Venus and Mars

originally posted by: uncommitted

For what it's worth, I think it may be significant Earth appears to be the only planet in our solar system with tectonic plates (obviously the gas giants couldn't have them), and I think that may be a clue to how as well as many other mitigating factors life not only happened, but progressed.

Intelligent past life on Venus may be questionable, but past life in general (even on the surface) is a real possibility that we cannot rule out just yet:

Venus possibly habitable for billions of years (Grinspoon)

Today, its atmospheric temperatures are hot enough to melt lead and concentrated sulfuric acid continuously drizzles down from thick sulphurous clouds that completely block out the Sun. But the planet once had a climate similar to Earth's and vast oceans of water. Planetary scientists agree that period ended when Venus lost its water due to a runaway greenhouse effect, but the question is when.

Until now, the best estimate (...) was four billion years ago - just 600 million years after the Solar System's birth. But new work by David Grinspoon, at the Southwest Research Institute in Boulder, CO suggests the momentous transition may have occurred much later. He points out the Kasting's estimate was just a lower limit on when the change happened, because it did not include the effect of clouds in the Venusian atmosphere.

Once the water was lost, Grinspoon says, plate tectonics would have stopped completely, and with it the most efficient way for the planet to shed its internal heat (*emphasis added*).

And further ...

Why Venus has No Moon (AAS)

Venus does not have a moon. We argue that this is at least as surprising as the presence of Earth's moon and more surprising than the absence of a substantial moon for Mercury or Mars. We do not know if Venus ever had a moon. The accepted explanation for Earth's moon is a giant impact with an impactor on the order of one Mars mass. Given current theories of solar system formation, it is unlikely that Venus would have avoided such a large collision.

A two large collision hypothesis is presented, and argued for (...) This hypothesis also allows Venus to eventually evolve to the current slow retrograde rotation state, an outcome that is otherwise difficult to explain quantitatively (*emphasis added*).

Do we really know enough about Venus to already jump to far reaching conclusions regarding past life on our planetary neighbor? Add in the fact that our sun was less luminous and powerful in the past and it becomes more plausible that Venus may have had a much more stable and hospitable environment in the past.

IMO, we will need a few more missions and a lot of science being done in order to unravel the true mystery of what happened to Venus in the past.

I'm not sure many are grasping what I was saying here. I believe, as Lear did, that what we're told about Venus is a complete lie. Well, I wouldn't say I completely believe it, but I see it as a real possibility.

originally posted by: wmd_2008

originally posted by: WhiteWine

Also I believe Mars in the coming future could become habitable? Since the Sun will grow bigger and get hotter, I suppose it will raise temperatures in the Red Planet, in turn helping it?

It cant SUPPORT a thick enough atmosphere it has no magnetic field like the Earth that's it put in the simplest of terms.

They're not insurmountable problems.

Many scientists are of the opinion that the colonisation of Mars by humans is a distinct possibility, if not a likelihood.

We better hope they're right because our future is bleak on the blue planet.

In about 5 billion years, the Sun will start to become a red giant and will likely swallow up Earth when it expands in size.

But long before then, the Sun will have become hotter, making life on Earth impossible.

This could be in as little as one billion years hence.

Mars is our only sanctuary.

originally posted by: CJCrawley

originally posted by: wmd_2008

originally posted by: WhiteWine

Also I believe Mars in the coming future could become habitable? Since the Sun will grow bigger and get hotter, I suppose it will raise temperatures in the Red Planet, in turn helping it?

It cant SUPPORT a thick enough atmosphere it has no magnetic field like the Earth that's it put in the simplest of terms.

They're not insurmountable problems.

Many scientists are of the opinion that the colonisation of Mars by humans is a distinct possibility, if not a likelihood.

We better hope they're right because our future is bleak on the blue planet.

In about 5 billion years, the Sun will start to become a red giant and will likely swallow up Earth when it expands in size.

But long before then, the Sun will have become hotter, making life on Earth impossible.

This could be in as little as one billion years hence.

Mars is our only sanctuary.

In 5 billion years there will be no human race unless we find a way to leave this solar system. I'd worry more about surviving the next hundred years let alone billions.

originally posted by: simsumre
I'm not sure many are grasping what I was saying here. I believe, as Lear did, that what we're told about Venus is a complete lie. Well, I wouldn't say I completely believe it, but I see it as a real possibility.

There is a serious issue here...Sol's "habitable zone"...Venus is too close to the Sun and is just outside the zone. This makes Venus too hot to support life as it is commonly known here on Earth.

Mars on the other hand is right on the outer edge of the zone, AND, the main reason there is no known life there is because Mars is t small to support the kind of magnetic field required to protect it. Thus it has little atmosphere, and of course little to no life as it is commonly known here on Earth.

Now, the reality is that Terrestrial science knows very little about either planet, but, from the little that is known we can reach the conclusion that there is no life and neither planet is capable of supporting it. We also know that life can thrive in extreme eviornments..so the probability of there being life on BOTH planets is very good.

We also know that it takes some 3.5 billion years for a planet to evolve intelligent life capable of advanced technology...AND, to the "Best" of Earth's scientific knowledge...Earth is the only place to have such life.

originally posted by: CJCrawley

originally posted by: wmd_2008

originally posted by: WhiteWine

Also I believe Mars in the coming future could become habitable? Since the Sun will grow bigger and get hotter, I suppose it will raise temperatures in the Red Planet, in turn helping it?

It cant SUPPORT a thick enough atmosphere it has no magnetic field like the Earth that's it put in the simplest of terms.

They're not insurmountable problems.

Many scientists are of the opinion that the colonisation of Mars by humans is a distinct possibility, if not a likelihood.

We better hope they're right because our future is bleak on the blue planet.

In about 5 billion years, the Sun will start to become a red giant and will likely swallow up Earth when it expands in size.

But long before then, the Sun will have become hotter, making life on Earth impossible.

This could be in as little as one billion years hence.

Mars is our only sanctuary.

Why is Mars our sanctuary in that scenario? Will it somehow avoid the heat not to mention the gravitational chaos that would be happening as the Earth is swallowed?

originally posted by: simsumre
I'm not sure many are grasping what I was saying here. I believe, as Lear did, that what we're told about Venus is a complete lie. Well, I wouldn't say I completely believe it, but I see it as a real possibility.

Um, except every single shred of evidence says Lear is wrong. There is absolutely no reason to think he is right. I talked about this a little in this podcast episode, Venus specifically in "Environment of Venus." Many of Lear's claims are factually wrong and easily shown to be wrong by the average person.

originally posted by: uncommitted

originally posted by: CJCrawley

originally posted by: wmd_2008

originally posted by: WhiteWine

Also I believe Mars in the coming future could become habitable? Since the Sun will grow bigger and get hotter, I suppose it will raise temperatures in the Red Planet, in turn helping it?

It cant SUPPORT a thick enough atmosphere it has no magnetic field like the Earth that's it put in the simplest of terms.

They're not insurmountable problems.

Many scientists are of the opinion that the colonisation of Mars by humans is a distinct possibility, if not a likelihood.

We better hope they're right because our future is bleak on the blue planet.

In about 5 billion years, the Sun will start to become a red giant and will likely swallow up Earth when it expands in size.

But long before then, the Sun will have become hotter, making life on Earth impossible.

This could be in as little as one billion years hence.

Mars is our only sanctuary.

Why is Mars our sanctuary in that scenario? Will it somehow avoid the heat not to mention the gravitational chaos that would be happening as the Earth is swallowed?

I'm not a scientist (much less an astrophysicist) so I don't know enough to answer your question, but I will have a go.

The red giant phase wont be for at least another 5 billion years; as I understand it, life on Earth will already have been long extinguished, 4 billion years earlier, or about 1 billion years hence.

In that initial phase (1 billion years hence), when the Sun becomes slightly smaller, brighter, and about 40% hotter, life on Earth will be unsustainable, but Mars - some 50 million miles further away - will experience helpful global warming (it's too cold at present).

So there is a window (probably a narrow one) when Mars will be habitable.

But yes, Mars too will be rendered uninhabitable as time progresses; it was ever only a temporary sanctuary.

originally posted by: simsumre
I'm not sure many are grasping what I was saying here. I believe, as Lear did, that what we're told about Venus is a complete lie. Well, I wouldn't say I completely believe it, but I see it as a real possibility.

There are those who say that the moon has all sorts of structures that NASA "scrubs" from their photos, therefore what we know about the moon is a lie. How does one proceed from hearing these claims? Well, the most obvious way is to see the photos of the same areas that are taken by amateur photographers. NASA doesn't have a monopoly on staring at the moon through a telescope. If you do this, you'll see hi-res pics of the same areas, sans moon bases.

I believe this Venus problem should and has been handled in the same way- the information available about Venus isn't from one shady org feeding us lies- you can confirm the truth about Venus by studying numerous unconnected sources.

a reply to: simsumre

IMO it can't be said often enough just how important the history of Venus is, especially since we don't know exactly how and when it changed from a presumed Earth-like twin to the toxic world we see today. Here's a related link & an excerpt with some more details:

Venus' Twisted History (scroll down)

Earth's sister planet is very similar to our home in many ways. It's roughly the same size, has the same gravitational pull, and sits in an area where, under the right circumstances, water could be liquid on the surface. In fact, for much of the solar system's youth, the two planets could have been more or less like twins.

But something happened to Venus. Instead of the planet maintaining a temperate climate, the scales tipped and the planet roasted.

The WHEN of such cataclysmic events is still subject to further research, although some scientists such as D. Grinspoon believe the overall changes could have occured much later in Venus' history. For those who are interested, here go a few more 'recent' discoveries by Venus Express:

1. Shape-Shifting-Polar-Vortices
2. Recent Volcanism
3. Spinning Venus is Slowing Down
4. Super Rotation is Speeding Up
5. Snow on Venus
6. Ozone Layer
7. Water Loss
8. A Magnetic Surprise

originally posted by: jeep3r
a reply to: simsumre

IMO it can't be said often enough just how important the history of Venus is, especially since we don't know exactly how and when it changed from a presumed Earth-like twin to the toxic world we see today. Here's a related link & an excerpt with some more details:

All of the science you linked not withstanding; Venus was NEVER a "twin" for Earth. It has always been much too close to Sol, even in the early days for much liquid water. It has always been too hot...period. Of course this does not preclude life, but, the life forms of Venus will be very unique to Venus, and be little like anything on Earth.

I think the best case would be for Venus to have high altitude microbes kind of like Earth does. Any speculation otherwise would necessarily be limited to pure speculation at this time.

By the way; when science speculates; it is no different than the average person's speculation...AND, there are vast differences between "educated guess" and "speculation" (though sometimes it's hard to see)

a reply to: tanka418

If that 'period' of yours is final, then all future research about planetary and stellar evolution is obsolete from this day on. However, it's an evolving field of science and we don't know all of the interdependencies just yet ...

A G2V star, like our sun, has a life cycle and therefore its own evolution. Although nuclear reactions in the main sequence are stable, radius and luminosity as well as energy output vary throughout the lifetime of a star:



Accordingly, the habitable zones shift as well:



Obviously, there are lots of parameters to consider and not all of them are known to make 100% accurate predictions for planetary and stellar evolution. Here go a few more links that may help grasp the complexity of this situation:

1. Will Earth's Future Mimic Venus' Past?
2. The Sun's Evolution
3. Circumstellar Habitable Zone

IMO it's much too early to conclude that Venus has always been too hot and too close to the sun for anything to have evolved there in the past. Again, it will take a few more missions to unravel the mystery of what happened to Venus. Perhaps then we'll be able to find out more with regard to previous habitability on that planet.

originally posted by: jeep3r
a reply to: tanka418

If that 'period' of yours is final, then all future research about planetary and stellar evolution is obsolete from this day on. However, it's an evolving field of science and we don't know all of the interdependencies just yet ...

A G2V star, like our sun, has a life cycle and therefore its own evolution. Although nuclear reactions in the main sequence are stable, radius and luminosity as well as energy output vary throughout the lifetime of a star:

Well perhaps not as "final" as you would imagine, but, in this case it as well be. Time, evolution, even on a planetary level are not your friends here.

The is growing evidence that as long ago as 3.5 billion years there was simple life on Mars, much like what was around on the Earth at that time. For Venus to have been the tropical paradise you think it may have been, Mars would have to have been well frozen. Problem is; Venus warmed up, Mars didn't. Today the mean temp for mars is 81 below. Now, I am fully aware that a significant part of Mars's temp issues are caused by the lack of atmosphere...So, even IF we roll the whole thing back to when Mars had an atmosphere, we will find that it would still be far too cold to produce the kinds of life we have evidence of.

While I believe that life will be found on Venus, either current or ancient; there exists no evidence of such that I am aware of...contrast that to Mars.

No, sorry man, the reality is that Venus has always been too close, and too hot...the only thing your solar evolution does is give Venus false hope (in the early days) of supporting life.

originally posted by: tanka418

For Venus to have been the tropical paradise you think it may have been, Mars would have to have been well frozen. Problem is: Venus warmed up, Mars didn't.

In order to relate Mars to Venus, on the one hand, and stellar to planetary evolution, on the other, we'd have to know more about what happened to the atmosphere of both planets in the past.

I know what you're getting at regarding current paradigms of habitability. We obviously think we can't have both in terms of Mars & Venus having been habitable at an earlier stage (considering their distances from the sun).

As for a 'frozen' Mars: how would a very dense but stable atmosphere in the past relate to surface heat despite the larger distance? What kind of atmosphere did Mars have in the past? Let's wait and see what the MAVEN mission brings ... IMO, the whole climate history of Mars and Venus will need to be researched for many years on until we can say anything really conclusive about potential complex life in the history of these two planets.

originally posted by: tanka418
By the way; when science speculates; it is no different than the average person's speculation...AND, there are vast differences between "educated guess" and "speculation" (though sometimes it's hard to see)

Science doesn't speculate; scientists do. If scientists's speculations are no different than the average person's, are you saying that nobody is better at speculating than anyone else?

originally posted by: conundrummer

originally posted by: tanka418
By the way; when science speculates; it is no different than the average person's speculation...AND, there are vast differences between "educated guess" and "speculation" (though sometimes it's hard to see)

Science doesn't speculate; scientists do. If scientists's speculations are no different than the average person's, are you saying that nobody is better at speculating than anyone else?

Agreed. tanka418, try replacing "science" with "doctor," and you'll see how your comment is misguided. I would much rather take a professional medical doctor's speculation on something in his/her area of expertise than the average person's speculation.

Could each of the planets in the habitable zone - Mars, Earth and Venus been habitable at the same time periods? If a species came to our solar system to colonize, could they have colonized all three planets simultaneously even if they had to make some bases underground? Some claim that Venus had liquid water oceans for 600,000 years to a couple billion years. Some claim that Mars had liquid water and a thick atmosphere 4 Billion years ago.

Our solar system will probably have a rebirth in 4 Billion years as Andromeda collides with the Milky Way. Maybe a new planetoid will be pulled into our solar system or something will smash into Jupiter with enough mass to create a new sun and habitable zones. We only have a couple hundred million years of atmosphere on Earth so we better get looking.

originally posted by: astrostu
Agreed. tanka418, try replacing "science" with "doctor," and you'll see how your comment is misguided. I would much rather take a professional medical doctor's speculation on something in his/her area of expertise than the average person's speculation.

No...My statement is wholly misunderstood!

What passes for speculation is in reality nothing more than flights of fancy; fantasy...And you have the Temerity to call what a professional says in his field; "speculation". Sorry; there is a vast difference.

a reply to: TamtammyMacx

Our solar system will probably have a rebirth in 4 Billion years as Andromeda collides with the Milky Way.

The collision will probably have no effect on the Solar System whatsoever.
In any case, the Sun will have matured and boiled away our oceans by then anyway.

originally posted by: tanka418
you have the Temerity to call what a professional says in his field; "speculation". Sorry; there is a vast difference.

So scientists aren't professionals?