After an entertaining survey of the human fascination with Mars over the centuries, the author offers an introduction to the geography, geology, and water processes of the planet. He then briefly describes the many successful missions by NASA and others to that distant world. But failure and frustration also get their due. As the author makes clear, going to Mars is not, and never will be, easy. Later in the book, he describes in detail what each upcoming mission will involve.
In the second half of the book, he offers the reader a glimpse inside the world of Earth-based "Mars analogs," places on Earth where scientists are conducting research in hostile environments that are eerily "Martian." Finally, he constructs a probable scenario of a crewed expedition to Mars, so that readers can see how earlier robotic missions and human Earth simulations will fit together.
All this is punctuated by numerous firsthand interviews with some of the finest Mars explorers of our day, including Stephen Squyres (Mars Exploration Rover), Bruce Murray (former director of the Jet Propulsion Laboratory), and Peter Smith (chief of the Mars Phoenix Lander and the upcoming OSIRIS-REx missions). These stellar individuals give us an insider's view of the difficulties and rewards of roaming the red planet.
The author's infectious enthusiasm and firsthand knowledge of the international space industry combine to make a uniquely appealing and accessible book about Mars.
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About the Author
Rod Pyle is the author of the widely praised books Destination Moon and Missions to the Moon, as well as the popular audiobook In Their Own Words: The Space Race. He has written and produced numerous documentaries for the History Channel and Discovery Communications, including the acclaimed Modern Marvels: Apollo 11 and Mars: 100 Years of Discovery. Pyle has been an assistant professor at the University of La Verne, California, and frequently lectures at NASA’s Johnson Space Center in Houston.
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DESTINATION MARSNew Explorations of the RED PLANET
By ROD PYLE
Prometheus BooksCopyright © 2012 Rod Pyle
All right reserved.
Chapter OneTHE FIRST MARTIAN
July 20, 1976: The Viking 1 orbiter instructed its lander to begin the separation sequence to start the long journey to the Martian surface. It was just after midnight at the Jet Propulsion Laboratory (JPL) in Pasadena, but as the probe was automated, no commands had been exchanged for some time. The onboard computer initiated a final round of systems checks. The explosives that joined the lander to the orbiter were armed ...
Anxious flight controllers, largely powerless at this distance, could only watch the time-delayed data as the onboard computers made their own decisions. At 00:00 onboard computers fired the pyrotechnics, separating the Viking lander, which soon fired its own braking thrusters to begin the slow fall out of Martian orbit. In the dusky skies above, the orbiter from which it had recently separated continued on its mission. Below spread the ruddy expanse of Mars: dusty, cold, unexplored ... and in about three and a half increasingly turbulent hours, home.
The Viking 1 lander, at ten feet wide by seven feet tall, was part of the largest and most expensive US unmanned mission to date. The orbiter, eight feet wide and ten tall, with a solar-panel span of thirty-two feet, shared the distinction. In a few weeks, Viking 2, a virtual twin, would arrive on Mars on an identical mission, but within a different landing zone on the opposite side of the planet.
The people who had sent Viking to this dangerous rendezvous waited out the landing confirmation signal in tense quiet. Only the most necessary words were spoken. There was an eighteen-minute delay between Earth and Mars at this distance; whatever happened to Viking now would be of its own doing. Many scientists on this program estimated a 50-50 chance of success, even with two landers. It was, in essence, a blind landing on a rocky, undulating landscape.
The Viking 1 lander was, for the first time in its short life, completely alone.
The tiny craft plummeted into the thin Martian atmosphere at 10,000 mph, still firing its braking thrusters. These rockets were models of simplicity. The fuel was a monopropellant and needed no ignition source and no other chemical mixed with it to explode into thrust. Further, instead of using complex pumps to feed the engine, the propellants were pressurized by stored helium gas. There was little to go wrong once they fired.
The lander was encased by a heat-resistant aeroshell, a dish-shaped structure that protected it from the heat of entry but also placed more demands upon its small digital brain. For as it plummeted through the upper reaches of the tenuous Martian atmosphere, Viking's computer was focused not just on a successful landing but also on conducting research in this wispy environment. Nothing is wasted in space exploration, and this early descent phase was no exception. As the computer labored to steer the craft, data began flowing in from sensors mounted on the aeroshell, providing data about charged particles surrounding the descending craft. Within the parade of arcane obsessions in the mind of the planetary scientist, understanding how the solar wind—high-energy particles streaming forth from the sun—interacts with the upper reaches of the Martian atmosphere is a thrill. The measurements now being recorded on the onboard tape drives should shed some light on this question. But Viking cared not; it simply stored the data for eventual delivery to Earth. Recording data was its raison d'être, and to this task it applied itself from its first moments.
At about 180 miles in altitude, another instrument switched on: the mass spectrometer. This would measure the makeup of the upper atmosphere, analyzing the thin gasses present to provide a more detailed accounting of the "air" to augment the painstakingly gathered information already gleaned from Earth-bound telescopes. This first US spacecraft to enter another planet's atmosphere would accomplish multiple objectives, but primary among them was searching for one capable of supporting life as we understood it in 1976.
At about sixty miles high, this group of instruments switched off and another set became active. These performed an elegant analysis of the pressure, density, and temperature of the lower atmosphere by measuring the slowing of the craft. It was a bit like a waltz with a nonexistent partner, where one's success is measured via self-observation rather than direct feedback from the surroundings. But it was enough.
At about seventeen miles, the trajectory shifted: the aeroshell was sufficiently aerodynamic that it began to generate some lift, and Viking began to glide across the Martian sky. All this was by design; it was another way to scrub off excess velocity. Eventually, weight and drag took their toll and the craft began its steep descent once more.
The continual hiss of the rockets was joined by the roar of the thickening atmosphere, which, while thin, would soon be enough for the single parachute, set to deploy at nineteen thousand feet, to slow the machine sufficiently to land in one piece. This slowing to a sane rate of descent would be aided by more rocket engines. These were ingeniously designed as three clusters of eighteen tiny nozzles that would provide adequate braking propulsion without disturbing the surface upon which it alighted. All this, plus the fanatical sterilization of the spacecraft, was critical to preserving the sanctity of the ground below. For this was central to its primary mission—the search for life.
The onboard radar was scanning the ground, providing excellent data for range to the surface. What it was not providing was any idea of how rough that surface might be. The Viking team back on Earth had searched for the best landing place it could find with Mariner 6 and 7 photographic surveys, and later with results from Mariner 9, but it was barely better than a rough guess. At the Mariner 9 camera resolutions, the best images heretofore available, items smaller than the Rose Bowl were nearly invisible. Anything smaller than that had to be inferred from the analysis of surrounding terrain, and this was more alchemy than science, based on Earth-bound geological assumptions. Teams had agonized over these images for years. Then, data from the just-arrived Viking orbiter cameras resulted in more eleventh-hour angst about the landing area and a new site was selected at the last moment. Now all JPL controllers could do was aim the gun, close their eyes, and squeeze the trigger. In short, Viking was what lab folk later referred to as a BDL—a Big, Dumb Lander. Much of what happened from now on was based on luck. Viking could crash and mission control would be blissfully unaware until eighteen minutes after the fact, when the signal would simply vanish.
Soon the lander unhooked from the parachute, now relying only on its tiny landing rockets to control the final descent. At three hundred feet up, low-level radar kicked in to give a last set of readings. At sixty feet, the computer worked to cancel any horizontal motion and the lander settled into a strictly downward mode. It would now land directly below, no matter what. So said the simple instructions burnt into its primitive memory, saved in tiny magnetic cores that lived at the intersection of minute, hair-thin wires. While brutishly dumb by today's standards (your toaster probably holds more data), it was an elegant and almost bombproof method of storing data.
Slowly, Viking descended the final few feet. The rockets would not shut off until the lander made ground contact. But what lay below? The Viking lander had a scant 8.5 inches of ground clearance; any rock larger than that would likely end the mission. Falling in the weak gravity at a leisurely 6 mph, about the speed a person can walk, Viking 1 settled onto Chryse Planitia, Greek for "Golden Plain," a large and relatively flat expanse not far from the Tharsis volcanic region.
Touchdown. Silence returned to Mars. The Viking 1 lander was down, alive and well, after a 440,000,000-mile journey.
The date was July 20, 1976, the seventh anniversary of the landing of Apollo 11 on the moon. It was the first US soft landing on another planet (a moon is a satellite), and the first probe to function for more than a minute on another planetary body (an earlier Soviet probe had landed, but failed upon touchdown). In fact, it would perform well beyond its builders' wildest expectations.
As the lander began surface operations, the Viking orbiter continued overhead, entering a new phase of its own science program. Armed with high-resolution cameras, it continued its observations while also acting as a relay station between the lander below and Earth, a blue star barely visible over the horizon.
Lander 1 went through a deliberate cycle of making sure that the descent engines and associated systems were shut down. It would not do to drip anything caustic or polluting onto the ground below. Hydrazine, the craft's volatile and corrosive fuel, would not be friendly to any microorganisms lurking about and would be a terrible way of saying hello. In fact, not so much as a microbe of Earth biota had been knowingly allowed to fester on Viking either; it had been baked, purged, and sterilized better than any surgeon's tool before launch. Nothing could be allowed to pollute the virgin Martian soil. As the engines were "safed," the computer queried the navigation system, or inertial guidance unit. This simple system, while no longer needed for steering the craft, would help to supply altitude and directional information, so it was run for another five minutes. This information was critical to aiming the radio dish toward Earth, so the more accurate the data, the better.
At the same time, the first postcard to home was being assembled. The Viking landers used a new type of imaging camera. Previous space probes had used state-of-the-art TV cameras, but at the time, the images were not up to what the designers had yearned for. For Viking, the camera stared upward into a mirror that swung vertically, "nodding" up and down. Between each nod the mirror would rotate a small amount. In this way, a series of strips were assembled over time, and these resulted in what was, for the day, a very high-resolution image. Two of these ingenious devices were mounted on each lander, allowing three-dimensional imaging, and the first job of the day was to send an image home.
But this first snapshot of another planet was not to be a splendid panoramic of the landing area; rather, it was a somewhat mundane image of the nearest footpad. This would accomplish multiple goals instantaneously: the safety (or lack thereof) of the landing site would be demonstrated by the placement of the footpad. The amount of sinking into the sandy soil (properly called regolith, as the word soil implies life within) would be shown, and this, along with other measurements such as the amount of slowing at contact and the designed-in collapsing of the lander's legs upon touchdown would supply information about the compactibility of the ground. Remember, nothing is wasted in space exploration.
Back on Earth, strips of the first picture from Mars began to come in. It was innocuous enough: a shot of footpad 3. If the probe had failed then and there, a lot of folks would have been very upset to have nothing more to show for the billion-dollar effort. But this shot was needed to ensure that the craft was stable. Cheers rang out at JPL and Caltech as the proof of a successful landing were made visible. But from Mars, the lander could not hear, nor would it have cared. It merely carried on in its eighteen kilobytes of programmed duties with dogged and ruthless determination.
Next on the lander's to-do list were the pyrotechnic events, known to most of us as explosions. In spaceflight, whether manned or unmanned, small explosives had long had a leading role. Then as now, they were used to separate the stages of rockets as they ascended away from Earth. They released spacecraft once in orbit. They opened and closed valves. And, in Viking's case, they were critical to beginning Mars-based activities. These are, by their nature, one-shot operations-as in, they work or they don't. Their duties included releasing safeties for the life-science experiments and opening the meteorology boom-an arm with instruments to measure wind speed, temperature, and the like. These performed without a hitch.
Now a second photo was taken, and this was the money shot: the first picture of the horizon of Chryse Planitia. As the lander went about its business, breath was again held in mission control. What would we see? What did the surface of Mars look like at ground level? Remember that these were the days of rotary telephones, bias-ply tires, and such state-of-the-art things as The Eagles: Greatest Hits via vinyl records. An image from the surface of Mars was heady stuff. And with the Viking orbiter disappearing over the horizon in about twelve minutes, and with it, the best link to home, this had to be done now.
Once again, Viking 1 did not disappoint. The first image, black and white but glorious nonetheless, slowly assembled, again, a strip at a time. The tension broke slightly as the first strip came in, but like a good mystery novel, Mars was only revealed a small bit at a time. The results were well worth the wait. After years of preparation, a billion dollars, and a journey of many times the 119 million miles then separating Earth from Mars, the first landscape was in. The data was still coming back long after the orbiter was out of touch, given the long transmission travel time across the vast darkness, and the lander went into a base-operation mode while out of communication.
But the picture ... oh, that second picture. It lacked color and was obscured on the bottom by various parts of the spacecraft. But there it was, in all its monochromatic glory: the horizon of Mars. Low, arid hills were off in the distance, and between the lander and those hills was an expanse of sharp, jagged rocks. Hundreds of them. And off to the right, dominating the horizon there, was the bright glow of the sun, unseen and above the frame. It was a dry, cloudless spectacle. For someone seeking the serenity of an English tea garden, or the Mars of Percival Lowell, it would not do. But for any human pining for a glimpse of another world, a world we could relate to, another planet to which we might one day travel, it was nirvana.
Viking 1 was, however, oblivious to such human emotion. The outbursts and cheers from Earth remained unheard. It had a primary mission of just sixty days on the surface, with an extended mission target of 120. At that point, Mars would pass behind the sun and communication would be lost for weeks. And while controllers on Earth planned to "safe" the lander during this time, their confidence in reawakening the machine after this period was limited. But true to what would become JPL's legacy of performing near miracles with distant machines, the first lander operated successfully for well over six years. And the tale of its ultimate demise is not one of equipment failure, but of human error.
With Viking's successful landing, there was now time—well over two months in the primary mission alone—to perform the tasks it was designed to do. The instructions came up from Earth in carefully coded batches, to be processed and executed in sequence. With mechanical exactitude, Viking 1 began its primary labors—taking color images of the surrounding surface, digging scoops of soil and dumping them carefully into small funnels that led to an onboard laboratory, and fulfilling its primary objective: the search for life on Mars.
Just under two months later, on September 3, 1976, the Viking 2 lander settled gently onto Utopia Planitia, 4,200 miles away to the northeast. Humanity now had two outposts on Mars, and the exploration of the red planet began in earnest. Overhead, the Viking orbiters continued to chip away at their intense workload, snapping pictures and sending reams of data earthward. What they imaged and reported would change our understanding of Mars overnight: the Martian Renaissance had begun.
Excerpted from DESTINATION MARS by ROD PYLE Copyright © 2012 by Rod Pyle. Excerpted by permission of Prometheus Books. All rights reserved. No part of this excerpt may be reproduced or reprinted without permission in writing from the publisher.
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Table of Contents
Foreword Robert Manning 9
1 The First Martian 17
2 Mars 101 27
3 In the Beginning: A Shining Red Eye 37
4 The End of an Empire: Mariner 4 51
5 Dr. Robert Leighton: The Eyes of Mariner 4 57
6 Continuing Travels to Dark and Scary Places: Mariners 6 and 7 61
7 Dr. Bruce Murray: It's All about the Image 67
8 Aeolian Armageddon: Mariner 9 73
9 Dr. Laurence Soderblom: The Eyes of Mariner 9 79
10 Viking's Search for Life: Where Are the Microbes? 83
11 Dr. Norman Horowitz: Looking for Life 99
12 Return to Mars: Mars Global Surveyor 107
13 Robert Brooks: It Takes a Team, Mars Global Surveyor 115
14 Roving Mars: Sojourner, the Pathfinder 123
15 Robert Manning, Mars Pathfinder: Bouncing to Mars 133
16 Mars Express: On the Fast Track 143
17 A Laugh in the Darkness: The Great Galactic Ghoul 147
2001: A Mars Odyssey 157
19 Dr. Jeffrey Plaut: Follow the Water 165
20 Twins of Mars: Spirit and Opportunity 171
21 Dr. Steve Squyres and the Mars Exploration Rovers: Dreams of Ice and Sand 189
22 Mars in HD: Mars Reconnaissance Orbiter 195
23 Dr. Richard Zurek, MRO: I Can See Clearly Now 209
24 Twins of Mars: Spirit and Opportunity, Part 2 213
25 From the Ashes, Like a Phoenix 229
26 Peter Smith: Polar Explorer 243
27 Mars Science Laboratory: Bigger Is Better 253
28 Dr. Joy Crisp, Mars Science Laboratory: Dig This 261
29 JPL 2020: The Once and Future Mars 267
30 Mars on Earth 271
31 The New Martians 281
32 The Road Ahead 289
Bibliography of Print Sources 313
Bibliography of Internet Sources 315