Wet, wild Mars stripped off by hot young star, left barren and red faced Powerful solar wind and radiation have stripped away most of the Martian atmosphere, transforming the planet from one that could have been wet and with the potential to harbor life, to the barren dusty place it is today. NASA's Mars Atmosphere and Volatile Evolution (MAVEN) mission was launched in 2013 to study the planet's …
Mars almost certainly has an iron-nickel core to account for the difference in its bulk density to those surface rocks we have analysed. The best bet is that Mars's core is something like 1800km in diameter.
What is likely to be different is that no part of Mars's core is convecting to drive a dynamo and hence no magnetic field. Mars would have cooled faster than Earth due to its smaller size, so the interior is going to be hot - just not hot enough. We don't know the Martian geotherm exactly, but it is entirely possible the whole planet is solid, although there are some tantalisingly fresh-looking lava flows that suggest limited volcanism has occurred within the last 2 million years.
Mars burnt out it's fissionable material which supplies internal heat, electron Flux and elemental atoms/molecules. Pterodactyl had eleven meter (36 ft) wingspan in the Jurassic Period because air density was four times present level due to loss from solar wind and ionization.
Dr John Brandenburg has more on Mars and Xenon-129 and Krypton-80 isotopes....
mars is lacking a large enough moon to knead the crust and keep the core from solidifying, Phobos is a lost cause, will probably spiral into the planet in a few million years, Deimos is tiny, before we think of setting up shop there, we need to send out hundreds of small mass drivers to the asteroid belt, nudge quite a few rocks into Deimos' path and hopefully collide and stick, once a large enough mass is built up, let the tidal stresses do their thing. may want to chuck a few bigger ones at Mars to soften it up for good measure.
The lack of a magnetosphere around Mars is the big puzzle piece that needs to be solved before we set up a colony.
"My apologies, the internet tells me they think it does have an iron nickel core but something caused the magnetic dynamo to stop turning."
Based on the old Velo I used to own, I expect some oil got on the drive belt. And that far in the past, you couldn't just nip into an electrical goods shop and put on a cheap belt from a washing machine to get you home.
Interestingly, the lop-sided hydrogen isotope abundances on Venus show that it lost its hydrogen to space. The tiny amounts of hydrogen in the Venusian atmosphere are highly enriched in the heavier deuterium than regular hydrogen because it is harder for the Sun to strip deuterium than the lighter isotope. Same approach as the new Mars study, different element.
Two possibilities:
1: the inability of the Venusian core to lose heat through Mantle convection. Here on Earth, the Mantle loses heat by vigorous convection, driving a temperature gradient within the Core.
Venus doesn't have plate tectonics and its crust appears to be highly rigid which suggests the Mantle also may not be convecting. Instead heat accumulates in the lower Mantle, reducing the ability of the Core to convect, so no magnetic field.
The lack of plate tectonics is one of the big mysteries on Venus, but the loss of water to space is probably involved. Here on Earth, water greatly reduces the melting point in the Mantle, drives processes such as serpentinisation which reduce the rigidity of the Crust and it reduces the viscosity of ductile rocks.
An absence of convection might explain the apparent catastrophic resurfacing of Venus between 0.6-0.3Ga when it looks like much of the Crust was reworked. If heat accumulates in the lower Mantle it will eventually undergo a burst of rapid convection to lose that heat, there would be enormous amounts of melting and - well it'd be spectacular.
The second possibility is that the Venusian core is deficient in lighter elements such as sulfur, oxygen and silicon which help reduce the melting point of the iron-nickel alloy in the Earth's Core. If Venus does lack these elements, its Core might have a similar temperature to Earth's but simply be unable to convect.
Errr, The other elephant in the room is Earth, which does not seem to have suffered similar losses, despite being closer to the active sun. If you're going to create a hypothesis, then you should produce the effects of that hypothesis on other planetary objects with different mass and orbital characteristics. If your hypothisis does not explain their armosphere, then the hypothesis is not valid. But, no doubt, it probably pulled in a large slab of funding.
Adding to my previous post. The concept of the solar wind accellerating the atmospheric gas to escape velocity, seems valid enough, but that surely, would only apply to that part of the atmosphere at the edges of the planetary disk. Across the sun facing side, the kinetic energy would be directed downwards, not up into space. Adding to that, the solar wind is comprised of hydrogen nuclei, positively charged. In the absence, largely, of a magnetic field, they would not be divered, but would be added to the atmosphere
One big surprise that I read of in Scientific American, was a theory that the only reason Earth still has a molten core, is that an Earth Moon collision occurred and heated it all up again. This was a collision that happened between two planets that were moving in almost the same speed and direction, so most of the detritus of said collision said within the orbit of the Earth/Moon system. This apparently happened after the other planets had already lost their core generators.
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