Title 2 why don't we colonize Venus rather than Mars?
Venus and Earth are essentially twins. They are similar in size, density,
gravity, and physical structure. Both are in the habitable zone of our star. Scientists have not
discovered any other neighboring planet in the entire galaxy that shares such similarities.
Yet, somewhere along the way, Earth became a cosmic paradise for life as we know it,
while Venus turned into a hellish landscape. Under its yellowish sulfuric acid clouds,
the greenhouse effect has made its surface hotter than Mercury's, even though the planet
itself is much farther from the Sun. A block of lead would melt on Venus's surface in the
same way that a block of ice melts on Earth. Terrible, yes, but also fascinating! With so
much to learn about a planet so close to Earth, why did NASA halt its exploration of Venus?
First, there isn't enough funding. NASA receives half of 1% of the federal budget,
and only a fraction of that goes to planetary science. Second, it's much easier to explore our
other neighbor, Mars, than to study Venus. Mars won't melt lead. Rovers have a lifespan measured
in decades. Meanwhile, any robotic mission to the Venusian surface is destined to be short and
brutal. Furthermore, Mars has a romantic appeal that Venus will never possess. Someday, humans
will walk on Mars and perhaps even settle there. The third, and perhaps the most devastating,
factor hindering the exploration of Venus is NASA's stubborn focus on missions
searching for extraterrestrial life. The question of whether we are alone
in the universe is too enticing from a media perspective for the agency to resist its allure...
In 2020, something seemed to change... Three years ago, when the famous story
of phosphine discovered on Venus was making its rounds worldwide,
a cute meme started circulating on social media. It showed a group of astrobiologists
aboard a Tesla speeding towards Mars, abruptly making a U-turn towards the "Venus" exit.
After the discovery of a "chemical signature" compatible with the presence of anaerobic life
in Venus's clouds, quite a few scientists would have eagerly taken that detour,
convinced that the second planet in the Solar System could offer more intriguing
research prospects than the more popular Mars. Then, the excitement over the discovery slowly
waned, and phosphine ended up in the scientific dustbin of initially contested and subsequently
repudiated findings... Venus returned to being Earth's "evil twin," and most astrobiologists
jumped back on the Tesla heading for Mars. The question now is this: Did they do the
right thing? Does Mars have to be the primary destination for human
exploration of the solar system? Why is there someone insisting
that it should be Venus, not Mars, at the center of our future exploratory plans?
“Roll intro”
In recent years, there has been a resurgence of enthusiasm regarding the potential colonization
of Mars, significantly fueled by NASA's Artemis missions and
SpaceX's ongoing Starship tests and developments. So, for most people,
Mars continues to be the planet destined to be touched first by human feet.
However, if this is undoubtedly true for public expectations,
there are quite a few NASA scientists convinced that there could be many advantages in choosing
to colonize Venus first, instead of Mars. Let's clear up any misconceptions right away:
Venus is a terrible place. Its atmosphere is almost entirely composed of carbon dioxide,
and sulfuric acid rains down from the clouds. The surface is a yellow, foggy desert,
dotted with volcanoes much larger than those on Earth. Its temperature, if that wasn't enough,
exceeds 460 degrees Celsius. Not exactly a hospitable place. Yet,
for some, Venus could be the most suitable place to make humans the first multi-planetary species
in history (at least, as far as we know). But is that really the case? Venus is located
in the habitable zone, the region around the Sun where conditions might exist to support
life on a planet. If Venus were much cooler, it would probably be the most Earth-like planet in
our solar system. But currently, its Earth Similarity Index is only 0.44 on a scale
from 0 (no similarity) to 1 (identical). The index is calculated based on density, radius,
surface temperature, and surface gravity. For comparison, Mars has an index of 0.799.
Certainly, Venus and Earth have very similar sizes and masses, but, of course,
this alone is not enough. Venus's atmosphere is incredibly dense and prevents any direct
observation of the planet's surface. Massive cloud systems, visible only in ultraviolet light, race
through Venus's skies at high speeds, completing a full longitudinal rotation in just four days.
Venus's atmosphere is also occasionally struck by powerful electrical discharges.
One positive aspect compared to Mars is that Venus's gravity is only slightly lower than
Earth's, while Mars's gravitational force is only 38% of Earth's and 40% of Venus's.
This means that Venus would not have the problem of bone and muscle loss that would
require Martian explorers to engage in strenuous daily gym exercises or, over very long periods,
condemn them to evolve into a new human species adapted to Martian gravity.
What's even more important, especially compared to Mars, is the amount of available solar energy on
Venus and the level of radiation protection it provides. The amount of radiation an astronaut
would be exposed to in Venus's atmosphere would be roughly the same as if they were
on Earth. On Mars, unshielded astronauts would be exposed to about 0.67 millisieverts per day,
which is 40 times more than on Earth, and they would likely need
to bury their habitats several meters below the surface to minimize exposure.
Regarding solar energy, Venus's proximity to the Sun provides it with 40% more sunlight
than what we get here on Earth and 240% more than what we would see on Mars.
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It's also important to note that Venus is often significantly closer to Earth
than Mars. Due to the way the orbits of Venus and Earth align over time, a crewed mission to
Venus would require a total of 440 days using existing or near-term propulsion technology:
110 days for the outbound journey, 30 days for the stay, and then 300 days for the return - with
the possibility to abort and start the return journey to Earth immediately after arrival.
It may seem like a long time to spend in space, and it certainly is. However,
getting to Mars and back using the same propulsion technology would involve at
least 500 days in space. A more realistic mission to Mars would probably last from 650
to 900 days (or more) due to the need to wait for a favorable orbital alignment for the return trip,
which means there's no chance of aborting the mission and returning home early.
So, these are the relatively few reasons that seem to favor exploring the Venusian
environment rather than the Martian one. Then there are the "against" reasons. But here,
we're really going into the heavy stuff. Imagine a warm and friendly planet with
an atmosphere rich in oxygen, blue skies, and abundant water... and then imagine it being
suddenly disrupted by volcanic activity. Thousands of volcanoes start spewing magma incessantly onto
the surface without stopping for hundreds of thousands of years. The result is a fiery world,
almost entirely covered in lava. A planet with a poisonous atmosphere dominated by sulfuric acid
and carbon dioxide, and its surface crushed by pressure 90 times higher than Earth's.
This is what happened to Venus, exacerbated to this day by the greenhouse effect triggered by the
cloudy cover. This is one of the reasons why many of the early probes sent to Venus were failures,
corroded by the acid rain caused by the reaction of sulfur dioxide and water in the atmosphere,
crushed by the pressure, and practically melted by the heat.
If we want to make some incredible comparisons, when it comes to habitability between Mars and
Venus, consider this: landers sent to the surface of Mars remained operational for years (the record
is held by Opportunity, which lasted almost 15 years), while the most enduring Venusian probe was
Venera 13, launched by the Russians in 1981, which managed to transmit data for... 127 minutes...
Quite a difference, wouldn't you say? To put it briefly, the surface of Venus
is a brutal, absolutely uninhabitable place. And as if that weren't enough, there are the winds.
To say that the winds on Venus are powerful is an understatement. At high altitudes,
they can reach speeds of nearly 400 kilometers per hour, while at the surface, the perceived
wind would be comparable to a gentle breeze. However, due to atmospheric density and pressure,
it would hit you with the force of a bulldozer! So, we must resign ourselves for now:
the surface of Venus is absolutely impractical for us. In this category,
Mars wins the comparison hands down. Is it game over, then?
No, because here comes the surprise... It's not on the surface that we might go to live but above it!
By pure chance, it has been discovered that in the upper part of Venus's clouds, there is a layer
where the temperature and pressure are similar to those on Earth. This has led some scientists to
discuss the possibility of colonizing the upper atmosphere of Venus by building "cities designed
to float at around fifty kilometers in altitude." As early as 2003, NASA had devised a plan for
the colonization of Venus that involved installing airships in Venus's atmosphere.
As absurd as it may sound, not even Elon Musk's mind could take it seriously,
but we are still within the bounds of science: colonizing the clouds of Venus could be much
simpler than living amidst the radiation of Mars. Put simply, a balloon filled with an atmosphere
of oxygen and nitrogen would serve as a lifting gas so that people can live inside the envelope.
Going outside would be possible for short periods (minutes) wearing only an oxygen-supplying mask,
although, for safety reasons, a sealed suit would be necessary because low
levels of sulfur trioxide would damage the skin in case of prolonged exposure.
In reality, things are a bit more complicated. The entire project involves the use of a special
vehicle named Havoc (High Altitude Venus Operational Concept), a spacecraft that,
once it reaches the planet, would be able to transform into an airship and hover at an
altitude of 50 kilometers above the surface. In this position, Venus's atmosphere would
still provide enough protection from radiation to create a comfortable environment for astronauts.
They would also be safe from the dangerous acid clouds,
with atmospheric pressure and gravity comparable to Earth's and temperatures around 30-50°C.
The module envisioned by NASA researchers could be built using existing technologies today,
although it would still require a couple of decades to develop. In NASA's plans,
Havoc could allow a crew to station on Venus for about a month, taking a total of 440 days for the
entire journey (110 to reach Venus, one month of stay, and then 300 to return home). It's a lengthy
period, but still shorter than a mission to Mars, which would require anywhere from 650 to 900 days.
If everything goes smoothly, a second mission could be sent, with the crew staying in the
atmosphere for 30 days. The fourth phase involves a one-year stay in the atmosphere,
leading to the fifth and final phase, which envisions a permanent human settlement.
As for the airship, which would become the explorers' home, a prototype for robotic
exploration is envisioned to be about 31 meters in size, powered by solar energy, and filled with
helium. To accommodate the crew, the idea is to have airships that are approximately 130 meters
long. The top of the airship would be covered with over a thousand square meters of solar panels,
with a gondola for instruments underneath. In the crewed version, there would be a small
habitat and an ascent vehicle to return to Venus's orbit, and then back home.
The project is still in its very early stages of development, and it's uncertain whether NASA will
decide to bring it to fruition. After all, we belong to a species that is very curious
but also very fickle in pursuing its dreams. We're the ones who conquered the Moon on our
first pioneering attempt, only to set aside the achievement for over half a century...
Mars, Venus, colonies, terraforming... Don't get too carried away. If we ever succeed, it will take
centuries, not years or decades. What do you think?