Venus

[Subroto Jana]

I would love to explore the planet Venus as it is the second planet from sun and is of almost similar size ,mass and composition as earth and is the brightest object in the sky and is close to our planet earth .It is named after the Roman Godess of Love and Beauty .It is the brightest object in the sky after moon and can cast shadows and on rare occassions it is visible even in the day time .

With a rotation period of 243 earth days, it takes longer to rotate about its axis than any other planet in the Solar system by far , and does so in the opposite direction to all but Uranus .HOW & WHY ?

Venus does not have any moons ,a distinction shared only with Mercury .WHY ?

Venus has a thick toxic atmosphere filled with carbon dioxide and it is perpetually shrouded in thick ,yellowish clouds of Sulphuric Acid that trap heat , causing a runaway greenhouse effect .It is the hottest planet in our solar system ,even though mercury is closest to the sun .Venus has crushing air pressure on its surface , more than 90 times that of the earth. WHAT LEAD TO THIS RUNAWAY GREENHOUSE EFFECT ? WHY VENUS 's atmosphere is not yet stripped off its surface .Venus has not lost its atmosphere yet .What is making that possible ?

Venus was the first planet to be explored by a spacecraft - NASA's Mariner 2 which successfully scanned and photographed on 14th December 1962 the cloud cover world so close to our home planet earth and so identical in so many ways .Since then numerous spacecraft from US and various other agencies have explored venus , including NASA's Magellan but only Russia could land their spacecraft on the surface of Venus but it did not survive the immense atmospheric pressure of Venus and its hostile environment .

Another interesting discovery is the discovery of Phosphine parts-per-billion levels could be a bio-marker .This raises the possibility that biological processes could be responsible .Phosphine is a toxic flammable gas with a characteristic smell of garlic or rotting fish .Phosphine is highly reactive and so survives for only a very short time .There could be an airborne ecosystem at temperate altitudes in Venus 's thick atmosphere .

Venusian atmosphere is highly acidic .So any form of life would need to be able to cope with this in someway ,perhaps coated with a thick protective layer or perhaps exploit the acidity .

The Planetary geologists recently concluded that Venus may have supported liquid water for many billions of years, until as recently as 700 millions of years ago .It then suffered a catastrophic greenhouse effect , which left it with a surface temperature hot enough to melt.

Understanding what went wrong will be crucial in preventing a similar catastrophe on earth .That's the reason why NASA ,ESA and other agencies must turn their attention urgently to Venus .



,

 

[Catastrophe]

Generally, a pretty good summary.

One point:
"Understanding what went wrong will be crucial in preventing a similar catastrophe on earth ."

I think we already know and may be running out of time to avoid it.

Cat

 

[Dragrath]

Covers the broader points the main thing to add to this is that there is one good reason for why Mercury and Venus are unlikely to have moons and it has to do with both the planets hill spheres (i.e. the region where a planet's gravity dominates its star) and the strength of tides varying as 1/r^3 it is certainly plausible that Mercury and Venus did have substantial moons of their own at one point as tidal interactions with both their planet and the Sun could very well have torn the moons out of their orbits/ The closer a massive planet is to the Sun the smaller the area that bodies can orbit that Planet. In the Case of Mercury this would most likely result in said moon either crashing into Mercury or the Sun during the first few hundred million years. Venus could potentially have had a longer lasting moon due to a combination of its higher mass and larger distance from the Sun but it would still be easier to tear a moon away from Venus compared to Earth or any other planets further out as distance from the Sun is the dominant factor in determining the size of a planets hill sphere

 

[Catastrophe]

Covers the broader points the main thing to add to this is that there is one good reason for why Mercury and Venus are unlikely to have moons and it has to do with both the planets hill spheres (i.e. the region where a planet's gravity dominates its star) and the strength of tides varying as 1/r^3 it is certainly plausible that Mercury and Venus did have substantial moons of their own at one point as tidal interactions with both their planet and the Sun could very well have torn the moons out of their orbits/ The closer a massive planet is to the Sun the smaller the area that bodies can orbit that Planet. In the Case of Mercury this would most likely result in said moon either crashing into Mercury or the Sun during the first few hundred million years. Venus could potentially have had a longer lasting moon due to a combination of its higher mass and larger distance from the Sun but it would still be easier to tear a moon away from Venus compared to Earth or any other planets further out as distance from the Sun is the dominant factor in determining the size of a planets hill sphere

Excellent points. Thank you. Cat

 

[Catastrophe]

Covers the broader points the main thing to add to this is that there is one good reason for why Mercury and Venus are unlikely to have moons and it has to do with both the planets hill spheres (i.e. the region where a planet's gravity dominates its star) and the strength of tides varying as 1/r^3 it is certainly plausible that Mercury and Venus did have substantial moons of their own at one point as tidal interactions with both their planet and the Sun could very well have torn the moons out of their orbits/ The closer a massive planet is to the Sun the smaller the area that bodies can orbit that Planet. In the Case of Mercury this would most likely result in said moon either crashing into Mercury or the Sun during the first few hundred million years. Venus could potentially have had a longer lasting moon due to a combination of its higher mass and larger distance from the Sun but it would still be easier to tear a moon away from Venus compared to Earth or any other planets further out as distance from the Sun is the dominant factor in determining the size of a planets hill sphere

Thank you. I was not aware of those points. Cat

 

[amongthestars931]

Generally, a pretty good summary.

One point:
"Understanding what went wrong will be crucial in preventing a similar catastrophe on earth ."

I think we already know and may be running out of time to avoid it.

Cat

I totally agree with this. We are destroying our planet at unprecedented speed. It's kind of saddening tbh.

 

[Trevize62]

There are some facts about Venus that must be pointed:
First of all, Venus receives from the Sun more or less two times the amount of heat than Earth, so this can easily explain the loss of its water.
Moreover, the claim that the planet may have had liquid water on its surface in the past is only supposed and lacks of any concrete support.
Also, the weakness of the magnetic field of Venus ( that is also produced by a mechanism completely different from the one operating on Mercury,Earth, Jupiter and Ganymedes) coexist on Venus with the presence of an atmosfere 90 times thicker than the Earth's one, in neat contrast with the hypothesis of the need of a strong magnetic field for preventing the loss of a planetary atmosphere (suggesting that perhaps we're wrong also about our hypoteses on Mars)
Finally: the highly extreme conditions at the surface of Venus make extremely difficult any attempt of exploration.
In conclusion, I think that we must revise our models of planetary evolution and that Venus will keep its mysteries for centuries to come.

 

[Dragrath]

There are some facts about Venus that must be pointed:
First of all, Venus receives from the Sun more or less two times the amount of heat than Earth, so this can easily explain the loss of its water.
Moreover, the claim that the planet may have had liquid water on its surface in the past is only supposed and lacks of any concrete support.
Also, the weakness of the magnetic field of Venus ( that is also produced by a mechanism completely different from the one operating on Mercury, Earth, Jupiter and Ganymedes) coexist on Venus with the presence of an atmosphere 90 times thicker than the Earth's one, in neat contrast with the hypothesis of the need of a strong magnetic field for preventing the loss of a planetary atmosphere (suggesting that perhaps we're wrong also about our hypotheses on Mars)
Finally: the highly extreme conditions at the surface of Venus make extremely difficult any attempt of exploration.
In conclusion, I think that we must revise our models of planetary evolution and that Venus will keep its mysteries for centuries to come.

Hmm you are right that there are many mysteries here but a few problems first the Sun was dimmer early on which has to be factored in and the state of the atmospheric system is strongly dependent on the way the system evolves. It is true we don't know whether Venus had oceans but we do have good evidence for it once having water.

The role of the Magnetosphere on Mars is complicated its biggest problem is that Mars has a weak remnant magnetization induced magnetic field from when the planet had a real magnetic field. This field is weak and decentralized so it connects directly to the solar wind i.e. its field lines are an open configuration. The consequence is any particles in Mars's atmosphere at any altitude that gets ionized or has intrinsic polarity is accelerated away along the magnetic field lines directly into the solar wind. This effect becomes extremely pronounced during a Martian global dust storm as the denser medium allows more water vapor to get into the air and allowing charge imbalances to build up. Once a molecule is charged it is then funneled on a one way trip out of the solar system.

Then there is the complicating factor that Mars lacks the gravity to prevent molecular nitrogen, water, argon, molecular oxygen, carbon monoxide, methane etc. from drifting away in significant amounts due to the temperatures of the upper Martian atmosphere meaning a significant upper tail of the velocity distribution exceeds the escape velocity of Mars. Add the ionization effect from remnant magnetization and they are gone. During a Martian dust storm residency times for water vapor are measured in hours to days as the natural buoyancy combined with the polar nature of the molecule and the magnetic field lines conspires to accelerate molecules away from the surface of Mars into the solar wind. It is quite tragic but Mars is the main culprit for the loss of its atmosphere as it effectively gives its atmosphere to the solar wind for free. There are also atmospheric gravity buoyancy balanced waves which propagate strongly up from the surface of Mars in a one way flow away from the planets surface further accelerating the loss of atmosphere in a manner like how a river flows downhill gases on Mars flow up and away thanks to the combination of these factors particularly during Martian Dust storms.

The point is that research on Mars's atmosphere has revealed that a weak magnetic field is worse than no magnetic field at all couple that with the impacts of the gravity of Venus and Mars and Venus's lack of remnant magnetization from the planet contributing to its induced magnetosphere and the difference is substantial. Surprisingly the water loss rate from Venus appears to be virtually identical to the water escape rate of Earth Mars on the other hand expels as much water as there is water vapor to expel....

Whatever process wiped Venus's magnetosphere did so cleanly where as Mars and the Moon for that matter have local remnant magnetization which actively funnels charged particles away from the surface into the solar wind. And even a magnetic dynamo isn't enough if the field is much weaker than the solar wind field as is seen with the not quite dead magnetic dynamo of Mercury where the solar wind is so dense it pushes the field lines away from the planets surface.

Weak magnetospheres are quite simply awful for maintaining an atmosphere so the best case for losing one is having any remnant magnetization get quickly erased else you become like Mars where literally any physical process that could effect atmospheric escape seems to be compounding to create an astonishing loss rate. Basically any dreams of terraforming Mars are hopeless and will only result in a planetary mass comet nucleus spewing out volatiles about as fast as you can throw them in unless you want to go through the effort to eliminate each and every contributing factor. Unfortunately the need to remove/destroy Mars's remnant magnetization is a bit problematic as it kind of requires melting Mars and then there is the need to block radiation from reaching Mars the need to add an artificial magnetosphere large enough to prevent the solar wind from wrapping back around to the planets surface... It is kind of Ugly.... Venus at least still has most of what would be needed to terraform it water is the main thing lacking that and the need to sequester that dense atmosphere into rock (as removing it would be getting rid of the planets valuable reserves of Carbon, Nitrogen Sulfur and Phosphorous pretty much the only significant source of said elements in the inner solar system aside from the Sun and Earth but I digress.

Martian atmospheric escape due to weak remnant magnetization:

https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018GL079972

Mars Doesn't Have Much of a Magnetosphere, But Here's a Map

Thanks to the MAVEN mission, we're learning a lot about the fate of Mars' atmosphere, after it lost its magnetosphere billions of years ago.

www.universetoday.com

Martian atmosphere loss to atmospheric gravity waves(which are waves where gravity is the balancing force yeah the term was coined a long time ago before we knew gravitational waves were a thing)

https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2020GL092095

https://arxiv.org/abs/2101.07698(This allows you to view the draft of the paper since the published version is pay walled)

 

[Trevize62]

Ok, but in every case, since its birth Venus has been always warmer than Earth, and this fact certainly played a crucial a role to differentiate the two planets.
Another important difference is the slow rotation speed of Venus, that undoubtly influenced the planet's climate from the beginning.
Also, we agree that the existence of an hydrosphere on Venus remains a proofless conjecture.
Moreover, Venus seems to lack plate tectonic activity, probably due to its extremely low speed of rotation, and appears to have an hot point type of tectonics; there is also no evidence that Venusian crust may have had a different behavior in the past.
More than two originally twin planets that experienced a different evolution, for what we concretely know about Venus it seems that Earth and Venus have been two very different worlds from their beginnings in many important aspects.

 

[Trevize62]

Covers the broader points the main thing to add to this is that there is one good reason for why Mercury and Venus are unlikely to have moons and it has to do with both the planets hill spheres (i.e. the region where a planet's gravity dominates its star) and the strength of tides varying as 1/r^3 it is certainly plausible that Mercury and Venus did have substantial moons of their own at one point as tidal interactions with both their planet and the Sun could very well have torn the moons out of their orbits/ The closer a massive planet is to the Sun the smaller the area that bodies can orbit that Planet. In the Case of Mercury this would most likely result in said moon either crashing into Mercury or the Sun during the first few hundred million years. Venus could potentially have had a longer lasting moon due to a combination of its higher mass and larger distance from the Sun but it would still be easier to tear a moon away from Venus compared to Earth or any other planets further out as distance from the Sun is the dominant factor in determining the size of a planets hill sphere

Unfortunately there are no proofs or evidences that support or deny the claim that Venus and/or Mercury could have had one or more moons. This is not a scientifical hypothesis, and any discussion about is a waste of time.

 

[Trevize62]

Hmm you are right that there are many mysteries here but a few problems first the Sun was dimmer early on which has to be factored in and the state of the atmospheric system is strongly dependent on the way the system evolves. It is true we don't know whether Venus had oceans but we do have good evidence for it once having water.

The role of the Magnetosphere on Mars is complicated its biggest problem is that Mars has a weak remnant magnetization induced magnetic field from when the planet had a real magnetic field. This field is weak and decentralized so it connects directly to the solar wind i.e. its field lines are an open configuration. The consequence is any particles in Mars's atmosphere at any altitude that gets ionized or has intrinsic polarity is accelerated away along the magnetic field lines directly into the solar wind. This effect becomes extremely pronounced during a Martian global dust storm as the denser medium allows more water vapor to get into the air and allowing charge imbalances to build up. Once a molecule is charged it is then funneled on a one way trip out of the solar system.

Then there is the complicating factor that Mars lacks the gravity to prevent molecular nitrogen, water, argon, molecular oxygen, carbon monoxide, methane etc. from drifting away in significant amounts due to the temperatures of the upper Martian atmosphere meaning a significant upper tail of the velocity distribution exceeds the escape velocity of Mars. Add the ionization effect from remnant magnetization and they are gone. During a Martian dust storm residency times for water vapor are measured in hours to days as the natural buoyancy combined with the polar nature of the molecule and the magnetic field lines conspires to accelerate molecules away from the surface of Mars into the solar wind. It is quite tragic but Mars is the main culprit for the loss of its atmosphere as it effectively gives its atmosphere to the solar wind for free. There are also atmospheric gravity buoyancy balanced waves which propagate strongly up from the surface of Mars in a one way flow away from the planets surface further accelerating the loss of atmosphere in a manner like how a river flows downhill gases on Mars flow up and away thanks to the combination of these factors particularly during Martian Dust storms.

The point is that research on Mars's atmosphere has revealed that a weak magnetic field is worse than no magnetic field at all couple that with the impacts of the gravity of Venus and Mars and Venus's lack of remnant magnetization from the planet contributing to its induced magnetosphere and the difference is substantial. Surprisingly the water loss rate from Venus appears to be virtually identical to the water escape rate of Earth Mars on the other hand expels as much water as there is water vapor to expel....

Whatever process wiped Venus's magnetosphere did so cleanly where as Mars and the Moon for that matter have local remnant magnetization which actively funnels charged particles away from the surface into the solar wind. And even a magnetic dynamo isn't enough if the field is much weaker than the solar wind field as is seen with the not quite dead magnetic dynamo of Mercury where the solar wind is so dense it pushes the field lines away from the planets surface.

Weak magnetospheres are quite simply awful for maintaining an atmosphere so the best case for losing one is having any remnant magnetization get quickly erased else you become like Mars where literally any physical process that could effect atmospheric escape seems to be compounding to create an astonishing loss rate. Basically any dreams of terraforming Mars are hopeless and will only result in a planetary mass comet nucleus spewing out volatiles about as fast as you can throw them in unless you want to go through the effort to eliminate each and every contributing factor. Unfortunately the need to remove/destroy Mars's remnant magnetization is a bit problematic as it kind of requires melting Mars and then there is the need to block radiation from reaching Mars the need to add an artificial magnetosphere large enough to prevent the solar wind from wrapping back around to the planets surface... It is kind of Ugly.... Venus at least still has most of what would be needed to terraform it water is the main thing lacking that and the need to sequester that dense atmosphere into rock (as removing it would be getting rid of the planets valuable reserves of Carbon, Nitrogen Sulfur and Phosphorous pretty much the only significant source of said elements in the inner solar system aside from the Sun and Earth but I digress.

Martian atmospheric escape due to weak remnant magnetization:

https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018GL079972

Mars Doesn't Have Much of a Magnetosphere, But Here's a Map

Thanks to the MAVEN mission, we're learning a lot about the fate of Mars' atmosphere, after it lost its magnetosphere billions of years ago.

www.universetoday.com

Martian atmosphere loss to atmospheric gravity waves(which are waves where gravity is the balancing force yeah the term was coined a long time ago before we knew gravitational waves were a thing)

https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2020GL092095

https://arxiv.org/abs/2101.07698(This allows you to view the draft of the paper since the published version is pay walled)

OK, but why Venus has also a weak magnetic field and its atmosphere did not escape?
I think there is something wrong in our modelks of planetary evolution.

 

[Catastrophe]

Have you seen Wiki The atmosphere of Venus?

"Venus is known not to have a magnetic field.[38][39] The reason for its absence is not at all clear, but it may be related to a reduced intensity of convection in the Venusian mantle. Venus only has an induced magnetosphere formed by the Sun's magnetic field carried by the solar wind.[38] This process can be understood as the field lines wrapping around an obstacle—Venus in this case. The induced magnetosphere of Venus has a bow shock, magnetosheath, magnetopause and magnetotail with the current sheet.[38][39]" and a lot more.

Cat

 

[Trevize62]

I know, and also underlined this in my post on this thread sent in date 12/03.. But my question remains. If Venus has only an induced and weak magnetosphere, why its atmosphere did not escape?

 

[Catastrophe]

T I thought my ref covered this. No?

Cat