after decades of research including multiple Landers and orbiters science
can definitively say Venus sucks seriously that place is the worst with
its boiling temperature intense pressure sulfuric acid rain and more but was it
always this bad according to new research from NASA and various
universities in Sweden in the u.s. Venus might have actually been the first
habitable world in the solar system and it might have maintained a reasonable
climate for billions of years finally rolling over into a runaway greenhouse
effect just a few hundred million years ago today venus is a different story
although the planet is roughly the same size and mass as Earth it has a
dramatically different environment the average global surface temperature is
about 475 degrees Celsius hot enough as I'm sure you've heard to melt lead the
atmospheric pressure on the surface of Venus is 90 times the pressure of Earth
want to experience the same kind of pressure dive down one kilometer under
the ocean and you'll get an idea how do we know the Venera program the Soviet
Union sent a fleet of spacecraft in the 70s and 80s to try and land on the
surface of Venus 18 were sent 13 actually made it into the atmosphere and
10 survived all the way down to the surface able to send back some data to
earth before they expired in the brutal environment but we're looking at Venus
4.5 billion years after its formation with the rest of the solar system and
over those eons the Sun has been heating up venus has been getting dried out and
many planetoids and asteroids have been smashing into each other but if we roll
the clock back when could Venus have been habitable and for how long a new
paper entitled was Venus the first habitable world of our solar system was
released in August 2019 the temps to give us a glimpse into the van news
in past it was written by dr. Michel way from NASA's Goddard Institute for Space
Studies as well as researchers from Sweden New York Arizona and Maryland
according to the study Venus probably started out with a
similar overall composition to earth including the same amounts of water and
gases in its atmosphere today of course it's bone-dry with a mere six
quadrillion kilograms of water in its atmosphere now I know six quadrillion
sounds like a lot and it is but Earth has more than 200,000 times as much
water in its oceans atmosphere astronomers were able to calculate how
much water it used to have based on the ratio between deuterium and hydrogen in
its atmosphere and this indicates that it must have had much more in the
ancient past even though Earth's atmosphere is 78%
nitrogen Venus actually has double that amount and of course an insane amount of
carbon dioxide planetary scientists have calculated that ancient Venus had
shallow seas across its surface measuring from four to 525 meters deep
the question is how much did it have and how quickly did it lose its water the
traditionally accepted answer was that Venus lost its water quickly within the
first hundred million years or so dr. Wayne his team used Goddard's Rock 3d
simulator that I mentioned in the previous episode to simulate an ancient
venus with shallow oceans and an earth-like atmosphere they worked with a
few assumptions the first is the length of a day on Venus today the planet takes
116 days to turn on its axis you could walk faster than Venus turns not only
that but the planet is rotating backward from the other worlds of the solar
system it's possible that Venus was smashed by a massive planetoid early on
in its history but it's also just possible that tidal interactions with
the Sun slow down as rotation rate almost immediate
and it's been rotating this slowly ever since they had to consider the surface
of ancient Venus which is actually a total mystery and that's because the
entire landscape was completely resurfaced just a few hundred million
years ago as if the planet turned itself inside out and it's believed this
happened because Venus doesn't have plate tectonics like Earth instead of
regular volcanism releasing heat and pressure the planet resurfaced itself in
a catastrophic event so they based their models on the current surface features
of Venus as mapped out by NASA's Magellan spacecraft they filled the
lowlands with water assuming an early ocean that was about
1/10 the volume of Earth's oceans and they assumed that early Venus had an
atmosphere as thick as Earth but made almost entirely of nitrogen with trace
amounts of carbon dioxide and methane like earth and then they just ran the
clock forward watching how the planet changed over billions of years as the
Sun heated up and Venus tried out what did they discover we'll get to that in a
second but first I'd like to thank Roman Brendel Matthew Nichols vengeful sorrow
Paul wheeler and the rest of our 825 patrons for their generous support
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today and get in on the action the team performed five simulations based on
different amounts of water coverage three of the scenarios assumed a deep
ocean with an average of 310 meters one scenario used the Earth's topography and
a 310 meter deep average ocean they also tried a scenario where all of Venus was
covered by water 158 metres deep they simulated the
planet at 4.2 billion years ago 715 million years ago and today watching as
the amount of radiation coming from the Sun increased over time today Venus
receives twice as much solar radiation per square meter as Earth does in all
five scenarios they found that Venus was able to maintain stable temperatures
ranging from a maximum temperature of 50 Celsius
to a minimum of 20 Celsius and it kept these stable temperatures for almost
three billion years in the beginning the planet had an incredibly thick
atmosphere of carbon dioxide but as it cooled down over the next three billion
years this carbon would have been drawn out of the atmosphere and locked away
into silicate rocks by 715 million years ago the planet would have had that one
atmosphere of nitrogen and other trace gases in fact it could have remained
stable with liquid water on its surface all the way until today but some
dramatic event happened hundreds of millions of years ago that transformed
the planet forever and it might have been linked to that volcanic resurfacing
that I mentioned earlier in fact Earth had a similar situation about 250
million years ago when the largest volcanic eruption in our planets history
covered an enormous amount of Siberia the eruptions carried on for two million
years and led to one of the greatest mass extinctions in our planets history
so that the worse and Venus never recovered with the extreme heat from the
molten rock releasing all that absorbed carbon dioxide into the atmosphere and
leading to a runaway greenhouse effect the simulations depend on the fact that
Venus cooled down and was able to condense water onto its surface to form
these global oceans and they assumed that this volcanic resurfacing happened
just once recently and wasn't a regular occurrence on Venus it's incredible to
think that Venus could have been habitable for billions of years and if
it wasn't for that catastrophic resurfacing it might still be habitable
today in order to get to the bottom of this mystery we need to return to Venus
with new orbiters balloons to study its atmosphere than even Rovers and Landers
made of tough new heat tolerant electronics to explore its surface
unfortunately there are no missions at Venus anymore and none are planned in
the near future so the mysterious history of Venus
have to remain that way for a few more years what do you think do you think
Venus should be a higher priority now let me know your thoughts in the
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Universe Today on iTunes Spotify or wherever you get your podcasts I'll put
a link in the show notes I talked about the plucky Soviet Venera program that
was able to actually land on the surface of Venus it was an incredible series of
missions that inflicted untold horrors on robotic spacecraft and if you want to
learn all about it watch this video next