Hot answers tagged

49

This is mostly due to the fact that Mars does not have plate tectonics. Therefore the plate stays above the hotspot without moving, allowing magma to rise and pile up at the same place for millions and millions of years. Above the Hawaii hotspot, the oceanic plate is moving, so volcanism tends to drift away with time (actually the volcanism happens at the ...


12

If water on Earth came from meteorites, why doesn't Mars have substantial water? First off, that's a conjecture regarding the origin of the Earth's water rather than a known fact. A few times a year or so, a new journal article will appear that argues that the Earth's water is primordial, then another arguing that it came from comets, then yet another ...


11

If I understood it correctly, the important point is the temperature difference between mars and earth. On earth increasing obliquity, as you wrote, leads to increased melting of ice, ie. you increase the amount of liquid water on earth. On mars average temperatures even during summer are too low to allow for liquid water. Higher obliquity doesn't really ...


9

The other answer is already pretty good: No plate tectonics and no water erosion allows material to pile up in one place, and then stay put. Neither is the case on earth: The plate moves away from the hot spot, transporting built up rocks with it and causing the magma to find another outlet a few miles over. Hawaii also tends to be a place where you can see ...


8

Firstly, Mars is farther away from the sun than Venus or Earth, so it gets less heat from the sun. Secondly, Venus & Earth are volcanically active, whereas Mars is volcanically inert. Thirdly, the atmosphere on Mars is much thinner than those on Venus and Earth. The density of the atmosphere on Venus is approximately $65\ \mathrm{kg/m}^3$, whereas, the ...


8

There are no circles, it is an image artifact. Here is another picture from Dingo Gap that shows nothing at the exact same position. Your mind is a well-trained pattern-matching machine that makes up patterns even when they are not actually there. In other words don't jump to conclusions. You are claiming that there are actual structures, which is one step ...


7

Like Michael, I find your question a little unclear, but the crux of it seems to be this: ... does science have to conclude [that a specimen is] just a rock because the composition is entirely from earth minerals? The answer is an emphatic no. There are lots of non-rocks out there, many of them manufactured by the (alleged) intelligence known as Homo ...


7

Trace fossils are marks or things left behind by living things do their thing, they are indirect remains of organisms, coprolites (poop), footprints, egg shells, ect. If we found a fossilized beehive or beaver dam those would also be trace fossils. Bioturbation is a specific type of traces fossil, marks of disturbances of the sediment itself animals leave ...


6

does serpentinization just refer to the formation of some hydrated minerals that happen to be of a class that is historically been referred to as serpentinite or it's subgroup Yes. In simple terms, the reaction is enstatite + forsterite + water = serpentine. MgSiO3 + Mg2SiO4 + 2H2O = Mg3Si2O5(OH)4 Forsterite and enstatite (or more generally, olivine and ...


6

The mantle of Mars is heterogeneous. While there are many things that are unknown about the Martian mantle and the entire internal structure of Mars, this is not one of them. The source of this finding comes from the analysis of meteorites originating from Mars. Analysis shows that 4.5 billion years ago - when Mars was forming along with the rest of the ...


6

It's not completely clear what you're trying to ask here, but I'll have a go at it anyway. If earth only had them would science say there are ancient artifacts from a past civilization? The only way "science" would say there are ancient artifacts from a past civilisation is if there is evidence to support that. This is not some kind of default thing ...


6

I think that the mechanism suggested in the article fits the bill the best: On Earth, microseisms are ubiquitous, caused largely by the sloshing of the ocean by storms and tides. Mars, despite the dreams of science fiction writers, has no present-day oceans. Instead, this newly discovered noise is likely caused by low-frequency pressure waves from ...


5

Mars did have a significant amount of water (and atmosphere) early in its history. According to NASA, there was enough to form an ocean covering about half its surface: https://www.nasa.gov/press/2015/march/nasa-research-suggests-mars-once-had-more-water-than-earth-s-arctic-ocean/ The reason it doesn't have a lot of water or atmosphere today is that much ...


5

They indicate wind direction (given by the long line or "barb") and speed (given by the shorter flags extending from each barb). In the same linked page you can read: The barbs extending from each wind speed data point indicate the compass direction of the wind (e.g., a wind blowing from the north will have a barb straight up above the point; a wind ...


5

Firstly I would disagree with your premise that 'most of Earth's sand contains tiny shells resembling sea shells'. Such biogenic sand is certainly true of some biologically productive sedimentary environments, but certainly far from all. For example, try finding shells in most of the sand in the Sahara desert, or any other desert for that matter. You will ...


5

Serpentinization is a system of, chemical reactions which convert anhydrous ferromagnesian silicate minerals (pyroxene, olivine) into hydrous silicate minerals (serpentine) plus some other possibilities like brucite and magnetite. Brucite forms if the precursor rocks are rich in magnesium (dunite, for example). Magnetite forms if there is enough iron ...


5

The most abundant elements are: Element Approximate % by weight Oxygen 46.6 Silicon 27.7 Aluminum 8.1 Iron 5.0 Calcium 3.6 Sodium 2.8 Potassium 2.6 Magnesium 2.1 All others 1.5 Source:http://hyperphysics.phy-astr.gsu.edu/hbase/Tables/elabund.html Based on data from a number of NASA and ESA ...


4

Although the Martian crust has has a similar set of the most-abundant elements as Earth's -- for instance, on both planets oxygen is #1 and silicon #2 -- there are some differences. Compared with Earth's crust, the Martian version has more iron and magnesium, and less aluminum, calcium, and alkali metals. The top five elements on Mars are shown here: ...


4

It would be interesting to read peer reviewed scientific papers that discuss the feasibility of "restarting Mars' core" via an asteroid impact. Some links would be appreciated. I am very sceptical that it could be achieved in such a manner. Small asteroid impacts would change the topography of the surface by creating new craters and spraying crater ejecta ...


4

In addition to @Erik answer, rocks as any other material dilates when it gets hotter and contracts as it gets colder. On Earth's such phenomena, and differences in temperature within rocks leads even to the cracking of rocks. That could be another source of microseismicity, because the thermal amplitude in Mars is huge. The temperatures on the two Viking ...


3

The possible source of methane is biological, and that is what everyone is hoping for, but the more likely source is geological, produced by chemical reactions between rock and water deep underground and issuing though fissures to the surface. We are dealing with very small amounts here which are difficult to detect and measure with precision. Once out in ...


3

We are already knowledgeable about some aspects of the requirements needed to terraform Mars & the Moon. As @David_Garcia_Bodego mentions in his comments, gravity is a major factor in celestial bodies being able to retain an atmosphere. This is because the gravity of a celestial body affects the escape velocity of that body. The other important factor ...


3

Quoting from the NASA website: The image covers an area 1.4 inches by 1.1 inches (3.6 by 2.7 centimeters). It was taken by the Mars Hand Lens Imager (MAHLI) camera on the rover's arm on Dec. 5, 2015, during the 1,184th Martian day, or sol, of Curiosity's work on Mars. Yes, it is possible to see shells in that scale. It is also possible that there are ...


3

Analogues to Mars Recurring Slope Linea (RSL) is a current study topic in Antarctica (Dry Valleys). On Earth, analogues are known as water tracks, which are linear zones of higher moisture along slopes in polar regions where water transit during snowmelt. This figure from Ward Hunt Island (NU, Canada) show well developed and typical water tracks. Source: ...


3

Just as there are many different rocks and soils on Earth, so there are many different rocks and soils on Mars. To reproduce a Martian soil, you need to bear two things in mind. Firstly it should have all the vital nutrients plants need to grow, and secondly it should have no component of biological origin. That rules out limestone for a start. Your soil ...


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