Imagine for a moment what vistas must be out there for us to discover.
In our limited explorations so far, we have yet to see even a fraction of the awesome
beauty that must be in the solar system.
When we explore the surfaces of other planets such as the moon or Mars, we play it safe,
going to areas that we are confident won’t pose too much of a risk to our spacecraft
upon landing.
While places like Gale crater on Mars offer very interesting geology and paint a picture
of a past wet Mars that might have once hosted life, it’s ultimately an alluvial plane
of muddy deposits and rock.
We don’t see yet is that planet’s equivalent of places like Yosemite or the Himalayas.
Take the Grand Canyon.
As majestic as it is, it is far from one of the greatest canyons in the solar system.
Greater is a place we’ve only ever seen from orbit, and indeed didn’t really know
existed until the 1970’s.
It’s really a system of canyons, known as Valles Marineris or the Valleys of Mariner
after NASA’s 1971-72 mission that discovered it.
This was after Mariner 9, and there is actually a small mystery in regards to that long dead
spacecraft.
We don’t actually know if it still exists.
When the mission ended, NASA estimated that the spacecraft would remain in Martian orbit
for at least 50 years.
That time is up, and it’s uncertain whether it has entered the Martian atmosphere and
crashed, or if it might still be in orbit clinging on to existence.
That in itself is interesting.
In say 10,000 years will this canyon still be named after a tiny short lived spacecraft
that arrived during a global dust storm only to see it clear and spot the magnificence
of the Valleys of Mariner and report the find back to earth.
Might someday human inhabitants of Mars no longer remember why the canyon has its name,
Mars is not really the place one would expect to find mariners after all, at least in the
modern geological epoch.
The valleys themselves are over 4000 kilometers long, and up to 200 kilometers wide.
They can reach depths of 7 kilometers, or 23,000 feet.
Oddly though, Earth still holds the record for the longest known canyon in the form of
the mid ocean ridge system.
But nothing on dry land on this world can compete with Valles Marineris, but the origin
of the feature is somewhat shrouded in mystery as it does not seem to be a canyon formed
solely by erosion, but rather may be a giant tectonic crack in the surface of Mars, though
erosion did play a part in its size, and there are some signs of the activities of liquid
water.
It’s also possible that it began as a huge lava channel.
As great as it is, however, we have never seen this astonishing feature of Mars up close,
and not from the ground, as magnificent as the view from its rims must be.
That’s likely to eventually change, and probably not in the too distant future.
The reason is Ingenuity, NASA’s Mars helicopter drone, that has been a resounding success
far exceeding its designed lifetime.
This opens the way for eventual missions using far more capable helicopters with greater
range to explore the Martian surface, including mountainous areas and canyons from the air
that would not otherwise be easily accessible to take a look.
These systems can also land on the ground and take images from that vantage point.
Drone technology used in space exploration in regards to both Mars and Titan promise
to show us the best those planets have to offer as far as alien vistas.
But ultimately, while those sights may be amazing, Earth still seems to sport the most
awesome beauty in the solar system, due in no small part to both its geology but also
its life in the form of the vast forests that exist on this world.
But for all earth’s beauty, it’s ultimately transient.
There was a time where this world was microbial, and the land barren and there will come a
time again in the future where it will be so again as the sun’s luminosity makes life
on this world increasingly difficult.
There will be many slow, but overall dramatic changes to this world in this coming time.
About 250-300 million years from now, most of the familiar mountain ranges and features
of earth will have eroded, and new features developed.
It’s thought that by this time continental drift will have forced all of the continents
back into a supercontinent, though what configuration it will look like depends on the model.
As this occurs, it will very likely spark off a glacial period that will drop sea levels,
increase oxygen levels and lower global temperatures regardless of the past activities of human
civilization, assuming we either left this world or went extinct.
But there will still be a marker of us left, by this time Earth’s fossil fuel reserves
may still not be fully recovered from our past presence, though the estimates on this
are wide ranging.
But there may be a weird effect from all of this.
It’s also possible that during this period of crashing coalescing landmasses and higher
oxygen levels, it may increase competition between species driving a burst of very rapid
evolution.
This could be exasperated by increased volcanism, and the brightening sun.
But it won’t last, whatever comes of rapid evolution from whatever progenitor species
survive our times can’t be predicted and it’s hard to imagine what it would look
like, but it will all come crashing down in a huge mass extinction that Earth-life will
probably never recover from due to the increasingly dropping habitability of earth.
Life may go out on this world with a bang, and then a long slow simmer of relentless
mass extinction.
And then it really all starts to fall apart about 500 million years from now.
The supercontinent in whatever form it takes will start to rift apart again, raising global
temperatures along with the increased heating from the brightening sun.
And that starts to disrupt a very important cycle on earth, the carbon-silicate cycle.
Weathering of rocks will increase, the oceans will begin to evaporate, and this in turn
will cause plate tectonics to slow and eventually cease.
Here we see a strange effect, this will actually cause carbon dioxide levels in earth’s atmosphere
to plummet.
What was once a problem in its abundances, becomes a problem in its lack.
And that is the first nail in the coffin for the plants.
99% of plant species alive today use a very specific type of photosynthesis dependent
on carbon dioxide in the atmosphere.
As the levels drop, the plants will slowly go extinct, species by species.
First go the herbaceous plants, then the deciduous forests, and finally the evergreens.
But herein is a question, we know life can adapt, it does it all the time, so what evolution
might occur under these new pressures is an open question.
There may be holdout species that manage to find new niches and survive in a new form.
This could involve the ability to dry out for long periods of time, something known
in earth bacteria today, or very efficient photosynthesis using less co2.
But then there is UV radiation, with plants dying comes decreasing oxygen, which increases
the sun’s deadly UV radiation reaching the surface.
And the hotter it gets, the more oxygen reacts out of the air without being replenished,
and that’s where the animals start to suffer.
Complex life will become simpler again, and the animal kingdom will see smaller and smaller
forms, and more efficient breathers.
For a time.
This probably also means that complex life on earth will retreat to the poles, hibernating
and doing what they can with their life cycle to hold on.
Only the oceans at this point, or what’s left of them, may still host complex life.
There are however hypotheses that the conditions of plate tectonics stopping may briefly give
earth as a waterworld a reprieve.
Eventually all remaining photosynthesis stops however, and that’s essentially the end
of life on land.
Any water, which at this point may just be pockets underground, or located at the poles
might be the only places life can hold on.
This is slated to happen about 900 million years from now, but after this period, all
that will be left will be the single-celled organisms.
Earth will in some ways once again resemble what it was when life first began here.
The high estimate for the last possible life on earth is 2.8 billion years from now, though
that’s very high and earth may be lifeless in under 1.5 billion years.
Oddly at this time though, Mars will have warmed and will probably look more like earth,
at least in temperatures, than earth will at that point.
About this time as well the moon will have moved far enough from earth to no longer moderate
it’s axial tilt, causing it shift and become chaotic.
And then comes the long slow march to the Sun’s red giant phase, which will happen
between 4.5 and 5.3 billion years from now.
This process will almost certainly result in the sun swallowing the earth.
But here’s the odd thing, the story of Earth doesn’t quite end there.
The question of what happens when a star eats a planet like earth has been open until recently.
Researchers led by Ricardo Yarza of the University of California, Santa Cruz recently presented
a model of the area of the solar environment around an engulfed planet.
It turns out that engulfing a relatively small planet like earth stirs up a star like the
sun, causing it to brighten, rotate faster, and change its chemical composition both from
the evaporating planet and the stirring, and even throw off shells of gas.
This may solve a mystery, some older highly evolved stars seem to rotate faster than predicted,
and it may be because they devoured members of their planetary systems.
Who knows what record of life in the universe has been lost that way already.
And weirdly enough this process of ejection may serve to save a planet from being engulfed
when it normally should have been.
Lose enough mass, and the planet simply moves into a very close in tight orbit and the smaller
star does not eat it.
This could explain why some white dwarf systems have seemingly impossibly close planets orbiting
near them.
All of this is subject to many factors, the mass of the planets, the size of the red giant
and so on, and may not happen with earth.
Instead earth may simply go through a death spiral of evaporation as it makes its way
to the sun’s core.
Before that process is likely finished, the earth will be reduced to the raw materials
of it’s bulk and will dissipate and incorporate themselves into the makeup of the sun.
Some of that material may even survive the sun’s planetary nebula stage as it throws
its outer layers off revealing a cooling white dwarf.
Some of earth’s material may indeed be part of that remnant, or even some scorched cinder
remnant of earth could end up closely orbiting that white dwarf, perhaps until the end of
the universe itself.
More of earth’s material could be ejected into the planetary nebula and may someday
be incorporated into future worlds.
But it has to be asked, with all this new heat from the giant sun, what happens to the
outer solar system?
First it heats during the red giant phase, no doubt creating entirely new vistas in the
solar system, such as surface oceans on Europa and possibly Enceladus and Titan, and new
geologic processes sculpting the worlds of the outer solar system.
New mountain ranges, and new canyons, not even imagined today.
But then as the sun becomes a cooling white dwarf, everything turns into ice again in
the outer solar system where it will remain so for trillions of years.
Effectively, so ends the solar system.
Thanks for listening!
I am futurist and science fiction author John Michael Godier currently not eyeing the sun
suspiciously, not good for the eyes, but still cognizant that we live next to a giant nuclear
ball.
And that’s how life arises, and ends, very dubious this universe and be sure to check
out my books at your favorite online book retailer and subscribe to my channels for
regular, in-depth explorations into the interesting, weird and unknown aspects of this amazing
universe in which we live.