Category Archives: Mars – Curiosity

News on Mars and the Curiosity rover

An “habitable” lake in Mars 3800 million years ago

As I mentioned in this blog a year and a half before (August 30th, 2012 “Is there life on Mars?”), the Curiosity rover began to walk by Mars, specifically inside the Gale crater, carrying its sophisticated instruments to analyze rocks, soil and atmosphere, that is, a well equipped geochemical laboratory analyzing the surface of another planet for the first time. You can see a video of 2 minutes of the 1st year of Curiosity here. As you know, one of the objectives of this analysis is to find evidence of whether there were favorable conditions for life on Mars, albeit in very bygone eras.

1 Mars-Gale-Crater-locator-400x400

The Curiosity rover is walking inside Gale Crater, east of Syrtis Major, the Mars most prominence visible through a telescope. Image NASA/ESA/Hubble.

 

Mars is a planet with some similar features on Earth, such as the length of day, slightly more than 24 hours, but the greater distance from the Sun and very tenuous atmosphere make the average temperature to be -63 ° C, with daily oscillations from +20°C to -140°C. Having no oceans, the land surface of Mars is equivalent to the Earth, because Mars is smaller.

2 Mars_Earth_Comparison

Comparison of Earth and Mars. The diameter of Mars is 3400 km, approx half of the Earth’s, but excluding oceans, the solid surface is similar on both planets. Image taken from T.E. Harrison, New Mexico State University.

 

Despite the difficulties to demonstrate the current existence of liquid water on Mars, from some years ago evidences have been found that there was water in the Martian surface, and it is being confirmed that during the first thousand million years there was plenty of water on Mars (Remind that both Mars and Earth are about 4.5 billion years).

3 marsnetwork

Appearance of a region of Mars indicating the flow of water in the distant past. Image taken from T.E. Harrison, New Mexico State University.

4 History_of_water_on_Mars

Water history in Mars, in billions of years. Image from T.E. Harrison, New Mexico State University.

Curiosity shows an “habitable” lake 3800 million years ago

Thus, Curiosity rover has been taking samples in various ways (see in Figure below the 5 cm holes taking samples) and analyzing them. Studying the data, scientists have been able to write a series of articles that have been published in Science and other prestigious journals.

5 drill holes

Two 5 cm holes made by Curiosity rover sampling in Yellowknife Bay of Gale Crater on Mars (NASA/JPL-Caltech/MSSS)

Among other articles, by last May was already published one (Williams et al 2013) with observations that the material extracted from the Yellowknife Bay of Gale Crater shows textures typical of fluvial sedimentary conglomerates, with rounded pebbles that indicate fluvial abrasion, and by their characteristics a water flow of nearly 1 meter per second has been deduced, with a depth of near 1 meter. Therefore, when this area was formed the climatic conditions, with abundant rivers, would have been very different from the current hyperarid and very cold environment.

A few weeks ago, on December 9th, Science Online has released a special edition dedicated to the latest findings of Curiosity, with 6 articles asserting that at Gale Crater there would have been a lake theoretically habitable for some organisms.

In one of the articles, maybe the most relevant one, Grotzinger et al (2013) describe the sedimentary rocks found by the rover and demonstrate that it corresponded to an aqueous environment with neutral pH, low salinity and different redox states of Fe and S. The presence of C, H, O, S, N and P (i.e., all biogenic elements) is also shown, and the authors estimate that this favorable environment for life could have lasted some few hundred thousand years, and therefore it demonstrates the biological feasibility of this fluvio-lacustrine environment of post-Noachian Mars, that is, about 3800 million years ago.

Therefore, these scientists deduced that this lake had fresh water, a water we could drink, and that around this lake various fluvial and lacustrine environments were present. This environment should be habitable for some organisms, and very similar to some current earth environments. The commented chemical compounds would be suitable for the survival of bacteria chemolithotrophic bacteria, id est, those which use inorganic compounds (such as Fe or S) as an energy source and use CO2 as a carbon source. On Earth we have many kind of these microbes, such as iron bacteria (Thiobacillus) or sulfur bacteria (including some sulfur thermophilic archaea) and the nitrifying ones. Although most of these chemolithotrophic bacteria on Earth are aerobic because they use atmospheric oxygen as electron acceptor, this metabolism is also known in some anaerobes, such as those that do the anoxic ammonium oxidation (process “Anammox”), for example Brocadia anammoxidans, or the same nitrifying bacteria in anaerobic conditions.

Therefore, with this habitable lake for some time, and with other similar environments, we can not reject the possibility that living beings had been sometimes in Mars.

6 view Gale crater

View from Yellowknife Bay in Gale Crater, looking W-NW. This area of sedimentary deposits was the bottom of a freshwater lake. Photo: NASA/JPL-Caltech.

7 Grotzinger-3-pia17596-br2 llac

Estimated size and shape of the lake that was in the Gale crater. There must have been other similar. The arrows indicate the direction of the alluvial fan that flowed into the crater from its wall. Photo: NASA/JPL-Caltech/MSSS.

Another aspect studied in this extra issue of Science is the possible presence of methane in the Martian atmosphere (Webster et al 2013). Just like on Earth, methane is a potential sign of biological activity in the past. Previous observations made from Earth or from the Mars orbit speculated on the presence of some 10 ppb of methane, and its subsurface biological origin was also discussed. Nevertheless, in the measurements made in situ by laser spectrometry of Curiosity rover using a specific spectral methane pattern, it has not been detected since the values found are lower than 1 ppb. This reduces the probability of recent methanogenic microbial activity on Mars and it is limiting the possible contribution of recent geological and extraplanetary sources.

Finally, in another article (Hassler et al 2013) about measures of cosmic rays on the surface of Mars that Curiosity has made over a year, models of radiation are elaborated, for the time calculation of possible subsurface microbial survival, and also for the preservation of organic compounds of biological origin finding them billions of years later. Unfortunately, the conclusion is that the powerful effect of cosmic rays would cause very difficult any of these possibilities. Unlike the Earth, the magnetic field of Mars is very weak and the atmosphere too, things that help bombardment of cosmic rays and the solar wind on the Martian surface. However, there is evidence that in the past Mars had a magnetic field more effective, so hope is not lost …..

Bibliography

Achenbach J. 2013. NASA Curiosity rover discovers evidence of freshwater Mars lake. The Washington Post, Health & Science online Dec 9.

Anderson PS. 2013. Curiosity rover confirms ancient martian lake. Spaceflight Insider online Dec 11.

Grotzinger JP et 72 al. 2013. A Habitable Fluvio-Lacustrine Environment at Yellowknife Bay, Gale Crater, Mars. Science DOI: 10.1126/science.1242777 online Dec 9, 2013.

Harrison, T.E., New Mexico State University:  http://astronomy.nmsu.edu/tharriso/ast105/Mars.html

Hassler DM et 23 al. 2013. Mars’ Surface Radiation Environment Measured with the Mars Science Laboratory’s Curiosity Rover. Science DOI: 10.1126/science.1244797 online Dec 9, 2013.

Kerr, RA. 2013. New Results Send Mars Rover on a Quest for Ancient Life. Science Now News, online Dec 9, 2013.

Science Special Collection Curiosity 2013. Curiosity at Yellowknife Bay, Gale Crater. Online: http://www.sciencemag.org/site/extra/curiosity/

Webster CR et al 2013. Low upper limit to methane abundance on Mars. Science 18 October 2013, Vol. 342 no. 6156 pp. 355-357

Williams RME et 38 al. 2013. Martian Fluvial Conglomerates at Gale Crater. Science 31 May 2013, Vol. 340 no. 6136 pp. 1068-1072

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“Curiosity”, what do you say, there was water in Mars, yes or not ?

Just three weeks ago I wrote here (Few news from Mars …….) a post on a study that provided disappointing evidence that Martian clay would not have been made ​​with liquid water. With that, existence of water on Mars should be less likely, and therefore life in this planet.
However, this past week the NASA’s Curiosity rover sent us a picture of the Martian surface rocks with an aspect which seem to be the product of a stream in the past.

streambedPhoto sent by Curiosity, possible evidence of a streambed on Mars. The width of the image is about 1 meter. Image: NASA / JPL-Caltech / MSSS.

According to NASA scientists, the shapes of these stones and their arrangement as gravel, are evidence of the remains of an old water streambed flowing down the slopes of Gale Crater, where the spacecraft mission to Mars Science Laboratory Curiosity landed in early August. This place has been called Hottah by NASA, by reminiscence of a rock formation in Canada with that name.

Gale craterPart of Gale crater where the mission of the Curiosity landed (the small cross inside of the ellipsis). Image: NASA / JPL-Caltech / UofA

Details of the photo (see below) show that these rocks are a conglomerate of stones, some of which are rounded and therefore likely product of water transport. From the size of gravels it carried, NASA scientists even have calculated that the water was moving about one meter per second, so it was a very impetuous flow.

detail of stoneDetail of rounded stones photo taken by Curiosity rover. Image: NASA / JPL-Caltech / MSSS

So this would be another evidence that in the past Mars had liquid water, and therefore the chances of life there have been increased. In fact, this is not the first finding that points to the possibility that there was water on Mars, since the first mission Mariner 9 in 1971 had already seen geological formations that seemed river beds and canyons .

In addition to the clays that I mentioned in my previous post, another possible evidence of water was found a year ago, when the Opportunity rover (much more “primitive” than the Curiosity), which is in Mars for 8 years, found bright veins of a mineral (picture here below), apparently gypsum, in Endeavour crater. As gypsum is formed by sedimentation with water on Earth, it is likely that this was the origin of that material on Mars some thousand million years ago.

mineral veinColoured image of a vein mineral similar to the gypsum, photographed by Opportunity rover in 2011. Image: NASA / JPL-Caltech / Cornell / ASU

The NASA scientists say these photos taken now by Curiosity are a great evidence of liquid water. Anyway, I do not want to be faithless, but I do not know if these stones and their arrangement could have been made otherwise, who knows, other liquid materials, or wind erosion, I do not know.

Well, as the same scientists from NASA say, this Curiosity mission planned for two years is beyond the visual confirmation of an old streambed. Analyses that the Curiosity equipment will do should allow to understand the chemical composition of these materials and their origin, trying to learn when and why Mars was dry, if the planet had been wet before. For this reason, Curiosity has to explore Mount Sharp, which is about 6 km from the center of the crater where it landed. At the base of this mountain there are clays and sulfates, according orbital observations, and therefore Curiosity will climb this mountain, 700 meters high, and there will help scientists decipher the history of Mars, wet and dry, and find some other evidences of the possibility of past life on Mars, and its habitability today.

References

NASA, News Releases, NASA Rover Finds Old Streambed On Martian Surface, 27 sept 2012

Mike Wall, Space.com Senior Writer, Curiosity’s ancient streambed discovery is just the latest clue. Space on NBCNews.com

IAS Preparation Online, Curiosity finds ancient stream bed on Mars

Mike Wall, Space.com Senior Writer, NASA Rover finds convincing evidence of water on Mars. Space.com

Few news from Mars, but there is a disappointing study on Earth

Two weeks ago I wrote in this blog (Is there life on Mars?) on the Mars Science Laboratory mission of NASA with the famous Curiosity rover, which its main aim is finding possible signs of past life in the red planet.

Well, as expected, until now there are no spectacular news, as in all scientific studies, things take time. The Curiosity has been taking photos (see one here) and taking samples and analyzing them. Today there are 40 days since the landing and it has walked about 150 meters. As stated in the last NASA chronicle, Curiosity continues its work “in good health”. So keep waiting.

martian landscapeOne of the photos taken by Curiosity at Gale crater with a 34 mm Mastcam camera. The mountains (far 15 km) are called Mount Sharp. Image: NASA/JPL-Caltech/MSSS

But today I want to comment some disappointing news regarding the possibilities that there had been life on Mars. It turns out that a recent study of French and American researchers (Meunier et al, 2012) provides evidences that Martian clays could have a direct magmatic origin and therefore they would not have made by contact of the basaltic crust with liquid water, as hypothesized until now. And so, the less likely the existence of liquid water on Mars in the past, less likelihood of living beings there.

Clays are hydrous silicates (of phyllosilicates group), mainly of aluminium (Al2O3 · 2 SiO2 · 2 H2O). They are minerals with granular structure, which originate on Earth mainly by decomposition of magmatic rocks containing silicate minerals such as the feldspar by the action of liquid water (this may contain carbonic acid and other compounds). Clays have been identified on Mars some years ago with the spectrometers of the OMEGA observatory carried by the Mars Express spacecraft of the European Agency, which is orbiting Mars (Bibring et al, 2006). It was believed until now that these clay minerals, abundant in Mars surface, would have been formed for a long time by interaction of liquid water with basaltic crust, decomposing the magmatic rocks, but early in Mars history, 3700 million years ago, at the same time that Earth life was beginning. The presence of liquid water would be a sign of warmer and wetter conditions on early Mars, and therefore more likely to carry life.

martian claysClay minerals (in red) exposed in the old crust of pyroxene (metallic silicates) of Mars at Mawrth Vallis, looking south. Image © Joseph Michalski

But the recent published work of Meunier et al. suggests a different mechanism that does not require prolonged reaction of rocks with water. Interestingly, evidence has been found on Earth, studying clays of Mururoa Atoll in French Polynesia, which are similar to Martians phyllosilicate clays. Using petrographic techniques (study of the mineral structures at the microscopic level), microanalysis of elements, and isotope ratio analysis, these researchers have found that the Mururoa clays, rich in Fe and Mg, are much richer in rare earth elements (lanthanides and other), and microscopic structures are very different from other more abundant clay on Earth, originated from aqueous weathering. The characteristics of the Mururoa clays assert that were originated by short pulses of degassing magma in the interstices of basalt, and the water contained in clays would be only of magmatic origin.

Meunier et al. have also studied clays of Martian meteorites and have found that some of them have similar characteristics as those of Mururoa. Especially the ratio of the isotopes carbon-13 and deuterium in Lafayette meteorite shows that their clay was formed by direct precipitation of magmatic fluid containing water, by degassing magma.

Therefore, if martian clays, very similar to those of Mururoa (at least in their spectra), are proved to be formed also by magmatic degassing, then the presence of liquid water in early Mars would be more difficult to prove, and this planet would not have had easy conditions of habitability, at the same early period when life began to flourish on Earth.

The place where Curiosity is walking around, the Gale Crater, is known to contain phyllosilicates, i.e. clays. So, we must therefore wait that this rover could find clays and analyze them, and wait for some news a little more optimistic.

References

Bibring, J-P. et al (2006) Global mineralogical and aqueous Mars histoy derived from OMEGA/Mars Express Data. Science 312, 5772, 400-404

Hynek, B. (2012) Planetary science: Unhabitable martian clays ? Nature Geoscience, News and Views, online 9 sept 2012: http://dx.doi.org/10.1038/ngeo1560

Meunier, A. et al (2012) Magmatic precipitation as a possible origin of Noachian clays on Mars. Nature Geoscience, online 9 sept 2012: http://dx.doi.org/10.1038/ngeo1572

http://en.wikipedia.org/wiki/Clay

Is there life in Mars ?

As you know, these days Mars is back in fashion. On August 6th, we have seen the Mars Science Laboratory (MSL) of the NASA [1] landing successfully on the red planet, and now the Curiosity rover is walking to see what is there. This robot of about 900 kg, the largest that has been managed to land safely on Mars, is very well equipped. It contains 10 scientific instruments, including infrared laser teledetector, mass spectrometer, gas chromatograph, X-ray diffraction, microscopic camera, radiation detector, weather stations, and more than 17 photographic cameras [2].

These equipments are designed to detect any trace of water, to analyze accurately the rocks, to study the minerals in the Martian surface, to measure the chirality of the molecules detected (you know, L-or D-, such as L-amino acids typical of living beings) and to take pictures in high resolution.

Curiosity rover

The Curiosity rover, of Mars Science Laboratory mission, NASA

 With these tools, the main objective of the MSL is determining whether there have been conditions conducive to life in Mars. Therefore, rather than looking directly for finding living beings, the goal is to try to find if there are any signs of past or present life, and also for looking the possibilities for a possible human settlement.

Life as we know it on Earth is based on the chemical elements of the basic biochemistry, namely carbon, oxygen, hydrogen, nitrogen, phosphorous, sulphur, and other trace elements. While these elements are found in many parts of the outer space, including Mars, it is necessary to quantify them to see if their proportions are indicative of a possible life, present or past, on Mars.

Of course, a key point in the search for life is to find liquid water, since on Earth there are living beings wherever there is liquid water, regardless of other conditions, aerobic or not, and extreme pHs and other inhospitable conditions. As you know, there are organisms on Earth everywhere, and among the so called extremophiles, either archaea or bacteria, there are some living at sea depths with enormous pressures, some others living at pH below 1 and temperatures near the boiling point, others a few hundred meters underground, others in the upper atmosphere, others endure radiation, others in a high osmotic pressure (e.g. saline environments). But in all cases, and even sometimes with very few nutrients, organisms live always in the presence of liquid water, even at low concentration. On Earth, wherever there is liquid water, always living beings are found, mainly microorganisms.

So well, is there liquid water in Mars ? It seems highly unlikely, but not impossible at all. There is water, certainly, especially ice at the poles (see picture) and in other places, but the low atmospheric pressure (the highest on the Martian surface is 0.6% of the Earth’s one), makes ice sublimating directly to water vapour, which is hardly retained by the atmosphere and escapes the planet. The Martian atmosphere contains 95% CO2, 3% N2, and traces of oxygen and water, as well as many particles in suspension. These give a tawny colour to the atmosphere, similar to the aspect of the planet as we see, due to abundance of iron oxide. Surface temperatures oscillate from about -140 °C at the poles to about 35 °C, occasionally at the equator. Therefore, even temporarily, there can be liquid water.

Mars true colour

True-colour view of Mars seen through NASA’s Hubble Space Telescope

Despite the current hostile conditions of Mars, there is geological evidence of the existence of liquid water in the past, like the geomorphology of valleys and channels, etc., and also by the presence of some minerals that only can be originated with water (e.g. hematite).

On the other hand, small amounts of methane and formaldehyde have been detected there. These compounds are mostly generated biologically on Earth, but conditions of the Martian atmosphere make them short-lived [3]. However, their geological origin seems also possible.

The habitability of Mars has been tested in the laboratory reproducing its conditions, by placing polar and alpine lichens at these conditions [4]. Surprisingly, it has been shown that these lichens can resist them.

The question of possible life on Mars had a peak in 1996, when scientific staff from NASA published in Science magazine [5] the microscopic images of a fragment of ALH84001, a meteorite from Mars. This stone seems to be of Martian origin, it was launched into space by the impact of a meteorite on Mars about 15 million years ago, and then it travelled till the Earth reaching the Antarctica, where it was found in 1984. The structures seen there recall bacterial chains, and so, it was proposed that they would be martian microfossils. However, there is no other evidence of the biological origin of these structures and afterwards an inorganic origin of the meteorite minerals has been proposed [6].

ALH84001 structures

Electronic microscopy of a fragment of ALH84001 meteorit (image of NASA)

Well, we wait with expectation the results of the tests done by the Curiosity. If evidence of past or present life on Mars is found, there will be very much to think about, especially in the sense that terrestrial organisms would not be alone in the universe. And in spite of the evidence that would be very simple microbial life, we should conclude that life is a feature very widespread in the universe.

What do you think ? Will Curiosity find evidence of life on Mars ?

Earth and Mars

Earth and Mars, at the same scale, two Bio-planets ? (image from NASA)

References

[1] NASA: http://www.nasa.gov/mission_pages/msl/

[2] Mahaffy, P. (2009) Sample analysis at Mars: Developing analytical tools to search for a habitable environment on the red planet. Geochemical News (Geochemical Society), 141, oct. 2009

[3] Krasnopolski, V.A. et al. (2004). Detection of methane in the Martian atmosphere: evidence for life?”. Icarus 172, 537–547

[4] DLR (German Aerospace Center) Surviving the conditions on Mars: http://www.dlr.de/dlr/en/desktopdefault.aspx/tabid-10081/151_read-3409/

[5] McKay, D.S. et al. (1996) Search for past life on Mars: Possible relic biogenic activity in Martian meteorite ALH84001. Science 273, 924–930

[6] Golden, D.C. et al. (2004) Evidence for exclusively inorganic formation of magnetite in Martian meteorite ALH84001. American Mineralogist 89, 681–695

[ ] … and Wikipedia:

– Mars Science Laboratory: http://en.wikipedia.org/wiki/Mars_Science_Laboratory

– Mars: http://en.wikipedia.org/wiki/Mars

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