A Year After A Space Probe Crashed Into A Comet, Scientists Retrieved Its Astonishing Last Photo

It’s 2017, and nearly a year has passed since the European Space Agency’s Rosetta spacecraft made a planned crash-landing on the comet it had taken a decade to reach. But since then, scientists have continued their painstaking work of combing through the reams of imaging data transmitted by the probe. And much to their surprise, they discover a strangely eerie photo they’ve never seen before.

Yet while that intriguing snap may have been unexpected, Rosetta had previously been fitted with the highly sophisticated camera OSIRIS. The German-made device was equipped with both a wide-angle and a narrow-angle lens capable of producing high-definition images, meaning it was able to take some 100,000 shots during Rosetta’s 12-year mission.

Of that staggering tally, around one-fifth of the images were captured as Rosetta made its way through space towards Comet 67P. Other photos taken during the journey to 67P included some of Mars and of a couple of asteroids that Rosetta passed on its trajectory.

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Even as Rosetta neared the end of its mission, the camera shutter kept clicking. And although some of the photographs suffered from an unexpected data corruption caused by a break in transmission, researchers were nevertheless able to interpret this information. The process then led the team to some quite astonishing shots of space – including the very last one that OSIRIS was able to take.

But what of the comet that Rosetta was studying? Well, its full name is 67P/Churyumov–Gerasimenko, although for simplicity’s sake we’ll just call it 67P. And, in case you were wondering, the last part of that moniker honors the two Soviet astronomers who originally discovered the comet in 1969.

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At the tail-end of the ’60s, Svetlana Gerasimenko captured images of a comet called 32P/Comas Solà using a powerful telescope. But, upon further inspection, her colleague Klim Churyumo realized that the astronomer had actually spotted an entirely different astronomical body. The “67P” designation comes, meanwhile, from the systematic comet-naming protocol.

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And the origins of the Rosetta mission can be traced right back to 1986. That year, spacecraft were dispatched to investigate Halley’s Comet at a time when it could be observed from Earth. Launches came from Russia and Japan as well as the European Space Agency (ESA), which would later send off the probe to investigate 67P.

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Scientists’ appetites for knowledge about comets were whetted by that encounter with Halley, and experts ultimately realized that there was much more to learn about these rocks speeding through space. Expanding our knowledge about comets could even throw light on other intriguing scientific questions, in fact. So, ESA and NASA began to cooperate in developing mission plans, although NASA’s financial constraints obliged it to withdraw from the project in 1992.

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At first, the idea had been to launch a probe that would take samples from the surface of a comet and actually return them to Earth. That concept was subsequently deemed to be over-ambitious, however. And while speaking to The Guardian in 2016, Gerald Schwehm, Rosetta’s original project manager, described the thought process that led to the mission’s final form.

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“We decided [that] if we could not get the comet to the laboratory, we’d get the laboratory to the comet,” Schwehm told The Guardian. “Surprisingly, it worked.” This approach meant, though, that the probe would have to carry scientific equipment – including radar, some optical spectrometers and the OSIRIS camera – weighing in at more than 350 pounds.

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The full weight of Rosetta was in excess of 6,500 pounds, of which the 220-pound lander Philae was part. And those necessary scientific instruments were housed in what was dubbed the payload support module, which sat at the summit of the spacecraft.

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To stop Rosetta from freezing up when it was far from the Sun, the probe was also fitted with a heating system. Yet while communications equipment was similarly on board, the distances involved in the mission meant that there was a considerable lag in transmitting and receiving signals to and from Earth. When Rosetta was about 250 million miles from Earth and nearing 67P, this delay came to more than 20 minutes.

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And to get Rosetta to the comet, engineers installed clusters of silicon solar panels that spread across nearly 700 square feet. These were accompanied by 24 pairs of thrusters, which were capable of propelling the spaceship at a velocity of an astonishing 7,500 feet per second.

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Then, once the probe’s sophisticated systems and instrumentation had been assembled to the satisfaction of the ESA engineers and scientists, it was time to schedule take-off. But, unfortunately, the first mooted attempt at launching was a bitter disappointment. Originally, the event was scheduled for January 12, 2003, with the chosen target being another comet named 46P/Wirtanen.

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In December 2002, however, the ESA was forced to cancel this plan when another launch using an Ariane 5 ECA carrier was unsuccessful. Crucially, the Ariane was the model of rocket that had been selected to send Rosetta out of Earth’s atmosphere and on into space, meaning there was ultimately no choice but to postpone the mission.

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As a result, the ESA experts had to come up with a new scheme. The launch was set instead for February 26, 2004, with the target comet this time around being 67P. And although some modifications to Rosetta were required before launch, much of the mission remained largely the same.

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So, after another brief delay of just a few days, Rosetta finally set off from the Guiana Space Centre in French Guiana on March 2, 2004. And, happily, Churyumov and Gerasimenko, the two astronomers who’d originally identified 67P, were both on hand to witness the event.

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No doubt to everyone’s relief, Rosetta blasted off into space without a hitch. The probe then followed a route through the inner Solar System that allowed it to use the power of planetary gravity in its journey. This included a flight past Earth in March 2005 as well as a fly-by near Mars two years later. The tour over the Red Planet was designed to put Rosetta on the right trajectory to intercept 67P.

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Skirting close to Mars was a tricky process, however, as it entailed Rosetta being in the shadow of the planet for a quarter of an hour. Shielded from the Sun, the craft’s solar panels would therefore be inoperative for that period, resulting in a worrying decrease in power for the ship’s systems; communication with Earth would be interrupted, too. In the event, though, the operation went smoothly.

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In fact, this part of the mission went so well that Rosetta was able to transmit some excellent images of Mars’ surface back to the European Space Operations Centre in Germany. Then, after another fly-by over Earth during November 2007, Rosetta headed off into deeper space – but not before there was a strange case of mistaken identity as the probe edged closer to our planet.

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You see, as Rosetta sped by Earth, an astronomer at the University of Arizona’s Catalina Sky Survey in Tucson mistook the spacecraft for a previously unidentified asteroid. This object was even given the name 2007 VN84, and fears arose that it might crash into our planet. Fortunately, though, respected Russian astronomer Denis Denisenko spotted that the new asteroid was actually Rosetta – thus bringing an end to the panic.

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As Rosetta subsequently sped through space towards its target, it passed the asteroid 21 Lutetia and took the opportunity to take photographs and register various scientific measurements. After that, in the summer of 2011, it was time for the craft to go into hibernation – a necessary power-saving measure.

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The shutdown meant that the probe – now almost half a billion miles from the Sun – was powered solely by its solar panels. And as the majority of systems, including communications, were turned off, there was consequently a lengthy period when mission control had no contact with Rosetta. Understandably, this made the moment when these elements were due to be switched back on a tense one for the ESA scientists and engineers.

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Yes, after some 31 months, the time came to awaken Rosetta from her slumber, with the big day arriving on January 20, 2014. And nerves at mission control weren’t exactly calmed by the fact that the expected first communication from the craft was 18 minutes late. Then, to jubilation among the ESA staff, Rosetta ultimately revived and, in time, sent a transmission.

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Now that Rosetta was back online, all of its systems needed to be checked as it sped towards its rendezvous with 67P. Mission control also put the probe through a series of maneuvers using the ship’s thrusters. These were executed so that Rosetta was in exactly the right position as it approached the comet.

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Now, Rosetta was able to get a much better look at 67P. But what the cameras ultimately captured turned out to be a major surprise for the scientists back in Germany. You see, they’d expected that the comet would most likely be potato-shaped; as it happens, though, 67P appeared nothing like an everyday vegetable.

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Instead, what the astonished experts saw in the images Rosetta was sending back was a rock with two distinct lumps that were joined by a neck-like structure. For all the world, it looked like a child’s bathtime rubber duck. And “rubber duck” quickly became the accepted – although hardly scientific – description of the comet’s shape.

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Amusing though it may have been, the rubber duck shape wasn’t good news for the mission. That irregular profile meant it would be more difficult to calculate the weak but important gravitational force exerted by the three-mile-long comet. And as it happens, determining this information was crucial to the final part of Rosetta’s mission.

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Specifically, once Rosetta was in the optimum position, the Philae lander would be launched. That way, Philae could actually touch down on 67P, take samples and analyze them on the spot. So, knowing how the comet’s gravity would influence the trajectory of the lander was exceptionally important.

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Then, on August 6, 2014, Rosetta reached its destination. The probe was only around 60 miles from the comet, and mission control began to perform a series of complicated maneuvers to edge the craft even closer. The engineers also took the opportunity to analyze the comet’s complex gravitational pull in detail.

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Cautiously, the scientists propelled Rosetta nearer to 67P until, on September 10, the spacecraft was less than 30 miles from the comet. At this point, Rosetta was actually within 67P’s gravitational field, although the gap between comet and craft was subsequently narrowed to just over five miles.

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Then, finally, it was time to launch Philae towards the comet’s surface. On November 12, 2014, the lander was released from Rosetta and, around seven hours later, eventually touched the surface of 67P. But the operation didn’t quite turn out as hoped. You see, Philae was equipped with harpoons that were designed to fire and anchor the lander to the comet. These vital pieces of equipment malfunctioned, however, leaving Philae to actually rebound off 67P twice.

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Nevertheless, Philae’s instrumentation was triggered, and so it began to take readings that were of considerable scientific value. Then another mishap occurred when Philae fell back towards the surface of 67P. In particular, the device became stuck in a shaded spot where its solar panels couldn’t operate, and this meant signals from the lander mostly stopped after just a couple of days.

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This turn of events was a major disappointment, of course, as it had been hoped that the lander would continue to transmit data from 67P’s surface for much longer. Even so, the Rosetta mission managed to make not only several important scientific findings, but also some space travel breakthroughs. It marked the very first time that a probe had landed on a comet, after all.

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And Philae operated for long enough to detect chemicals on the comet, including hydrogen sulfide, hydrogen cyanide and ammonia – a sour-smelling mixture, for sure. In addition, Rosetta’s instruments detected some organic compounds suspended in a mist around 67P, with this lending credence to the idea that life on Earth might have been seeded by comets.

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So, despite the mishap with Philae’s landing, the mission was very far from a failure. In 2016 Professor Mark McCaughrean, the ESA’s senior science advisor, told BBC Radio 4, “It’s giving us a real insight into the building blocks of the solar system and the material which could have formed life on Earth – not life itself, but the raw building blocks. But more importantly for me, it’s engaged the public in a way [that] is just unparalleled for a robotics space mission.”

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As for Rosetta? Well, the ESA scientists decided to land the probe on the comet, too. This controlled descent came on September 30, 2016, and took more than half a day. And while Rosetta headed for the comet, the OSIRIS camera continued to take and transmit images, with the last captured at a height of just 80 feet above 67P’s surface.

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At least, everyone thought that shot was the last image from Rosetta. But, as it happens, it wasn’t. Towards the end of Rosetta’s last transmission of data back to Earth, there had been a disruption in the flow. Then, after technicians later discovered some pieces of data on the mission server, they recognized that this was partial information from a photograph.

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Using these fragments and some specialized software, the scientists were then able to construct one more image. And, rather incredibly, it appeared that this shot had been taken from just 60 feet above 67P – making it the most close-up view of a comet ever seen to date.

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Indeed, there’s no overestimating the incredible achievements of Rosetta’s 12-year mission. And the ESA’s spacecraft operations manager, Andrea Accomazzo, summed these up in an interview with the The Guardian. “Rosetta has been comparable to the Moon landing,” she said. “It’s that order of magnitude. As a child, I could only have dreamt [of] something like this. It’s interesting to see how many emotions landing on a comet still trigger in very many people.”

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So, Rosetta’s findings suggest that comets may have played a big part in helping create life on Earth. But what about Mars? Well, for decades now, scientists and amateur space enthusiasts alike have hoped to discover proof of beings on other planets. And if one man is to be believed, NASA may already have collected the evidence – all the way back in the ’70s.

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More than four decades ago, two U.S. space probes landed on the surface of Mars. Equipped with a series of experiments, the craft then began searching for evidence of life on the Red Planet. And according to scientist Gilbert Levin, they found what they were looking for, too. So, why hasn’t NASA been shouting from the rooftops about this monumental discovery?

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Ever since the first investigations of Mars in the 17th century, people have been preoccupied with one question: could there be life on this distant planet? Even today, finding proof that we’re not alone in the universe remains the holy grail of countless researchers who spend their days looking to the stars. And from the 1960s, NASA has been leading the race to answer this conundrum once and for all.

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To that end, in 1993 NASA launched the Mars Exploration Program – an endeavor with four distinct goals. Along with determining whether life has ever existed on the Red Planet, the project seeks to study both the geological make-up and meteorological conditions of this far-off piece of the universe. In addition, NASA aims to lay the groundwork for human visitors to Mars.

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And over the years, NASA has made many attempts to gather data about Mars, which is located 140 million miles from Earth. The first successful mission was launched back in 1964, when Mariner 4 rocketed into space from Cape Canaveral in Florida. Then, the following year, the probe undertook a fly-by of the planet – a pioneering feat in itself.

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That was far from the only breakthrough made, either. As the probe passed close to Mars, it managed to capture images of the terrain below – the first-ever close-up glimpse of a planet from deep space. But then, later that year, communications stopped, only resuming briefly in 1967.

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Today, Mariner 4 has been abandoned, a wreck of a spacecraft floating uselessly somewhere around the sun. Over the years, though, other NASA missions have taken up the mantle. In 1969, for example, both Mariner 6 and Mariner 7 traveled to Mars, sending vital information back to Earth during their respective journeys.

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Apparently, these later probes were tasked with laying the groundwork for future research – including the hunt for life on the Red Planet. But while neither Mariner 6 nor Mariner 7 spotted any actual Martians, it wouldn’t be long before a NASA mission uncovered something intriguing.

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Still, the space agency saw some failure in the interim. Setting off from Cape Canaveral in May 1971, Mariner 8 was intended to be the first probe to go into orbit around Mars. Yet unfortunately there was an equipment failure during the launch, and this led the craft to crash down into the Atlantic Ocean.

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Undeterred, NASA launched Mariner 9 just weeks later, beating the Soviet Union in the race to send a probe into Martian orbit. And for almost a year, the craft circled the Red Planet, ultimately transmitting more than 7,000 images back to researchers on Earth.

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Mariner 9 proved an invaluable source of data, too. In total, it photographed 85 percent of Mars’ surface, revealing in detail a complex terrain of canyons and craters. But for those hoping for signs of life in the vicinity, there was sadly very little to go on.

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Meanwhile, another ambitious NASA project was coming to the end of its run. Back in the 1960s, it seems, some had believed that man would land on Mars as early as the 1980s. And as a precursor to these hypothetical missions, the agency therefore initiated the Voyager Mars Program in 1966.

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Originally, the Voyager Mars Program intended to send a series of probes into outer space in the mid-’70s. But this endeavor was ultimately called off in 1971 – the same year in which Mariner 9 reached Martian orbit. According to experts, the design of the proposed Voyager Mars spacecraft was flawed, and so such a rocket may have proved both costly and dangerous to launch.

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Yet despite this cancellation, NASA’s big plans for Mars did not fade away. And, eventually, the Voyager Mars Program evolved into the Viking Program. This time, the objectives of the mission were threefold: to capture detailed images of the planet, to study its composition and to uncover whether life existed there.

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In fact, the Viking Program would go on to develop the very first landers designed to search for biosignatures – indicators of past or present life – on Mars. So, on August 20, 1975, Viking 1 left Cape Canaveral, arriving at the Red Planet close to a year later. Viking 2, on the other hand, departed Earth on September 9, 1975, and found Mars a month after its partner probe in 1976.

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Both Viking 1 and Viking 2 consisted of two parts. One of these, the orbiter, was designed to detach above the Martian atmosphere and take snapshots of the planet below. The lander, by contrast, would continue on and finally come to rest on the alien terrain.

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And for just over four weeks, Viking 1 orbited around Mars, scanning for a suitable landing site. Then, to the delight of those at NASA, the units successfully detached, with each embarking on its unique mission. Altogether, the program cost somewhere in the region of $1 billion – or around $5 billion today.

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So, what exactly did NASA get for its money? Well, amazingly, the Viking Program delivered results that would inform the study of Mars for decades to come. While the landers of both Viking 1 and Viking 2 busied themselves on the surface below, the orbiters gathered a steady stream of information about the Red Planet. And with that data, researchers were able to develop a startling theory.

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By this point, NASA knew that the surface of the planet was littered with the remnants of extinct volcanoes. Incredibly, though, the images captured by the two orbiters revealed something new: evidence that water may have once existed. For example, the probes detected geological aspects on Mars that could have been created as the result of flowing liquid.

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The two Viking orbiters also detected signs that there was still water on the planet – albeit deep underground. And even though this data has been questioned over the years, it has never been disproved. Understandably, then, some researchers have jumped on the possible presence of water as proof that Mars could once have supported life.

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As the Viking orbiters delivered these revelations back to Earth, however, the two landers were busy conducting experiments on the surface. Deployed to different locations on Mars, they were tasked to search the planet for evidence of life, among other things. And what they found continues to cause controversy to this day.

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After their respective arrivals on Mars, each of the landers carried out a series of identical procedures designed to collect soil samples from the surface. Near the equator of the planet, Viking 1 utilized its robotic arm to place specimens within a special container; in the northern hemisphere, Viking 2 completed the exact same process.

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Together, the NASA team back on Earth hoped that these samples would ultimately provide more information about the biology of Mars – determining, perhaps, how likely it was to support life. And while the majority of the materials were later found to contain no evidence of any thriving organisms, there were also some surprising results.

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In one experiment, a device known as a gas chromatograph mass spectrometer identified the chemicals present in Martian soil. Ultimately, this test concluded that the samples showed little sign of organic life. There was also a gas exchange study, which looked at the vapors released by the specimens in a laboratory setting.

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In the so-called pyrolytic release experiment, meanwhile, the samples were subjected to conditions designed to mimic those on Mars. Apparently, researchers theorized that any microorganisms present would convert the carbon in the atmosphere into biomass, which could then be detected. But, yet again, this process also failed to turn up anything notable.

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Unlike the other tests, though, the labeled release experiment yielded results that made scientists think twice about life on Mars. In fact, after just one month on the Red Planet, Viking 1 had apparently delivered data that suggested something truly exciting.

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The labeled release experiment was a relatively simple affair. Essentially, it took a sample of Martian soil and doused it in a special mixture of nutrients. Then, if any microorganisms were present in the specimen, they would begin to metabolize the solution – a process that could be monitored and tracked.

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Crucially, both the pyrolytic release and labeled release experiments incorporated control tests that would allow researchers to check the results. If either of these experiments returned a positive response, the same soil would then be subjected to a secondary procedure. And by heating the sample, researchers would thus be able to determine whether or not the reaction had been by chemical or biological means.

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Even before Viking 1 had landed on Mars, researchers had conducted a number of trial runs of the labeled release experiment. Crucially, not a single one had returned a false result. And when the lander relayed the first set of data to Earth on July 30, 1976, staff at NASA were in for a shock.

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Amazingly, the results of the first labeled release experiment suggested that there were indeed living microbes present on Mars. Not only that, but this conclusion was also supported by the control test – apparently confirming that the activity was biological rather than chemical. The stunning finding didn’t appear to be a one-off, either.

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Over the course of the program, both Viking 1 and Viking 2 continued to conduct labeled release experiments on Mars, with NASA ultimately receiving four indications of the presence of microbes in Martian soil. Apparently, the data resembled that collected from samples here on planet Earth.

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But if this was the case, you may ask, why wasn’t more of a fanfare made of this remarkable discovery? Well, unfortunately, the results did not appear to bear up to scrutiny. And when another Viking experiment, a molecule analysis, failed to turn up any corroborating evidence, NASA reached a rather disappointing conclusion.

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Ultimately, the agency’s researchers concluded, the positive results generated by the labeled release experiment were not proof of microbial activity on Mars. Instead, they represented something in the Martian soil that was merely echoing the appearance of life. Yet not everyone agreed with this conclusion. And in 1997 two of the scientists involved in the study explained their own views on the matter.

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In the book Mars: The Living Planet, engineer Dr. Gilbert Levin and co-experimenter Patricia Ann Straat – along with academic Barry DiGregorio – discussed the labeled release procedures. And according to Levin, the tests really had indicated the presence of microbial life on Mars. That’s an opinion he still holds to this day, in fact.

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For many years, Levin remained in the minority, with his conclusions questioned by most of his fellow scientists. But the engineer received vindication of a sort in April 2012, when the results of a new analysis were released. Over at the University of Southern California, ex-NASA project director Joseph Miller had decided to take another look at the labeled release experiment.

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Together with Giorgio Bianciardi from the University of Siena in Italy, Miller ran the Viking Program’s data through a different test. This time, the process involved a method known as cluster analysis, which divided the biological and non-biological indicators. And the scientists consequently reached a fascinating conclusion: Levin may have been right after all.

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“We just plugged all the [Viking experimental and control] data in and said, ‘Let the cluster analysis sort it out,’” Miller told National Geographic in 2012. “What happened was [that] we found two clusters. One cluster constituted the two active experiments on Viking, [while] the other cluster was the five control experiments.”

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This wasn’t all. During the study, the researchers also compared the data collected by the Viking Program with various samples – both biological and non-biological – from Earth. And according to Miller, the results spoke for themselves. “It turned out that all the biological experiments from Earth sorted with the active experiments from Viking, and all the non-biological data series sorted with the control experiments,” he explained. “It was an extremely clear-cut phenomenon.”

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Elsewhere, the specialists found evidence to suggest that a circadian rhythm – an internal day clock found in all organisms – could be detected in the Viking Program’s samples. However, Miller has since expressed his disappointment in NASA for failing to take the necessary measures to investigate this further. And in a 2019 article for Scientific American, Levin also puzzled over the agency’s apparent loss of interest in the search for extraterrestrial life.

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According to Levin, NASA has never sent any life-detection equipment back to Mars to check up on the Viking program’s original results. Even so, that hasn’t stopped more astonishing finds from emerging over the years. When the Curiosity rover landed in 2012, for example, it found reason to suggest that the Martian environment may once have provided suitable conditions for life to thrive.

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Methane has also been detected in the atmosphere of Mars, further hinting at the presence of biological organisms there. But at present, NASA only has one future mission planned to the Red Planet to collect Martian soil. If alien life is ever discovered, then, it may be down to the work of private companies such as Elon Musk’s SpaceX.

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