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HISTORY
Space Exploration to Mars
Beginning with Soviet Mars flybys in the 1960s and continuing up to this day, Mars has been explored for the past 60 years.
By Will Street
Jul. 25, 2019, 11:30 AM
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Introduction
A reddish colour in the sky that was associated with warfare and destruction, Mars was named after the Roman god of war. It has long been the source of fascination for humanity and featured heavily in popular culture during the early and mid 20th century, when it was imagined as being the home of intelligent life.
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Between 1912 and 1948, American writer Edgar Rice Burroughs (1875-1950) published an eleven-volume series of mass-market novels where an American civil war solider was magically transported to Mars and embarks on a series of adventures. He depicted Mars as a romanticised, dying planet with factionalised and war-like inhabitants.
Similarly, in 1950, Ray Bradbury (1920-2012) published The Martian Chronicles, depicting humans escaping from Earth to Mars, where they encountered Martians with strong powers of empathy and telepathy. Alternatively, the 1958 British film, Quatermass and the Pit, presented humans as, in fact, descended from the war-like inhabitants of Mars.
Four years later, in 1962, Robert Heinlein’s novel, Stranger in a Strange, presented a Martian travelling to Earth and went as far as to explore how humans’ culture might develop from Martian immigration.
These cultural dreams of a populated Mars stemmed from the contemporary science that argued Mars was suitable to sustain intelligent life. In the late 19th Century, astronomers, Giovanni Schiaparelli (1835-1910) and Percival Lowell (1855-1916) were interested in the planet Mars, and, from their observations, they advocated that Mars had once been a watery planet, speculating that the topographical features visible had been constructed by intelligent beings. The theme continued up to the 1960s.
However, these dreams of an inhabited planet were dashed when the first American probe flyby in 1964 showed a cratered Moon-like surface, destroying hopes of intelligent life existing on the planet.
Nonetheless, the space exploration missions of the 20th and 21st Centuries have done much to further our understanding of the red planet. In analysis below, I look at the various exploration missions undertaken to the planet Mars.
Early Expectations of the Planet Mars
During the late 19th Century and early 20th Century, it was commonly believed that the planet Mars had been home to great populaces, but was now a dying planet. There was a general theory that, since its origins, the sun had gradually cooled allowing planets further out in the solar system to once flourish.
The Italian, Giovanni Schiaparelli, created a map of Mars during the Great Opposition of 1877, when Mars’ orbit was closest to Earth’s. His map illustrated a series of linear structures on the surface, which he called canali - the Italian word for “channels”. This was mistranslated into English as “canals”, and generally fuelled expectations that Mars' inhabitants had divided the waterways into channels and that the first probe would show signs of life currently or previously having existed.
The belief of canals was furthered by American astronomer Percival Lowell also in the 19th Century, who built an observatory, which would later be called the Lowell Observatory, near Flagstaff, Arizona, to study Mars. Accepting the theory of Martian canals, he proposed that Mars had once been a watery planet and that the canals had been built by intelligent beings. His theory became the foundation of those arguing in favour of life existing on Mars for the next forty years.
Although Lowell wrote three books relating to the subject, which earned him widespread popular success, few astronomers accepted his theory, and subsequent telescope-based astronomical studies failed to confirm his findings.
Nonetheless, Lowell’s theory permeated much of the popular culture up to 1965. Life magazine, in one of their periodicals in 1944, claimed that the canals served to irrigate Martian vegetation that changed from green to brown over the seasons. In television, Walt Disney, showed animated flying saucers skimming over Martian plains of plants and animal life in a widely viewed broadcast in 1957.
These widely held views of an irrigated and populated Mars, were only acutely damaged by 1965 when the first American probes showed no signs of sophisticated life or past civilisation. It marked the end of credence towards Schiaperelli and Lowell’s popular maps.
The 1960s and the Mariner Probes
Emerging throughout the early to mid 20th Century was a popular cultural dream of exploring Mars. Rocket pioneer, Werner von Braun, heavily advocated exploring Mars, devising a grandiose plan in 1957 of a landing on Mars lasting 443 days and involving ten spacecraft and seventy crew members. In the Soviet Union, the Dovzhenko Film Studio produced a movie entitled The Sky Calls in 1959, imagining a race between two superpowers to travel to Mars.
In 1959, a trip to Mars was listed as a central objective in NASA’s long-range plan for space exploration during the 1970s. However, it would be the Soviet Union was the first to a send a robotic spacecraft towards the location of Mars. Between October 1960 and November 1964, the Soviet Union launched six missions to Mars, however none were successful.
In a similar vein, NASA’s initial probes to Mars in the 1960s were unsuccessful as well. The Americans launched two probes to Mars in 1964, however only one, Mariner 4, was able to reach its intended location.
Arriving in the vicinity of Mars on 15 July 1965 and flying as low as 9,846 (6,118 mi.) from its surface, Mariner 4 broke both the record of longest space probe operation and the furthest distance for radio communications.
It was this probe that sent back images showing a cratered, Moon-like surface, which was the first indication that dashed many’s hopes that intelligent life might exist on the planet. Mariner 4 also measured the Martian atmosphere, calculating that the surface pressures on Mars were somewhere between 4.1 and 7.0 millibars, enabled improvements on the calculation of the planet’s mass and revealed that Mars had no magnetic field equivalent to Earth’s.
The results prompted NASA to start looking for simple life existing or ever existing on Mars, rather the intelligent life that had been hoped for.
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However, NASA launched a further two Mariner missions in 1969. Mariner 6 and Mariner 7 were launched within a month of each other and both reached their intended targets, arriving in the vicinity of Mars in 1969. The two probes sent back data regarding the Martian atmosphere and surface, confirming the planets Moon-like appearance.
Another Mariner mission was launched, Mariner 8, however its launch vehicle failed. The sequel, Mariner 9, successfully reached Mars and took photos that would prove to be illusive in scientists’ understanding of the planet. The probe identified that volcanoes had once been active on the planet, a large amount of geological activity had occurred some time Mars’ past and that the ice noticeable seasonally on the poles was comprised of carbon dioxide. This prompted a resurgence of interest in Mars, principally because the findings of Mariner 9 hinted that some form of life might once have existed there.
Viking 1 and 2 Landings
NASA’s foundations for a landing on Mars had been laid in 1969 through the Mariner 6 and 7 probes. Such a landing would come in the 1970s in the form of the Vikings 1 and 2 expeditions. Between 1975 and 1982, NASA conducted two landings on Mars, launching two twin orbiters, each with its own robot that would land on Mars.
The mission was intended to build on the experience and knowledge gained from the Mariner missions, and to answer the question of whether simple life might exist on the planet. Viking 1 touched down on the Golden Plain region of Mars on 20 July 1976, and immediately transmitted its photos back to NASA’s control base. Secondly, Viking 2 landed about 200 kilometres west of the crater Mie in the Nowhere Plains in September 1976 and did the same.
Although the Soviet Union had landed a space craft on Mars in 1973, the Vikings landers were the first space craft to operate on an extra-terrestrial planet for an extended period. They monitored Mars’ weather, finding cyclical variations and a extremely harsh climate that would seem to preclude life existing.
The probe also studied the Martian soil, providing no clear evidence for the presence of living microorganisms in the soil surrounding the robot. It was an indication, rather, of a sterile soil, and led many NASA scientists to conclude that the combination of strong ultra-violet radiation from the Sun, the extreme dryness of the soil and general oxidising nature of the chemistry ensured that Mars was self-sterilising.
There was a peculiar outline of a human face that was observed by Viking 1 in the rock on the surface. It prompted speculations in society and popular culture that it was fossilised skull, however the later Mars Global Surveyor in 2001 would reveal it as an optical illusion. The apparent picture of a sterile Mars resulted in NASA not launching another probe to Mars for the following 17 years.
Renaissance in Mars Exploration
After a hiatus in Mars exploration, during which the Soviet Union attempted and failed to send probes to Phobos, one of Mars' moons, and NASA lost contact with another probe travelling to Mars in 1993, the Mars Pathfinder was launched by NASA in 1996 and successfully landed on the Red Planet in 1997.
The space craft used inflatable airbags to bounce along the surface of Mars as it descended, before coming to rest and releasing a tiny rover, Sojourner, that would roam the surface of the planet.
Mars Pathfinder was launched as an attempt to try and find whether life that could tolerate extremely harsh conditions existed on Mars, similar to that at the bottom of the oceans on Earth.
The rover was launched from the space craft down a ramp and took close up pictures of the planet’s surface both in colour and black and white. It also had a rear-mounted alpha-particle X-ray spectrometer that studied the chemical composition of the rock and soil over which it travelled. It thus was able to record important new information about rocks that had washed down into the Mars Valley floodplain, a channel in Mars’ northern hemisphere where long before liquid had once passed through.
Intended to operate only for thirty days, the rover managed to work for nearly three months, capturing far more data than NASA had predicted. Returning more than 1.2 GB of data and more than 10,000 pictures of the planet’s surface, the rover proved a success for the scientists and was enormously popular within society at the time, with 47 million people recorded as attempting to access details of the mission online at one point.
Following the Mars Pathfinder expedition, the impetus for NASA became the search for water on Mars, working on the premise that life first existed on Earth in water.
Therefore, in November 1996, NASA launched the Mars Global Surveyor, which successfully entered a Martian orbit in 1998. It was designed to map Mars’ surface in greater detail and, by using MGS images, scientists were able to identify geographical features on the surface of Mars that were probably created by fast-flowing water. The results prompted scientists to speculate that there may yet still be some water hidden under the surface of Martian soil.
The subsequent NASA probe, Mars Reconnaisance Orbiter, was launched in August 2005 and successfully reached the vicinity of Mars in March 2006. It showed indications of dry riverbeds, floodplains and gullies on Martian cliffs and crater walls, along with sedimentary deposits. It therefore suggested that water had once flown across the planet and, perhaps, also that microbial life might have existed there some time in the past.
Discoveries by the Mars Pathfinder and the MGS and MRO probes suggested that perhaps some simple life forms might exist beneath the planet’s polar ice caps or subterranean hot springs and, while scientists accepted that they lacked substantial evidence at least in the 2000s, NASA generally believed that future exploration would hopefully be able to illuminate whether or not it did.
The Mars Global Surveyor’s primary goal was its mapping mission which it carried until the project’s completion in January 2001. Following that point, it was assigned a number of different tasks, one of which was operating as a relay platform for communication between Earth and the various lander missions on Mars’ surface. This extended mission was carried out until November 2006, when NASA lost contact with the spacecraft.
The Mar’s Global Surveyor’s sequel, the Mars Reconnaissance Orbiter, was equipped with enough propellant to last until the 2030s and is still in operation today, continuing in its search for water on Mars.
Spirit and Opportunity
Launched in June and July 2003 respectively, the next landers on the surface of Mars were Spirit and Opportunity, named after the winning entry of a student essay competition. The two rovers were launched in an effort to search for evidence of water affecting the shape of Martian geology.
Although intended only to last ninety days, the two rovers continued working for far longer than expected. NASA lost contact with Spirit on the 22nd March 2010, while Opportunity lasted until the 10th June 2018. Spirit landed in the centre of the massive Gusev Crater on the 4th January 2004 using airbags to soften the landing. In the same way, Opportunity landed on the planet’s surface in the Souther Plains region three weeks later.
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Once landed, the rovers took panoramic images of their surroundings, which gave scientists back on Earth enough information to select promising geographical features for the two robots to examine. Using their six mechanical wheels, the two rovers drove to their designated destinations.
Notwithstanding their different names, the two rovers were identical in design, possessing a panoramic camera, a miniature thermal emission spectrometer, a Mössbauer spectrometer, an alpha-particle X-ray spectrometer, microscopic imager, a rock abrasion tool for dissecting weathered rock to expose the interior and a dextrous robotic arm with its own camera attached to enable it to turn and view the rocks it picked up. In total they weighed roughly 180 kilograms.
Spirit explored the Gusev Crater and its basalt base, which showed little signs of past water on the planet. It then travelled to the Colombia Hills, named after the astronauts who perished in 2003 disintegration of the Space Shuttle Colombia. There, it found a number of rocks, which indicated that early Mars had been subjected to a large number of meteorite impacts, explosive volcanism and that there had been substantial amounts of subsurface water. It also found highly salty patches of soil, that had been affected by past water and discovered finely layered rock, that further suggested water had once existed on the planet.
In contrast to the undulating crater of Spirit’s location, Opportunity landed close to a thin outcrop of rock that provided the perfect opportunity for an analysis of the geology. The rover confirmed that a body of water had once flowed gently over the location and by also testing sands that had become petrified by water and wind action, and soaked by groundwater, it suggested that the Martian environment might have been suitable to support simple life and preserve fossils. It also enabled an examination of an even deeper and broader subsection of rock than Spirit.
Principally, Spirit and Opportunity confirmed for scientists that the rocks on Mars had once been soaked in water. The two robots covered a large distance, Spirit travelling 5.5 kilometres and Opportunity almost 10 kilometres by the 6th February 2007. Opportunity’s total distance travelled on the 27th July 2014 was 40.25 kilometres, giving it the world record for extra-terrestrial distance travelled.
Curiosity
During the 2000s the first non-Soviet/Russia or American space crafts were launched in an effort to study Mars. In 2003, the Japanese probe, Nozomi, was launched, however it endured a fatal failure in its electrical systems. The European Space Agency (ESA), conversely, successfully reached Mars in 2004 through its Mars Express probe. Unfortunately, the lander space craft, the British Beagle 2, failed to make contact with its mission controllers upon landing on the Martian surface. However, the Mars Express is still in operation today and the longevity it has endured in its position has made it a uniquely valuable platform for acquiring scientific data about Mars. Alongside the Mars Express, the ESA’s ExoMars Trace Gas Orbiter and the Indian Space Research Organisations’ (ISRO) Mangalyaan orbiter constitute the three non-Russian or American probes in orbit around Mars currently.
However, the following landing on Mars came in the form of NASA’s rover, Curiosity, which landed on Mars on the 6th August 2012. The purpose of Curiosity was generally to study to the surface chemistry, the atmospheric conditions and characterise the broad spectrum of surface radiation affecting the planet.
The rover touched down in the Gale Crater and immediately transmitted photos of its location back to NASA’s control base. The rover’s large size, at 899 kilograms and the size of a small car, precluded an airbag descent to the surface similar to Sojourner, Spirit and Opportunity. Rather, the descent module deployed a parachute three minutes prior to landing, before switching to retrorockets and deploying an effectual “sky crane” system, lowering the rover onto the ground by means of a tether.
The main discoveries of Curiosity were that the radiation levels on Mars’ surface were comparable to those found by astronauts on board the ISS. This would allow for a human space expedition to be possible. Further, the rover found evidence of an ancient streambed, suggesting knee-high water would have run across the location a long time before. It also identified some essential ingredients for life, including sulphur, oxygen, nitrogen, hydrogen, carbon and phosphorous. Having found the presence of water, the question remains for the rover to examine whether Mars was capable of supporting life either in the past or presently. The rover is still operating on Mars at the moment.
The Future of Exploration of Mars
Currently, with indications of water running across the planet a long time in the past, and the presence of frozen water currently at the polar ice caps, the search remains to find either life existing or a fossilised sign of life.
However, a study of whether microbial life ever existed would be greatly assisted by being able to take a sample back from Mars to Earth. Scientists would be able to carry out a range of geochemical studies and age-dating techniques that a rover on Mars couldn’t. Such an analysis would require a range of samples taken from different locations across Mars. A sample return component was listed in NASA’s decade-long programme of strategic Mars missions during the first decade of the 21st Century however, by the time of the Curiosity mission, the sample return component had been dropped.
The idea of a sample return faces problems such as the enormous cost of the mission and ensuring the sample is isolated from contamination with other material. It may as yet prove more effective to send astronauts to Mars to collect samples manually.
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A base on Mars would require a two-year allowance for the journey to the planet and must also be equipped with the necessary equipment to survive on the planet. This would include a laboratory, habitat, rovers, a power plant for generating electricity on the planet, food and an ascent vehicle for the return journey, fuelled by propellant that would require a manufacturing plant as well.
As the atmosphere of Mars is comprised predominately of carbon dioxide, the gas could be pumped into a reaction chamber to be mixed with liquid hydrogen and heated. The resulting process produces water and methane, an element which could then be pumped through a cryogenic cooler, which would reduce the substance to a liquid state, which could then be used as rocket fuel. The water left from the reaction chamber could also be passed through an electrolysis unit and separated into hydrogen and oxygen. A greenhouse would also be needed to grow food.
While on the planet, astronauts could use automated rovers to explore the planet and also drill into the substrata to search for water, any life that might exist, possible fossils and natural resources that could be used.
However, there are numerous problems facing a potential human expedition to Mars. Cosmic radiation penetrating the solar system from other galaxies could be a problem, as could solar flares of radiation from the sun. To avoid this, astronauts would have to keep the transit time minimal and use the protection from Mars’ atmosphere.
Nonetheless, the obstacles facing an expedition to Mars could be overcome with sufficient funding. Donald Trump announced on the 11th December 2017 that he intended to refocus NASA objectives towards a base on the moon, however other nations may yet still choose to focus and unite their efforts towards a base on Mars. The 2030s as the decade for a base on Mars may prove accomplishable.
Conclusion
Hopes and aspirations for Mars have changed much over the centuries. From the great civilisations of sophisticated life envisaged in the 19th and early 20th Centuries to the biologically moribund verdict of the seventies, knowledge of the planet has continued to increase incrementally. Today, rovers and probes investigate the planet, with a future base some way off on the horizon. The question remains over whether life, however simple that may be, does or has ever existed on the planet and whether definitive signs, living or fossilised, can be found.