In 2012, NASA’s Curiosity rover landed in the Gale Crater on Mars and began exploring for clues about the planet’s past and subsequent evolution. Since 2014, it has been investigating Mount Sharp (aka. Aeolis Mons) – the central peak within Mars’ Gale Crater – in the hopes of learning more about Mars’ warm, watery past (and maybe find signs of past life!)
On February 15th of this year (Sol 2320), Curiosity gave mission controllers a bit of a scare when it suffered a technical glitch and automatically entered safe mode. Luckily, as of Thursday, Feb. 28th, Curiosity’s science team reported that after getting the rover back online and running a series of checks, the rover is in good shape and ready to resume normal science operations.
Some very clever people have figured out how to use MSL Curiosity’s navigation sensors to measure the gravity of a Martian mountain. What they’ve found contradicts previous thinking about Aeolis Mons, aka Mt. Sharp. Aeolis Mons is a mountain in the center of Gale Crater, Curiosity’s landing site in 2012.
Gale Crater is a huge impact crater that’s 154 km (96 mi) in diameter and about 3.5 billion years old. In the center is Aeolis Mons, a mountain about 5.5 km (18,000 ft) high. Over an approximately 2 billion year period, sediments were deposited either by water, wind, or both, creating the mountain. Subsequent erosion reduced the mountain to its current form.
Now a new paper published in Science, based on gravity measurements from Curiosity, shows that Aeolis Mons’ bedrock layers are not as dense as once thought.
In the course of exploring Mars, the many landers, rovers and orbiters that have been sent there have captured some truly stunning images of the landscape. Between Spirit, Opportunity,Curiosity, the Mars Reconnaissance Orbiter (MRO) and others, we have treated to some high-definition images over the years of sandy dunes, craters and mountains – many of which call to mind places here on Earth.
However, if one were to describe the region where NASA’s Interior Exploration using Seismic Investigations, Geodesy and Heat Transport (InSight) lander will be landing (on Nov. 26th, 2018), the word “plain” would probably come to mind (and it would be appropriate). This region is known as Elysium Planitia, and it is where InSight will spend the next few years studying Mars’ interior structure and tectonic activity for the sake of learning more about its history.
The possibility that life could exist on Mars has captured the imagination of researchers, scientists and writers for over a century. Ever since Giovanni Schiaparelli (and later, Percival Lowell) spotted what they believed were “Martian Canals” in the 19th century, humans have dreamed of one day sending emissaries to the Red Planet in the hopes of finding a civilization and meeting the native Martians.
While the Mariner and Viking programs of the 1960s and 70s shattered the notion of a Martian civilization, multiple lines of evidence have since emerged that indicate how life could have once existed on Mars. Thanks to a new study, which indicates that Mars may have enough oxygen gas locked away beneath its surface to support aerobic organisms, the theory that life could still exist there has been given another boost.
Ever since it landed on the Red Planet in 2012, the Curiosity rover has showed no signs of slowing down! For the past six years, it has ventured across the Gale Crater, scaled Mount Sharp, and taken numerous drill samples. And in the process, it has found evidence that liquid water (and possibly even life) once existed on the Martian surface.
It has also taken many breathtaking pictures that have catalogued its progress. Last month (on Aug. 9th), the rover took another 360-degree panoramic photo of its location. In addition to showing how the skies were still darkened by the fading dust storm and the rover’s dust-covered body, the picture also captured and the site where the latest drill sample was obtained.
Martian dust storms, which occur during the summer season in the planet’s southern hemisphere, can get pretty intense. Over the course of the past few weeks, a global dust storm has engulfed Mars and forced the Opportunity rover to suspend operations. Given that this storm is much like the one that took place back in 2007, which also raged for weeks, there have been concerns over how this development could affect rover operations.
Meanwhile the Curiosity rover managed to snap pictures of the thickening haze caused by the storm. Though Curiosity is on the other side of the planet from where Opportunity is currently located, atmospheric dust has been gradually increasing over it. But unlike Opportunity, which runs on solar power, Curiosity will remain unaffected by the global storm thanks to its nuclear-powered battery, and is therefore in a good position to study it.
As already noted, Martian storms occur during summer in the southern hemisphere, when sunlight warms dust particles and lifts them higher into the atmosphere, creating more wind. The resulting wind kicks up yet more dust, creating a feedback loop that NASA scientists are still trying to understand. Since the southern polar region is pointed towards the Sun in the summer, carbon dioxide frozen in the polar cap evaporates.
This has the effect of thickening the atmosphere and increasing the surface pressure, which enhances the process by helping suspend dust particles in the air. In some cases, the dust clouds can reach up to 60 km (40 mi) or more in elevation. Though they are common and can begin suddenly, Martian dust storms typically stay contained to a local area and last only about a weeks.
By contrast, the current storm has lasted for several weeks and is currently covering an area that would span North America and Russia combined. While smaller than the storm that took place back in 2007, this storm has intensified to the point where it created a perpetual state of night over the rover’s location in Perseverance Valley and led to a level of atmospheric opacity that is much worse than the 2007 storm.
When dust storms occur, scientists measure them based on their opacity level (tau) to determine how much sunlight they will prevent from reaching the surface. Whereas the 2007 storm had a tau level of about 5.5, this most recent storm reached an estimated tau of 10.8 earlier this month over the Perseverance Valley – where Opportunity is located.
The intensity of the storm also led Bruce Canton, deputy principal investigator of the Mars Color Imager (MARCI) camera onboard NASA’s Mars Reconnaissance Orbiter (MRO), to declare that the storm has officially become a “planet-encircling” (or “global”) dust event. Above the Gale Crater, where Curiosity is located, the tau reading is now above 8.0 – the highest ever recorded by the mission.
While the storm has some worried about the fate of Opportunity, which is Mars’ oldest active rover (having remained in operation for over 14 years), it is also an chance to address one of the greatest questions scientists have about Mars. For example, why do some storms span the entire planet and last for months while others are confined to small areas and and last only a week?
The animation (shown above) consists of a series of daily photos captures by Curiosity’s Mast Camera (Mastcam), which show the sky getting hazier over time. While taking these pictures, Curiosity was facing the crater rim, about 30 km (18.6) away from where it stands inside the crater. This sun-obstructing wall of haze is about six to eight times thicker than normal for this time of season.
Nevertheless, Curiosity’s engineers – which are based at NASA’s Jet Propulsion Laboratory in Pasadena, California – have studied how the growing dust storm could affect the rover’s instruments and concluded that it poses little risk. Ironically enough, the largest impact will be on the rover’s cameras, which require extra exposure time due to the low lighting conditions.
As Jim Watzin, the director of NASA’s Mars Exploration Program at the agency’s headquarters in Washington, explained in a NASA press release earlier this month:
“This is the ideal storm for Mars science. We have a historic number of spacecraft operating at the Red Planet. Each offers a unique look at how dust storms form and behave – knowledge that will be essential for future robotic and human missions.”
However, all dust events, regardless of size, help to shape the Martian surface. As such, studying their physics is critical to understanding the Martian climate, both past and present. As Rich Zurek, the chief scientist for the Mars Program Office at NASA’s Jet Propulsion Laboratory, indicated:
“Each observation of these large storms brings us closer to being able to model these events – and maybe, someday, being able to forecast them. That would be like forecasting El Niño events on Earth, or the severity of upcoming hurricane seasons.”
The ability to understand the causes and dynamics of Martian dust storms would not only lead to a better understand of how weather works on other planets, it would also be of immense importance if and and when humans begin traveling to the Red Planet on a regular basis. For instance, if SpaceX really does intend to bring tourists to Mars in the future, said tourists will want to avoid booking during “storm season”.
And if humans should choose to someday make Mars their home, they will need to know when planet-spanning dust storms are coming, especially since their habitats will likely be relying on wind and solar power. In the meantime, NASA and other space agencies will continue to monitor this storm and the Opportunity rover is expected to come through (fingers crossed!) unscathed!
The latest discovery came on Thursday, May 7th, when NASA announced that the Curiosity rover had once again discovered organic molecules. This time, however, the molecules were found in three-billion-year-old sedimentary rocks located near the surface of lower Mount Sharp. This evidence, along with new atmospheric evidence, are another indication that ancient life may have once existed on the Red Planet.
As Thomas Zurbuchen, the associate administrator for the Science Mission Directorate at NASA Headquarters, explained in a recent NASA press release:
“With these new findings, Mars is telling us to stay the course and keep searching for evidence of life. I’m confident that our ongoing and planned missions will unlock even more breathtaking discoveries on the Red Planet.”
In the first paper, the authors indicate how Curiosity’sSample Analysis at Mars (SAM) suite detected traces of methane in drill samples it took from Martian rocks. Once these rocks were heated, they released an array of organics and volatiles similar to how organic-rich sedimentary rocks do on Earth. On Earth, such deposits are indications of fossilized organic life, which may or may not be the case with the samples examined by Curiosity.
However, this evidence is bolstered by the fact that Curiosity has also found evidence that the Gale Crater was once an ancient lakebed. In addition to water, this lakebed contained all the chemical building blocks and energy sources that are necessary for life. As Jen Eigenbrode of NASA’s Goddard Space Flight Center, and the lead author of the first study, explained:
“Curiosity has not determined the source of the organic molecules. Whether it holds a record of ancient life, was food for life, or has existed in the absence of life, organic matter in materials holds chemical clues to planetary conditions and processes… The Martian surface is exposed to radiation from space. Both radiation and harsh chemicals break down organic matter. Finding ancient organic molecules in the top five centimeters of rock that was deposited when Mars may have been habitable, bodes well for us to learn the story of organic molecules on Mars with future missions that will drill deeper.”
In the second paper, the team described how Curiosity’s SAM suite also detected seasonal variations in methane in the Martian atmosphere. These results were obtained over the course of nearly three years on Mars, which works out to almost six Earth years. While the team admits that water-rock chemistry could have generated the methane, they cannot rule out the possibility that it was biological in origin.
In the past, methane and organic molecules have been detected in Mars’ atmosphere and in drill samples, the former of which appeared to spike unpredictably. However, these new results indicate that within the Gale Crater, low levels of methane peak during the warm summer months and drop in the winter months every year. As Chris Webster, a researcher from NASA’s Jet Propulsion Laboratory (JPL) and the lead author of the second paper, explained:
“This is the first time we’ve seen something repeatable in the methane story, so it offers us a handle in understanding it. This is all possible because of Curiosity’s longevity. The long duration has allowed us to see the patterns in this seasonal ‘breathing.'”
To find this organic material, Curiosity drilled into sedimentary rocks (known as mudstone) in four areas in the Gale Crater. These rocks formed over the course of billions of years as sediments were deposited at the bottom of the ancient lake by flowing water. The drill samples were then analyzed by SAM, which used its oven to heat the samples to over 500 °C (900 °F) to release organic molecules from the powdered rock.
These results indicate that some of the drill samples contained sulfur (which could have preserved the organic molecules) as well as thiophenes, benzene, toluene, and small carbon chains – such as propane or butene. They also indicated organic carbon concentrations of about 10 parts per million or more, which is consistent with carbon concentrations observed in Martian meteorites and about 100 times what has been previously detected on Mars’ surface.
While this does not constitute evidence of past life on Mars, these latest findings have increased confidence that future missions will find more organics, both on the surface and slightly beneath the surface. But above all, they have bolstered confidence that Mars may have once had life of its own. As Michael Meyer, the lead scientist for NASA’s Mars Exploration Program, summarized:
“Are there signs of life on Mars? We don’t know, but these results tell us we are on the right track.”
In the coming years, additional missions will also be searching for signs of past life, including NASA’s Mars 2020 rover and the European Space Agency’s ExoMars rover.The Mars 2020 rover will also leave samples behind in a cache that could be retrieved by a future crewed mission for sample-return analysis. So if there was life on Mars (or, fingers crossed, still is) we are sure to find it soon enough!
And be sure to check out this video of this latest discovery by Curiosity, courtesy of NASA’s Jet Propulsion Laboratory:
In fact, back in January of 2018, the rover had spent a total of 2,000 Earth days on Mars. And as of March 22nd, 2018, NASA’s Mars Curiosity rover had reached its two-thousandth Martian day (Sol) on the Red Planet! To mark the occasion, NASA released a mosaic photo that previews what the rover will be investigating next (hint: it could shed further light on whether or not Mars was habitable in the past).
The image (shown at top and below) was assembled from dozens of images taken by Curiosity‘s Mast Camera (Mastcam) on Sol 1931 (back in January). To the right, looming in the background, is Mount Sharp, the central peak in the Gale Crater (where Curiosity landed back in 2012). Since September of 2014, the rover has been climbing this feature and collecting drill samples to get a better understanding of Mars’ geological history.
In the center of the image is the rover’s next destination and scientific target. This area, which scientists have been studying from orbit, is rich in clay minerals, which indicates that water once existed there. In the past, the Curiosity rover found evidence of clay minerals on the floor of the Gale Crater. This confirmed that the crater was a lake bed between 3.3 and 3.8 billion years ago.
Mount Sharp, meanwhile, is believed to have formed from sedimentary material that was deposited over a period of about 2 billion years. By examining patches of clay minerals that extend up the mountain’s side, scientists hope to gain insight into the history of Mars since then. These include how long water may have persisted on its surface and how the planet made the transition to the cold and desiccated place it is today.
The Curiosity science team is eager to analyze rock samples pulled from the clay-bearing rocks seen in the center of the image, and not just because of the results they could provide. Recently, the science team developed a new drilling technique to compensate for the failure of a faulty motor (which allows the drill to extend and retract). When the rover begins to drill again, it will be the first time since December 2016.
All told, the rover has spent a total of about 2055 Earth days (5 years and 230 days), which means Curiosity now ranks third behind the Opportunity (5170 days; 5031 sols) and the Spirit rovers (2269 days; 2208 sols) in terms of total time spent on Mars. Since it arrived on Mars in 2012, Curiosity has also traveled a total distance of 18.7 km (11.6 mi) and studied more than 180 meters (600 feet) vertical feet of rock.
But above all, Curiosity‘s greatest achievement has been the discovery that Mars once had all the necessary conditions and chemical ingredients to support microbial life. Based on their findings, Curiosity‘s international science team has concluded that habitable conditions must have lasted for at least millions of years before Mars’ atmosphere was stripped away.
Finding the evidence of this, and how the transition occurred, will not only advance our understanding of the history of Mars, but of the Solar System itself. It also might provide clues as to how Mars could be made into a warmer, wetter environment again someday!
Since it landed on Mars in 2012, the Curiosity rover has used its drill to gather samples from a total of 15 sites. These samples are then deposited into two of Curiosity’s laboratory instruments – the Sample Analysis at Mars (SAM) or the Chemistry and Mineralogy X-ray Diffraction (CheMin) instrument – where they are examined to tell us more about the Red Planet’s history and evolution.
Unfortunately, in December of 2016, a key part of the drill stopped working when a faulty motor prevented the bit from extending and retracting between its two stabilizers. After managing to get the bit to extend after months of work, the Curiosity team has developed a new method for drilling that does not require stabilizers. The new method was recently tested and has been proven to be effective.
The new method involves freehand drilling, where the drill bit remains extended and the entire arm is used to push the drill forward. While this is happening, the rover’s force sensor – which was originally included to stop the rover’s arm if it received a high-force jolt – is used to takes measurements. This prevents the drill bit from drifting sideways and getting stuck in rock, as well as providing the rover with a sense of touch.
The test drill took place at a site called Lake Orcadie, which is located in the upper Vera Rubin Ridge – where Curiosity is currently located. The resulting hole, which was about 1 cm (half an inch) deep was not enough to produce a scientific sample, but indicated that the new method worked. Compared to the previous method, which was like a drill press, the new method is far more freehand.
“We’re now drilling on Mars more like the way you do at home. Humans are pretty good at re-centering the drill, almost without thinking about it. Programming Curiosity to do this by itself was challenging — especially when it wasn’t designed to do that.”
This new method was the result of months of hard work by JPL engineers, who practiced the technique using their testbed – a near-exact replica of Curiosity. But as Doug Klein of JPL, one of Curiosity’s sampling engineers, indicated, “This is a really good sign for the new drilling method. Next, we have to drill a full-depth hole and demonstrate our new techniques for delivering the sample to Curiosity’s two onboard labs.”
Of course, there are some drawbacks to this new method. For one, leaving the drill in its extended position means that it no longer has access to the device that sieves and portions rock powder before delivering it to the rover’s Collection and Handling for In-Situ Martian Rock Analysis (CHIMRA) instrumet. To address this, the engineers at JPL had to invent a new way to deposit the powder without this device.
Here too, the engineers at JPL tested the method here on Earth. It consists of the drill shaking out the grains from its bit in order to deposit the sand directly in the CHIMRA instrument. While the tests have been successful here on Earth, it remains to be seen if this will work on Mars. Given that both atmospheric conditions and gravity are very different on the Red Planet, it remains to be seen if this will work there.
This drill test was the first of many that are planned. And while this first test didn’t produce a full sample, Curiosity’s science team is confident that this is a positive step towards the resumption of regular drilling. If the method proves effective, the team hopes to collect multiple samples from Vera Rubin Ridge, especially from the upper side. This area contains both gray and red rocks, the latter of which are rich in minerals that form in the presence of water.
Samples drilled from these rocks are expected to shed light on the origin of the ridge and its interaction with water. In the days ahead, Curiosity’s engineers will evaluate the results and likely attempt another drill test nearby. If enough sample is collected, they will use the rover’s Mastcam to attempt to portion the sample out and determine how much powder can be shaken from the drill bit.
On August 5th, 2012, after spending over 8 months in space, NASA’s Curiosity rover landed on Mars. As part of the NASA Mars Science Laboratory (MSL) mission, and the latest in a series of rovers deployed to the Martian surface, Curiosity had some rather ambitious research goals. In addition to investigating Mars’ climate and geology, the rover was also tasked with revealing more about Mars’ past and determining if it ever supported microbial life.
And recently, the Curiosity rover hit another major milestone in its exploration of the Red Planet. As of January 26th, 2018 the rover has spent a total of 2,000 days on Mars, which works out to 5 years, 5 months and 21 days – or 1947 Martian days (sols). That’s especially impressive when you consider that the mission was only meant to last 687 days (668 sols), or just little under 2 years.
In all that time, the Curiosity rover has accomplished some major feats and has the scars to prove it! Some of it’s wheels have become teared, holed and cracked and its drill has been pushed almost to the point of breaking. And yet, Curiosity is still hard at work pushing itself up a mountain – both literally and figuratively! The rover has also managed to exceed everyone’s expectations.
As Ashwin Vasavada, the MSL Project Scientist, told Universe Today via email:
“In terms of challenges, the first 2000 days of Curiosity’s mission went better than I could have hoped. For much of the time, the rover remained as capable as the day it landed. We had a scare in the first year when a memory fault triggered additional problems and nearly resulted in the loss of the mission. We famously wore down our wheels pretty early, as well, but since then we’ve kept that under control. In the last year, we’ve had a major problem with our drill. That’s the only major issue currently, but we believe we’ll be back to drilling in a month or so. If that works out, we’ll amazingly be back to having all systems ready for science!”
As of the penning of this article, the rover is climbing Mount Sharp in order to collect further samples from Mars’ past. Also known as Aeolis Mons, this mountain resides in the center of the Gale Crater where Curiosity landed in 2012 and has been central to Curiosity’s mission. Standing 5,500 meters (18,000 ft) above the valley floor, Mount Sharp is believed to have formed from sediment that was slowly deposited by flowing water over billions of years.
This is all in keeping with current theories about how Mars once had a denser atmosphere and was able to sustain liquid water on its surface. But between 4.2 and 3.7 billion years ago, this atmosphere was slowly stripped away by solar wind, thus turning Mars into the cold and desiccated place that we know today. As a result, the study of Mount Sharp was always expected to reveal a great deal about Mars’ geological evolution.
In it’s first year, Curiosity achieved a major milestone when the rover obtained drill samples from low-lying areas that indicated that lakes and streams existed in the Gale Crater between 3.3 to 3.8 billion years ago. In addition, the rover has also obtained ample evidence that the crater once had all the chemical elements and even a chemical source of energy needed for microbial life to exist.
“NASA’s charge to our mission was to determine whether Mars ever had conditions suitable for life,” said Vasavada. “Success was not a foregone conclusion. Would we arrive safely? Would the scientific instruments work? Would the area we chose for the landing site hold the clues we were looking for? For me, meeting each of these objectives are the highlights of the mission. I’ll never forget witnessing the launch, or nervously waiting for a safe touchdown. Discovering an ancient, freshwater lake environment at Gale crater was profound scientifically, but also was the moment that I knew that our team had delivered what we promised to NASA.”
Basically, by scaling Mount Sharp and examining the layers that were deposited over the course of billions of years, Curiosity is able to examine a living geological record of how the planet has evolved since then. Essentially, the lower layers of the mountain are believed to have been deposited 3.5 billion years ago when the Gale Crater was still a lakebed, as evidenced by the fact that they are rich in clay minerals.
The upper layers, meanwhile, are believed to have been deposited over the ensuing millions of years, during which time the lake in the Gale Crater appears to have grown, shrunk, disappeared and then reappeared. Basically, by scaling the mountain and obtaining samples, Curiosity will be able to illustrate how Mars underwent the transition from being a warmer, wetter place to a frozen and dry one.
As Vasavada explained, this exploration is also key to answering a number of foundational questions about the search for life beyond Earth:
“Curiosity established that Mars was once a suitable home for life; it had liquid water, key chemical building blocks, and energy sources required by life in the lake and groundwater environment within Gale crater. Curiosity also has detected organic molecules in ancient rocks, in spite of all the degradation that could have occurred in three billion years. While Curiosity cannot detect life itself, knowing that Mars can preserve organic molecules bodes well for missions that will explore ancient rocks, looking for signs of past life.”
At this juncture, its not clear how much longer Curiosity will last. Considering that it has already lasted over twice as long as originally intended, it is possible the rover will remain in operation for years to come. However, unlike the Opportunity rover – who’s mission was intended to last for 90 days, but has remained in operation for 5121 days (4984 sols) – Curiosity has a shelf life.
Whereas Opportunity is powered by solar cells, Curiosity is dependent on its Multi-Mission Radioisotope Thermoelectric Generator (MMRTG). Eventually, this slow-fission reactor will exhaust its supply of nuclear fuel and the rover will be forced to come to a halt. And considering how the rover has been put through its paces in the past 5 years, there’s also the chance that it will suffer a mechanical failure.
But in the meantime, there’s plenty of work to be done and lots of opportunities for vital research. As Vasavada put it:
“Curiosity won’t last forever, but in the years we have left, I hope we can complete our traverse through the lowermost strata on Mount Sharp. We’re well over halfway through. There are changes in the composition of the rocks ahead that might tell us how the climate of Mars changed over time, perhaps ending the era of habitability. Every day on Mars still counts, perhaps even more than before. Now every new discovery adds a piece to a puzzle that’s more than halfway done; it reveals more given all the other pieces already around it.”
And be sure to check out this retrospective of the Curiosity rover’s mission, courtesy of NASA: