Using its HiRISE camera, the MRO has noted existence of tall networks of ridges on Mars that have diverse origins. Credit: NASA/JPL-Caltech/Univ. of Arizona
Mars has some impressive geological features across its cold, desiccated surface, many of which are similar to featured found here on Earth. By studying them, scientists are able to learn more about the natural history of the Red Planet, what kinds of meteorological phenomena are responsible for shaping it, and how similar our two planets are. A perfect of example of this are the polygon-ridge networks that have been observed on its surface.
One such network was recently discovered by the Mars Reconnaissance Orbiter (MRO) in the Medusae Fossae region, which straddles the planet’s equator. Measuring some 16 story’s high, this ridge network is similar to others that have been spotted on Mars. But according to a survey produced by researchers from NASA’s Jet Propulsion Laboratory, these ridges likely have different origins.
This survey, which was recently published in the journal Icarus, examined both the network found in the Medusae Fossae region and similar-looking networks in other regions of the Red Planet. These ridges (sometimes called boxwork rides), are essentially blade-like walls that look like multiple adjoining polygons (i.e. rectangles, pentagons, triangles, and similar shapes).
Shiprock, a ridge-feature in northwestern New Mexico that is 10 meters (30 feet) tall, which formed from lava filling an underground fracture that resisted erosion better than the material around it did. Credit: NASA
While similar-looking ridges can be found in many places on Mars, they do not appear to be formed by any single process. As Laura Kerber, of NASA’s Jet Propulsion Laboratory and the lead author of the survey report, explained in a NASA press release:
“Finding these ridges in the Medusae Fossae region set me on a quest to find all the types of polygonal ridges on Mars… Polygonal ridges can be formed in several different ways, and some of them are really key to understanding the history of early Mars. Many of these ridges are mineral veins, and mineral veins tell us that water was circulating underground.”
Such ridges have also been found on Earth, and appear to be the result of various processes as well. One of the most common involves lava flowing into preexisting fractures in the ground, which then survived when erosion stripped the surrounding material away. A good example of this is the Shiprock (shown above), a monadrock located in San Juan County, New Mexico.
Examples of polygon ridges on Mars include the feature known as “Garden City“, which was discovered by the Curiosity rover mission. Measuring just a few centimeters in height, these ridges appeared to be the result of mineral-laden groundwater moving through underground fissures, which led to standing mineral veins once the surrounding soil eroded away.
Mineral veins at the “Garden City” site, examined by NASA’s Curiosity Mars rover. Credit: NASA/JPL
At the other end of the scale, ridges that measure around 2 kilometers (over a mile) high have also been found. A good example of this is “Inca City“, a feature observed by the Mars Global Surveyor near Mars’ south pole. In this case, the feature is believed to be the result of underground faults (which were formed from impacts) filling with lava over time. Here too, erosion gradually stripped away the surrounding rock, exposing the standing lava rock.
In short, these features are evidence of underground water and volcanic activity on Mars. And by finding more examples of these polygon-ridges, scientists will be able to study the geological record of Mars more closely. Hence why Kerber is seeking help from the public through a citizen-science project called Planet Four: Ridges.
Established earlier this month on Zooniverse – a volunteer-powered research platform – this project has made images obtained by the MRO’s Context Camera (CTX) available to the public. Currently, this and other projects using data from CTX and HiRISE have drawn the participation of more than 150,000 volunteers from around the world.
By getting volunteers to sort through the CTX images for ridge formations, Kerber and her team hopes that previously-unidentified ones will be identified and that their relationship with other Martian features will be better understood.
Credit and copyright: ESA/DLR/FU Berlin (G. Neukum)
Ah, the good old days. ESA’s Mars Express imaged Reull Vallis, a river-like structure believed to have formed when running water flowed in the distant Martian past, cuts a steep-sided channel on its way towards the floor of the Hellas basin. A thicker atmosphere that included methane and hydrogen in addition to carbon dioxide may have allowed liquid water to flow on Mars at different times in the past according to a new study. Credit and copyright: ESA/DLR/FU Berlin (G. Neukum)
Water. It’s always about the water when it comes to sizing up a planet’s potential to support life. Mars may possess some liquid water in the form of occasional salty flows down crater walls, but most appears to be locked up in polar ice or hidden deep underground. Set a cup of the stuff out on a sunny Martian day today and depending on conditions, it could quickly freeze or simply bubble away to vapor in the planet’s ultra-thin atmosphere.
These rounded pebbles got their shapes after polished in a long-ago river in Gale Crater. They were discovered by Curiosity rover at the Hottah site. Credit: NASA/JPL-Caltech
Evidence of abundant liquid water in former flooded plains and sinuous river beds can be found nearly everywhere on Mars. NASA’s Curiosity rover has found mineral deposits that only form in liquid water and pebbles rounded by an ancient stream that once burbled across the floor of Gale Crater. And therein lies the paradox. Water appears to have gushed willy-nilly across the Red Planet 3 to 4 billion years ago, so what’s up today?
Blame Mars’ wimpy atmosphere. Thicker, juicier air and the increase in atmospheric pressure that comes with it would keep the water in that cup stable. A thicker atmosphere would also seal in the heat, helping to keep the planet warm enough for liquid water to pool and flow.
Different ideas have been proposed to explain the putative thinning of the air including the loss of the planet’s magnetic field, which serves as a defense against the solar wind.
This figure shows a cross-section of the planet Mars revealing an inner, high density core buried deep within the interior. Magnetic field lines are drawn in blue, showing the global scale magnetic field associated with a dynamic core. Mars must have had such a field long ago, but today it’s not evident. Perhaps the energy source that powered the early dynamo shut down. Credit: NASA/JPL/GSFC
Convection currents within its molten nickel-iron core likely generated Mars’ original magnetic defenses. But sometime early in the planet’s history the currents stopped either because the core cooled or was disrupted by asteroid impacts. Without a churning core, the magnetic field withered, allowing the solar wind to strip away the atmosphere, molecule by molecule.
Solar wind eats away the Martian atmosphere
Measurements from NASA’s current MAVEN mission indicate that the solar wind strips away gas at a rate of about 100 grams (equivalent to roughly 1/4 pound) every second. “Like the theft of a few coins from a cash register every day, the loss becomes significant over time,” said Bruce Jakosky, MAVEN principal investigator.
This graph shows the percent amount of the five most abundant gases in the atmosphere of Mars, as measured by the Sample Analysis at Mars (SAM) instrument suite on the Curiosity rover in October 2012. The season was early spring in Mars’ southern hemisphere. Credit: NASA/JPL-Caltech, SAM/GSFC
Researchers from the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS) suggest a different, less cut-and-dried scenario. Based on their studies, early Mars may have been warmed now and again by a powerful greenhouse effect. In a paper published in Geophysical Research Letters, researchers found that interactions between methane, carbon dioxide and hydrogen in the early Martian atmosphere may have created warm periods when the planet could support liquid water on its surface.
The team first considered the effects of CO2, an obvious choice since it comprises 95% of Mars’ present day atmosphere and famously traps heat. But when you take into account that the Sun shone 30% fainter 4 billion years ago compared to today, CO2 alone couldn’t cut it.
“You can do climate calculations where you add CO2 and build up to hundreds of times the present day atmospheric pressure on Mars, and you still never get to temperatures that are even close to the melting point,” said Robin Wordsworth, assistant professor of environmental science and engineering at SEAS, and first author of the paper.
NASA’s Cassini spacecraft looks toward the night side of Saturn’s largest moon and sees sunlight scattering through the periphery of Titan’s atmosphere and forming a ring of color. The breakdown of methane at Titan into hydrogen and oxygen may also have occurred on Mars. The addition of hydrogen in the company of methane and carbon dioxide would have created a powerful greenhouse gas mixture, significantly warming the planet. Credit: NASA/JPL-Caltech/Space Science Institute
Carbon dioxide isn’t the only gas capable of preventing heat from escaping into space. Methane or CH4 will do the job, too. Billions of years ago, when the planet was more geologically active, volcanoes could have tapped into deep sources of methane and released bursts of the gas into the Martian atmosphere. Similar to what happens on Saturn’s moon Titan, solar ultraviolet light would snap the molecule in two, liberating hydrogen gas in the process.
When Wordsworth and his team looked at what happens when methane, hydrogen and carbon dioxide collide and then interact with sunlight, they discovered that the combination strongly absorbed heat.
Carl Sagan,American astronomer and astronomy popularizer, first speculated that hydrogen warming could have been important on early Mars back in 1977, but this is the first time scientists have been able to calculate its greenhouse effect accurately. It is also the first time that methane has been shown to be an effective greenhouse gas on early Mars.
This awesome image of the Tharsis region of Mars taken by Mars Express shows several prominent shield volcanoes including the massive Olympus Mons (at left). Volcanoes, when they were active, could have released significant amounts of methane into Mars’ atmosphere. Click for a larger version. Credit: ESA
When you take methane into consideration, Mars may have had episodes of warmth based on geological activity associated with earthquakes and volcanoes. There have been at least three volcanic epochs during the planet’s history — 3.5 billion years ago (evidenced by lunar mare-like plains), 3 billion years ago (smaller shield volcanoes) and 1 to 2 billion years ago, when giant shield volcanoes such as Olympus Monswere active. So we have three potential methane bursts that could rejigger the atmosphere to allow for a mellower Mars.
The sheer size of Olympus Mons practically shouts massive eruptions over a long period of time. During the in-between times, hydrogen, a lightweight gas, would have continued to escape into space until replenished by the next geological upheaval.
“This research shows that the warming effects of both methane and hydrogen have been underestimated by a significant amount,” said Wordsworth. “We discovered that methane and hydrogen, and their interaction with carbon dioxide, were much better at warming early Mars than had previously been believed.”
I’m tickled that Carl Sagan walked this road 40 years ago. He always held out hope for life on Mars. Several months before he died in 1996, he recorded this:
” … maybe we’re on Mars because of the magnificent science that can be done there — the gates of the wonder world are opening in our time. Maybe we’re on Mars because we have to be, because there’s a deep nomadic impulse built into us by the evolutionary process, we come after all, from hunter gatherers, and for 99.9% of our tenure on Earth we’ve been wanderers. And, the next place to wander to, is Mars. But whatever the reason you’re on Mars is, I’m glad you’re there. And I wish I was with you.”
An artist’s impression of what Mars might have looked like with water. Credit: ESO/M. Kornmesser
For some time, scientists have suspected that life may have existed on Mars in the deep past. Owing to the presence of a thicker atmosphere and liquid water on its surface, it is entirely possible that the simplest of organisms might have begun to evolve there. And for those looking to make Mars a home for humanity someday, it is hoped that these conditions (i.e favorable to life) could be recreated again someday.
But as it turns out, there are some terrestrial organisms that could survive on Mars as it is today. According to a recent study by a team of researchers from the Arkansas Center for Space and Planetary Sciences (ACSPS) at the University of Arkansas, four species of methanogenic microorganisms have shown that they could withstand one of the most severe conditions on Mars, which is its low-pressure atmosphere.
Methanogenic organisms that were found in samples of deep volcanic rocks along the Columbia River and in Idaho Falls. Credit: NASA
To put it simply, Methanogens are ancient group of organisms that are classified as archaea, a species of microorganism that do not require oxygen and can therefore survive in what we consider to be “extreme environments”. On Earth, methanogens are common in wetlands, ocean environments, and even in the digestive tracts of animals, where they consume hydrogen and carbon dioxide to produce methane as a metabolic byproduct.
And as several NASA missions have shown, methane has also been found in the atmosphere of Mars. While the source of this methane has not yet been determined, it has been argued that it could be produced by methanogens living beneath the surface. As Rebecca Mickol, an astrobiologist at the ACSPS and the lead author of the study, explained:
“One of the exciting moments for me was the detection of methane in the Martian atmosphere. On Earth, most methane is produced biologically by past or present organisms. The same could possibly be true for Mars. Of course, there are a lot of possible alternatives to the methane on Mars and it is still considered controversial. But that just adds to the excitement.”
As part of the ongoing effort to understand the Martian environment, scientists have spent the past 20 years studying if four specific strains of methanogen – Methanothermobacter wolfeii, Methanosarcina barkeri, Methanobacterium formicicum, Methanococcus maripaludis – can survive on Mars. While it is clear that they could endure the low-oxygen and radiation (if underground), there is still the matter of the extremely low air-pressure.
Graduate students Rebecca Mickol and Navita Sinha prepare to load methanogens into the Pegasus Chamber housed in W.M. Keck Laboratory. Credit: University of Arkansas
With help from the NASA Exobiology & Evolutionary Biology Program (part of NASA’s Astrobiology Program), which issued them a three-year grant back in 2012, Mickol and her team took a new approach to testing these methanogens. This included placing them in a series of test tubes and adding dirt and fluids to simulate underground aquifers. They then fed the samples hydrogen as a fuel source and deprived them of oxygen.
The next step was subjecting the microorganisms to pressure conditions analogues to Mars to see how they might hold up. For this, they relied on the Pegasus Chamber, an instrument operated by the ACSPS in their W.M. Keck Laboratory for Planetary Simulations. What they found was that the methanogens all survived exposure to pressures of 6 to 143 millibars for periods of between 3 and 21 days.
This study shows that certain species of microorganisms are not dependent on a the presence of a dense atmosphere for their survival. It also shows that these particular species of methanogens could withstand periodic contact with the Martian atmosphere. This all bodes well for the theories that Martian methane is being produced organically – possibly in subsurface, wet environments.
This is especially good news in light of evidence provided by NASA’s HiRISE instrument concerning Mars’ recurring slope lineae, which pointed towards a possible connection between liquid water columns on the surface and deeper levels in the subsurface. If this should prove to be the case, then organisms being transported in the water column would be able to withstand the changing pressures during transport.
The possible ways methane might get into Mars’ atmosphere, ranging from subsurface microbes and weathering of rock and stored methane ice called a clathrate. Ultraviolet light can work on surface materials to produce methane as well as break it apart into other molecules (. Credit: NASA/JPL-Caltech/SAM-GSFC/Univ. of Michigan
The next step, according to Mickol is to see how these organisms can stand up to temperature. “Mars is very, very cold,” she said, “often getting down to -100ºC (-212ºF) at night, and sometimes, on the warmest day of the year, at noon, the temperature can rise above freezing. We’d run our experiments just above freezing, but the cold temperature would limit evaporation of the liquid media and it would create a more Mars-like environment.”
Scientists have suspected for some time that life may still be found on Mars, hiding in recesses and holes that we have yet to peek into. Research that confirms that it can indeed exist under Mars’ present (and severe) conditions is most helpful, in that it allows us to narrow down that search considerably.
In the coming years, and with the deployment of additional Mars missions – like NASA’s Interior Exploration using Seismic Investigations, Geodesy and Heat Transport (InSight) lander, which is scheduled for launch in May of next year – we will be able to probe deeper into the Red Planet. And with sample return missions on the horizon – like the Mars 2020 rover – we may at last find some direct evidence of life on Mars!
This peculiar rock, photographed on Jan. 12 (Sol 1577) by NASA's Curiosity rover, appears to be a metal meteorite. When confirmed, this will be the rover's third meteorite find on the Red Planet. Click for the high resolution original. Credit: NASA/JPL-Caltech/MSSS
This peculiar rock, photographed on Jan. 12 (Sol 1577) by NASA’s Curiosity rover, appears to be a metal meteorite. When confirmed, this would be the rover’s third meteorite find on the Red Planet. Click for the high resolution original. Credit: NASA/JPL-Caltech/MSSS
Rolling up the slopes of Mt. Sharp recently, NASA’s Curiosity rover appears to have stumbled across yet another meteorite, its third since touching down nearly four and a half years ago. While not yet confirmed, the turkey-shaped object has a gray, metallic luster and a lightly-dimpled texture that hints of regmaglypts. Regmaglypts, indentations that resemble thumbprints in Play-Doh, are commonly seen in meteorites and caused by softer materials stripped from the rock’s surface during the brief but intense heat and pressure of its plunge through the atmosphere.
Oddly, only one photo of the assumed meteorite shows up on the Mars raw image site. Curiosity snapped the image on Jan. 12 at 11:21 UT with its color mast camera. If you look closely at the photo a short distance above and to the right of the bright reflection a third of the way up from the bottom of the rock, you’ll spy three shiny spots in a row. Hmmm. Looks like it got zapped by Curiosity’s ChemCam laser. The rover fires a laser which vaporizes part of the meteorite’s surface while a spectrometer analyzes the resulting cloud of plasma to determine its composition. The mirror-like shimmer of the spots is further evidence that the gray lump is an iron-nickel meteorite.
Meet Egg Rock, another iron-nickel meteorite and Curiosity’s second meteorite find. The white spots/holes are where the object was zapped by the rover’s laser to determine its composition. The rover spotted Egg Rock (about the size of a golfball) on Oct. 27, 2016. Credit: NASA/JPL-Caltech
Curiosity has driven more than 9.3 miles (15 km) since landing inside Mars’ Gale Crater in August 2012. It spent last summer and part of fall in a New Mexican-like landscape of scenic mesas and buttes called “Murray Buttes.” It’s since departed and continues to climb to sequentially higher and younger layers of the lower part of Mt. Sharp to investigate additional rocks. Scientists hope to create a timeline of how the region’s climate changed from an ancient freshwater lake environment with conditions favorable for microbial life (if such ever evolved) to today’s windswept, frigid desert.
Assuming the examination of the rock proves a metallic composition, this new rock would be the eighth discovered by our roving machines. All of them have been irons despite the fact that at least on Earth, iron meteorites are rather rare. About 95% of all found or seen-to-fall meteorites are the stony variety (mostly chondrites), 4.4% are irons and 1% stony-irons.
Curiosity found this iron meteorite called “Lebanon” back in 2014. It’s about two yards or two meters wide (left to right). The smaller piece in the foreground is named “Lebanon B. This photo combines a series of high-resolution circular images across the middle taken by the Remote Micro-Imager (RMI) with a MastCam image. Credit: NASA/JPL-Caltech/LANL/CNES/IRAP/LPGNantes/CNRS/IAS/MSSS
NASA’s Opportunity rover found five metal meteorites, and Curiosity’s rumbled by its first find, a honking hunk of metallic gorgeousness named Lebanon, in May 2014. If this were Earth, the new meteorite’s smooth, shiny texture would indicate a relatively recent fall, but who’s to say how long it’s been sitting on Mars. The planet’s not without erosion from wind and temperature changes, but it lacks the oxygen and water that would really eat into an iron-nickel specimen like this one. Still, the new find looks polished to my eye, possibly smoothed by wind-whipped sand grains during the countless Martian dust storms that have raged over the eons.
Curiosity really knows how to put you on Mars. This view of exposed bedrock and dark sands was taken by the rover’s navigation camera on Friday, Jan. 13. Credit: NASA/JPL-Caltech/MSSS
Why no large stony meteorites have yet to be been found on Mars is puzzling. They should be far more common; like irons, stonies would also display beautiful thumprinting and dark fusion crust to boot. Maybe they simply blend in too well with all the other rocks littering the Martian landscape. Or perhaps they erode more quickly on Mars than the metal variety.
Every time a meteorite turns up on Mars in images taken by the rovers, I get a kick out of how our planet and the Red One not only share water, ice and wind but also getting whacked by space rocks.
A view of Earth and its Moon, as seen from Mars. It combines two images acquired on Nov. 20, 2016, by the HiRISE camera on NASA's Mars Reconnaissance Orbiter, with brightness adjusted separately for Earth and the moon to show details on both bodies. Credit: NASA/JPL-Caltech/Univ. of Arizona.
The incredible HiRISE camera on board the Mars Reconnaissance Orbiter turned its eyes away from its usual target – Mars’ surface – and for calibration purposes only, took some amazing images of Earth and our Moon. Combined to create one image, this is a marvelous view of our home from about 127 million miles (205 million kilometers) away.
Alfred McEwen, principal investigator for HiRISE said the image is constructed from the best photo of Earth and the best photo of the Moon from four sets of images. Interestingly, this combined view retains the correct positions and sizes of the two bodies relative to each other. However, Earth and the Moon appear closer than they actually are in this image because the observation was planned for a time at which the Moon was almost directly behind Earth, from Mars’ point of view, to see the Earth-facing side of the Moon.
A view of Earth and its Moon, as seen from Mars. It combines two images acquired on Nov. 20, 2016, by the HiRISE camera on NASA’s Mars Reconnaissance Orbiter, with brightness adjusted separately for Earth and the moon to show details on both bodies. Credit: NASA/JPL-Caltech/Univ. of Arizona.
“Each is separately processed prior to combining (in correct relative positions and sizes), so that the Moon is bright enough to see,” McEwen wrote on the HiRISE website. “The Moon is much darker than Earth and would barely show up at all if shown at the same brightness scale as Earth. Because of this brightness difference, the Earth images are saturated in the best Moon images, and the Moon is very faint in the best (unsaturated) Earth image.”
Earth looks reddish because the HiRISE imaging team used color filters similar to the Landsat images where vegetation appears red.
“The image color bandpasses are infrared, red, and blue-green, displayed as red, green, and blue, respectively,” McEwen explained. “The reddish blob in the middle of the Earth image is Australia, with southeast Asia forming the reddish area (vegetation) near the top; Antarctica is the bright blob at bottom-left. Other bright areas are clouds. We see the western near-side of the Moon.”
HiRISE took these pictures on Nov. 20, 2016, and this is not the first time HiRISE has turned its eyes towards Earth.
Back in 2007, HiRISE took this image, below, from Mars’ orbit when it was just 88 million miles (142 million km) from Earth. This one is more like how future astronauts might see Earth and the Moon through a telescope from Mars’ orbit.
An image of Earth and the Moon, acquired on October 3, 2007, by the HiRISE camera on NASA’s Mars Reconnaissance Orbiter. Credit: NASA/JPL-Caltech/University of Arizona.
If you look closely, you can make out a few features on our planet. The west coast outline of South America is at lower right on Earth, although the clouds are the dominant features. In fact, the clouds were so bright, compared with the Moon, that they almost completely saturated the filters on the HiRISE camera. The people working on HiRISE say this image required a fair amount of processing to make such a nice-looking picture.
You can see an image from a previous Mars’ orbiter, the Mars Global Surveyor, that took a picture of Earth, the Moon and Jupiter — all in one shot — back in 2003 here.
NASA’s Opportunity rover scans around and across to vast Endeavour crater on Dec. 19, 2016, as she climbs steep slopes on the way to reach a water carved gully along the eroded craters western rim. Note rover wheel tracks at center. This navcam camera photo mosaic was assembled from raw images taken on Sol 4587 (19 Dec. 2016) and colorized. Credit: NASA/JPL/Cornell/Ken Kremer/kenkremer.com/Marco Di Lorenzo
NASA’s Opportunity rover scans around and across to vast Endeavour crater on Dec. 19, 2016, as she climbs steep slopes on the way to reach a water carved gully along the eroded craters western rim. Note rover wheel tracks at center. This navcam camera photo mosaic was assembled from raw images taken on Sol 4587 (19 Dec. 2016) and colorized. Credit: NASA/JPL/Cornell/Ken Kremer/kenkremer.com/Marco Di Lorenzo
On the brink of 4600 Sols of a profoundly impactful life, NASA’s long lived Opportunity rover celebrates the Christmas/New Year’s holiday season on Mars marching relentlessly towards an ancient water carved gully along the eroded rim of vast Endeavour crater – the next science target on her heroic journey traversing across never before seen Red Planet terrains.
“Opportunity is continuing its great 21st century natural history expedition on Mars, exploring the complex geology and record of past climate here on the rim of the 22-km Endeavour impact crater,” writes Larry Crumpler, a science team member from the New Mexico Museum of Natural History & Science, in a mission update.
Indeed, New Years Day 2017 equates to 4600 Sols, or Martian Days – of boundless exploration and epic discovery by the longest living Martian rover ever dispatched by humanity to survey the most Earth-like planet in our solar system.
One can easily imagine our beloved Princess Leia gazing quite proudly upon the feistiness and resourcefulness of this never-give-up Martian Princess rover – climbing steeply uphill no less – nearly 13 YEARS into her 3 MONTH mission!!
“Not a boring flat terrain, but heroically rugged terrain,” says Crumpler.
“Hopefully the brakes are good! For a rover that originally landed 12 years ago on what amounts to a flat parking lot, the current terrain is about as different and rugged as any mountain goat rover could handle.”
Indeed she is 51 times beyond her “warrantied” life expectancy of merely 90 Sols roving the surface of the 4th rock from the Sun during her latest extended mission. (And this time round, the clueless Washington bean counters did not even dare threaten to shut her down – lest they suffer the wrath of a light saber or sister Curiosity’s laser canon !!).
Check out the glorious view from Opportunity’s current Martian holiday season exploits in our newest photo mosaics created by the imaging team of Ken Kremer and Marco Di Lorenzo.
“Opportunity has begun the ascent of the steep slopes here in the inner wall of Endeavour impact crater after completion of a survey of outcrops close to the crater floor. The goal now is to climb back to the rim where the terrain is less hazardous, drive south quickly about 1 km south, and arrive at the next major mission target on the rim before the next Martian winter,” Crumpler elaborated.
On Christmas Day 2016, NASA’s Opportunity rover scans around vast Endeavour crater as she ascends steep rocky slopes on the way to reach a water carved gully along the eroded craters western rim. This navcam camera photo mosaic was assembled from raw images taken on Sol 4593 (25 Dec. 2016) and colorized. Credit: NASA/JPL/Cornell/Ken Kremer/kenkremer.com/Marco Di Lorenzo
After surviving the scorching ‘6 minutes of Terror’ plummet through the thin Martian atmosphere, Opportunity bounced to an airbag cushioned landing on the plains of Meridiani Planum on January 24, 2004 – nearly 13 years ago!
Opportunity was launched on a Delta II rocket from Cape Canaveral Air Force Station in Florida on July 7, 2003.
NASA’s Opportunity rover scans ahead to Spirit Mound and vast Endeavour crater as she celebrates 4500 sols on the Red Planet after descending down Marathon Valley. This navcam camera photo mosaic was assembled from raw images taken on Sol 4500 (20 Sept 2016) and colorized. Credit: NASA/JPL/Cornell/ Ken Kremer/kenkremer.com/Marco Di Lorenzo
The newest 2 year extended mission phase just began on Oct. 1, 2016 as the six wheeled robot was stationed at the western rim of Endeavour crater at the bottom of Marathon Valley at a spot called “Bitterroot Valley” and completing investigation of nearby “Spirit Mound.”
She is now ascending back up to the top of the crater rim for the southward trek to ‘the gully’ in 2017.
“Opportunity is making progress towards the next science objective of the extended mission,” researchers leading the Mars Exploration Rover (MER) Opportunity mission wrote in a status update.
“The rover is headed toward an ancient water-carved gully about a kilometer south of the rover’s current location on the rim of Endeavour Crater.”
Endeavour crater spans some 22 kilometers (14 miles) in diameter.
Opportunity has been exploring Endeavour since arriving at the humongous crater in 2011. Endeavour crater was formed when it was carved out of the Red Planet by a huge meteor impact billions of years ago.
“Endeavour crater dates from the earliest Martian geologic history, a time when water was abundant and erosion was relatively rapid and somewhat Earth-like,” Crumpler explains.
“So in addition to exploring the geology of a large crater, a type of feature that no one has ever explored in its preserved state, the mission seeks to take a close look at the evidence in the rocks for the past environment. Thus we are trying to stick to the crater rim where the oldest rocks are.”
But the crater slopes ahead are steep! As much as 20 degrees and more – and thus potentially dangerous! So the team is commanding Opportunity to proceed ahead with caution to “the gully” which is the primary target of her latest extended mission.
The rover has even done “quite a bit of exploratory driving in an effort to attain a good vantage point for finding a path through a troubling area of boulder patch and steep slopes ahead. The concern was whether the available routes to avoid the boulders were all too steep to traverse, in which case we would have to forgo the current ‘Extended Mission 10’ (EM10) route and backtrack to find a different route to our main objective, the ‘gully.’”
“The slopes here exceed 20 degrees and the surface consists of flat outcrops of impact breccias covered with tiny rocks that act like ball bearings,” Crumpler writes. “Anyone who has attempted to walk on a 20 degree slope with a covering of fine pebbles on hard outcrop can attest to the difficulty. Opportunity has been operating at these extreme slope for several months. But going down hill is one thing, And going back up hill is another entirely.”
NASA’s Opportunity rover discovers a beautiful Martian dust devil moving across the floor of Endeavour crater as wheel tracks show robots path today exploring the steepest ever slopes of the 13 year long mission, in search of water altered minerals at Knudsen Ridge inside Marathon Valley on 1 April 2016. This navcam camera photo mosaic was assembled from raw images taken on Sol 4332 (1 April 2016) and colorized. Credit: NASA/JPL/Cornell/ Ken Kremer/kenkremer.com/Marco Di Lorenzo
As of today, Sol 4598, Dec. 29, 2016, Opportunity has taken over 215,900 images and traversed over 27.12 miles (43.65 kilometers) – more than a marathon.
See our updated route map below.
The rover surpassed the 27 mile mark milestone early last month on November 6 (Sol 4546).
The power output from solar array energy production is currently 414 watt-hours, before heading into another southern hemisphere Martian winter in 2017.
Meanwhile Opportunity’s younger sister rover Curiosity traverses and drills into the lower sedimentary layers at the base of Mount Sharp.
Stay tuned here for Ken’s continuing Earth and planetary science and human spaceflight news.
13 Year Traverse Map for NASA’s Opportunity rover from 2004 to 2016. This map shows the entire 43 kilometer (27 mi) path the rover has driven on the Red Planet during nearly 13 years and more than a marathon runners distance for some 4600 Sols, or Martian days, since landing inside Eagle Crater on Jan 24, 2004 – to current location at the western rim of Endeavour Crater. After descending down Marathon Valley and after studying Spirit Mound, the rover is now ascending back uphill on the way to a Martian water carved gully. Rover surpassed Marathon distance on Sol 3968 after reaching 11th Martian anniversary on Sol 3911. Opportunity discovered clay minerals at Esperance – indicative of a habitable zone – and searched for more at Marathon Valley. Credit: NASA/JPL/Cornell/ASU/Marco Di Lorenzo/Ken Kremer/kenkremer.com
Artist concept of the Mars Ice Home. Credit: NASA.
At first glance, a new concept for a NASA habitat on Mars looks like a cross between Mark Watney’s inflatable potato farm from “The Martian” and the home of Luke’s Uncle Owen on Tatooine from “Star Wars.”
The key to the new design relies on something that may or may not be abundant on Mars: underground water or ice.
The “Mars Ice Home” is a large inflatable dome that is surrounded by a shell of water ice. NASA said the design is just one of many potential concepts for creating a sustainable home for future Martian explorers. The idea came from a team at NASA’s Langley Research Center that started with the concept of using resources on Mars to help build a habitat that could effectively protect humans from the elements on the Red Planet’s surface, including high-energy radiation.
The Mars Ice Home concept. Credit: Clouds Architecture Office, NASA Langley Research Center, Space Exploration Architecture.
Langley senior systems engineer Kevin Vipavetz who facilitated the design session said the team assessed “many crazy, out of the box ideas and finally converged on the current Ice Home design, which provides a sound engineering solution,” he said.
The advantages of the Mars Ice Home is that the shell is lightweight and can be transported and deployed with simple robotics, then filled with water before the crew arrives. The ice will protect astronauts from radiation and will provide a safe place to call home, NASA says. But the structure also serves as a storage tank for water, to be used either by the explorers or it could potentially be converted to rocket fuel for the proposed Mars Ascent Vehicle. Then the structure could be refilled for the next crew.
A cutaway of the interior of the Mars Ice Home concept. Credit: NASA Langley/Clouds AO/SEArch.
Other concepts had astronauts living in caves, or underground, or in dark, heavily shielded habitats. The team said the Ice Home concept balances the need to provide protection from radiation, without the drawbacks of an underground habitat. The design maximizes the thickness of ice above the crew quarters to reduce radiation exposure while also still allowing light to pass through ice and surrounding materials.
Team members of the Ice Home Feasibility Study discuss past and present technology development efforts in inflatable structures at NASA’s Langley Research Center. Credits: Courtesy of Kevin Kempton/NASA.
“All of the materials we’ve selected are translucent, so some outside daylight can pass through and make it feel like you’re in a home and not a cave,” said Kevin Kempton, also part of the Langley team.
One key constraint is the amount of water that can be reasonably extracted from Mars. Experts who develop systems for extracting resources on Mars indicated that it would be possible to fill the habitat at a rate of one cubic meter, or 35.3 cubic feet, per day. This rate would allow the Ice Home design to be completely filled in 400 days, so the habitat would need to be constructed robotically well before the crew arrives. The design could be scaled up if water could be extracted at higher rates.
The team wanted to also include large areas for workspace so the crew didn’t have to wear a pressure suit to do maintenance tasks such as working on robotic equipment. To manage temperatures inside the Ice Home, a layer of carbon dioxide gas — also available on Mars — would be used as in insulation between the living space and the thick shielding layer of ice.
“The materials that make up the Ice Home will have to withstand many years of use in the harsh Martian environment, including ultraviolet radiation, charged-particle radiation, possibly some atomic oxygen, perchlorates, as well as dust storms – although not as fierce as in the movie ‘The Martian’,” said Langley researcher Sheila Ann Thibeault.
Artist's impression of geysers at the Martian south polar icecap as southern spring begins. Credit: NASA/JPL-Caltech/Arizona State University/Ron Miller
For years, scientists have understood that in Mars’ polar regions, frozen carbon dioxide (aka. dry ice) covers much of the surface during the winter. During the spring, this ice sublimates in places, causing the ice to crack and jets of CO² to spew forth. This leads to the formation of dark fans and features known as “spiders”, both of which are unique to Mars’ southern polar region.
For the past decade, researchers have failed to see these features changing from year-to-year, where repeated thaws have led to their growth. However, using data from the Mars Reconnaissance Orbiter‘s (MRO) HiRISE camera, a research team from the University of Colorado, Boulder and the Planetary Science Institute in Arizona have managed to catch sight of the cumulative growth of a spider for the first time from one spring to the next.
Spiders are so-named because of their appearance, where multiple channels converge on a central pit. Dark fans, on the other hand, are low-albedo patches that are darker than the surrounding ice sheet. For some time, astronomers have been observed these features in the southern polar region of Mars, and multiple theories were advanced as to their origin.
HiRISE images of the Martian landscape, showing outgassing and the formation of dark fans and “spiders”. Credit: NASA/JPL
In 2007, Hugh Kieffer of the Space Science Institute in Boulder, Colorado theorized that the dark fans and spiders were linked, and that both features were the result of spring thaws. In short, during Mars’ spring season – when the southern polar region is exposed to more sunlight – the Sun’s rays penetrates the ice sheets and warm the ground underneath.
This causes gas flows to form beneath the ice that build up pressure, eventually causing the ice to crack and triggering geysers. These geysers deposit mineral dust and sand across the surface downwind from the eruption, while the cracks in the ice grow and become visible from orbit. While this explanation has been widely-accepted, scientists have been unable to observe this process in action.
By using data from the MRO’s High Resolution Imaging Science Experiment (HiRISE), the research team was able to spot a small-channeled troughs in the southern region which persisted and grew over a three year period. In addition to closely resembling spidery terrain, it was in proximity to dark fan sites. From this, they determined that they were witnessing a spider that was in the process of formation.
As Dr. Ganna Portyankina – a researcher from the Laboratory for Atmospheric and Space Physics at the University of Colorado, Boulder, and the lead author on the team’s research paper – explained to Universe Today via email,
“We have observed different changes in the surface caused by CO² jets before. However, they all were either seasonal changes in surface albedo, like dark fans, or they were only short-lived and were gone the next year, like furrows. This time, the troughs have stayed over several years and they develop dendritic-type of extension – right the way we expect the large spiders to develop.”
Spiders trace a delicate pattern on top of the residual polar cap, after the seasonal carbon-dioxide ice slab has disappeared. Next spring, these will likely mark the sites of vents when the CO2 icecap returns. This MOC image is about 2 miles wide. Credit: NASA/JPL/MSSS
Furrows that were similar to the spidery terrain have been spotted at Mars’ north pole in the past, which coincided with a Martian spring. On these occasions, scientists using data from HiRISE instrument reported seeing small furrows on sand dunes, where eruptions had deposited dark fans. However, in what is typical of northern furrows, these were non-persisting annual occurrences, disappearing when summer winds deposited sand in them.
In contrast, the troughs Dr. Portyankina and her team observed in the southern polar region were persistent over a three-year period. During this time, these features extended and developed new “tributaries”, forming a dendritic pattern that resembled a Martian spider. From this, they concluded that the previously-observed northern furrows have the same cause – i.e. sublimation causing outgassing.
However, they also concluded that the northern furrows do not develop over time because of the high-mobility of dune material in the northern polar region. The difference, it seems, comes down to the presence of erosive sand material in the north and south, which creates (or starts) the erosive process that leads to the formation of spider-like troughs – which both kick-stars the process but can also erase it.
“Many locations in the south polar regions with seasonal dark fans show no visible sand deposits,” said Dr. Portyankina. “Dark fans in those locations might be only a mix of regolith and dust, or even just dust on its own – as it is really everywhere on Mars… [T]hose locations that have sand will experience higher erosion simply because there is granular material in the gas flow. Basically, it is old simple sandblasting. This means, it must be easier and faster to carve spiders in those locations.”
Images of dark spots (left) and fans (right) observed on top of the Martian south polar cap taken in southern spring. Credit: NASA/JPL/MSSS
In other words, where sand exists beneath the ice sheet, the ground beneath that is likely to be rockier (i.e. harder)> The formation of spider terrain may thereofre require that the ground beneath the ice be soft enough to be carved, but not so loose that it will refill the channels during a single seasonal cycle. In short, the formation of spidery terrain appears to be dependent upon the difference in surface composition between the poles.
In addition, from the many year’s of HiRISE data that has been accumulated, Dr. Portyankina and her team were also able to gauge the current rate of erosion in Mars’ southern polar region. Ultimately, they estimated that smaller spider-like furrows would require a thousand Martian years (about 1,900 Earth years) in order to become a full-scale spider.
This study is certainly significant, since understanding how seasonal changes and present-day erosion lead to the creation of new topographical features is important when it comes to understanding the processes that shape Mars’ polar regions. As we get closer and closer to the day when crewed missions and even settlement become a reality, knowing how these processes shape the planet will be fundamental to making a go of things on Mars.
This self-portrait of NASA's Curiosity Mars rover shows the vehicle at the "Big Sky" site. Credit: NASA/JPL-Caltech/MSSS
Following is the final excerpt from my new book, “Incredible Stories From Space: A Behind-the-Scenes Look at the Missions Changing Our View of the Cosmos.” The book is an inside look at several current NASA robotic missions, and this excerpt is part 3 of 3 posted here on Universe Today, of Chapter 2, “Roving Mars with Curiosity.” You can read Part 1 here, and Part 2 here. The book is available in print or e-book (Kindle or Nook) Amazon and Barnes & Noble.
How to Drive a Mars Rover
How does Curiosity know where and how to drive across Mars’ surface? You might envision engineers at JPL using joysticks, similar to those used for remote control toys or video games. But unlike RC driving or gaming, the Mars rover drivers don’t have immediate visual inputs or a video screen to see where the rover is going. And just like at the landing, there is always a time delay of when a command is sent to the rover and when it is received on Mars.
“It’s not driving in a real-time interactive sense because of the time lag,” explained John Michael Morookian, who leads the team of rover drivers.
The actual job title of Morookian and his team are ‘Rover Planners,’ which precisely describes what they do. Instead of ‘driving’ the rovers per se; they plan out the route in advance, program specialized software, and upload the instructions to Curiosity.
“We use images taken by the rover of its surroundings,” said Morookian. “We have a set of stereo images from four black-and-white Navigation Cameras, along with images from the Hazcams (hazard avoidance cameras), supported by high-resolution color images from the MastCam that give us details about the nature of the terrain ahead and clues about types of rocks and minerals at the site. This helps identify structures that look interesting to the scientists.”
Using all available data, they can create a three-dimensional visualization of the terrain with specialized software called the Rover Sequencing and Visualization Program (RSVP).
“This is basically a Mars simulator and we put a simulated Curiosity in a panorama of the scene to visualize how the rover could traverse on its path,” Morookian explained. “We can also put on stereo glasses, which allow our eyes to see the scene in three dimensions as if we were there with the rover.
In virtual reality, the rover drivers can manipulate the scene and the rover to test every possibility of which routes are the best and what areas to avoid. There, they can make all the mistakes (get stuck in a dune, tip the rover, crash into a big rock, drive off a precipice) and perfect the driving sequence while the real rover remains safe on Mars.
“The scientists also review the images for features that are interesting and consult with the Rover Planners to help define a path. Then we compose the detailed commands that are necessary to get Curiosity from Point A to Point B along that path,” Morookian said. “”We can also incorporate the commands needed to give the rover direction to make contact with the site using its robotic arm.”
When Curiosity’s Navigation Cameras (Navcams) take black-and-white images and send them back to Earth each day, rover planners combine them with other rover data to create 3D terrain models. By adding a computerized 3D rover model to the terrain model, rover planners can understand better the rover’s position, as well as distances to, and scale of, features in the landscape. Credit: NASA/JPL-Caltech.
So, every night the rover is commanded to shut down for eight hours to recharge its batteries with the nuclear generator. But first Curiosity sends data to Earth, including pictures of the terrain and any science information. On Earth, the Rover Planners take that data, do their planning work, complete the software programing and beam the information back to Mars. Then Curiosity wakes up, downloads the instructions and sets to work. And the cycle repeats.
Curiosity also has an AutoNav feature which allows the rover to traverse areas the team hasn’t seen yet in images. So, it could go over the hill and down the other side to uncharted territory, with the AutoNav sensing potential hazards.
“We don’t use it too often because it is computationally expensive, meaning it takes much longer for the rover to operate in that mode,” Morookian said. “We often find it’s a better trade to just come in the next day, look at the images and drive as far as we can see.”
A view of the Space Flight Operations Facility at the Jet Propulsion Laboratory, where all the data going both to and from all planetary missions is sent and received via the Deep Space Network. Credit: Nancy Atkinson.
As Morookian showed me the various rooms used by rover planning teams at JPL, he explained how they need to operate over a number of different timescales.
“We not only have the daily route planning,” he said, “but also do long-range strategic planning using orbital imagery from the HiRISE camera on the Mars Reconnaissance Orbiter and choose paths based on features seen from orbit. Our team works strategically, looking many months out to define the best paths.”
Another process called Supra-Tactical looks out to just the next week. This involves science planners managing and refining the types of activities the rover will be doing in the short term. Also, since no one on the team lives on Mars Time anymore, on Fridays the Rover Planners work out the plans for several days.
“Since we don’t work weekends, Friday plans contain multiple sols of activities,” Morookian said. “Two parallel teams decide which days the rover will drive and which days it will do other activities, such as work with the robotic arm or other instruments.”
The data that comes down from the rover over the weekend is monitored, however, and if there is a problem, a team is called in to do a more detailed assessment. Morookian indicated they’ve had to engage the emergency weekend team several times, but so far there have been no serious problems. “It does keep us on our toes, however,” he said.
The rover features a number of reactive safety checks on the amount of overall tilt of the rover deck and the articulation of the suspension system of the wheels, so if the rover is going over an object that is too large, it will automatically stop.
Curiosity wasn’t built for speed. It was designed to travel up to 660 feet (200 meters) in a day, but it rarely travels that far in a Sol. By early 2016 the rover had driven a total of about 7.5 miles (12 km) across Mars’ surface.
This image shows a close-up of track marks left by the Curiosity rover. Holes in the rover’s wheels, seen here in this view, leave imprints in the tracks that can be used to help the rover drive more accurately. The imprint is Morse code for ‘JPL,’ and aids in tracking how far the rover has traveled. Credit: NASA/JPL-Caltech.
There are several ways to determine how far Curiosity has traveled, but the most accurate measurement is called ‘Visual Odometry.’ Curiosity has specialized holes in its wheels in the shape of Morse code letters, spelling out ‘JPL’ – a nod to the home of the rover’s science and engineering teams – across the Martian soil.
“Visual odometry works by comparing the most recent pair of stereo images collected roughly every meter over the drive,” said Morookian. “Individual features in the scene are matched and tracked to provide a measure of how the camera (and thus the rover) has translated and rotated in 3 dimensional space between the two images and it tells us in a very real sense how far Curiosity has gone.”
Careful inspection of the rover tracks can reveal the type of traction the wheels have and if they have slipped, for instance due to high slopes or sandy ground.
Unfortunately, Curiosity now has new holes in its wheels that aren’t supposed to be there.
Rover Problems
Morookian and Project Scientist Ashwin Vasavada both expressed relief and satisfaction that overall — this far into the mission — Curiosity is a fairly healthy rover. The entire science payload is currently operating at nearly full capability. But the engineering team keeps an eye on a few issues.
“Around sol 400, we realized the wheels were wearing faster than we expected,” Vasavada said.
The team operating the Curiosity Mars rover uses the Mars Hand Lens Imager (MAHLI) camera on the rover’s arm to check the condition of the wheels at routine intervals. This image of Curiosity’s left-middle and left-rear wheels is part of an inspection set taken on April 18, 2016, during the 1,315th sol of the rover’s work on Mars. Credit: NASA/JPL-Caltech/MSSS.
And the wear didn’t consist of just little holes; the team started to see punctures and nasty tears. Engineers realized the holes were being created by the hard, jagged rocks the rover was driving over during that time.
“We weren’t fully expecting the kind of ‘pointy’ rocks that were doing damage,” Vasavada said. “We also did some testing and saw how one wheel could push another wheel into a rock, making the damage worse. We now drive more carefully and don’t drive as long as we have in the past. We’ve been able to level off the damage to a more acceptable rate.”
Early in the mission, Curiosity’s computer went into ‘safe mode’ several times, as Curiosity’s software recognized a problem, and the response was to disallow further activity and phone home.
Specialized fault protection software runs throughout the modules and instruments, and when a problem occurs, the rover stops and sends data called ‘event records’ to Earth. The records include various categories of urgency, and in early 2015, the rover sent a message that essentially said, “This is very, very bad.” The drill on the rover’s arm had experienced a fluctuation in an electrical current – like a short circuit.
“Curiosity’s software has the ability to detect shorts, like the ground fault circuit interrupter you have in your bathroom,” Morookian explained, “except this one tells you ‘this is very, very bad’ instead of just giving you a yellow light.”
Since the team can’t go to Mars and repair a problem, everything is fixed either by sending software updates to the rover or by changing operational procedures.
Curiosity’s drill in the turret of tools at the end of the robotic arm positioned in contact with the rock surface for the first drilling of the mission on the 170th sol of Curiosity’s work on Mars (Jan. 27, 2013) in Yellowknife Bay. The picture was taken by the front Hazard-Avoidance Camera (Hazcam). Image credit: NASA/JPL-Caltech.
“We are just more careful now with how we use the drill,” Vasavada said, “and don’t drill with full force at the beginning, but slowly ramp up. It’s sort of like how we drive now, more gingerly but it still gets the job done. It hasn’t been a huge impact as of yet.”
A lighter touch on the drill also was necessary for the softer mudstones and sandstones the rover encountered. Morookian said there was concern the layered rocks might not hold up under the assault of the standard drilling protocol, and so they adjusted the technique to use the lowest ‘settings’ that still allows the drill to make sufficient progress into the rock.
But opportunities to use the drill are increasing as Curiosity begins its traverse up the mountain. The rover is traveling through what Vasavada calls a “target rich, very interesting area,” as the science team works to tie together the geological context of everything they are seeing in the images.
Finding Balance on Mars
While the diversion at Yellowknife Bay allowed the team to make some major discoveries, they felt pressure to get to Mt. Sharp, so “drove like hell for a year,” Vasavada said.
Now on the mountain, there is still the pressure to make the most of the mission, with the goal of making it through at least four different rock units – or layers — on Mt. Sharp. Each layer could be like a chapter in the book of Mars’ history.
A portion of a panorama from Curiosity’s Mastcam shows the rugged surface of ‘Naukluft Plateau’ plus part of the rim of Gale Crater, taken on April 4, 2016 or Sol 1301. Credit: NASA/JPL-Caltech/MSSS
“Exploring Mt. Sharp is fascinating,” Vasavada said, “and we’re trying to maintain a mix between really great discoveries, which – you hate to say — slows us down, and getting higher on the mountain. Looking closely at a rock in front of you means you’ll never be able to go over and look at that other interesting rock over there.”
Vasavada and Morookian both said it’s a challenge to preserve that balance every day — to find what’s called the ‘knee in the curve’ or ‘sweet spot’ of the perfect optimization between driving and stopping for science.
Then there’s the balance between stopping to do a full observation with all the instruments and doing ‘flyby science’ where less intense observations are made.
“We take the observations we can, and generate all the hypotheses we can in real time,” Vasavada said. “Even if we’re left with 100 open questions, we know we can answer the questions later as long as we know we’ve taken enough data.”
Curiosity’s primary target is not the summit, but instead a region about 1,330 feet (400 meters) up where geologists expect to find the boundary between rocks that saw a lot of water in their history, and those that didn’t. That boundary will provide insight into Mars’ transition from a wet planet to dry, filling in a key gap in the understanding of the planet’s history.
he Curiosity rover recorded this view of the Sun setting at the close of the mission’s 956th sol (April 15, 2015), from the rover’s location in Gale Crater. This was the first sunset observed in color by Curiosity. The image comes from the left-eye camera of the rover’s Mast Camera (Mastcam). Credit: NASA/JPL-Caltech/MSSS/Texas A&M University.
No one really knows how long Curiosity will last, or if it will surprise everyone like its predecessors Spirit and Opportunity. Having made it past the ‘prime mission’ of one year on Mars (two Earth years), and now in the extended mission, the one big variable is the RTG power source. While the available power will start to steadily decrease, both Vasavada and Morookian don’t expect that to be in an issue for at least four more Earth years, and with the right “nurturing,” power could last for a dozen years or more.
But they also know there’s no way to predict how long Curiosity will go, or what unexpected event might end the mission.
The Beast
Does Curiosity have a personality like the previous Mars rovers?
“Actually no, we don’t seem to anthropomorphize this rover like people did with Spirit and Opportunity,” Vasavada said. “We haven’t bonded emotionally with it. Sociologists have actually been studying this.” He shook his head with an amused smile.
Vasavada indicated it might have something to do with Curiosity’s size.
“I think of it as a giant beast,” he said straight-faced. “But not in a mean way at all.”
Curiosity appears to be photobombing Mount Sharp in this selfie image, a mosaic created from several MAHLI images. Credit: NASA/JPL-Caltech/MSSS/Edited by Jason Major.
What has come to come to characterize this mission, Vasavada said, is the complexity of it, in every dimension: the human component of getting 500 people to work and cooperate together while optimizing everyone’s talents; keeping the rover safe and healthy; and keeping ten instruments going every day, which are sometimes doing completely unrelated science tasks.
“Every day is our own little ‘seven minutes of terror,’ where so many things have to go right every single day,” Vasavada said. “There are a million potential issues and interactions, and you have to constantly be thinking about all the ways things can go wrong, because there are a million ways you can mess up. It’s an intricate dance, but fortunately we have a great team.”
Then he added with a smile, “This mission is exciting though, even if it’s a beast.”
“Incredible Stories From Space: A Behind-the-Scenes Look at the Missions Changing Our View of the Cosmos” is published by Page Street Publishing, a subsidiary of Macmillan.
Author Nancy Atkinson at JPL with a model of the Curiosity Rover.
Curiosity's view of Mount Sharp, taken with the MastCam on Sept. 9th, 2015. Credit: NASA/JPL-Caltech/MSSS
Following is Part 2 of an excerpt from my new book, “Incredible Stories From Space: A Behind-the-Scenes Look at the Missions Changing Our View of the Cosmos.” The book is an inside look at several current NASA robotic missions, and this excerpt is part 2 of 3 which will be posted here on Universe Today, of Chapter 2, “Roving Mars with Curiosity.” You can read Part 1 here. The book is available in print or e-book (Kindle or Nook) Amazon and Barnes & Noble.
Living on Mars Time
The landing occurred at 10:30 pm in California. The MSL team had little time to celebrate, transitioning immediately to mission operations and planning the rover’s first day of activity. The team’s first planning meeting started at 1 o’clock in the morning, ending about 8 a.m. They had been up all night, putting in a nearly 40-hour day.
This was a rough beginning of the mission for the scientists and engineers who needed to live on ‘Mars Time.’
A day on Mars day is 40 minutes longer than Earth’s day, and for the first 90 Mars days – called sols — of the mission, the entire team worked in shifts around the clock to constantly monitor the newly landed rover. To operate on the same daily schedule as the rover meant a perpetually shifting sleep/wake cycle where the MSL team would alter their schedules 40 minutes every day to stay in sync with the day and night schedules on Mars. If team members came into work at 9:00 a.m., the next day, they’d come in at 9:40 a.m., and the next day at 10:20 a.m., and so on.
Those who have lived through Mars Time say their bodies continually feel jet-lagged. Some people slept at JPL so as not to disrupt their family’s schedule, some wore two watches so they would know what time it was on two planets.
About 350 scientists from around the world were involved with MSL and many of them stayed at JPL for the first 90 sols of the mission, living on Mars Time.
But it took less than 60 Earth days for the team to announce Curiosity’s first big discovery.
Water, Water …
A 16-ft. (5 m) high sand dune on Mars called Namib Dune is part of the dark-sand ‘Bagnold Dunes’ field along the northwestern flank of Mount Sharp. Images taken from orbit indicate that dunes in the Bagnold field move as much as about 3 feet (1 m) per Earth year. This image is part of a 360 degree panorama taken by the Curiosity rover on Dec. 18, 2015 or the 1,197th Martian day, or sol, of the rover’s work on Mars. Credit: NASA/JPL-Caltech/MSSS.
Ashwin Vasavada grew up in California and has fond childhood memories of visiting state and national parks in the southwest United States with his family, playing among sand dunes and hiking in the mountains. He’s now able to do both on another planet, vicariously through Curiosity. The day I visited Vasavada at his office at JPL in early 2016, the rover was navigating through a field of giant sand dunes at the base of Mount Sharp, with some dunes towering 30 feet (9 meters) above the rover.
“It’s just fascinating to see dunes close up on another planet,” Vasavada said. “And the closer we get to the mountain, the more fantastic the geology gets. So much has gone on there, and we have so little understanding of it … as of yet.”
At the time we talked, Curiosity was approaching four Earth years on Mars. The rover is now studying those enticing sedimentary layers on Mt. Sharp in closer detail. But first, it needed to navigate through the “Bagnold Dunes” which form a barrier along the northwestern flank of the mountain. Here, Curiosity is doing what Vasavada calls “flyby science,” stopping briefly to sample and study the sand grains of the dunes while moving through the area as quickly as possible.
Now working as the lead Project Scientist for the mission, Vasavada plays an even larger role in coordinating the mission.
“It’s a constant balance of doing things quickly, carefully and efficiently, as well as using the instruments to their fullest,” he said.
Since the successful August 2012 landing, Curiosity has sent back tens of thousands of images from Mars – from expansive panoramas to extreme close-ups of rocks and sand grains, all of which are helping to tell the story of Mars’ past.
‘Selfies’ taken by the Curiosity rover are actually a mosaic created from numerous images taken with the Mars Hand Lens Imager (MAHLI), located on the end of the rover’s robotic arm. However, the arm is not shown in the selfies, because with the wrist motions and turret rotations used in pointing the camera for the component images, the arm was positioned out of the shot in the frames or portions of frames used in this mosaic. However, the shadow of the arm is visible on the ground. This low-angle selfie shows the vehicle at the site from which it reached down to drill into a rock target called “Buckskin” on lower Mount Sharp. Credit: NASA/JPL-Caltech/MSSS.
The images the public seems to love the most are the ‘selfies,’ the photos the rover takes of itself sitting on Mars. The selfies aren’t just a single image like the ones we take with our cell phones, but a mosaic created from dozens of separate images taken with the Mars Hand Lens Imager (MAHLI) camera at the end of the rover’s robotic arm. Other fan favorites are the pictures Curiosity takes of the magnificent Martian landscape, like a tourist documenting its journey.
Vasavada has a unique personal favorite.
“For me, the most meaningful picture from Curiosity really isn’t that great of an image,” he said, “but it was one of our first discoveries so it has an emotional tie to it.”
Within the first 50 sols, Curiosity took pictures of what geologists call conglomerates: a rock made of pebbles cemented together. But these were no ordinary pebbles — they were pebbles worn by flowing water. Serendipitously, the rover had found an ancient streambed where water once flowed vigorously. From the size of pebbles, the science team could interpret the water was moving about 3 feet (1 meter) per second, with a depth somewhere between a few inches to several feet. This geological feature on Mars is exposed bedrock made up of smaller fragments cemented together, or what geologists call a sedimentary conglomerate, and is evidence for an ancient, flowing stream. Some of embedded and loose gravel are round in shape, leading the Curiosity science team to conclude it were transported by a vigorous flow of water. Curiosity’s 100-millimeter Mastcam telephoto lens on its 39th sol of the mission (Sept. 14, 2012). Credit: NASA/JPL-Caltech/MSSS
“When you see this picture, and whether you are a gardener or geologist, you know what this means,” Vasasvada said excitedly. “At Home Depot, the rounded rock for landscaping are called river pebbles! It was mind-blowing to me to think that the rover was driving through a streambed. That picture really brought home there was actually water flowing here long ago, probably ankle to hip deep.”
Vasavada looked down. “It still gives me the shivers, just thinking about it,” he said, with his passion for exploration and discovery visibly evident.
From that early discovery, Curiosity continued to find more water-related evidence. The team took a calculated gamble and instead of driving straight towards Mt. Sharp, took a slight detour to the east to an area dubbed ‘Yellowknife Bay.’
“Yellowknife Bay was something we saw with the orbiters,” Vasavada explained, “and there appeared to be a debris fan fed by a river—evidence for flowing water in the ancient past.”
This map shows the route driven by NASA’s Curiosity Mars rover from the location where it landed in August 2012 to its location in September 2016 at “Murray Buttes,” and the path planned for reaching destinations at “Hematite Unit” and “Clay Unit” on lower Mount Sharp. Credits: NASA/JPL-Caltech/Univ. of Arizona
Here, Curiosity fulfilled ones of its main goals: determining whether Gale Crater ever was habitable for simple life forms. The answer was a resounding yes. The rover sampled two stone slabs with the drill, feeding half-baby-aspirin-sized portions to SAM, the onboard lab. SAM identified traces of elements like carbon, hydrogen, nitrogen, oxygen, and more —the basic building blocks of life. It also found sulfur compounds in different chemical forms, a possible energy source for microbes.
Data gathered by Curiosity’s other instruments constructed a portrait detailing how this site was once a muddy lakebed with mild – not acidic – water. Add in the essential elemental ingredients for life, and long ago, Yellowknife Bay would have been the perfect spot for living organisms to hang out. While this finding doesn’t necessarily mean there is past or present life on Mars, it shows the raw ingredients existed for life to get started there at one time, in a benign environment.
“Finding the habitable environment in Yellowknife Bay was wonderful because it really showed the capability our mission has to measure so many different things,” Vasavada said. “A wonderful picture came together of streams that flowed into a lake environment. This was exactly what we were sent there to find, but we didn’t think we’d find it that early in the mission.”
Still, this lakebed could have been created by a one-time event over just hundreds of years. The ‘jackpot’ would be to find evidence of long-term water and warmth.
That discovery took a little longer. But personally, it means more to Vasavada.
Mars’ climate was one of Vasavada’s early interests in his career and he spent years creating models, trying to understand Mars’ ancient history.
“I grew up with pictures of Mars from the Viking mission,” he said, “and thinking of it as a barren place with jagged volcanic rock and a bunch of sand. Then I had done all this theoretical work about Mars climate, that rivers and oceans perhaps once existed on Mars, but we had no real evidence.”
That’s why the discovery made by Curiosity in late 2015 is so exciting to Vasavada and his team.
“We didn’t just see the rounded pebbles and remnants of the muddy lake bottom at Yellowknife Bay, but all along the route,” Vasavada said. “We saw river pebbles first, then tilted sandstones where the river emptied into lakes. Then as we got to Mt. Sharp, we saw huge expanses of rock made of the silt that settled out from the lakes.”
The explanation that best fits the “morphology” in this region — that is, the configuration and evolution of rocks and land forms – is rivers formed deltas as they emptied into a lake. This likely occurred 3.8 to 3.3 billion years ago. And the rivers delivered sediment that slowly built up the lower layers of Mt. Sharp.
Curiosity picture showing the layers and color variations on Mount Sharp, Mars. Credit: NASA/JPL
“My gosh, we were seeing this full system now,” Vasavada explained, “showing how the entire lower few hundred meters of Mount Sharp were likely laid down by these river and lake sediments. That means this event didn’t take hundreds or thousands of years; it required millions of years for lakes and rivers to be present to slowly build up, millimeter by millimeter, the bottom of the mountain.”
For that, Mars also needed a thicker atmosphere than it has now, and a greenhouse gas composition that Vasavada said they haven’t quite figured out yet.
But then, somehow dramatic climate change caused the water to disappear and winds in the crater carved the mountain to its current shape.
The rover had landed in exactly the right place, because here in one area was a record of much of Mars’ environmental history, including evidence of a major shift in the planet’s climate, when the water that once covered Gale Crater with sediment dried up.
“This all is a significant driver now for what we need to explain about Mars’ early climate,” Vasavada said. “You don’t get millions of years of climate change from a single event like a meteor hit. This discovery has broad implications for the entire planet, not just Gale Crater.”
Other Discoveries
• Silica: The rover made a completely unanticipated discovery of high-content silica rocks as it approached Mt. Sharp. “This means that the rest of the normal elements that form rocks were stripped away, or that a lot of extra silica was added somehow,” Vasavada said, “both of which are very interesting, and very different from rocks we had seen before. It’s such a multifaceted and curious discovery, we’re going to take a while figuring it out.”
• Methane on Mars: Methane is usually a sign of activity involving organic matter — even, potentially, of life. On Earth, about 90 percent of atmospheric methane is produced from the breakdown of organic matter. On Mars, methane has been detected by other missions and telescopes over the years, but it was tenuous – the readings seemed to come and go, and are hard to verify. In 2014, the Tunable Laser Spectrometer within the SAM instrument observed a ten-fold increase in methane over a two-month period. What caused the brief and sudden increase? Curiosity will continue to monitor readings of methane, and hopefully provide an answer to the decades-long debate.
• Radiation Risks for Human Explorers: Both during her trip to Mars and on the surface, Curiosity measured the high-energy radiation from the Sun and space that poses a risk astronauts. NASA will use data from the Radiation Assessment Detector (RAD) instrument Curiosity’s data to design future missions to be safe for human explorers.
Tomorrow: The conclusion of this chapter, including ‘How To Drive a Mars Rover, and ‘The Beast.’ Part 1 is available here.
“Incredible Stories From Space: A Behind-the-Scenes Look at the Missions Changing Our View of the Cosmos” is published by Page Street Publishing, a subsidiary of Macmillan.
