THE EXTRAORDINARY VIKING MISSION OPENED A NEW AGE OF SPACE EXPLORATION. IT ALSO OPENED A CONTROVERSY THAT PERSISTS TODAY
On August 20, 1975, a Titan IIIE rocket with a Centaur upper stage launched from Florida's Cape Canaveral. On reaching Earth orbit, the Centaur booster separated from Titan and injected the Viking 1 spacecraft - nestled inside its nose cone - into interplanetary space. The destination: Mars. (To reduce the chances of mission failure, three weeks later, NASA launched its twin, Viking 2.)
Composed of an orbiter and a lander, Viking 1 traversed 460 million miles of interplanetary space and entered Mars orbit 10 months later. While the orbiter imaged the planet's surface, the lander bided its time.
MARINER DISCOVERS "FLOW FEATURES"
The audacious Viking program was preceded by the Mariner orbital missions from 1964-1971. While the early Mariners dispelled any possibility of artificial canals on Mars (and with it, any pending "War of the Words" conflict), Mariner 9 "far exceeded its expectations in every way." Orbital imaging revealed a Martian surface of "ancient river beds, craters, massive, extinct volcanoes, canyons, (and) layered polar deposits." Surprisingly, it also revealed an unexpectedly dynamic planet with "weather fronts, ice clouds, localized dust storms, morning fogs and more."
I recall my awe on hearing the word "riverbeds," or, more scientifically, "flow features." In the search for life, this was Mariner 9’s fundamental discovery. Where there had been water, there may have been life. Perhaps, microbial life was still present just under the Martian surface. Alternatively, possibly only remnants of past life remained. Regardless, the discovery of any signs of present or ancient life would profoundly change the likelihood we are not alone in the cosmos. The search for signs life, past or present, was on! The means to this end: two intrepid Vikings.
MISSION DEVELOPMENT
The first serious consideration of searching for life on Mars originated in the early '60s. Miquel Pairolí, in the biography Joan Oró, writes:
In 1964, when the Apollo Program was still under development, a reunion of about 100 scientists was held at Stanford University in California, directed by Nobel Prize winner Joshua Lederberg, to plan for the exploration of planet Mars, through what would be called project Viking.
Klaus Biemann, having worked in mass spectrometry, had suggested sending a small mass spectrometer like the one developed by engineer (Kevin) Griffin at the Jet Propulsion Laboratory. However, Dr. Oró suggested that, for the analyses to be more reliable and definitive, the mass spectrometer could be complemented with a gas chromatograph, reproducing, at a small scale, the LKB instrument that Oró utilized in his laboratory at the University of Houston.
Development of the extraordinary Viking missions took shape at Langley Research Center in Hampton, Virginia. NASA scientist Gerald Soffen was appointed to direct the program, a Science Steering Group was created, and three project missions were defined:
Obtain high-resolution images of the Martian surface.
Characterize the structural composition of the atmosphere and surface.
Search for evidence of life on Mars.
A broad search for scientists specialized in research pertinent to the defined missions resulted in the selection of "an outstanding cross-section of the scientific community." Viking was a genuinely collaborative effort. Not only did it involve NASA and the Langley Research Center, but also the Jet Propulsion Laboratory (JPL) in Pasadena, CA, various aerospace companies, and multiple research scientists throughout the country.
THE VIKINGS TAKE SHAPE
Deciding on the overall structure of the craft, or crafts, was the crucial first step. Two identical spacecraft would be created. Should the launch, orbit, or landing of Viking 1 fail, Viking 2 would be following right behind. Furthermore, each spacecraft would be composed of an orbiter and a lander. The research scientist selected to join the mission, armed with a vision of the project's structure, could now focus on their areas of expertise. Thirteen research groups - such as Orbiter Imaging, Inorganic Chemistry, and Radio Science – were created.
The orbiters would contain a high-resolution camera to systematically image the planet's surface. The resulting collection of overlapping images would be knit to create a detailed map of Mars. The Viking 1 orbiter would be used to confirm the Viking 1 landing site and to search for a favorable landing site for the approaching Viking 2 lander. Even more critical, the orbiters would relay signals from the Viking landers to JPL on Earth.
By building the imaging and signal relay functions into the orbiters, the landers could be packed with research instruments - miniature laboratories that would be landed on the planet. Add a power source, a high gain antenna, three legs, a robotic arm with a scoop, two cameras along with a few other essentials, and you have a Viking lander ready for a ground-based examination of Mars.
Viking Lander at the Smithsonian National Air and Space Museum. Alex Oró, a grandson of Joan Oró standing to the right of the lander.
VIKING 1 SOFT LANDS ON MARS
After the month of recognizance by the Viking 1 orbiter, the lander – built by Martin Marietta and weighing 1,270 pounds - separated from the orbiter and faced the gravitational pull of Mars. NASA reported:
About 2 a.m. July 20, 1976, the Viking 1 lander separated from the orbiter and began its perilous descent to the surface. Plunging through the thin Martian atmosphere at nearly 10,000 miles per hour, the lander was protected by a heat-shielding aeroshell. At about 19,000 feet, a large parachute was deployed, slowing the hurtling spacecraft. At 4,000 feet, the parachute and aeroshell were released, and rockets fired, further slowing the lander's descent to just six miles per hour.
Following an "agonizing" 19 minutes - the time for the signal to reach Earth - JPL received confirmation from the craft. Viking 1 was on the surface of Mars and able to communicate! Mission director Tom Young described the reaction at JPL:
The excitement was overwhelming! People were hugging each other, jumping up and down - doing all those things you do when an extraordinary event has taken place.
Top left: First photograph from the surface of Mars. Top right: View during the congratulatory comments of President Gerald Ford. Bottom left: The first color picture from Mars. Bottom right: More detailed image of the reddish, rock strewn surface of Mars.
The world anxiously awaited the first image. Soon after landing, the imaging signal began to scroll across JPL's monitors. There it was—the rock-strewn surface of Mars. Vitally important, one the Viking three footpads could be seen solidly planted on the Martian surface; the vessel sat securely on the western slope of Chryse Planitia (the Plains of Gold).
SEARCHING FOR SIGNS OF LIFE
The research team's observations and studies proceeded in a coordinated fashion. Of the thirteen research groups, two were dedicated to the question of life: the Biology Group and the Molecular Analysis Group. (The persistent controversy on whether the Vikings detected signs of life on Mars 44-years ago would develop between these two groups.)
The Biology Group's experiments were the first to proceed. The group’s members included:
Dr. Harold P. Klein, Ames Research Center, Moffett Federal Airfield, CA
Dr. Norman H. Horowitz, California Institute of Technology, Pasadena, CA
Dr.Joshua Lederberg, Stanford University, Stanford, CA
Dr. Gilbert V. Levin, Biospherics, Inc., Rockville, MD
Vance I Omaya, Ames Research Center, Moffett Federal Airfield, CA
Alexander Rich, Massachusetts Institute of Technology, Cambridge, MA
The Biology Group had designed "three distinct investigations" to search for biologic activity in the soil samples: Pyloric Release, Labeled Release, and Gas Exchange. The Pyloric Release and Gas Exchange experiments were negative revealing no signs of life. However, the Labeled Release (LR) experiment was positive! No doubt, a buzz a spread among JPL’s scientific community.
Dr. Klaus Biemann, lead of the Molecular Analysis Group.
Now, it was the Molecular Analysis Group's turn to begin their investigations. Under the leadership of Dr. Klaus Biemann of Massachusetts Institute of Technology, members included:
Dr. DuWayne M. Anderson, U.S. Army Cold Regions Research Engineering Laboratory, Hanover, NH
Dr. Alfred O.C. Neir, University of Minnesota, Minneapolis, MN
Dr. Leslie E. Orgel, Salk Institute, San Diego, CA
Dr. John Oró, University of Houston, TX
Dr. Tobias Owen, State University of New York, Stony Brook, NY
Dr. Priestley Toulmin III, U.S. Geological Survey, Reston, VA
Dr. Harold C. Urey, University of California at San Diego, La Jolla, CA
The group's instrument, a gas chromatographer - mass spectrometer (GCMS), would perform a highly sensitive analysis of the Martian soil looking for signs of organic matter coming from living microorganisms, or from residuals of past life. First developed in 1959, GCMS can detect organic matter down to a few parts per billion.
GCMS was the core instrument in my father's research laboratory at the University of Houston. In addition to its essential role in his origin-of-life studies, John Oró (Joan in his native Catalan) and other scientists, including Klaus Biemann, had used GCMS to analyze the moon rocks brought back to Earth by the Apollo 11 astronauts in 1969.
The photo on the left shows the gas chromatograph - mass spectrometer (GCMS) at the laboratory of Dr. John Oró at the University of Houston in the 1960’s. On the right is a graphic of the miniturized GCMS, approximately 1 cubit foot in size, that searched for organic matter on Mars.
I had seen the GCMS in the 1960s on occasional visits to my father’s lab. The problem: it was a huge instrument. Although the mass spectrometer portion of GCMS had been reduced in size by JPL mechanical engineer Kevin Griffin, additional reduction was needed. Furthermore, when combined gas spectrometry, the resulting instrument would overwhelm the lander.
Dr. John Oró, origin of life scientist and member of the Molecular Analysis Group at JPL.
In the early ‘70s, my father made at least three consecutive trips to JPL, spending a month or more each summer. Among the Group’s activities: further miniaturization of GCMS. The challenge was daunting. Upon his return from JPL, using analogies, he would explain the Group’s progress to the family. The first summer, the apparatus had been reduced to the size of a “sea trunk,” still too massive to send to Mars. The following summer, it was reduced to the size of a “large suitcase.” By the third, the size a “valise.” The final GCMS that analyzed Martian soil had been reduced to approximately one cubic foot.
LIFE ON MARS, OR NOT?
Once NASA consolidated the results of Viking’s scientific studies, it was time to talk to the press. The prime question: had life been discovered on Mars? Marc Valldeoriola, in his biography Joan Oró: El Scientific de La Vida (The Scientist of Life), describes the event:
It was a strange day for everyone. It was a Friday in 1976. The press room at NASA’s Jet Propulsion Laboratory in Pasadena, California, was full to overflowing, and the convened reporters were expecting some important news. … Space agency scientists had the results from the Viking probes … but no one had said anything and the secrecy with which the mission had been carried out was, in the public’s view, confirmation of rumors that had been circulating for some time: indeed, they had discovered life on the red planet.
The Biology Group was the first to present its results: one of their three experiments had shown signs of life! Frenzied questions erupted from the gathered reporters: “Is the life extraterrestrial? Will we be able to communicate with it? Will our lives change?” The reporters appeared to assume NASA had discovered signs of sentient life. In response, one the Biology Group scientist emphasized they were talking about signs of microbial life.
As the flurry of questions continued, Joan Oró from the Molecular Analysis Group approached the speaker’s platform and spoke:
“Gentlemen, my colleagues have shown you a slide of calculations that spoke on the existence of life. But I will give you a second version that, from other calculations, makes me reach a different conclusion: there is no life on Mars.”
Thus began a still-brewing controversy: did the Vikings discover signs of life on Mars, or not? What evidence of life did the Biology Group uncover? What evidence did the Molecular Analysis Group find that negated that discovery? As it turns out, the answer hinged on what the GCMS did not discover.
Following the completion of the biology experiments, Viking’s robotic arm scooped soil from the Martian surface and channeled it into the GCMS. Earthen soil contains inorganic and organic matter (non-living and living matter). The latter represents the miracle of life. Studies in the 1950s and ’60s revealed that living matter can arise from non-living matter. Two members of the GCMS team had made the fundamental breakthroughs in this field. In 1953, at Harold Urey’s lab, graduate student Stanley Miller demonstrated that, in simulated primitive Earth conditions, amino acids could arise from non-living matter. In 1961, Joan Oró had shown that even nucleic acids such as adenine, a building block of the DNA we all carry, could also arise from non-living matter.
The Viking’s GCMS had not found even the minutest sign of organic matter - down to the few parts per billion - in the Martian soil! Whatever caused the reaction in the Labeled Release experiment, it could not be life.
THE CONTROVERSY PERSISTS
The controversy continues to smolder. In 2019, Gilbert Levin, the LR principal investigator, published his most recent argument. Nevertheless, in a review of that opinion, Paul Scott reported:
The consensus from most scientists in the years since then has been that there was something in the soil mimicking life, but it wasn’t life itself.
I have yet to encounter another possibility: could both experiments, though showing contradictory results, have been correct? It is now generally agreed that Mars is “self-sterilizing” due to the intense ultraviolet radiation falling on the planet’s surface and the perchlorate salts within Martian soil that can destroy organic compounds. Consistent with this, GCMS found no organic matter to the few parts per billion in the surface soil at either the Chryse Planitia or Utopia Planitia sites.
The surface and subsurface soils, at whatever depth they transition, differ in character. Mars surface soil is exceedingly dry, yet subsurface water is known to exist on Mars. At what depth did the transition zone occur at each landing site?
The LR and GCMS samples were taken on different days and not likely to have been collected at the same trench. Could the LR soil have contained small amounts of subsurface soil containing traces of organic matter while the GCMS received samples only from sterilized surface soil?
Countering this argument are the findings that the LR experiment was positive at both sites, and the GCMS findings were negative at both. This consistency at sites separated by approximately 4,000 miles (6,460 kilometers) argues for some other factor affecting the LR experiment.
The Perseverance Rover is currently scheduled to launch on July 30,2020.
ENTER PERSEVERANCE
So here we are. The 44th anniversary of the first landing on Mars and uncertainty on the presence of life on the planet persists. Fortunately, in Yoda’s words: “there is another.” Its name: Perseverance.
The primary goal of NASA’s Perseverance Rover’s is to “determine whether life ever existed on Mars.” NASA’s Mars 2020 Mission Overview details the process:
For the first time, the rover carries a drill for coring samples from Martian rocks and soil. It gathers and stores the cores in tubes on the Martian surface, using a strategy called "depot caching." Caching demonstrates a new rover capability of gathering, storing, and preserving samples. It could potentially pave the way for future missions that could collect the samples and return them to Earth for intensive laboratory analysis.
The name “Perseverance,” the winning entry submitted to NASA’s “Name the Rover” contest by seventh-grader Alexander Mather from Burke, Virginia, is apt for the challenge. Perseverance provides a new opportunity to answer the question of life on Mars..
Following summer at Space Camp in Alabama, Mather’s interest had morphed from video games to space. As he and his generation rise, Mars’ secrets will be revealed. I know my father and so many others who intensely poured their being into the Viking missions are delighted.