It is time for another planet and this time last of inner ones. Ladies and gentlemen I present you - Mars.
Mars is the fourth planet from the Sun in the Solar System. Named after the Roman god of war, Mars, it is often described as the "Red Planet" as the iron oxide prevalent on its surface gives it a reddish appearance. Mars is a terrestrial planet with a thin atmosphere, having surface features reminiscent both of the impact craters of the Moon and the volcanoes, valleys, deserts, and polar ice caps of Earth. The rotational period and seasonal cycles of Mars are likewise similar to those of Earth, as is the tilt that produces the seasons. Mars is the site of Olympus Mons, the highest known mountain within the Solar System, and of Valles Marineris, one of the largest canyons. The smooth Borealis basin in the northern hemisphere covers 40% of the planet and may be a giant impact feature. Martian tectonism, the formation and change of a planet's crust, differs from Earth's. In the dead of a Martian winter, clouds of snow blankets the Red Planet's poles - but unlike our water-based snow, the particles on Mars are frozen crystals of carbon dioxide. Most of the Martian atmosphere is composed of carbon dioxide, and in the winter, the poles get so cold - cold enough to freeze alcohol - that the gas condenses, forming tiny particles of snow. The buildup is about 50 percent larger at Mars' south pole than its north pole. Just as snow on Earth affects the way heat is distributed around the planet, snow particles on Mars may have a similar effect, reflecting sunlight in various ways, depending on the size of each particle.
Where Earth tectonics involve sliding plates that grind against each other or spread apart in the seafloors, Martian tectonics seem to be vertical, with hot lava pushing upwards through the crust to the surface. Periodically, great dust storms engulf the entire planet. The effects of these storms are dramatic, including giant dunes, wind streaks, and wind-carved features. The Mars Reconnaissance Orbiter has been studying Mars with an advanced set of instruments since 2006. It has returned more data about the planet than all other spacecraft combined. Below scene is from early spring in the northern hemisphere of Mars. These dunes are covered with a layer of seasonal carbon dioxide ice (dry ice). Bluish cracks in the ice are visible across the top of some of the dunes.
When a meteorite careens toward the dusty surface of the Red Planet, it kicks up dust and can cause avalanching even before the rock from outer space hits the ground. We expected that some of the streaks of dust that we see on slopes are caused by seismic shaking during impact. Surprise came when we found that it rather looks like shockwaves in the air trigger the avalanches even before the impact. Because of Mars' thin atmosphere, which is 100 times less dense than Earth's, even small rocks that would burn up or break up before they could hit the ground here on Earth crash into the Martian surface relatively unimpeded. Each year, about 20 fresh craters between 1 and 50 meters show up in images taken by the HiRISE (The High Resolution Imaging Science Experiment) camera on board NASA's Mars Reconnaissance Orbiter.
HiRISE made another amazing picture. Below picture was taken by the HiRISE camera too and it shows wind-driven sand dunes on Mars, rippling in a similar way as on Earth. The sunlight is coming from the upper left direction, and where the light hits the surface you can see the familiar reddish cast; that’s actually from very fine-grain dust laden with iron oxide, or in ther words - rust. But the shadows, where the Sun doesn’t reach, it’s cold enough that carbon dioxide in the Martian air freezes out, forming a thin layer of dry ice on the surface. In this image - where the colors have been enhanced so you can see the effects better - this shades the dunes blue. You can see the frost not just covering the dunes in general, but hiding in the troughs of the ripples too.
The non-color-enhanced version showing the entire dune region can be found here - and is stunning in its own right.
The sand on Mars is actually basaltic, making it look grey to the eye. Those grains are big enough that they don’t move as easily as the finer dust, and they pile up to form the big dunes, with the redder dust coating them. The color can change when frost forms, as in the picture above, but you also get incredibly dramatic and simply stunning patterns when dust devils - tornado-like vortices that form when wind blows over warm air rising off the surface - lift up the red dust and expose the grey basalt underneath. The swirling patterns are intricate and incredible, as you can see in picture below.
Mars is a pretty incredible place. It’s way too easy to easy to think of it as a cold, dry, dead world, but that’s not really true: it has an atmosphere (though thin), it has seasons, and it even has weather. Here, HiRISE camera is in action again and it captured this magnificent twisting dust devil towering over the landscape. Dust devils are wind vortices, like tornadoes, but generally not as violent. They form when sunlight warms the surface of Mars. The air just above it gets warmer and rises. If there is a crosswind, it can blow across the rising air and start it spinning like waves breaking on a beach. But since the air is rising, it can lift up vertically while still spinning, forming a dust devil.
Dust devils are most common in the spring, when atmospheric conditions are best for them, and it happens to be late spring in this location on Mars when picture was taken. In March 2012 another Martian dust devil roughly 20 km high was captured whirling its way along the Amazonis Planitia region of Northern Mars - picture below:
And if you wish to see video made upon pictures captured by NASA folks, click here - it is worth it. But browsing over Mars surface revealed recently something new too - new class of landform. Researchers call the structures periodic bedrock ridges. The ridges look like sand dunes but, rather than being made from material piled up by the wind, the scientists say the ridges actually form from wind erosion of bedrock. These bedforms look for all the world like sand dunes but they are carved into hard rock by wind. It is something there are not many analogs for on Earth.
High-resolution photos of lava flows on Mars reveal coiling spiral patterns that resemble snail or nautilus shells. Such patterns have been found in a few locations on Earth, but never before on Mars. The new result came out of research into possible interactions of lava flows and floods of water in the Elysium volcanic province of Mars.
For years, researchers debated whether sand dunes observed on Mars were mostly fossil features related to past climate, rather than currently active. In the past two years, researchers using images from HiRISE camera have detected and reported sand movement. Now, scientists using HiRISE images have determined that entire dunes as thick as 61 meters are moving as coherent units across the Martian landscape. This is unexpected because Mars has a much thinner atmosphere than Earth, is only about one percent as dense, and its high-speed winds are less frequent and weaker than Earth's. The study examined images taken in 2007 and 2010 of the Nili Patera sand dune field located near the Martian equator. By correlating the ripples' movement to their position on the dune, the analysis determined the entire dunes are moving. Scientists calculate that if someone stood in the Nili Patera dunes and measured out a one-meter width, they would see more than 1500 liters of sand pass by in an Earth year, about as much as in a child's sand box.
Scientists believe that 3.5 billion years ago, Mars experienced the largest known floods in the solar system. This water may even have pooled into lakes or shallow oceans. But where did the ancient floodwater come from, how long did it last, and where did it go? At present, Mars is too cold and its atmosphere is too thin to allow liquid water to exist at the surface for long. There's water ice close to the surface and more water frozen in the polar ice caps, but the quantity of water required to carve Mars's great channels and flood plains is not evident on - or near - the surface today. Images from NASA's Mars Global Surveyor spacecraft suggest that underground reserves of water may break through the surface as springs. The answers may lie deep beneath Mars's red soil.
Unraveling the story of water on Mars is important to unlocking its past climate history, which will help us understand the evolution of all planets, including our own. Water is also believed to be a central ingredient for the initiation of life; the evidence of past or present water on Mars is expected to hold clues about past or present life on Mars, as well as the potential for life elsewhere in the universe. The discovery of the mineral jarosite in rocks analyzed by the Mars Rover Opportunity, on the Martian surface had special meaning for a team of Syracuse University scientists who study the mineral here on Earth. Jarosite can only form in the presence of water. Its presence on Mars means that water had to exist at some point in the past. The trick is in figuring out if jarosite can be used as a proxy for determining when, and under what conditions, water was present on the planet. Jarosite is a byproduct of the weathering of rocks exposed at the surface of a planet (such as Earth and Mars). The mineral forms when the right mixture of oxygen, iron, sulfur, potassium and water is present. Once formed, the crystals begin to accumulate argon, which is produced when certain potassium isotopes in the crystals decay. Potassium decay is a radioactive process that occurs at a known rate. By measuring the isotopes of argon trapped within the crystals, scientists can determine the age of the crystals. However, because argon is a gas, it can potentially escape rapidly from the crystals under hot conditions or slowly over long durations at cold conditions. In order to determine the reliability of the "argon clock" in jarosite, the scientists had to determine the temperature limits to which the crystals could be subjected and still retain the argon. Using a combination of experiments and computer modeling, the team found that argon remains trapped inside the crystals for long periods of time over a range of planetary surface temperatures. Study results suggest that 4 billion-year-old jarosite will preserve its argon and, along with it, a record of the climate conditions that existed at the time it formed. The scientists are in the process of conducting further studies on jarosite that formed less than 50 million years ago in the Big Horn Basin in Wyoming, which they hope will reveal when the minerals formed and how fast environmental conditions changed from water-saturated to dry. The results can be used as a context for interpreting findings on other planets.
By the end of 2011 NASA's Mars Exploration Rover Opportunity has found bright veins of a mineral, apparently gypsum, deposited by water (see picture above). Gypsum is formed in water at a temperature lower than 60°C. Its presence on Mars indicates that conditions conducive to life have existed there at least temporarily. Analysis of the vein will help improve understanding of the history of wet environments on Mars. This tells a slam-dunk story that water flowed through underground fractures in the rock. This stuff is a fairly pure chemical deposit that formed in place right where we see it. That can't be said for other gypsum seen on Mars or for other water-related minerals Opportunity has found. It's not uncommon on Earth, but on Mars, it's the kind of thing that makes geologists jump out of their chairs. The vein examined most closely by Opportunity is about the width of a human thumb (1 to 2 cm), 40 to 50 cm long, and protrudes slightly higher than the bedrock on either side of it. Observations by the durable rover reveal this vein and others like it within an apron surrounding a segment of the rim of Endeavour Crater. None like it were seen in the 33 km of crater-pocked plains that Opportunity explored for 90 months before it reached Endeavour, nor in the higher ground of the rim. The spectrometer identified plentiful calcium and sulfur, in a ratio pointing to relatively pure calcium sulfate. Calcium sulfate can exist in many forms, varying by how much water is bound into the minerals' crystalline structure. The multi-filter data from the camera suggest gypsum, a hydrated calcium sulfate. Observations from orbit had detected gypsum on Mars previously. A dune field of windblown gypsum on far northern Mars resembles the glistening gypsum dunes in White Sands National Monument in New Mexico. At the moment it is a mystery where the gypsum sand on northern Mars comes from. It will be important to see if there are deposits like this in other areas of Mars.
Until now, Earth was the only planet known to have vast reservoirs of water in its interior. Scientists analyzed the water content of two Martian meteorites originating from inside the Red Planet. They found that the amount of water in places of the Martian mantle is vastly larger than previous estimates and is similar to that of Earth's. The results not only affect what we know about the geologic history of Mars, but also have implications for how water got to the Martian surface. The data raise the possibility that Mars could have sustained life and this study was published in June 2012. The scientists analyzed what are called shergottite meteorites. These are fairly young meteorites that originated by partial melting of the Martian mantle - the layer under the crust - and crystallized in the shallow subsurface and on the surface. They came to Earth when ejected from Mars approximately 2.5 million years ago. Meteorite geochemistry tells scientists a lot about the geological processes the planet underwent. Based on the mineral's water content, the scientists estimated that the Martian mantle source from which the rocks were derived contained between 70 and 300 parts per million (ppm) water. For comparison, the upper mantle on Earth contains approximately 50-300 ppm water. Hauri and team were able to determine these values with new techniques and new standards they developed that can quantify water in apatite using a technology called secondary ion mass spectrometry (SIMS).
However, one must ask whether it makes sense to see Mars as good target to be populated with life - Mars may have been arid for more than 600 million years, making it too hostile for any life to survive on the planet. The researchers have spent three years analysing data on Martian soil that was collected during the 2008 NASA Phoenix mission to Mars. Phoenix touched down in the northern arctic region of the planet to search for signs that it was habitable and to analyse ice and soil on the surface. The results of the soil analysis at the Phoenix site suggest the surface of Mars has been arid for hundreds of millions of years, despite the presence of ice and the fact that previous research has shown that Mars may have had a warmer and wetter period in its earlier history more than three billion years ago. The team also estimated that the soil on Mars had been exposed to liquid water for at most 5000 years since its formation billions of years ago. They also found that Martian and Moon soil is being formed under the same extremely dry conditions. Satellite images and previous studies have proven that the soil on Mars is uniform across the planet, which suggests that the results from the team's analysis could be applied to all of Mars. This implies that liquid water has been on the surface of Mars for far too short a time for life to maintain a foothold on the surface. Even though there is an abundance of ice, Mars has been experiencing a super-drought that may well have lasted hundreds of millions of years. The Mars we know today contrasts sharply with its earlier history, which had warmer and wetter periods and which may have been more suited to life. Future NASA and ESA missions that are planned for Mars will have to dig deeper to search for evidence of life, which may still be taking refuge underground. Nevertheless, once upon the time Mars must have been nice planet.
Above picture is not real, but it is motivated by the fact that ESA's Mars Express has returned strong evidence for an ocean once covering part of Mars. Using radar, it has detected sediments reminiscent of an ocean floor within the boundaries of previously identified, ancient shorelines on Mars. The MARSIS radar was deployed in 2005 and has been collecting data ever since. The existence of oceans on ancient Mars has been suspected before and features reminiscent of shorelines have been tentatively identified in images from various spacecraft. But it remains a controversial issue. Two oceans have been proposed: 4 billion years ago, when warmer conditions prevailed, and also 3 billion years ago when subsurface ice melted, possibly as a result of enhanced geothermal activity, creating outflow channels that drained the water into areas of low elevation. MARSIS penetrates deep into the ground, revealing the first 60-80 meters of the planet's subsurface. Throughout all of this depth, we see the evidence for sedimentary material and ice. The sediments revealed by MARSIS are areas of low radar reflectivity. Such sediments are typically low-density granular materials that have been eroded away by water and carried to their final destination. This later ocean would however have been temporary. Within a million years or less the water would have either frozen back in place and been preserved underground again, or turned into vapour and lifted gradually into the atmosphere - probably not long enough for life to form. In order to find evidence of life, astrobiologists will have to look even further back in Mars' history when liquid water existed for much longer periods. Nevertheless, this work provides some of the best evidence yet that there were once large bodies of liquid water on Mars and is further proof of the role of liquid water in the martian geological history. This adds new pieces of information to the puzzle but the question remains: where did all the water go?
In a rough-and-tumble wonderland of plunging canyons and towering buttes, some of the still-raw bluffs are lined with soaring, six-sided stone columns so orderly and trim, they could almost pass as relics of a colossal temple. The secret of how these columns, packed in edge to edge, formed en masse from a sea of molten rock is encrypted in details as tiny as the cracks running across their faces. To add to this mystery's allure, decoding it might do more than reveal the life story of some local lava: it might help explain the history of Mars.
We can see the columns at the edges of the lava flow easily, but we're confident that in some cases the entire lava flow is jointed. Extensive jointing is likely the case in Marte Vallis, where basalt columns were exposed when the impact of a large object gouged out a crater, and in the Channeled Scablands, where they were revealed when flood waters swept away swaths of land. It's possible to figure out how quickly the basalt cooled, and thus how quickly the columns formed, by measuring the distance from one small horizontal crack, called a stria, to the next. As the lava is cooling, the contraction creates stress. It pulls, pulls, pulls, and then the pressure gets too great, and click! You get a fracture plane. That's a stria. And it keeps going like this - pull, pull, pull, click! - until you get a series of faint lines up and down the column. In this way, the heights of the striae say something about the cooling process, as do the widths of the columns. Scientists have developed models of how the stria height relates to the cooling rate of basalt on Earth. But details such as striae are too small to be seen in the images of the Martian columns. That means the stria height must be deduced from a feature that can be resolved: the column width. To figure out how these two features are related, the LPSA interns measured both characteristics at three locations in the scablands. We had to make some assumptions about the conditions on Mars, but if the cooling processes were similar on Mars and Earth, and if water was involved in the cooling, then the cooling time in Marte Vallis was between 2 and 8 years, compared to 2 years for the Channeled Scablands. Other researchers say the cooling can be uniform without the aid of water. By fleshing out the details of how basalt columns formed in the scablands, then, scientists should get some valuable information about the history of water on the surface of Mars. As the discussions continue, so does the legacy of the Channeled Scablands.
Mars is not interesting only on surface abd beneath - there is some action in the air too - check following picture and let's see what do you see.
You see that little puffy think on the top, just as some kind of the cloud in high altitude atmosphere? Clouds over the Red Planet are common enough, and can be spotted through small telescopes, though one at this altitude is pretty much unusual. They’ve been seen before like this, so it’s not completely unheard of, but that doesn’t make it any less interesting.
Scientists debated for some time what would be the best place to search for signs of life on Mars - present or past one. It turns out craters made by asteroid impacts may be the best place to look for signs of life on other planets, a study suggests. Tiny organisms have been discovered thriving deep underneath a site in the US where an asteroid crashed some 35 million years ago for example. Scientists believe that the organisms are evidence that such craters provide refuge for microbes, sheltering them from the effects of the changing seasons and events such as global warming or ice ages.
There has been little agreement among scientists about the origin of the large carbon macromolecules detected in Martian meteorites. Theories about their origin include contamination from Earth or other meteorites, the results of chemical reactions on Mars, or that they are the remnants of ancient Martian biological life. But as you might know, there are craters of all kinds. Check following picture taken by HiRISE:
You may think these are mounds and not craters, but that’s an illusion. Our brain uses illumination to gauge up and down in pictures like these, and assumes the sunlight is coming from above. However, these really are craters, but the illumination is coming from below - north is roughly toward the top of the picture and the crater field is at a northern latitude of about 50°. Flip the picture over if it helps. But that’s not the weirdest thing about these craters. What’s really odd is they aren’t circular. Impacts are generally round unless the impact is at a very shallow angle or, the terrain suddenly goes from one kind of material to another, creating a discontinuity or, something happened after the crater was formed to distort it. A shallow-angle impact is almost certainly not the case here, since there are so many craters spread out over the region that an incoming object would’ve had to break up into a gazillion pieces, all of which came in at that angle. Not impossible, but it seems unlikely. The changing terrain idea doesn’t work, since again the craters are spread out over the area. You might see one crater with a sudden break in its rim or change in shape, but dozens? Spread out in all directions? Nope. That leaves after effects, and in this case we have two more clues. One is that all the craters have their long axes aligned; in other words they all point in the same direction. The other is that every crater has roughly the same features: a small crater in the lower left hand side, and the shallow floor reaching up and to the right. Another clue? The illumination angle again: the Sun is shining so that it illuminates the upper right side of the crater wall. Why is that last part important? Because sunlight on Mars turns ice into water vapor. At this latitude on Mars, water ice has been seen just below the surface. In fact, one way it’s seen is when small meteorite impacts carve out craters, exposing it. These craters are all small (the biggest one in this shot is about 75 meters across), and judging from their appearances are all about the same age. That implies they’re secondary craters, caused when ejected debris from an impact rains back down to the surface. These secondary impacts plopped down all over this terrain, blasting through the top layer of the Martian surface and exposing the ice underneath. The Sun then started to melt the ice (or more properly sublimate it; with the very thin atmosphere there ice goes directly from a solid to a gas), and as it did so the terrain around it collapsed a bit. The Sun shines from the south to the north, so the northern rims of the craters receive the most heat, and expand in that direction. Then, some time later, what you have left are small circular craters - the original impacts - off to one side of an elongated crater that extends in a northward direction, and that extended part has a flat bottom due to the disappearing layer of ice that used to be there. This is at least the idea which Phil Plait finds to suite the probable truth. University of Colorado Boulder research team recently finished counting, outlining and cataloging a staggering 635000 impact craters on Mars that are roughly a kilometer or more in diameter. As the largest single database ever compiled of impacts on a planet or moon in our solar system, the new information will be of help in dating the ages of particular regions of Mars.
Mars has some remarkable geological characteristics, including the largest volcanic mountain in the solar system, Olympus Mons; volcanoes in the northern Tharsis region that are so huge they deform the planet's roundness; and a gigantic equatorial rift valley, the Valles Marineris. This canyon system stretches a distance equivalent to the distance from New York to Los Angeles; Arizona's Grand Canyon could easily fit into one of the side canyons of this great chasm. Debate over the origin of large-scale polygons (hundreds of meters to kilometers in diameter) on Mars remains active even after several decades of detailed observations. Similarity in geometric patterns on Mars and Earth has long captured the imagination. Geologists at The University of Texas at Austin examined these large-scale polygons and compare them to similar features on Earth's seafloor, which they believe may have formed via similar processes. Understanding these processes may in turn fuel support for the idea of ancient oceans on Mars.
Through examination of THEMIS, MOLA, Viking, and Mariner data and images, planetary scientists have found that areas on the northern plains of Mars are divided into large polygon-shaped portions and that sets of these polygons span extensive areas of the Martian surface. Smaller polygon-shaped bodies are found elsewhere on Mars, but these are best explained by thermal contraction processes similar to those in terrestrial permafrost environments and not likely to form larger polygons. On Earth, polygon-shaped areas, with the edges formed by faults, are common in fine-grained deep-sea sediments. Some of the best examples of these polygon-fault areas are found in the North Sea and the Norwegian Sea. These are imaged using detailed, 3-D seismic surveys conducted to search for offshore oil and gas deposits. Images reproduced in this paper show that these deep-water polygons are also 1000 meters or greater in diameter. Physical mechanism of polygon formation requires a thick, wet, and mechanically weak layer of sediment. In the northern plains of Mars, where the surface is basically flat, the polygons have very regular shapes and sizes - remarkably similar to the deep-sea polygons found on Earth. In places where the topography on Mars is more varied, and where there may be evidence for other sediment-transport features on the surface, areas of deformed and disrupted polygons can be found - again similar to the disrupted polygons here on Earth. On the basis of these striking similarities, the University of Texas at Austin team concluded that these features most likely share a common origin and were formed by similar mechanisms in a similar environment. The team argues that the Martian polygons were formed within a thick, wet, and weak layer of fine-grained sediments that were deposited in a deep-water setting, similar to the Earth polygons. Thus, these interesting geometric features may provide additional evidence for the existence of an ocean in the northern portion of Mars approximately three billion years ago.
Mars also has two small moons, Phobos and Deimos (see above picture for trajectories). Although no one knows how they formed, they may be asteroids snared by Mars's gravity. A mission to a Martian moon Phobos could return with alien life, according to experts at Purdue University. A sample from the moon Phobos, which is much easier to reach than the Red Planet itself, would almost surely contain Martian material blasted off from large asteroid impacts. If life on Mars exists or existed within the last 10 million years, a mission to Phobos could yield our first evidence of life beyond Earth. When an asteroid hits the surface of a planet it ejects a cone-shaped spray of surface material, similar to the splash created when someone does a cannonball into a swimming pool. These massive impacts pulverize the surface material and scatter high-speed fragments. Researchers calculated that the bulk of the fragments from such a blast on Mars would be particles about one-thousandth of a millimeter in diameter, or 100 times smaller than a grain of sand, but similar in size to terrestrial bacteria. The team followed the possible paths the tiny particles could take as they were hurtled from the planet's surface through space, examining possible speeds, angles of departure and orbital forces. The team plotted more than 10 million trajectories and evaluated which would intercept Phobos and where they might land on the moon during its eight-hour orbit around Mars (as seen on picture above).
The new findings, which suggest optimal depths and locations to probe for organic molecules like those that compose living organisms as we know them, could help the newest Mars rover scout for evidence of life beneath the surface and within rocks. The results suggest that, should Mars harbor simple organic molecules, NASA's prospects for discovering them during Curiosity's explorations are better than previously thought. While these simple molecules could provide evidence of ancient Martian life, they could also stem from other sources like meteorites and volcanoes. Complex organic molecules could hint more strongly at the possibility of past life on the planet. These molecules, made up of 10 or more carbon atoms, could resemble known building blocks of life such as the amino acids that make up proteins. Although complex carbon structures are trickier to find because they're more vulnerable to cosmic radiation that continuously bombards and penetrates the surface of the Red Planet, the new research by Pavlov and his colleagues provides suggestions for where to start looking. The amounts of radiation that rock and soil is exposed to over time, and how deep that radiation penetrates - an indicator of how deep a rover would have to sample to find intact organic molecules - is a subject of ongoing research. The scientists report that chances of finding these molecules in the first 2 centimeters of Martian soil is close to zero. That top layer, they calculate, will absorb a total of 500 million grays of cosmic radiation over the course of one billion years - capable of destroying all organic material. A mere 50 grays, absorbed immediately or over time, would cause almost certain death to a human. However, within 5 to 10 centimeters beneath the surface, the amount of radiation reduces tenfold, to 50 million grays. Although that's still extreme, the team reports that simple organic molecules, such as a single formaldehyde molecule, could exist at this depth - and in some places, specifically young craters, the complex building blocks of life could remain as well.
Before humans can safely go to Mars, we need to know much more about the planet's environment, including the availability of resources such as water. So far we had many missions and one is just about to make landing. The first successful fly-by of Mars was on July 14-15, 1965, by NASA's Mariner 4. On November 14, 1971 Mariner 9 became the first space probe to orbit another planet when it entered into orbit around Mars. The first to contact the surface were two Soviet probes: Mars 2 lander on November 27 and Mars 3 lander on December 2, 1971 - Mars 2 failed during descent and Mars 3 seconds after landing. Mars 6 failed during descent but did return some atmospheric data in 1974. The 1975 NASA launches of the Viking program consisted of two orbiters, each having a lander; both landers successfully touched down in 1976. Viking 1 remained operational for six years, Viking 2 for three. The Viking landers relayed the first color panoramas of Mars and the orbiters mapped the surface so well that the images remain in use. The Soviet probes Phobos 1 and 2 were sent to Mars in 1988 to study Mars and its two moons, but with a focus on Phobos. Phobos 1 lost contact on the way to Mars. Phobos 2, while successfully photographing Mars and Phobos, failed before it was set to release two landers to the surface of Phobos. Roughly two-thirds of all spacecraft destined for Mars have failed without completing their missions. Failures since Viking include Phobos 1 & 2 (1988), Mars Observer (1990), Mars 96 (1996), Mars Climate Orbiter (1999), Mars Polar Lander with Deep Space 2 (1999), Nozomi (2003), Beagle 2 (2003), and Fobos-Grunt with Yinghuo-1 (2011). With last one, Russia has unfortunate score where each mission to Mars has failed.
Following the 1992 failure of the Mars Observer orbiter, the NASA Mars Global Surveyor achieved Mars orbit in 1997. This mission was a complete success, having finished its primary mapping mission in early 2001. Contact was lost with the probe in November 2006 during its third extended program, spending exactly 10 operational years in space. The NASA Mars Pathfinder, carrying a robotic exploration vehicle Sojourner, landed in the Ares Vallis on Mars in the summer of 1997, returning many images. The NASA Phoenix Mars lander arrived on the north polar region of Mars on May 25, 2008. Its robotic arm was used to dig into the Martian soil and the presence of water ice was confirmed on June 20. The mission concluded on November 10, 2008 after contact was lost. Rosetta came within 250 km of Mars during its 2007 flyby. Dawn flew by Mars in February 2009 for a gravity assist on its way to investigate Vesta and then Ceres. Mars is currently host to three functional orbiting spacecraft: Mars Odyssey, Mars Express, and the Mars Reconnaissance Orbiter, and one on the surface - the Mars Exploration Rover Opportunity. Evidence of ancient water at a Martian crater is the latest in a long series of discoveries by a surprisingly long-lived Mars Exploration Rover Opportunity. The latest discovery was made at the rim of the Endeavour Crater, a large ancient impact crater on Mars measuring 20km in diameter - this was the third area on Mars visited by the Mars rovers that has produced evidence of "habitable" ancient geological environments.
Opportunity has been exploring the Meridiani region of Mars since landing in January 2004. It arrived at the Cape York section of the rim of Endeavour Crater in August 2011, and has been studying rock and soil targets on Cape York since then. Above picture shows NASA's Mars Rover Opportunity catching its own late-afternoon shadow in this dramatically lit view eastward across Endeavour Crater on Mars. The rover used the panoramic camera between about 4:30 and 5:00 pm. local Mars time to record images taken through different filters and combined into this mosaic view.
NASA began a historic voyage to Mars with the November 26, 2011 launch of the Mars Science Laboratory, which carries a car-sized rover named Curiosity. The mission will pioneer precision landing technology and a sky-crane touchdown to place Curiosity near the foot of a mountain inside Gale Crater on August 6, 2012. During a nearly two-year prime mission after landing, the rover will investigate whether the region has ever offered conditions favorable for microbial life, including the chemical ingredients for life. Curiosity's ambitious science goals are among the mission's many differences from earlier Mars rovers. It will use a drill and scoop at the end of its robotic arm to gather soil and powdered samples of rock interiors, then sieve and parcel out these samples into analytical laboratory instruments inside the rover. Curiosity carries 10 science instruments with a total mass 15 times as large as the science-instrument payloads on the Mars rovers Spirit and Opportunity. Some of the tools are the first of their kind on Mars, such as a laser-firing instrument for checking the elemental composition of rocks from a distance, and an X-ray diffraction instrument for definitive identification of minerals in powdered samples.
To haul and wield its science payload, Curiosity is twice as long and five times as heavy as Spirit or Opportunity. Because of its one-ton mass, Curiosity is too heavy to employ airbags to cushion its landing as previous Mars rovers could. Part of the Mars Science Laboratory spacecraft is a rocket-powered descent stage that will lower the rover on tethers as the rocket engines control the speed of descent. The mission's landing site offers Curiosity access for driving to layers of the mountain inside Gale Crater. Observations from orbit have identified clay and sulfate minerals in the lower layers, indicating a wet history.
Precision landing maneuvers as the spacecraft flies through the Martian atmosphere before opening its parachute make Gale a safe target for the first time. This innovation shrinks the target area to less than one-fourth the size of earlier Mars landing targets. Without it, rough terrain at the edges of Curiosity's target would make the site unacceptably hazardous. The innovations for landing a heavier spacecraft with greater precision are steps in technology development for human Mars missions. In addition, Curiosity carries an instrument for monitoring the natural radiation environment on Mars, important information for designing human Mars missions that protect astronauts' health.
Now think about this: the rover weighs 890 kg, nearly a ton. The Mars air is thick enough that engineers have to deal with it, but too thin to bring Curiosity all the way to the surface safely. So they need a heat shield to slow it initially, a parachute to brake even more, and then rocket motors to drop it the rest of the way. It may sound strange, landing on Mars is harder than getting stuff back to Earth from space, or landing on the Moon. Our air is thick enough to make it relatively simple to slow something down enough for a comfortable landing, and since the Moon has no air, you just use rockets the whole way. Not so easy on Mars. Check following video which gives some insights into mission and how landing will look like. You MUST watch it - it is crazy - so crazy that it might just work. And is just few days away!
The area where NASA's Curiosity rover will land has a geological diversity that scientists are eager to investigate, as seen in this false-color map below based on data from NASA's Mars Odyssey orbiter.
Credits: National Geographic, Wikipedia, Arizona State University College of Liberal Arts and Sciences, Syracuse University, NASA, University of Arizona, Imperial College London, ESA, MIT, Carnegie Institution, University of Gothenburg, Purdue University, American Geophysical Union