A view from the "Kimberley" formation on Mars taken by NASA's Curiosity rover. The strata in the foreground dip towards the base of Mount Sharp, indicating flow of water toward a basin that existed before the larger bulk of the mountain formed. This image was taken by the Mast Camera (Mastcam) on Curiosity on Sol 580 of the mission and has been “white balanced” to adjust for the lighting on Mars make the sky appear light blue. Credits: NASA/JPL-Caltech/MSSS
It’s all about the detail.
In a way, Mars looks like a dusty, dead, dry, boring planet. But science says otherwise. Science says that Mars used to be wet and warm, with an atmosphere. And science says that it was wet and warm for billions of years, easily long enough for life to appear and develop.
But we still don’t know for sure if any life did happen there.
Curiosity at Mt. Sharp, Gale Crater, Mars. To the left of the rover are two drill holes into the rocks "Aberlady" and "Kilmarie." Curiosity found high concentrations of clay in both rocks. Image Credit: NASA/JPL-Caltech/MSSS
Clay is a big deal on Mars because it often forms in contact with water. Find clay, and you’ve usually found evidence of water. And the nature, history, and current water budget on Mars are all important to understanding that planet, and if it ever supported life.
Panoramic image of the Curiosity rover, from September 2016. The pale outline of Aeolis Mons can be seen in the distance. Credit: NASA/JPL-Caltech/MSSS
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.
Mosaic image of the Curiosity rover on Mars, which recently turned up more evidence that supports the idea that the planet was once habitability. Credit: NASA/JPL-Caltech/MSSS.
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.
MRO image of Gale Crater illustrating the landing location and trek of the Rover Curiosity. Credits: NASA/JPL, illustration, T.Reyes
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.
Image of Mount Sharp taken by the Curiosity rover on Aug. 23rd, 2012. The layers at the base of Mt. Sharp show the geological history of Mars. Credit: NASA/JPL-Caltech/MSSS.
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.
Image taken of drill sample obtained at the ‘Lubango’ outcrop target on Sol 1320, Apr. 23, 2016. Lubango is located in the Stimson unit on the lower slopes of Mount Sharp inside Gale Crater. Credit: NASA/JPL/MSSS/Ken Kremer/kenkremer.com/Marco Di Lorenzo
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:
NASA’s Curiosity rover raised robotic arm with drill pointed skyward while exploring Vera Rubin Ridge at the base of Mount Sharp inside Gale Crater - backdropped by distant crater rim. This navcam camera mosaic was stitched from raw images taken on Sol 1833, Oct. 2, 2017 and colorized. Credit: NASA/JPL/Ken Kremer/kenkremer.com/Marco Di Lorenzo
NASA’s Curiosity rover raised robotic arm with drill pointed skyward while exploring Vera Rubin Ridge at the base of Mount Sharp inside Gale Crater – backdropped by distant crater rim. This navcam camera mosaic was stitched from raw images taken on Sol 1833, Oct. 2, 2017 and colorized. Credit: NASA/JPL/Ken Kremer/kenkremer.com/Marco Di Lorenzo
5 years after a heart throbbing Martian touchdown, Curiosity is climbing Vera Rubin Ridge in search of “aqueous minerals” and “clays” for clues to possible past life while capturing “truly breathtaking” vistas of humongous Mount Sharp – her primary destination – and the stark eroded rim of the Gale Crater landing zone from ever higher elevations, NASA scientists tell Universe Today in a new mission update.
“Curiosity is doing well, over five years into the mission,” Michael Meyer, NASA Lead Scientist, Mars Exploration Program, NASA Headquarters told Universe Today in an interview.
“A key finding is the discovery of an extended period of habitability on ancient Mars.”
The car-sized rover soft landed on Mars inside Gale Crater on August 6, 2012 using the ingenious and never before tried “sky crane” system.
A rare glimpse of Curiosity’s arm and turret mounted skyward pointing drill is illustrated with our lead mosaic from Sol 1833 of the robot’s life on Mars – showing a panoramic view around the alien terrain from her current location in October 2017 while actively at work analyzing soil samples.
“Your mosaic is absolutely gorgeous!’ Jim Green, NASA Director Planetary Science Division, NASA Headquarters, Washington D.C., told Universe Today
“We are at such a height on Mt Sharp to see the rim of Gale Crater and the top of the mountain. Truly breathtaking.”
The rover has ascended more than 300 meters in elevation over the past 5 years of exploration and discovery from the crater floor to the mountain ridge. She is driving to the top of Vera Rubin Ridge at this moment and always on the lookout for research worthy targets of opportunity.
Additionally, the Sol 1833 Vera Rubin Ridge mosaic, stitched by the imaging team of Ken Kremer and Marco Di Lorenzo, shows portions of the trek ahead to the priceless scientific bounty of aqueous mineral signatures detected by spectrometers years earlier from orbit by NASA’s fleet of Red Planet orbiters.
NASA’s Curiosity rover as seen simultaneously on Mars surface and from orbit on Sol 1717, June 5, 2017. The robot snapped this self portrait mosaic view while approaching Vera Rubin Ridge at the base of Mount Sharp inside Gale Crater – backdropped by distant crater rim. This navcam camera mosaic was stitched from raw images and colorized. Inset shows overhead orbital view of Curiosity (blue feature) amid rocky mountainside terrain taken the same day by NASA’s Mars Reconnaissance Orbiter. Credit: NASA/JPL/Ken Kremer/kenkremer.com/Marco Di Lorenzo
“Curiosity is on Vera Rubin Ridge (aka Hematite Ridge) – it is the first aqueous mineral signature that we have seen from space, a driver for selecting Gale Crater,” NASA HQ Mars Lead Scientist Meyer elaborated.
“And now we have access to it.”
The Sol 1833 photomosaic illustrates Curiosity maneuvering her 7 foot long (2 meter) robotic arm during a period when she was processing and delivering a sample of the “Ogunquit Beach” for drop off to the inlet of the CheMin instrument earlier in October. The “Ogunquit Beach” sample is dune material that was collected at Bagnold Dune II this past spring.
The sample drop is significant because the drill has not been operational for some time.
“Ogunquit Beach” sediment materials were successfully delivered to the CheMin and SAM instruments over the following sols and multiple analyses are in progress.
To date three CheMin integrations of “Ogunquit Beach” have been completed. Each one brings the mineralogy into sharper focus.
Researchers used the Mastcam on NASA’s Curiosity Mars rover to gain this detailed view of layers in “Vera Rubin Ridge” from just below the ridge. The scene combines 70 images taken with the Mastcam’s right-eye, telephoto-lens camera, on Aug. 13, 2017. Credit: NASA/JPL-Caltech/MSSS
What’s the status of the rover health at 5 years, the wheels and the drill?
“All the instruments are doing great and the wheels are holding up,” Meyer explained.
“When 3 grousers break, 60% life has been used – this has not happened yet and they are being periodically monitored. The one exception is the drill feed (see detailed update below).”
NASA’s Curiosity rover explores sand dunes inside Gale Crater with Mount Sharp in view on Mars on Sol 1611, Feb. 16, 2017, in this navcam camera mosaic, stitched from raw images and colorized. Credit: NASA/JPL/Ken Kremer/kenkremer.com/Marco Di Lorenzo
NASA’s 1 ton Curiosity Mars Science Laboratory (MSL) rover is now closer than ever to the mineral signatures that were the key reason why Mount Sharp was chosen as the robots landing site years ago by the scientists leading the unprecedented mission.
Along the way from the ‘Bradbury Landing’ zone to Mount Sharp, six wheeled Curiosity has often been climbing. To date she has gained over 313 meters (1027 feet) in elevation – from minus 4490 meters to minus 4177 meters today, Oct. 19, 2017, said Meyer.
The low point was inside Yellowknife Bay at approx. minus 4521 meters.
VRR alone stands about 20 stories tall and gains Curiosity approx. 65 meters (213 feet) of elevation to the top of the ridge. Overall the VRR traverse is estimated by NASA to take drives totaling more than a third of a mile (570 m).
Curiosity images Vera Rubin Ridge during approach backdropped by Mount Sharp. This navcam camera mosaic was stitched from raw images taken on Sol 1726, June 14, 2017 and colorized. Credit: NASA/JPL/Marco Di Lorenzo/Ken Kremer/kenkremer.com
“Vera Rubin Ridge” or VRR is also called “Hematite Ridge.” It’s a narrow and winding ridge located on the northwestern flank of Mount Sharp. It was informally named earlier this year in honor of pioneering astrophysicist Vera Rubin.
The intrepid robot reached the base of the ridge in early September.
The ridge possesses steep cliffs exposing stratifications of large vertical sedimentary rock layers and fracture filling mineral deposits, including the iron-oxide mineral hematite, with extensive bright veins.
VRR resists erosion better than the less-steep portions of the mountain below and above it, say mission scientists.
Curiosity rover raises robotic arm high while scouting the Bagnold Dune Field and observing dust devils inside Gale Crater on Mars on Sol 1625, Mar. 2, 2017, in this navcam camera mosaic stitched from raw images and colorized. Note: Wheel tracks at right, distant crater rim in background. Credit: NASA/JPL/Ken Kremer/kenkremer.com/Marco Di Lorenzo
What’s ahead for Curiosity in the coming weeks and months exploring VRR before moving onward and upwards to higher elevation?
“Over the next several months, Curiosity will explore Vera Rubin Ridge,” Meyer replied.
“This will be a big opportunity to ground-truth orbital observations. Of interest, so far, the hematite of VRR does not look that different from what we have been seeing all along the Murray formation. So, big question is why?”
“The view from VRR also provides better access to what’s ahead in exploring the next aqueous mineral feature – the clay, or phyllosilicates, which can be indicators of specific environments, putting constraints on variables such as pH and temperature,” Meyer explained.
The clay minerals or phyllosilicates form in more neutral water, and are thus extremely scientifically interesting since pH neutral water is more conducive to the origin and evolution of Martian microbial life forms, if they ever existed.
How far away are the clays ahead and when might Curiosity reach them?
“As the crow flies, the clays are about 0.5 km,” Meyer replied. “However, the actual odometer distance and whether the clays are where we think they are – area vs. a particular location – can add a fair degree of variability.”
The clay rich area is located beyond the ridge.
Over the past few months Curiosity make rapid progress towards the hematite-bearing location of Vera Rubin Ridge after conducting in-depth exploration of the Bagnold Dunes earlier this year.
“Vera Rubin Ridge is a high-standing unit that runs parallel to and along the eastern side of the Bagnold Dunes,” said Mark Salvatore, an MSL Participating Scientist and a faculty member at Northern Arizona University, in a mission update.
“From orbit, Vera Rubin Ridge has been shown to exhibit signatures of hematite, an oxidized iron phase whose presence can help us to better understand the environmental conditions present when this mineral assemblage formed.”
Curiosity is using the science instruments on the mast, deck and robotic arm turret to gather detailed research measurements with the cameras and spectrometers. The pair of miniaturized chemistry lab instruments inside the belly – CheMin and SAM – are used to analyze the chemical and elemental composition of pulverized rock and soil gathered by drilling and scooping selected targets during the traverse.
A key instrument is the drill which has not been operational. I asked Meyer for a drill update.
“The drill feed developed problems retracting (two stabilizer prongs on either side of the drill retract, controlling the rate of drill penetration),” Meyer replied.
“Because the root cause has not been found (think FOD) and the concern about the situation getting worse, the drill feed has been retracted and the engineers are working on drilling without the stabilizing prongs.”
“Note, a consequence is that you can still drill and collect sample but a) there is added concern about getting the drill stuck and b) a new method of delivering sample needs to be developed and tested (the drill feed normally needs to be moved to move the sample into the chimera). One option that looks viable is reversing the drill – it does work and they are working on the scripts and how to control sample size.”
Ascending and diligently exploring the sedimentary lower layers of Mount Sharp, which towers 3.4 miles (5.5 kilometers) into the Martian sky, is the primary destination and goal of the rover’s long term scientific expedition on the Red Planet.
“Lower Mount Sharp was chosen as a destination for the Curiosity mission because the layers of the mountain offer exposures of rocks that record environmental conditions from different times in the early history of the Red Planet. Curiosity has found evidence for ancient wet environments that offered conditions favorable for microbial life, if Mars has ever hosted life,” says NASA.
Stay tuned. In part 2 we’ll discuss the key findings from Curiosity’s first 5 years exploring the Red Planet.
As of today, Sol 1850, Oct. 19, 2017, Curiosity has driven over 10.89 miles (17.53 kilometers) since its August 2012 landing inside Gale Crater from the landing site to the ridge, and taken over 445,000 amazing images.
Stay tuned here for Ken’s continuing Earth and planetary science and human spaceflight news.
Map shows route driven by NASA’s Mars rover Curiosity through Sol 1827 of the rover’s mission on Mars (September 27, 2017). Numbering of the dots along the line indicate the sol number of each drive. North is up. Since touching down in Bradbury Landing in August 2012, Curiosity has driven 10.84 miles (17.45 kilometers). The base image from the map is from the High Resolution Imaging Science Experiment Camera (HiRISE) in NASA’s Mars Reconnaissance Orbiter. Credit: NASA/JPL/UA
Curiosity’s Traverse Map Through Sol 1717. This map shows the route driven by NASA’s Mars rover Curiosity through the 1717 Martian day, or sol, of the rover’s mission on Mars (June 05, 2017). The base image from the map is from the High Resolution Imaging Science Experiment Camera (HiRISE) in NASA’s Mars Reconnaissance Orbiter. Credit: NASA/JPL-Caltech/Univ. of Arizona
NASA’s Curiosity rover as seen simultaneously on Mars surface and from orbit on Sol 1717, June 5, 2017. The robot snapped this self portrait mosaic view while approaching Vera Rubin Ridge at the base of Mount Sharp inside Gale Crater - backdropped by distant crater rim. This navcam camera mosaic was stitched from raw images and colorized. Inset shows overhead orbital view of Curiosity (blue feature) amid rocky mountainside terrain taken the same day by NASA’s Mars Reconnaissance Orbiter. Credit: NASA/JPL/Ken Kremer/kenkremer.com/Marco Di Lorenzo
NASA’s Curiosity rover as seen simultaneously on Mars surface and from orbit on Sol 1717, June 5, 2017. The robot snapped this self portrait mosaic view while approaching Vera Rubin Ridge at the base of Mount Sharp inside Gale Crater – backdropped by distant crater rim. This navcam camera mosaic was stitched from raw images and colorized. Inset shows overhead orbital view of Curiosity (blue feature) amid rocky mountainside terrain taken the same day by NASA’s Mars Reconnaissance Orbiter. Credit: NASA/JPL/Ken Kremer/kenkremer.com/Marco Di Lorenzo
You can catch a glimpse of what its like to see NASA’s Curiosity Mars rover simultaneously high overhead from orbit and trundling down low across the Red Planet’s rocky surface as she climbs the breathtaking terrain of Mount Sharp – as seen in new images from NASA we have stitched together into a mosaic view showing the perspective views; see above.
Earlier this month on June 5, researchers commanded NASA’s Mars Reconnaissance Orbiter (MRO) to image the car sized Curiosity rover from Mars orbit using the spacecrafts onboard High Resolution Imaging Science Experiment (HiRISE) telescopic camera during Sol 1717 of her Martian expedition – see below.
HiRISE is the most powerful telescope ever sent to Mars.
And as she does nearly every Sol, or Martian day, Curiosity snapped a batch of new images captured from Mars surface using her navigation camera called navcam – likewise on Sol 1717.
Since NASA just released the high resolution MRO images of Curiosity from orbit, we assembled together the navcam camera raw images taken simultaneously on June 5 (Sol 1717), in order to show the actual vista seen by the six wheeled robot from a surface perspective on the same day.
The lead navcam photo mosaic shows a partial rover selfie backdropped by the distant rim of Gale Crater – and was stitched together by the imaging team of Ken Kremer and Marco Di Lorenzo.
The feature that appears bright blue at the center of this scene is NASA’s Curiosity Mars rover amid tan rocks and dark sand on Mount Sharp, as viewed by the HiRISE camera on NASA’s Mars Reconnaissance Orbiter on June 5, 2017. The rover is about 10 feet long and not really as blue as it looks here. The image was taken as Curiosity was partway between its investigation of active sand dunes lower on Mount Sharp, and “Vera Rubin Ridge,” a destination uphill where the rover team intends to examine outcrops where hematite has been identified from Mars orbit. Credits: NASA/JPL-Caltech/Univ. of Arizona
Right now NASA’s Curiosity Mars Science Laboratory (MSL) rover is approaching her next science destination named “Vera Rubin Ridge” while climbing up the lower reaches of Mount Sharp, the humongous mountain that dominates the rover’s landing site inside Gale Crater.
“When the MRO image was taken, Curiosity was partway between its investigation of active sand dunes lower on Mount Sharp, and “Vera Rubin Ridge,” a destination uphill where the rover team intends to examine outcrops where hematite has been identified from Mars orbit,” says NASA.
“HiRISE has been imaging Curiosity about every three months, to monitor the surrounding features for changes such as dune migration or erosion.”
The MRO image has been color enhanced and shows Curiosity as a bright blue feature. It is currently traveling on the northwestern flank of Mount Sharp. Curiosity is approximately 10 feet long and 9 feet wide (3.0 meters by 2.8 meters).
“The exaggerated color, showing differences in Mars surface materials, makes Curiosity appear bluer than it really looks. This helps make differences in Mars surface materials apparent, but does not show natural color as seen by the human eye.”
See our mosaic of “Vera Rubin Ridge” and Mount Sharp below.
Curiosity images Vera Rubin Ridge during approach backdropped by Mount Sharp. This navcam camera mosaic was stitched from raw images taken on Sol 1726, June 14, 2017 and colorized. Credit: NASA/JPL/Marco Di Lorenzo/Ken Kremer/kenkremer.com
Curiosity is making rapid progress towards the hematite-bearing location of Vera Rubin Ridge after conducting in-depth exploration of the Bagnold Dunes earlier this year.
“Vera Rubin Ridge is a high-standing unit that runs parallel to and along the eastern side of the Bagnold Dunes,” says Mark Salvatore, an MSL Participating Scientist and a faculty member at Northern Arizona University, in a new mission update.
“From orbit, Vera Rubin Ridge has been shown to exhibit signatures of hematite, an oxidized iron phase whose presence can help us to better understand the environmental conditions present when this mineral assemblage formed.”
Curiosity will use her cameras and spectrometers to elucidate the origin and nature of Vera Rubin Ridge and potential implications or role in past habitable environments.
“The rover will turn its cameras to Vera Rubin Ridge for another suite of high resolution color images, which will help to characterize any observed layers, fractures, or geologic contacts. These observations will help the science team to determine how Vera Rubin Ridge formed and its relationship to the other geologic units found within Gale Crater.”
To reach Vera Rubin Ridge, Curiosity is driving east-northeast around two small patches of dunes just to the north. She will then turn “southeast and towards the location identified as the safest place for Curiosity to ascend the ridge. Currently, this ridge ascent point is approximately 370 meters away.”
Curiosity rover raises robotic arm high while scouting the Bagnold Dune Field and observing dust devils inside Gale Crater on Mars on Sol 1625, Mar. 2, 2017, in this navcam camera mosaic stitched from raw images and colorized. Note: Wheel tracks at right, distant crater rim in background. Credit: NASA/JPL/Ken Kremer/kenkremer.com/Marco Di Lorenzo
Ascending and diligently exploring the sedimentary lower layers of Mount Sharp, which towers 3.4 miles (5.5 kilometers) into the Martian sky, is the primary destination and goal of the rovers long term scientific expedition on the Red Planet.
“Lower Mount Sharp was chosen as a destination for the Curiosity mission because the layers of the mountain offer exposures of rocks that record environmental conditions from different times in the early history of the Red Planet. Curiosity has found evidence for ancient wet environments that offered conditions favorable for microbial life, if Mars has ever hosted life,” says NASA.
NASA’s Curiosity rover explores sand dunes inside Gale Crater with Mount Sharp in view on Mars on Sol 1611, Feb. 16, 2017, in this navcam camera mosaic, stitched from raw images and colorized. Credit: NASA/JPL/Ken Kremer/kenkremer.com/Marco Di Lorenzo
As of today, Sol 1733, June 21, 2017, Curiosity has driven over 10.29 miles (16.57 kilometers) since its August 2012 landing inside Gale Crater, and taken over 420,000 amazing images.
Stay tuned here for Ken’s continuing Earth and planetary science and human spaceflight news.
Learn more about the upcoming SpaceX launch of BulgariaSat 1, recent SpaceX Dragon CRS-11 resupply launch to ISS, NASA missions and more at Ken’s upcoming outreach events at Kennedy Space Center Quality Inn, Titusville, FL:
June 22-24: “SpaceX BulgariaSat 1 launch, SpaceX CRS-11 and CRS-10 resupply launches to the ISS, Inmarsat 5 and NRO Spysat, EchoStar 23, SLS, Orion, Commercial crew capsules from Boeing and SpaceX , Heroes and Legends at KSCVC, ULA Atlas/John Glenn Cygnus launch to ISS, SBIRS GEO 3 launch, GOES-R weather satellite launch, OSIRIS-Rex, Juno at Jupiter, InSight Mars lander, SpaceX and Orbital ATK cargo missions to the ISS, ULA Delta 4 Heavy spy satellite, Curiosity and Opportunity explore Mars, Pluto and more,” Kennedy Space Center Quality Inn, Titusville, FL, evenings
Curiosity’s Traverse Map Through Sol 1717. This map shows the route driven by NASA’s Mars rover Curiosity through the 1717 Martian day, or sol, of the rover’s mission on Mars (June 05, 2017). The base image from the map is from the High Resolution Imaging Science Experiment Camera (HiRISE) in NASA’s Mars Reconnaissance Orbiter. Credit: NASA/JPL-Caltech/Univ. of Arizona
Mars, as photographed with the Mars Global Surveyor, is identified with the Roman god of war. Credit: NASA
This week, from March 20th to 24th, the 48th Lunar and Planetary Science Conference will be taking place in The Woodlands, Texas. Every year, this conference brings together international specialists in the fields of geology, geochemistry, geophysics, and astronomy to present the latest findings in planetary science. One of the highlights of the conference so far has been a presentation about Mars’ weather patterns.
When it comes to cloud formations, gravity waves are the result of gravity trying to restore them to their natural equilibrium. And while common on Earth, such formation were not thought to be possible around Mars’ equatorial band, where the gravity waves were seen. All of this was made possible thanks to Curiosity’s advantageous position inside the Gale Crater.
Panoramic image showing cirrus clouds in the Martian atmosphere, taken by the Opportunity rover in 2006. Credit: NASA/JPL/Cornell/M. Howard, T. Öner, D, Bouic & M. Di Lorenzo
Located near Mars’ equator, Curiosity has managed to consistently record what is known as the Aphelion Cloud Belt (ACB). As the name would suggest, this annually-recurring phenomena appears during the aphelion season on Mars (when it is farthest from the Sun) between the latitudes of 10°S and 30°N. During aphelion, the point farthest from the Sun, the planet is dominated by two cloud systems.
These include the aforementioned ACB, and the polar phenomena known as Polar Hood Clouds (PHCs). Whereas PHCs are characterized by clouds of carbon dioxide, clouds that form around Mars’ equatorial band are made up water-ice. These cloud systems them dissipate as Mars gets closer to the Sun (perihelion), where increases in temperature lead to the creation of dust storms that limit cloud formation.
During the nearly five years that Curiosity has been operational, the rover has recorded over 500 movies of the equatorial Martian sky. These movies have taken the form of both Zenith Movies (ZMs) – which involve the camera being pointed vertically – and Supra-Horizon Movies (SHM), which were aimed at a lower angle of elevation to keep the horizon in frame.
Using Curiosity’s navigation camera, Jacob Kloos and Dr. John Moores – two researchers from CRESS – made eight recordings of the ACB over the course of two Martian years – specifically between Mars Years 31 and Mars Years 33 (ca. 2012 to 2016). By comparing ZM and SHM movies, they were able to discern changes in the clouds that were both diurnal (daily) and annual in nature.
What they found was that between 2015 and 2016, Mars’ ACB underwent changes in opacity (aka. changes in density) during its diurnal cycle. After periods of enhanced early morning activity, the clouds would reach a minimum by late morning. This is followed by a second, lower peak in the late afternoon, which indicated that Mars’ early morning hours are the most favorable time for the formation of thicker clouds.
Hubble images show cloud formations (left) and the effects of a global dust storm on Mars. Credit: NASA/James Bell (Cornell Univ.), Michael Wolff (Space Science Inst.), and Hubble Heritage Team (STScI/AURA)
As for inter-annual variability, they found that between 2012 and 2016, when Mars moved away from aphelion, there was a corresponding 38% increase in the number of higher-opacity clouds. However, believing these results to be the result of a statistical bias caused by an uneven distribution of videos, they concluded that the difference in opacity was more along the lines of about 5%.
These variations were all of this is consistent with tidal temperature variations, where cooler daytime or seasonal temperatures result in greater levels of condensation in the air. The trend of increasing clouds throughout the day was unexpected, however, as higher temperatures should lead to a decrease in saturation. However, as they explained during their presentation, this too could be attributed to daily changes:
“One explanation for the afternoon enhancement put forth by Tamppari et. al. is that as atmospheric temperatures increase the throughout the day, enhanced convection lifts water vapor to the saturation altitude, therefore increasing the likelihood of cloud formation. In addition to water vapor, dust could also be lifted, which act as condensation nuclei, allowing for more efficient cloud formation.”
However, what was most interesting was the fact that during one of day of observation – Sol 1302, or April 5th, 2016 – the team managed to observe something surprising. When looking at the horizon during an SHM, the NavCam caught sight of parallel rows of clouds which all pointed in the same direction. While such ripples are known to happen in the polar regions (where PHCs are concerned), spotting them over the equator was unexpected.
Sunset photographed from Gale Crater by the Mars Curiosity rover on April 15, 2015 taken using the left eye of the rover’s Mastcam. Credit: NASA/JPL-Caltec
But as Moore explained in an interview with Science Magazine,seeing an Earth-like phenomenon on Mars is consistent with what we’ve seen so far from Mars. “The Martian environment is the exotic wrapped in the familiar,” he said. “The sunsets are blue, the dust devils enormous, the snowfall more like diamond dust, and the clouds are thinner than what we see on the Earth.”
At present, it is not clear which mechanism could be responsible for creating these ripples in the first place. On Earth, they are caused by disturbances below in the troposphere, solar radiation, or jet stream sheer. Knowing what could account for them on Mars will likely reveal some interesting things about its atmosphere’s dynamics. At the same time, further research is necessary before scientists can say definitely that gravity waves were observed here.
But in the meantime, these findings are fascinating, and are sure to help advance our knowledge of the Red Planet’s atmosphere and the water cycle on Mars. As ongoing research has shown, Mars still experiences flows of liquid salt water on its surface, and even experiences limited precipitation. And in telling us more about Mars’ present-day meteorology, it could also reveal things about the planet’s watery past.
To see the recordings of Martian clouds, click here,here and here.
Image taken by the Mars Hand Lens Imager (MAHLI) of Curiosity's wheels on March 19, 2017. Credit: NASA
Since it landed on August 6th, 2012, the Curiosityrover has spent a total of 1644 Sols (or 1689 Earth days) on Mars. And as of March 2017, it has traveled almost 16 km (~10 mi) across the planet and climbed almost a fifth of a kilometer (0.124 mi) uphill. Spending that kind of time on another planet, and traveling that kind of distance, can certainly lead to its share of wear of tear on a vehicle.
That was the conclusion when the Curiosity science team conducted a routine check of the rover’s wheels on Sunday, March 19th, 2017. After examining images taken by the Mars Hand Lens Imager (MAHLI), they noticed two small breaks in the raised treads on the rover’s left middle wheel. These breaks appeared to have happened since late January, when the last routine check of the wheels took place.
To get around, the Curiosity rover relies on six solid aluminum wheels that are 40 cm (16 in) wide. The skin of the wheels is thinner than a US dime, but each contains 19 zigzag-shaped treads that are about 0.75 cm (three-quarters of an inch) thick. These “grousers”, as they are called, bear most of the rover’s weight and provide most of the wheel’s traction.
Close-up image of the broken grousers on Curiosity’s left-middle wheel. Credit: NASA/JPL-Caltech/MSSS
Ever since the rover was forced to cross a stretch of terrain that was studded with sharp rocks in 2013, the Curiosity team has made regular checks on the rover’s wheels using the MAHLI camera. At the time, the rover was moving from the Bradbury Landing site (where it landed in 2012) to the base of Mount Sharp, and traversing this terrain caused holes and dents in the wheels to grow significantly.
However, members of Curiosity’s science team emphasized that this is nothing to be worried about, as it will not affect the rover’s performance or lifespan. As Jim Erickson, the Curiosity Project Manager at NASA’s Jet Propulsion Laboratory, said in a recent NASA press statement:
“All six wheels have more than enough working lifespan remaining to get the vehicle to all destinations planned for the mission. While not unexpected, this damage is the first sign that the left middle wheel is nearing a wheel-wear milestone.”
In addition to regular monitoring, a wheel-longevity testing program was started on Earth in 2013 using identical aluminum wheels. These tests showed that once a wheel got to the point where three of its grousers were broken, it had passed about 60% of its lifespan. However, Curiosity has already driven more than 60% of the total distance needed for it to make it to all of its scientific destinations.
Graphic depicting aspects of the driving distance, elevation, geological units and time intervals of NASA’s Curiosity Mars rover mission, as of late 2016. Credit: NASA/JPL-Caltech
“This is an expected part of the life cycle of the wheels and at this point does not change our current science plans or diminish our chances of studying key transitions in mineralogy higher on Mount Sharp.”
At present, Curiosity is examining sand dunes in the geographical region known as the Murray Buttes formation, which is located on the slope of Mount Sharp. Once finished, it will proceed up higher to a feature known as “Vera Rubin Ridge”, inspecting a layer that is rich in the mineral hematite. From there, it will proceeded to even higher elevations to inspect layers that contain clays and sulfates.
Getting to the farthest destination (the sulfate unit) will require another 6 km (3.7 mi) of uphill driving. However, this is a short distance compared to the kind of driving the rover has already performed. Moreover, the science team has spent the past four years implementing various methods designed to avoid embedded rocks and other potentially hazardous terrain features.
MRO image of Gale Crater illustrating the landing location and trek of the Rover Curiosity. Credits: NASA/JPL, illustration, T.Reyes
It is expected that this drive up Mount Sharp will yield some impressive scientific finds. During its first year on Mars, Curiosity succeeded in gathering evidence in the Gale Crater that showed how Mars once had conditions favorable to life. This included ample evidence of liquid water, all the chemical elements needed for life, and even a chemical source of energy.
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. Luckily, the rover’s wheels seem to have more than enough life to make these and (most likely) other scientific finds.
Curiosity rover raises robotic arm high while scouting the Bagnold Dune Field and observing dust devils inside Gale Crater on Mars on Sol 1625, Mar. 2, 2017, in this navcam camera mosaic stitched from raw images and colorized. Note: Wheel tracks at right, distant crater rim in background. Credit: NASA/JPL/Ken Kremer/kenkremer.com/Marco Di Lorenzo
Curiosity rover raises robotic arm high while scouting the Bagnold Dune Field and observing dust devils inside Gale Crater on Mars on Sol 1625, Mar. 2, 2017, in this navcam camera mosaic stitched from raw images and colorized. Note: Wheel tracks at right, distant crater rim in background. Credit: NASA/JPL/Ken Kremer/kenkremer.com/Marco Di Lorenzo
Tis a season of incredible wind driven activity on Mars like few before witnessed by our human emissaries ! Its summer on the Red Planet and the talented scientists directing NASA’s Curiosity rover have targeted the robots cameras so proficiently that they have efficiently spotted a multitude of ‘Dust Devils’ racing across across the dunes fields of Gale Crater– see below.
The ‘Dust Devils’ are actually mini tornadoes like those seen on Earth.
This sequence of images shows a dust-carrying whirlwind, called a dust devil, on lower Mount Sharp inside Gale Crater, as viewed by NASA’s Curiosity Mars Rover during the summer afternoon of Sol 1613 (Feb. 18, 2017). The navcam camera images are in pairs that were taken about 12 seconds apart, with an interval of about 90 seconds between pairs. Timing is accelerated and not fully proportional in this animation. Contrast has been modified to make frame-to-frame changes easier to see. A black frame provides a marker between repeats of the sequence. Credit: NASA/JPL-Caltech/TAMU
Furthermore they whip up the dust more easily in the lower gravity field on Mars compared to Earth. Mars gravity is about one third of Earth’s.
Right now it’s summer inside the rovers southern hemisphere landing site at Gale Crater. And summer is the windiest time of the Martian year.
“Dust devils are whirlwinds that result from sunshine warming the ground, prompting convective rising of air that has gained heat from the ground. Observations of Martian dust devils provide information about wind directions and interaction between the surface and the atmosphere,” as described by researchers.
So now is the best time to observe and photograph the dusty whirlwinds in action as they flitter amazingly across the craters surface carrying dust in their wake.
This sequence of images shows a dust-carrying whirlwind, called a dust devil, scooting across ground inside Gale Crater, as observed on the local summer afternoon of NASA’s Curiosity Mars Rover’s 1,597th Martian day, or sol (Feb. 1, 2017). Set within a broader southward view from the rover’s Navigation Camera, the rectangular area outlined in black was imaged multiple times over a span of several minutes to check for dust devils. Images from the period with most activity are shown in the inset area. The images are in pairs that were taken about 12 seconds apart, with an interval of about 90 seconds between pairs. Timing is accelerated in this animation. Credits: NASA/JPL-Caltech/TAMU
Therefore researchers are advantageously able to utilize Curiosity in a new research campaign that “focuses on modern wind activity in Gale” on the lower slope of Mount Sharp — a layered mountain inside the crater.
NASA’s Curiosity rover explores sand dunes inside Gale Crater with Mount Sharp in view on Mars on Sol 1611, Feb. 16, 2017, in this navcam camera mosaic stitched from raw images and colorized. Credit: NASA/JPL/Ken Kremer/kenkremer.com/Marco Di Lorenzo
Indeed, this past month Curiosity began her second sand dune campaign focusing on investigating active dunes on the mountain’s northwestern flank that are ribbon-shaped linear dunes.
“In these linear dunes, the sand is transported along the ribbon pathway, while the ribbon can oscillate back and forth, side to side,” said Nathan Bridges, a Curiosity science team member at the Johns Hopkins University Applied Physics Laboratory in Laurel, Maryland, in a statement.
The left side of this 360-degree panorama from NASA’s Curiosity Mars rover shows the long rows of ripples on a linear shaped dune in the Bagnold Dune Field on the northwestern flank of Mount Sharp. The rover’s Navigation Camera recorded the component images of this mosaic on Feb. 5, 2017. Credits: NASA/JPL-Caltech
These new dunes are different from those investigated during the first dune campaign back in late 2015 and early 2016 that examined crescent-shaped dunes, including Namib Dune in our mosaic below.
The initial dune campaign actually involved the first ever up-close study of active sand dunes anywhere other than Earth, as I reported at the time.
Curiosity explores Red Planet paradise at Namib Dune during Christmas 2015 – backdropped by Mount Sharp. Curiosity took first ever self-portrait with Mastcam color camera after arriving at the lee face of Namib Dune. This photo mosaic shows a portion of the full self portrait and is stitched from Mastcam color camera raw images taken on Sol 1197, Dec. 19, 2015. Credit: NASA/JPL/MSSS/Ken Kremer/kenkremer.com/Marco Di Lorenzo
By snapping a series of targeted images pointed in just the right direction using the rovers mast mounted navigation cameras, or navcams, the researchers have composed a series of ‘Dust Devil’ movies – gathered together here for your enjoyment.
“We’re keeping Curiosity busy in an area with lots of sand at a season when there’s plenty of wind blowing it around,” said Curiosity Project Scientist Ashwin Vasavada of NASA’s Jet Propulsion Laboratory, Pasadena, California.
“One aspect we want to learn more about is the wind’s effect on sorting sand grains with different composition. That helps us interpret modern dunes as well as ancient sandstones.”
The movies amply demonstrate that Mars is indeed an active world and winds are by far the dominant force shaping and eroding the Red Planets alien terrain – despite the thin atmosphere less than 1 percent of Earth’s.
Indeed scientists believe that wind erosion over billions of years of time is what caused the formation of Mount Sharp at the center of Gale Crater by removing vast amounts of dust and sedimentary material — about 15,000 cubic miles (64,000 cubic kilometers) — as Mars evolved from a wet world to the dry, desiccated planet we see today.
Gale crater was originally created over 3.6 billion years ago when a gigantic asteroid or comet smashed into Mars. The devastating impact “excavated a basin nearly 100 miles (160 kilometers) wide. Sediments including rocks, sand and silt later filled the basin, some delivered by rivers that flowed in from higher ground surrounding Gale.”
Winds gradually carved away so much sediment and dirt that we are left with the magnificent mountain in view today.
The whirlwinds called “dust devils” have been recorded moving across terrain in the crater, in sequences of afternoon images taken several seconds apart.
The contrast has been enhanced to better show the dust devils in action.
Watch this short NASA video showing Martian Dust Devils seen by Curiosity:
Video Caption: Dust Devils On Mars Seen by NASA’s Curiosity Rover. On recent summer afternoons on Mars, navigation cameras aboard NASA’s Curiosity Mars rover observed several whirlwinds carrying Martian dust across Gale Crater. Dust devils result from sunshine warming the ground, prompting convective rising of air. All the dust devils were seen in a southward direction from the rover. Timing is accelerated and contrast has been modified to make frame-to-frame changes easier to see. Credit: NASA/JPL
The team is also using the probes downward-looking Mars Descent Imager (MARDI) camera for a straight down high resolution up-close view looking beneath the rover. The purpose is to check for daily movement of the dunes she is sitting on to see “how far the wind moves grains of sand in a single day’s time.”
This pair of images shows effects of one Martian day of wind blowing sand underneath NASA’s Curiosity Mars rover on a non-driving day for the rover. Each image was taken just after sundown by the rover’s downward-looking Mars Descent Imager (MARDI). The area of ground shown in the images spans about 3 feet (about 1 meter) left-to-right. The images were taken on Jan. 23, 2017 (Sol 1587) and Jan. 24, 2017 (Sol 1588). The day-apart images by MARDI were taken as a part of investigation of wind’s effects during Martian summer, the windiest time of year in Gale Crater. Credit: NASA/JPL-Caltech/MSSS
These dune investigations have to be done now, because the six wheeled robot will soon ascend Mount Sharp, the humongous layered mountain at the center of Gale Crater.
Ascending and diligently exploring the sedimentary lower layers of Mount Sharp, which towers 3.4 miles (5.5 kilometers) into the Martian sky, is the primary destination and goal of the rovers long term scientific expedition on the Red Planet.
“Before Curiosity heads farther up Mount Sharp, the mission will assess movement of sand particles at the linear dunes, examine ripple shapes on the surface of the dunes, and determine the composition mixture of the dune material,” researchers said.
NASA’s Curiosity rover extends robotic arm to investigate sand dunes inside Gale Crater on Mars on Sol 1619, Feb. 24, 2017. Credit: NASA/JPL/MSSS/Ken Kremer/kenkremer.com/Marco Di Lorenzo
Curiosity is also using the science instruments on the robotic arm turret to gather detailed research measurements with the cameras and spectrometers.
As of today, Sol 1625, March 2, 2017, Curiosity has driven over 9.70 miles (15.61 kilometers) since its August 2012 landing inside Gale Crater, and taken over 391,000 amazing images.
Stay tuned here for Ken’s continuing Earth and planetary science and human spaceflight news.
This map shows the two locations of a research campaign by NASA’s Curiosity Mars rover mission to investigate active sand dunes on Mars. In late 2015, Curiosity reached crescent-shaped dunes, called barchans. In February 2017, the rover reached a location where the dunes are linear in shape. Credits: NASA/JPL-Caltech/Univ. of Arizona
This map shows the route driven by NASA’s Mars rover Curiosity through Sol 1612 (February 17, 2017) of the rover’s mission on Mars. The base image from the map is from the High Resolution Imaging Science Experiment Camera (HiRISE) in NASA’s Mars Reconnaissance Orbiter. Image Credit: NASA/JPL-Caltech/Univ. of Arizona
Bedrock at this site added to a puzzle about ancient Mars by indicating that a lake was present, but that little carbon dioxide was in the air to help keep a lake unfrozen. Credit: NASA/JPL-Caltech/MSSS
The study of Mars’ surface and atmosphere has unlocked some ancient secrets. Thanks to the efforts of the Curiosity rover and other missions, scientists are now aware of the fact that water once flowed on Mars and that the planet had a denser atmosphere. They have also been able to deduce what mechanics led to this atmosphere being depleted, which turned it into the cold, desiccated environment we see there today.
At the same time though, it has led to a rather intriguing paradox. Essentially, Mars is believed to have had warm, flowing water on its surface at a time when the Sun was one-third as warm as it is today. This would require that the Martian atmosphere had ample carbon dioxide in order to keep its surface warm enough. But based on the Curiosity rover’s latest findings, this doesn’t appear to be the case.
These findings were part of an analysis of data taken by the Curiosity’s Chemistry and Mineralogy X-ray Diffraction (CheMin) instrument, which has been used to study the mineral content of drill samples in the Gale Crater. The results of this analysis were recently published in Proceedings of the National Academy of Science, where the research team indicated that no traces of carbonates were found in any samples taken from the ancient lake bed.
Simulated view of Gale Crater Lake on Mars, depicting a lake of water partially filling Mars’ Gale Crater. Credit: NASA/JPL-Caltech/ESA/DLR/FU Berlin/MSSS
To break it down, evidence collected by Curiosity (and a slew of other rovers, landers and orbiters) has led scientists to conclude that roughly 3.5 billion years ago, Mars surface had lakes and flowing rivers. They have also determined, thanks to the many samples taken by Curiosity since it landed in the Gale Crater in 2011, that this geological feature was once a lake bed that gradually became filled with sedimentary deposits.
However, for Mars to have been warm enough for liquid water to exist, its atmosphere would have had to contain a certain amount of carbon dioxide – providing a sufficient Greenhouse Effect to compensate for the Sun’s diminished warmth. Since rock samples in the Gale Crater act as a geological record for what conditions were like billions of years ago, they would surely contain plenty of carbonate minerals if this were the case.
Carbonates are minerals that result from carbon dioxide combining with positively charged ions (like magnesium and iron) in water. Since these ions have been found to be in good supply in samples of Martian rock, and subsequent analysis has shown that conditions never became acidic to the point that the carbonates would have dissolved, there is no apparent reason why they wouldn’t be showing up.
Along with his team, Thomas Bristow – the principal investigator for the CheMin instrument on Curiosity – calculated what the minimum amount of atmospheric carbon dioxide would need to be, and how this would have been indicated by the levels of carbonate found in Martian rocks today. They then sorted through the years worth of the CheMin instrument’s data to see if there were any indications of these minerals.
Comparison of X-ray diffraction patterns of two different samples analyzed by Curiosity’s Chemistry and Mineralogy (CheMin) instrument. Credit: NASA/JPL-Caltech/Ames
But as he explained in a recent NASA press release, the findings simply didn’t measure up:
“We’ve been particularly struck with the absence of carbonate minerals in sedimentary rock the rover has examined. It would be really hard to get liquid water even if there were a hundred times more carbon dioxide in the atmosphere than what the mineral evidence in the rock tells us.”
In the end, Bristow and his team could not find even trace amounts of carbonates in the rock samples they analyzed. Even if just a few tens of millibars of carbon dioxide had been present in the atmosphere when a lake existed in the Gale Crater, it would have produced enough carbonates for Curiosity’s CheMin to detect. This latest find adds to a paradox that has been plaguing Mars researchers for years.
Basically, researchers have noted that there is a serious discrepancy between what surface features indicate about Mars’ past, and what chemical and geological evidence has to say. Not only is there plenty of evidence that the planet had a denser atmosphere in the past, more than four decades of orbital imaging (and years worth of surface data) have yielded ample geomorphological evidence that Mars once had surface water and an active hydrological cycle.
The Gale Crater – the landing location and trek of the Rover Curiosity – as it is today, imaged by the MRO. Credits: NASA/JPL, illustration, T.Reyes
However, scientists are still struggling to produce models that show how the Martian climate could have maintained the types of conditions necessary for this to have been the case. The only successful model so far has been one in which the atmosphere contained a significant amount of CO2 and hydrogen. Unfortunately, an explanation for how this atmosphere could be created and sustained remains elusive.
In addition, the geological and chemical evidence for such a atmosphere existing billions of years ago has also been in short supply. In the past, surveys by orbiters were unable to find evidence of carbonate minerals on the surface of Mars. It was hoped that surface missions, like Curiosity, would be able to resolve this by taking soil and drill samples where water had been known to exist.
But as Bristow explained, his team’s study has effectively closed the door on this:
“It’s been a mystery why there hasn’t been much carbonate seen from orbit. You could get out of the quandary by saying the carbonates may still be there, but we just can’t see them from orbit because they’re covered by dust, or buried, or we’re not looking in the right place. The Curiosity results bring the paradox to a focus. This is the first time we’ve checked for carbonates on the ground in a rock we know formed from sediments deposited under water.”
Annontated version of the bedrock site in the Gale Crater where the Curiosity rover has taken drill samples. Credit: NASA/JPL-Caltech/MSSS
There are several possible explanations for this paradox. On the one hand, some scientists have argued that the Gale Crater Lake may not have been an open body of water and was perhaps covered in ice, which was just thin enough to still allow for sediments to get in. The problem with this explanation is that if this were true, there would be discernible indications left behind – which would include deep cracks in the soft sedimentary lakebed rock.
But since these indications have not been found, scientists are left with two lines of evidence that do not match up. As Ashwin Vasavada, Curiosity’s Project Scientist, put it:
“Curiosity’s traverse through streambeds, deltas, and hundreds of vertical feet of mud deposited in ancient lakes calls out for a vigorous hydrological system supplying the water and sediment to create the rocks we’re finding. Carbon dioxide, mixed with other gases like hydrogen, has been the leading candidate for the warming influence needed for such a system. This surprising result would seem to take it out of the running.”
Luckily, incongruities in science are what allow for new and better theories to be developed. And as the exploration of the Martian surface continues – which will benefit from the arrival of the ExoMars and the Mars 2020missions in the coming years – we can expect additional evidence to emerge. Hopefully, it will help point the way towards a resolution for this paradox, and not complicate our theories even more!
