Astronomy

Are there Earth rocks on Mars?

Are there Earth rocks on Mars?

Certain meteorites found on Earth have been established to come from Mars: a giant impact ejected rocks from Mars, these rocks traveled through interplanetary space, and went through the Earth's atmosphere without completely burning up.

Might it be possible to find a meteorite on Mars that comes from Earth from the same kind of mechanism?

Earth's gravity is stronger than Mars', so I guess you would need a bigger impact to send debris into interplanetary space. And the atmosphere is thicker on Earth, so the impacting body would need to be even bigger for enough of it to touch the ground. And you also need to give the rocks more energy so that they can go outwards in the Sun's gravitational well. So I'm guessing that impacts that might be violent enough are rarer for the Earth than they are for Mars.

Might it be possible for there to be Earth meteorites on Mars? And if so, is there any chance that we might stumble upon one?


Well if no one is going to answer this I will. The answer is we don't know for sure. We speculate that there should be earth rocks on mars but until we 'see' one and analyze it we will not know for sure. The comments here all point to this answer.

Mars hit with thousands of Earth rocks possibly containing life following asteroid impacte talks about the Chicxulub impact and how it probably spread rocks to all the terrestrial planets in our solar system and the moons of all the planets.

The statement comes from Penn State University researchers who have calculated the approximate number of rocks from our planet large enough to possibly carry life that have made their way into space over the past few billion years.

Said the paper's lead author Rachel Worth: “We find that rock capable of carrying life has likely transferred from both Earth and Mars to all of the terrestrial planets in the solar system and Jupiter. Any missions to search for life on Titan or the moons of Jupiter will have to consider whether biological material is of independent origin, or another branch in Earth's family tree.”

The article cites its source as The BBC's Dinosaur asteroid 'sent life to Mars' which cites a 2013 paper published in Astrobiology Seeding Life on the Moons of the Outer Planets via Lithopanspermia:

The asteroid that wiped out the dinosaurs may have catapulted life to Mars and the moons of Jupiter, US researchers say.

They calculated how many Earth rocks big enough to shelter life were ejected by asteroids in the last 3.5bn years.

The Chicxulub impact was strong enough to fire chunks of debris all the way to Europa, they write in Astrobiology.

Thousands of potentially life-bearing rocks also made it to Mars, which may once have been habitable, they add.

"We find that rock capable of carrying life has likely transferred from both Earth and Mars to all of the terrestrial planets in the solar system and Jupiter," says lead author Rachel Worth, of Penn State University.


It is certainly possible for rocks from Earth to be ejected and impact - and survive impact - on Mars. However, without doing specific isotopic analysis to determine the origin, one cannot simply look at a meteorite and determine its source body. No rovers that we have now have the capability to measure these isotopes.

With that overview, it is much harder for a rock from Earth to land on Mars: Going outwards in the solar system is harder to do than going inwards for ejected material. I don't know of any really recent work done on this, but a model by Melosh & Tonks (1993; abstract here) found that only 5% of material ejected from Earth will hit Mars, but more from Mars hit Earth. Gladman et al. (1996) also looked at the Mars ejection question and found that about 7.5% of ejecta from Mars will make it to Earth, but I don't see them doing a corresponding analysis for Earth-to-Mars.

Most dynamic work that I know of has modeled stuff coming to Earth because it's stuff on Earth that we can really analyze and have a chance of determining is origin.


Mars might support microbial life, deep underground

Planetary scientist Jesse Tarnas of Brown University and NASA’s Jet Propulsion Laboratory led a new study on the possibility of microbial life beneath the surface of Mars. Here he is at the Kidd Creek Mine in Canada, sampling groundwater 1.5 miles (2.4 km) underground. Image via University of Toronto Stable Isotope Laboratory/ Jesse Tarnas.

Has life ever existed on Mars? Could there still be life somewhere on the planet today? Those are still unanswered questions, but growing evidence over the past few decades has suggested that ancient Mars was quite habitable, at least for microscopic organisms. Evidence for the possibility of the existence present-day Martian life has also increased.

A new study from scientists at Brown University suggests that the Martian subsurface might be a good place to look for possible present-day microbial life on the planet. It’s an idea that has also been suggested in in other studies, but the new research, published April 15, 2021, in the peer-reviewed journal Astrobiology, finds evidence that rocks below the planet’s surface could produce the same kinds of chemical energy that sustain microbial life underground on Earth.

The scientists came to this tentative but tantalizing conclusion after studying Martian meteorites, pieces of Martian rock that eventually landed on Earth after being blasted off Mars’ surface by impacts. By analyzing the chemical composition of the meteorites, the researchers determined that if those rocks were in continuous contact with water, they would produce the same kind of chemical energy that supports microbial communities below the surface on Earth.

Artist’s illustration of subsurface lakes on Mars. Such lakes, or groundwater, would be the best place to search for current Martian life, according to the new study. Chemical interactions with rocks in the crust would provide all the ingredients necessary to sustain microbial ecosystems. Image via NASA/ JPL/ Science Focus.

The results are exciting since the rocks are thought to represent a wide swath of the Martian crust. Jesse Tarnas, a postdoctoral researcher at NASA’s Jet Propulsion Laboratory who led the study, said in a statement:

The big implication here for subsurface exploration science is that wherever you have groundwater on Mars, there’s a good chance that you have enough chemical energy to support subsurface microbial life. We don’t know whether life ever got started beneath the surface of Mars, but if it did, we think there would be ample energy there to sustain it right up to today.

Tarnas led the study while completing his Ph.D. at Brown University.

The possibility of present-day life may then be dependent on there being groundwater or other subsurface water on Mars. We know from rover and orbital missions that there is ample evidence for groundwater in Mars’ past, but what about now?

The researchers say that there should be groundwater in places on Mars even now, and indeed, the first evidence for subsurface water on Mars was found in 2018. The Mars Advanced Radar for Subsurface and Ionosphere Sounding (MARSIS) instrument on the Mars Express orbiter found evidence for a 12.5-mile wide (20-km wide) lake beneath the ice at the Martian south pole. The water is thought to be kept liquid by salts and pressure from the ice above it. In October 2020, three more smaller but similar lakes close to the first one were also announced.

Despite the cold subsurface environment, such lakes or other groundwater could potentially still support life today, if it ever started. In similar conditions on Earth, vast biomes exist completely separated from the world above on the surface. The microbes in these biomes use the byproducts of the chemical reactions for energy, despite the lack of sunlight. Biomes are defined as “the world’s major communities, classified according to the predominant vegetation and characterized by adaptations of organisms to that particular environment.”

To search for present-day life on Mars, some experts believe we should drill deep underground, as in this artist’s concept. Image via NASA/ JPL/ NBC News.

How do those reactions happen?

They occur when rocks below the surface come into contact with water. Radiolysis, for example – the dissociation of molecules by ionizing radiation – happens when radioactive elements within rocks react with water trapped in pores and fracture spaces. The chemical reaction breaks the water molecules into hydrogen and oxygen. The hydrogen dissolves in the remaining groundwater, while the oxygen is soaked up by minerals such as pyrite (also known as fools gold). This forms sulfate minerals. One prime location for this kind of chemical activity is the Kidd Creek Mine in Ontario, Canada.

This is great for microbes, which consume the hydrogen for fuel, and use the oxygen to “burn” the fuel.

Microbial ecosystems such as this have been found on Earth more than a mile (1.6 km) deep underground, where the water has never seen sunlight for more than a billion years. These organisms are known as sulfate-reducing microorganisms.

Since these environments are common on Earth, could they also exist on Mars? The researchers decided to look for evidence of similar radiolysis habitats beneath the Martian surface. They combined data from the Curiosity rover, orbiters and directly from the meteorites. They searched specifically for radioactive elements like thorium, uranium and potassium, along with sulfide minerals that could be converted to sulfate. The researchers also wanted to see if the rocks had enough pore space to hold liquid water.

Radar image from Mars Express in 2018 showing the first detected largest lake beneath the south polar ice. Image via ESA/ NASA/ JPL/ ASI/ Univ. Rome/ R. Orosei et al. 2018.

The results were very encouraging. All the necessary ingredients were found, in enough abundance, in several types of Martian meteorites. Older rocks like regolith breccias were found to be the most likely to be able to support microbial life. Those rocks from Mars’ crust are more than 3.6 billion years old.

If there is a good chance of microbial life beneath Mars’ surface today, then how do we look for it?

You would need to dig a lot deeper than any rover or lander has before, using a small drill probe, according to the researchers. It would be challenging, but not impossible. If such an endeavor were to actually find life, it would then of course be well worth the effort. Co-author Jack Mustard at Brown University said:

The subsurface is one of the frontiers in Mars exploration. We’ve investigated the atmosphere, mapped the surface with different wavelengths of light and landed on the surface in half-a-dozen places, and that work continues to tell us so much about the planet’s past. But if we want to think about the possibility of present-day life, the subsurface is absolutely going to be where the action is.

A similar study from Rutgers University reported on in December 2020 also recommended looking deep underground for any Martian microbes. That study focused on how geothermal heat could melt subsurface ice.

In 2020, the discovery of three more subsurface lakes was announced, adjacent to the first larger one beneath the South Pole (in blue here). This is a radar map from Mars Express. Could there still be groundwater elsewhere on Mars also? Image via ESA/ Ars Technica.

NASA’s Perseverance rover has just started its mission to search for signs of ancient life in an ancient river delta, and ESA’s ExoMars rover Rosalind Franklin will soon launch to look for evidence of life as well. The rover can drill deeper than Perseverance, about 2 meters, although probably still not enough to reach any groundwater that may exist below. These are the first missions since the Viking landers in the late 1970s/early 1980s that are designed specifically to look for life (with mixed results still debated today). Up until now, most other rovers and landers have focused on finding evidence for habitable conditions on ancient Mars, which they have done, in spades.

If Tarnas and his colleagues are right, then to find current life, we need to look underground. The old adage of Mars exploration may well turn out to be right after all: to look for life, follow the water.

Bottom line: Mars has the right ingredients for current subsurface microbial life, according to a new study from Brown University.


Spacecraft Exploration of Mars

Figure 1. Mars Photographed by the Hubble Space Telescope: This is one of the best photos of Mars taken from our planet, obtained in June 2001 when Mars was only 68 million kilometers away. The resolution is about 20 kilometers—much better than can be obtained with ground-based telescopes but still insufficient to reveal the underlying geology of Mars. (credit: modification of work by NASA and the Hubble Heritage Team (STScI/AURA))

Mars has been intensively investigated by spacecraft. More than 50 spacecraft have been launched toward Mars, but only about half were fully successful. The first visitor was the US Mariner 4, which flew past Mars in 1965 and transmitted 22 photos to Earth. These pictures showed an apparently bleak planet with abundant impact craters. In those days, craters were unexpected some people who were romantically inclined still hoped to see canals or something like them. In any case, newspaper headlines sadly announced that Mars was a “dead planet.”

In 1971, NASA’s Mariner 9 became the first spacecraft to orbit another planet, mapping the entire surface of Mars at a resolution of about 1 kilometer and discovering a great variety of geological features, including volcanoes, huge canyons, intricate layers on the polar caps, and channels that appeared to have been cut by running water. Geologically, Mars didn’t look so dead after all.

The twin Viking spacecraft of the 1970s were among the most ambitious and successful of all planetary missions. Two orbiters surveyed the planet and served to relay communications for two landers on the surface. After an exciting and sometimes frustrating search for a safe landing spot, the Viking 1 lander touched down on the surface of Chryse Planitia (the Plains of Gold) on July 20, 1976, exactly 7 years after Neil Armstrong’s historic first step on the Moon. Two months later, Viking 2 landed with equal success in another plain farther north, called Utopia. The landers photographed the surface with high resolution and carried out complex experiments searching for evidence of life, while the orbiters provided a global perspective on Mars geology.

Mars languished unvisited for two decades after Viking. Two more spacecraft were launched toward Mars, by NASA and the Russian Space Agency, but both failed before reaching the planet.

The situation changed in the 1990s as NASA began a new exploration program using spacecraft that were smaller and less expensive than Viking. The first of the new missions, appropriately called Pathfinder, landed the first wheeled, solar-powered rover on the martian surface on July 4, 1997 Figure 2.

Figure 2. Surface View from Mars Pathfinder: The scene from the Pathfinder lander shows a windswept plain, sculpted long ago when water flowed out of the martian highlands and into the depression where the spacecraft landed. The Sojourner rover, the first wheeled vehicle on Mars, is about the size of a microwave oven. Its flat top contains solar cells that provided electricity to run the vehicle. You can see the ramp from the lander and the path the rover took to the larger rock that the mission team nicknamed “Yogi.” (credit: NASA/JPL)

An orbiter called Mars Global Surveyor (MGS) arrived a few months later and began high-resolution photography of the entire surface over more than one martian year. The most dramatic discovery by this spacecraft, which is still operating, was evidence of gullies apparently cut by surface water, as we will discuss later. These missions were followed in 2003 by the NASA Mars Odyssey orbiter, and the ESA Mars Express orbiter, both carrying high-resolution cameras. A gamma-ray spectrometer on Odyssey discovered a large amount of subsurface hydrogen (probably in the form of frozen water). Subsequent orbiters included the NASA Mars Reconnaissance Orbiter to evaluate future landing sites, MAVEN to study the upper atmosphere, and India’s Mangalayaan, also focused on study of Mars’ thin layers of air. Several of these orbiters are also equipped to communicate with landers and rovers on the surface and serve as data relays to Earth.

In 2003, NASA began a series of highly successful Mars landers. Twin Mars Exploration Rovers (MER), named Spirit and Opportunity, have been successful far beyond their planned lifetimes. The design goal for the rovers was 600 meters of travel in fact, they have traveled jointly more than 50 kilometers. After scouting around its rim, Opportunity drove down the steep walls into an impact crater called Victoria, then succeeded with some difficulty in climbing back out to resume its route (Figure 3). Dust covering the rovers’ solar cells caused a drop in power, but when a seasonal dust storm blew away the dust, the rovers resumed full operation. In order to survive winter, the rovers were positioned on slopes to maximize solar heating and power generation. In 2006, Spirit lost power on one of its wheels, and subsequently became stuck in the sand, where it continued operation as a fixed ground station. Meanwhile, in 2008, Phoenix (a spacecraft “reborn” of spare parts from a previous Mars mission that had failed) landed near the edge of the north polar cap, at latitude 68°, and directly measured water ice in the soil.

Figure 3. Victoria Crater: (a) This crater in Meridiani Planum is 800 meters wide, making it slightly smaller than Meteor crater on Earth. Note the dune field in the interior. (b) This image shows the view from the Opportunity rover as it scouted the rim of Victoria crater looking for a safe route down into the interior. (credit a: modification of work by NASA/JPL-Caltech/University of Arizona/Cornell/Phio State University credit b: modification of work by NASA/JPL/Cornell)

In 2011, NASA launched its largest (and most expensive) Mars mission since Viking. The 1-ton rover Curiosity, the size of a subcompact car, has plutonium-powered electrical generators, so that it is not dependent on sunlight for power. Curiosity made a pinpoint landing on the floor of Gale crater, a site selected for its complex geology and evidence that it had been submerged by water in the past. Previously, Mars landers had been sent to flat terrains with few hazards, as required by their lower targeting accuracy. The scientific goals of Curiosity include investigations of climate and geology, and assessment of the habitability of past and present Mars environments. It does not carry a specific life detection instrument, however. So far, scientists have not been able to devise a simple instrument that could distinguish living from nonliving materials on Mars.

The Curiosity rover required a remarkably complex landing sequence and NASA made a video about it called 𔄟 Minutes of Terror” that went viral on the Internet.

A dramatic video summary of the first two years of Curiosity’s exploration of the martian surface can be viewed as well:


Mushrooms on Mars? Five unproven claims that alien life exists

Mushroom-like structures on Mars. Credit: NASA

A recent study claims to have found evidence for mushroom-like life forms on the surface of Mars. As it happens, these particular features are well known and were discovered by cameras aboard Nasa's Mars Exploration Rover Opportunity, shortly after it landed in 2004.

They are not, in fact, living organisms at all, but "haematite concretions"—small sphere-shaped pieces of the mineral haematite, and their exact origin is still debated by scientists. Haematite is a compound of iron and oxygen and is commercially important on Earth. The spherical rocks on Mars may have been created by the gradual accumulation of the material in slowly evaporating liquid water environments. They could also have been produced by volcanic activity.

Either way, mushrooms they are not. The area around Opportunity's landing site is littered with them—they can be seen all over the surface and were also found buried beneath the soil and even embedded within rocks.

These space "mushrooms" were not the first claim of alien life. On August 7, 1996, the then US president Bill Clinton stood on the White House lawn and announced the possibility that scientists had discovered the ancient, fossilized remains of micro-organisms in a meteorite that had been recovered from Antarctica in 1984.

The meteorite, ALH 84001, is one of a handful of rocks we have from Mars. These were blasted off the surface of the planet by volcanic eruptions or meteorite impacts, drifted through space probably for millions of years, before ending up on Earth.

The tiny structures discovered within, using powerful microscopes, resemble microscopic worm-like organisms and are likely to be billions of years old. Debate over the true origins of these structures continues today—many scientists have pointed out that well known inorganic processes are quite capable of producing structures which resemble living organisms. In other words, simply because something might look a bit like life (mushrooms or otherwise), that does not mean it is.

High-resolution scanning electron microscope image of the structures. Credit: NASA

In the 1970s Nasa's Viking robotic landers carried a series of experiments designed to test the Martian soil for the presence of microorganisms.

The experiments chemically treated small samples of Martian soil in reaction chambers on board the landers. In one of them, nutrients containing radioactive carbon-14 were added to the soil samples. In theory, this should be absorbed by any growing and multiplying microbes. The carbon-14 would then increasingly be "breathed out" over time, showing a steady increase in concentration within the reaction chamber.

After the chemical analyses, each soil sample was steadily heated to hundreds of degrees to destroy any microbes, with the intention of seeing whether any such reactions in the soil ceased. Intriguingly, this particular experiment did show a steady increase in carbon-14 over time which was indeed terminated after heating to above the boiling point of water. Several inorganic chemical reactions have been proposed as an explanation. These results therefore remain inconclusive and are still debated today.

More recently, minute quantities of methane have been found in the Martian atmosphere. This is also intriguing as living organisms on Earth are known to release methane. Once again, however, it must be stressed that this not conclusive proof of life. Methane can also be produced by several inorganic processes, including by heated rocks.

In 1977, the Big Ear radio telescope in the US detected an unusual radio signal while scanning the sky. The signal lasted for just a couple of minutes, was very high powered and was detected over a narrow range of frequencies. These factors make it quite difficult to envisage a natural cause, as most natural radio sources can be detected across a wide range of frequencies.

Alien megastructure? Credit: Droneandy/Shutterstock

The exact signal has not been detected again since, despite frequent radio surveys of the same part of the sky. The signal was so remarkable at the time that the astronomer on duty, Jerry Ehman, circled the print out of the signal with red pen and wrote "Wow!" next to it.

Various explanations have been proposed over the years including, recently, that the signal was generated by a passing comet, or transmissions from an Earth-orbiting satellite. The exact origin of the Wow! signal is still not fully agreed upon today, and remains an intriguing mystery.

A key tool of planet hunting is the dimming method—observing light from a star to see if it periodically dips in a regular fashion as an orbiting planet passes in front of it. In 2015, professional astronomers working with citizen scientists from the Planet Hunters project announced the discovery of a nearby star displaying unusually strong and consistent dimming over time.

Tabby's Star is named after astronomer Tabitha Boyajian who was lead author on the paper announcing the discovery. Data from the Kepler Space Telescope showed not just a regular dimming, as one might expect from a planetary orbit, but highly irregular dips in the light and, interestingly, a consistent decrease in light output over several years.

This highly unusual behavior prompted numerous theories to explain the observations, including cometary dust or debris from a massive impact gradually spreading out to cover the face of the star. Some also speculated that these were signatures of an advanced alien species building a structure around the star. But further observations have found no corroborating evidence to support this possibility. For example, radio telescopes have failed to detect any unusual radio emissions from the star. Today, the scientists behind the discovery believe that the unusual dips in light are caused by clouds of cosmic dust passing across the face of the star.

As exciting as they are, it is important to treat claims of alien life with a healthy dose of skepticism, and this is indeed what scientists do. No conclusive evidence that extraterrestrial life exists has been found … yet.

This article is republished from The Conversation under a Creative Commons license. Read the original article.


Zzzzzt! Mars might be sparky

Given that the atmosphere there is pretty dry, it doesn't get thunderstorms. So, large-scale lightning bolts are probably nonexistent.

More Bad Astronomy

Still, what about smaller scale electrical discharges? There's reason to think those might exist on Mars. For example, on Earth, volcanic eruptions can create decent-sized bolts as ash particles rub against each other (and quite violently) inside the plume. This generates a charge via the triboelectric effect, when molecules in one particle give up an electron or two to molecules in other particles (the same thing that happens when you rub a balloon against your hair to build up a static charge which you can use to stick the balloon to a wall). The plume separates the charges, and when enough charge is built up this way, craaaaaack! There's a sudden sharp flow of electricity to restore balance. In other words, strokes of lightning.

An eruption of Japan’s Sakarujima volcano creates bolts of lightning due to grains of ash rubbing against each other and building up an electric charge. Credit: Getty Images / Mike Lyvers

These bolts, on the scale of tens of meters, are much smaller than lightning bolts from storms, which can be hundreds of meters long. Still, Mars is a grainy place (small particles made as rocks erode), and windy, too. Dust storms on the fourth planet can get quite large, and there are numerous (and quite sizable) dust devils, too vortices similar to tornadoes that can loft particles from the surface. Could these create lightning similar to terrestrial volcanoes?

There is some evidence of static charge buildup on Mars images taken by Sojourner, the first rover sent by NASA, showed dust building up on the metal wheels and other parts, but it unfortunately wasn't equipped to measure if this was due to static electricity or not. But it's an indication it might be, and such a mechanism might play a role on Mars.

Time-lapse video of an eruption by Volcán de Colima in Mexico, showing huge static discharge lightning bolts due to the triboelectric effect as rough ash particles rub against each other. Credit: César Cantú

Scientists have experimented in the lab for years trying to find out. Basically, they take simulated Martian grains (using basalt particles, a volcanic mineral extremely common on Mars) and use flowing air to whirl them around in a chamber to see if they gather charge and then discharge it. However, there are issues that complicate things for example, they use small chambers to contain grains, and the grains can hit the walls of the chamber which can affect the way the grains charge and discharge. Also, they don't always simulate Martian atmospheric conditions.

A new experiment aimed to get around that. They used volcanic grains from Earth to simulate Martian ones, and made a cylindrical glass chamber about 10 centimeters tall to contain them. They filled it with carbon dioxide — the air on Mars is nearly all CO2 — and reduced the pressure to that of Mars as well (in this case about 0.8% of Earth's at sea level). They then blew the air around such that the grains spun around the chamber and bumped into each other (this has the delightful description of entrained fluidized grain flow) while avoiding the glass walls, then used a device to measure the electric potential inside the chamber.

A towering dust devil on Mars seen from orbit. The plume was 30 meters wide and 800 meters high. Credit: NASA/JPL-Caltech/University of Arizona

What they found is that within minutes the grains built up a decent static charge, which then discharged as sparks between grains (similar to the sparks you get when you rub your feet on a carpet and touch someone). The current flow was small, but they detected discharges every few seconds, with a greater charge building up over time.

This shows that yes indeed, grains of basalt near the Martian surface can build up a triboelectric charge. The charge is small, though, so it's not likely that you'd get huge bolts on Mars. Also, the air on Mars tends to break down (that is, allow current to flow) much more easily than Earth's air, so it takes a far smaller charge to get a spark. That means the huge charge needed for big bolts is unlikely to build up.

However, the experiment shows that smaller bolts, similar to what's seen in Earthly volcanoes, are at least possible. So dust devils and dust storms (which can get very large, like covering-the-entire-planet large) might be able to produce small bolts. There are other factors that are difficult to reproduce on Earth in the lab, so it's not clear if this happens or not.

The experiment also showed that grain collisions with the walls have an effect as well. The put an acrylic tube in the glass chamber and measured what happens when the grains charge up they saw lots more positive discharges as opposed to the usual negative ones. Acrylic builds up a negative charge by taking electrons from the grains, so the positively charged grains tend to contact the walls, drawn by the opposite charge. This means that experiments that don't account for wall contact will likely get spurious results.

Artwork of a Martian dust storm approaching a rover, with small lightning bolts created from electric charge built up as dust grains rub against each other. Credit: NASA

This all has impact on what we know about circumstances on Mars. Dust buildup on rovers is a problem, and will no doubt be a problem for astronauts who eventually travel there (the same thing happened on the Moon to the Apollo astronauts). The charge buildup on grains can affect how dust is lofted into the Martian atmosphere and how grains aggregate, and can even affect the chemistry that occurs on the planet's surface. Understanding how the charge builds and discharges is an important part of understanding Mars in general.

Also, I can imagine being a scientist on Mars getting samples out on the surface and seeing a dust storm approach. It would be scary enough — visibility can drop, and the dust will get into everything * — but to also see it approaching with ten-meter-long bolts of electricity sizzling through it? Yikes.

Just another fun way Mars is weird. And sparky.

* Unlike some depictions, dust storm winds can't blow things around the air pressure on Mars is so low that even hurricane-speed winds would feel like a gentle breeze. However, particles in that wind would still be moving quickly and would give you quite the rash. Best to avoid them.


Are the rocks in the asteroid belt between Mars and Jupiter the same kind of rocks you’d find on the earth?

There are different types of asteroids, made of different things. Ones that most closely resemble Earth's composition in terms of the elements that go into them are the carbonaceous asteroids, but not necessarily in the same molecular configurations youɽ find on Earth. The rocks formed on Earth can be made by very different processes, through compression of sedimentary layers as an example. Stony meteorites do resemble igneous rocks like basalt, though. Other asteroids are made mostly of iron instead, and don't much resemble things youɽ find on Earth's surface - perhaps further down towards or in Earth's core things are similar, though - while others still are a mixture of iron and silicates.

Thank you for your reply! Does this also mean that a ‘regular Earth-rock’ would not survive in space?

Also worth noting that some do contain fairly high concentrations of precious metals, particularly platinum group metals. Which is why people are looking at asteroid mining despite the outrageously high cost. Some asteroids are estimated in the trillions of dollars of platinum and palladium.

what was the asteroid that wiped the dinosaurs out composed of?

Are asteroids and Earth rocks similarly dense? Most earth rocks are quite dense because they are being compressed by everything around them, but I imagine that there could easily be a lot of voids in a rock that formed in space, kind of like a pumice

Other asteroids are made mostly of iron instead, and don't much resemble things youɽ find on Earth's surface

Actually, meteors were the primary source of iron for humans during the Bronze Age, before the advent of extractive metallurgy in the early Iron Age (1200 BC).

Other asteroids are made mostly of iron instead, and don't much resemble things youɽ find on Earth's surface - perhaps further down towards or in Earth's core things are similar, though -

So would that make it something like a big roundish lump of native copper (except composed of iron instead of copper)?

Well, while we've got an accretion guy in the room, I have a question: is accretion the only way to get iron meteorites? Do you need to have had a planet build up, differentiate with the iron sinking to the middle, then get blasted apart? I've read that most all irons might be the offspring of 16 Psyche (thought to be the exposed core of a young planet) but I think this was speculation.

Are these asterpids oxidized or are they a more pure iron that would be easier to smelt?

Doubts have emerged over the last decade that the Earth's bulk composition is chondritic.

The 142Nd/144Nd ratio of the Earth is greater than the solar ratio as inferred from chondritic meteorites, which challenges a fundamental assumption of modern geochemistry—that the composition of the silicate Earth is ‘chondritic’, meaning that it has refractory element ratios identical to those found in chondrites.

Campbell, I.H. and O’Neill, H.S.C., 2012. Evidence against a chondritic Earth. Nature, 483(7391), pp.553-558.

Caro, G., Bourdon, B., Halliday, A.N. and Quitté, G., 2008. Super-chondritic Sm/Nd ratios in Mars, the Earth and the Moon. Nature, 452(7185), pp.336-339.

I've read somewhere that it's actually quite common for asteroids to be made of iron. So common in fact, that we never really to worry about running out?

(yes that's a question mark, since you probably know more about this than I do)

No, that's one of the reasons why meteorites can be identified easily, and how we discovered Martian meteorites. Asteroidal material has give through different processes than most Earth rocks. For some, chondrites, they've gone through very little processing. Existing as fused together masses of tiny grains of primitive material. Interestingly, these types of rocks have a mixture of elements in them consistent with the average of elements in rocky planets, containing a lot more iron, gold, iridium, etc. than ordinary crustal rocks on Earth.

Asteroids do contain processed materials, but the processes are different than on Earth. As asteroids and other "planetesimals" accreted during the early Solar System some got large enough to hold onto enough heat to melt, and differentiate into metal cores and stony crusts. These objects were subjected to later collisions which shattered them into smaller asteroids, leading to individual metallic and stony asteroids. The stony asteroids tend to be more "primitive" types of silicate rock than youɽ find on Earth, however.

Most rocks in the asteroid belt are chondrites, about 3/4 of them. About a sixth of the rocks are stony asteroids, which are the closest to Earth rocks but only as distant cousins, and the rest are metallic or other varieties.

Also, some Earth rocks undoubtedly do exist in space, and we will one day run across them as meteorites on the moon or Mars, but they are comparatively rare.


Amazing Tech Behind the Mission to Collect Rocks on Mars to Bring Back to Earth

If you could bring something back from Mars to Earth, what would you choose? This question is becoming reality, as ESA opens a call for scientists to join a NASA team working to determine which martian samples should be collected and stored by the Perseverance rover set to launch this Summer.

Perseverance is a standalone mission seeking signs of habitable conditions on our neighbor planet, but it is also part of the international Mars Sample Return campaign that ESA Member States agreed to finance last year during Space19+.

In a clean room at NASA’s Jet Propulsion Laboratory in Pasadena, USA, engineers observed the first driving test for NASA’s Mars 2020 rover on December 17, 2019. Credit: NASA/JPL-Caltech

Traveling over 53 million km to Mars, landing, collecting samples and launching a vehicle to return to Earth is unprecedented. This campaign will span a decade and involve four launches, including three from Earth and the first launch from another planet.

Interplanetary geo-caching

When Perseverance lands on Mars it will scout the area for over a year. One of its main tasks will be to collect samples in cigar-sized metal cylinders that it will leave on the surface for pickup at a later date. As part of this international collaboration, ESA plans to provide a sophisticated Sample Fetch Rover to be operated during NASA’s Sample Retrieval Lander mission in the middle of this decade.

The ESA rover will collect the samples that the Perseverance rover gathered and bring them to the lander, where they will be carefully stored in a Mars Ascent Vehicle (MAV). The MAV will launch the sample container from the martian surface, placing it in orbit around Mars.

Another important ESA contribution will be the biggest and most robust spacecraft flying to Mars – the Earth Return Orbiter that will rendezvous with the sample and bring it to Earth.

Packing for a return to Earth

Although the full campaign is in its early project phase, scientific experts must be selected now so they can begin training and operate alongside the Perseverance science team to enhance the value of the samples that will be collected. The selected scientists will also have to anticipate the needs of future investigators who may analyze these samples for a very diverse range of studies on Earth.

“We encourage applications from experts outside of the space field,” says ESA’s interim Mars Sample Return Programme Scientist Dr. Gerhard Kminek. “We need field geologists and laboratory experts who know how to pick the right samples based on information from the instruments that Perseverance has on-board.”

ESA’s human spaceflight team leader adds, “experts selected through this call will receive training to form part of the international team of martian-geologists-at-a-distance. These are exciting times and we are looking forward to receiving the best proposals Europe has to offer.”

Uncovering the secrets of our Solar System

Studying Mars samples on Earth will allow scientists to use instruments more powerful than anything that could be flown on robotic missions. The chance to learn and share resources, including sending samples to the best laboratories around the world, offers incredible opportunities for new discoveries.

An artist’s impression of ESA’s Earth Return Orbiter spacecraft that is part of the Mars Sample Return series of missions to bring back samples from Mars. The image shows the elements of Earth Return Orbiter. Including the basketball-sized container with samples from Mars, the Orbit Insertion Module – a chemical propulsive stage for inserting the spacecraft into Mars orbit that is ejected to save mass on the return to Earth – and the Earth entry capsule that will splash down on Earth. Credit: ESA

Samples may be analyzed again and again, enabling new information to be extracted – much like with lunar samples brought to Earth in the 1960s and 1970s, which continue to reveal new discoveries to this day.

Martian soil collected by NASA’s Mars rover Curiosity at a sandy patch called Rocknest. The bright particle near the center of the image, and similar ones elsewhere in the pit, are assessed by the mission’s science team assessed to be native Martian material. Credit: NASA

Gerhard concludes, “There are many reasons to study Mars, but one of the most pressing is that, while life arose and evolved on Earth, we still don’t know if life had a chance on Mars. Planetary scientists can study rocks, sediments, and soils for clues to uncover the geological and potential biological history of Mars. Then, by comparing those findings with Earth we also learn more about our own planet.


Ancient river systems on Mars seen in unparalleled detail

The satellite image of the exposed Martian cliff face. Credit: NASA JPL-Caltech UoA Matt Balme & William McMahon

Researchers have spent decades looking for evidence of ancient water on Mars. As technology has progressed, more evidence has come to light that rivers, lakes and even oceans were once abundant on the red planet.

Modern Mars is icy and dusty and unlikely to have much liquid water on the surface, if any at all. But billions of years ago, Mars was warmer and could have had enough liquid water to support life. In fact, experts think Mars is one of the most likely places we will find evidence of extraterrestrial life.

A high-resolution satellite has captured detailed images of a rocky Martian cliff face revealing that it was formed by rivers more than 3.7 billion years ago. That is roughly the same time that life was starting to begin on Earth.

It's the first time that scientists have been able to examine these kinds of rocks up close.

Geologists Dr. Francesco Salese and William McMahon from Utrecht University, the Netherlands, were supported by an international team including Dr. Matt Balme at the Open University and Dr. Joel Davis, a postdoctoral researcher at the Museum. Their findings are published in the journal Nature Communications.

Joel says, "We've never seen an outcrop with this amount of detail on it that we can definitely say is so old. This is one more piece of the puzzle in the search for ancient life on Mars, providing novel insight into just how much water occupied these ancient landscapes."

The team examined images of taken by NASA's High Resolution Imaging Science Experiment (HiRISE) on the Mars Reconnaissance Orbiter spacecraft. The images were taken inside the enormous Hellas impact crater in the southern Martian hemisphere, one of the largest impact craters in the solar system.

A 200-metre-thick stack of layered rocks are visible within the cliff walls, shown in enough detail that Joel and his colleagues could be sure they are sedimentary rocks, formed by running water. The rivers would have continuously shifted their gullies, creating sandbanks.

The ExoMars rover prototype Bruno. ExoMars 2020 will be the first mission to take core samples from deep within the Martian surface.

The images also show that the river processes that formed these rocks occurred over a very long time period.

Joel explains, "The rivers that formed these rocks weren't just a one-off event—they were probably active for tens to hundreds of thousands of years."

This evidence bolsters hope that sedimentary rocks from this period could be ideal for the search for evidence of past life on Mars.

William McMahon, co-lead author of the paper, says, "Here on Earth, sedimentary rocks have been used by geologists for generations to place constraints on what conditions were like on our planet millions or even billions of years ago.

"Now we have the technology to extend this methodology to another terrestrial planet, Mars, which hosts an ancient sedimentary rock record that extends even further back in time than our own."

In 2022, the European Space Agency (ESA) is due to launch the Rosalind Franklin ExoMars Rover, which will explore similar terrains to determine whether there has ever been life on Mars, and to better understand the history of water on the planet.

Joel and his colleagues at the Museum will help the ESA team to interpret the rover's findings. These new images are a great sign that the rover could be successful in its mission.


Are the rocks in the asteroid belt between Mars and Jupiter the same kind of rocks you’d find on the earth?

There are different types of asteroids, made of different things. Ones that most closely resemble Earth's composition in terms of the elements that go into them are the carbonaceous asteroids, but not necessarily in the same molecular configurations youɽ find on Earth. The rocks formed on Earth can be made by very different processes, through compression of sedimentary layers as an example. Stony meteorites do resemble igneous rocks like basalt, though. Other asteroids are made mostly of iron instead, and don't much resemble things youɽ find on Earth's surface - perhaps further down towards or in Earth's core things are similar, though - while others still are a mixture of iron and silicates.

Thank you for your reply! Does this also mean that a ‘regular Earth-rock’ would not survive in space?

Also worth noting that some do contain fairly high concentrations of precious metals, particularly platinum group metals. Which is why people are looking at asteroid mining despite the outrageously high cost. Some asteroids are estimated in the trillions of dollars of platinum and palladium.

what was the asteroid that wiped the dinosaurs out composed of?

Are asteroids and Earth rocks similarly dense? Most earth rocks are quite dense because they are being compressed by everything around them, but I imagine that there could easily be a lot of voids in a rock that formed in space, kind of like a pumice

Other asteroids are made mostly of iron instead, and don't much resemble things youɽ find on Earth's surface

Actually, meteors were the primary source of iron for humans during the Bronze Age, before the advent of extractive metallurgy in the early Iron Age (1200 BC).

Other asteroids are made mostly of iron instead, and don't much resemble things youɽ find on Earth's surface - perhaps further down towards or in Earth's core things are similar, though -

So would that make it something like a big roundish lump of native copper (except composed of iron instead of copper)?

Well, while we've got an accretion guy in the room, I have a question: is accretion the only way to get iron meteorites? Do you need to have had a planet build up, differentiate with the iron sinking to the middle, then get blasted apart? I've read that most all irons might be the offspring of 16 Psyche (thought to be the exposed core of a young planet) but I think this was speculation.

Are these asterpids oxidized or are they a more pure iron that would be easier to smelt?

Doubts have emerged over the last decade that the Earth's bulk composition is chondritic.

The 142Nd/144Nd ratio of the Earth is greater than the solar ratio as inferred from chondritic meteorites, which challenges a fundamental assumption of modern geochemistry—that the composition of the silicate Earth is ‘chondritic’, meaning that it has refractory element ratios identical to those found in chondrites.

Campbell, I.H. and O’Neill, H.S.C., 2012. Evidence against a chondritic Earth. Nature, 483(7391), pp.553-558.

Caro, G., Bourdon, B., Halliday, A.N. and Quitté, G., 2008. Super-chondritic Sm/Nd ratios in Mars, the Earth and the Moon. Nature, 452(7185), pp.336-339.

I've read somewhere that it's actually quite common for asteroids to be made of iron. So common in fact, that we never really to worry about running out?

(yes that's a question mark, since you probably know more about this than I do)

This makes me wonder where all this iron came from. I know from the Big Bang but where before that ? Never mind. I Googled it.

No, that's one of the reasons why meteorites can be identified easily, and how we discovered Martian meteorites. Asteroidal material has give through different processes than most Earth rocks. For some, chondrites, they've gone through very little processing. Existing as fused together masses of tiny grains of primitive material. Interestingly, these types of rocks have a mixture of elements in them consistent with the average of elements in rocky planets, containing a lot more iron, gold, iridium, etc. than ordinary crustal rocks on Earth.

Asteroids do contain processed materials, but the processes are different than on Earth. As asteroids and other "planetesimals" accreted during the early Solar System some got large enough to hold onto enough heat to melt, and differentiate into metal cores and stony crusts. These objects were subjected to later collisions which shattered them into smaller asteroids, leading to individual metallic and stony asteroids. The stony asteroids tend to be more "primitive" types of silicate rock than youɽ find on Earth, however.

Most rocks in the asteroid belt are chondrites, about 3/4 of them. About a sixth of the rocks are stony asteroids, which are the closest to Earth rocks but only as distant cousins, and the rest are metallic or other varieties.

Also, some Earth rocks undoubtedly do exist in space, and we will one day run across them as meteorites on the moon or Mars, but they are comparatively rare.


These Rocks Mean Water!

Exploratory results from Curiosity indicate that the bottom layers of the mountain were built mostly with material deposited by ancient rivers and lakes over a period of no more than 500 million years. As the rover has crossed the crater, scientists have seen evidence of ancient fast-moving streams in the layers of rock. Just as they do here on Earth, streams of water carried coarse pieces of gravel and bits of sand along as they flowed. Eventually that material "dropped out" of the water and formed deposits.In other places, the streams emptied out into larger bodies of water. The silt, sand, and rocks they carried were deposited on the lake beds, and the material formed fine-grained mudstone.

The mudstone and other layered rocks provide crucial clues that the standing lakes or other bodies of water were around for quite a long time. They might have widened during times where there was more water or shrank when water wasn't so abundant. This process could have taken hundreds to millions of years.Over time, the rock sediments built up the base of Mt. Sharp. The rest of the mountain could have been built up by continued wind-blown sand and dirt.

All that happened a long time in the past, from whatever water was available on Mars. Today, we see only the rocks where lake shores once existed. And, even though there's water known to exist beneath the surface — and occasionally it escapes — the Mars we see today is frozen by time, low temperatures, and geology — into the dry and dusty desert our future explorers will visit.