when viewed in a 1950's telescope, the frozen polar ice caps could distinguish Mars from the moon. These icy poles sometimes contain frozen water but have a core of frozen carbon dioxide, or dry ice. The matian surface generally is rust-colored though, because it is literrallly covered in rust. Iron oxide is a prevalent soil component.
When first observed during the 1960's Mariner orbital missions to Mars, the red planet has craters and fault rifts like the moon but unlike our lunar neighbor, shows signs of ancient water flowing across its surface.
"River valleys with extensive tributaries," said Chaikin, show that Mars was "once a place where water flowed in vast quantities." Even in more recent geological times, "tiny channels on the walls of craters have been observed from the orbiting Mars Global Surveyor, and this water may trickle down embankments below a frost layer."
Attempts to resolve this watery past with Mars' apparent dryness today rely on understanding the planet's climate history, said Chaikin. "The atmosphere is seven parts in a thousand compared to Earth's pressure at sea level, which is too thin for liquid water" to be exposed. The current round of rover missions have taken up the mantle of tracing this watery past, and uncovered the ground-truth to compare to what previously could only be speculated upon.
On the question of life on Mars or one of Jupiter's moons like Europa, Chaikin noted that "life is found in hostile environments ranging from mid-ocean ridges to dry and salty places. Even inside rocks. Life is proving more clever and resilient than previously imagined."
Comparing the Moon and Mars visually on the surface is difficult, said Chaikin, because almost all the Apollo astronauts have noted that images of the lunar surface cannot do justice to seeing the brilliant Sun in complete blackness for yourself.
|Schematic of major mission events during entry, descent and landing.
Credit: NASA/JPL/ Cornell University/ Dan Maas
Referring to the computer renderings of the "brilliant Dan Maas, who created wonderful animations before the Mars Exploration Rovers landed", Chaikin thought the human eye looking on the martian surface would be struck foremost by the red, rusty surface compared to the grey lunar landscape. But both are "desolate places. On the Moon, the brilliant sunlight and black sky make a striking scene. On Mars, the sky is peach-colored, while the light is diffuse with dust, kind of like Los Angeles. The dust floating in the thin martian air scatters enough light to make the sky blue at sunset. The martian sunset is the reverse of what we have here." While the daylight sky on Earth is blue and its sunset pink, the martian daylight is pink and the sunsets are blue.
Catching up Chaikin's unique historical perspective on exploration to the present rover missions, he agreed with the incredible luck that JPL scientists and engineers felt when the first images from the Opportunity rover were viewed. "The rovers bounce haphazardly, the lander unfolds, and its camera takes a look around. What are the chances of bouncing into a crater, one with an outcrop thought to be martian bedrock? This outcrop on the crater rim includes rocks in the same place they were formed, not blasted from some other impact. And like sedimentary rocks, these are layered with their geological history."
The luck of landing in a crater exposing bedrock however was dwarfed by finding water evidence only ten meters from the lander's base station. "The spherical grains, called concretions, are the geological equivalent of hail stones. They speak of being formed in water. Meridiani Planum was once drenched with water, maybe billions of years ago. But we don't have to speculate anymore, Mars has given us ground-truth as evidence of water"--the first such finding on the surface of another world.
|Hematite shows a right and left peak in the Mossbauer spectra, with a higher concentration at the crater rim than the floor. Credit: NASA/JPL/Mainz
While Chaikin marvelled at the luck and resourceful of the robotic rovers, he shared an Apollo anecdote to illustrate what a human explorer might bring to our understanding of Mars. "Nothing can replace the power of the human mind and hand in exploration. These robots are incredible and currently the only way to do exploration. But even the builders of the robots agree that eventually we will have to have humans for the next level of discovery."
To illustrate historically, Chaikin selected the mission of the only trained geologist to the moon. During his packed surface itinerary, Apollo 17's Harrison Schmidt made one happenstance discovery on the moon. The lunar soil is almost exclusively grey and tan, but as Schmidt walked across the dusty surface, he saw that his boot was kicking up alot of the grey soil. Underneath his own bootprint, he saw a layer that was not muted in hues of grey, but instead struck his geologist's eye as unlike anything thought to exist on the moon. What Schmidt's boot revealed was the first and only lunar region that differed from its surrounding strata.
|Is Mars habitable for humans? Credit: NASA
Chaikin described Schmidt's find as not unlike what a human might find on Mars--"the moon revealed a layer of brilliantly orange soil. Where Schmidt's boot had kicked up grey to reveal orange were these microscopic glassy beads, not entirely unlike the spherules or concretions found by the Opportunity rover on Mars." If beads on Mars meant water, beads on the moon meant active volcanoes. "On the moon, the orange soil meant that lunar geology had a time when lava or a fiery fountain sprayed molten material high into the air and formed these orange, glassy beads. Those beads then had been exhumed by an impact or crater."
Could a robot transmit enough high-resolution imagery, kick over enough rocks, or turn over mounds of lunar soil to have mimicked Schmidt and found the first orange soil on the moon? Was a geologist's trained eye a better means of discovery than a roomful of the best terrestrial experts pouring over mission photos?
|Apollo 17 astronaut, Harrison Schmidt uncovered orange lunar soil, made of tiny orange, glassy spheres (inset lower left) and formed by a fire fountain (inset right) as evidence of past volcanic lava flows. Would a robot or imagery alone have found the orange moon dust? Credit: NASA
Chaikin did not complete any judgements on whether a robot or human could best map Mars. In either case, a good camera lens is almost always going to filter the actual objects observed. A glass layer will inevitably come between a raw planetary landscape and our best trained eyes. But Chaikin did offer a philosophical perspective: "There will be no substitute for the sound of a human voice from another planet, one to which we have never been to before."
Related Web Pages
Spirit's images and slideshow
Opportunity image gallery and slideshow
Making the Moon
Review of Theories of Moon-Forming Impact (Planetary Science Institute)
Big Bang, New Moon (SwRI)
Ion Drive to the Moon
SMART-1: Chips Off the Terrestrial Block
Treasures from the Lunar Attic
End of an Era, Dawn of Another?