If you look out into the horizon of an early morning sky, you may be able to spot
the morning star, Venus, shining prominently. Venus is the second closest planet to the Sun,
and one of Earth’s nearest neighbors. The latter half of the 20th century brought
about a whole host of missions to Venus, with NASA and the Soviet Union both sending
probes to investigate the planet. Eventually, interest in reaching Venus lost its momentum,
and there have been few missions in the previous two decades. However, now NASA plans a new mission
to Venus, which aims to learn more about the planet than any carried out before.
This is Unveiled, and today we’re answering the extraordinary question;
why is NASA returning to Venus, Earth’s evil twin?
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Throughout human history, Venus has been one of the most prominent objects in the sky. It
holds the award for being the brightest object in the sky, after the Sun and the Moon. It has
long been known as both the morning star and evening star, appearing low in the horizon
during dusk and dawn - leading the ancient Greeks to believe it was two separate objects.
Irrespective of its nickname, Venus is not a star of course, but a rocky planet covered in a thick,
dense atmosphere. Another title it’s been given is ‘Earth’s evil twin’. While Venus
has a similar size and mass to our own planet, it has an extremely toxic atmosphere primarily
composed of carbon dioxide. Dense clouds of sulfuric acid give the planet a yellowish tint.
While human fascination with Venus harks back to ancient times, the first major discovery
about its nature came in 1761. This was the discovery of Venus’ atmosphere by Russian
scientist Mikhail Lomonosov. We didn’t learn any major new information about
the planet until the 20th century, when the space race started to gain momentum.
It was the Soviet Union’s Venera 1 that carried out the first flyby of Venus, in 1961. In fact,
it was also the first spacecraft to ever perform an interplanetary flight. However,
contact with the probe was lost before the flyby. The first truly successful interplanetary
mission was completed by NASA a year later, in 1962, with the probe Mariner 2. Before this,
people imagined that Venus’ atmosphere might be obscuring a vibrant, tropical world hidden
deep below the clouds. Science fiction writers from the time would depict the morning star as
a vibrant and luscious world hosting jungles and dinosaurs, strikingly similar to an ancient Earth.
Unluckily for science fiction writers, Mariner 2 dispelled these far-reaching depictions,
discovering the planet’s surface to be far hotter than imagined and completely inhospitable.
The Soviet Union later launched many more Venera probes. In 1965, Venera 3 became the first space
probe to enter the atmosphere of another planet … and to crash on the surface. Unfortunately,
communication was lost before it could transmit data back. Venera 4 in 1967 was
far more successful, entering the atmosphere and transmitting a heap of exciting data back
to Earth. It found this atmosphere to be much denser and hotter than anticipated. Both the
Venera and Mariner missions continued throughout the following decades,
with Venera 9 and 10 actually landing on the surface in 1975, and transmitting images of
what they saw back to Earth. Both probes lasted roughly an hour before burning up,
but still captured some of the earliest images of a planet other than our own. In 1982,
Venera 13 and 14 managed to obtain the first images in color of Venus’ surface. The Venera
15 and 16 orbiters brought the Venera program to a close, mapping out an impressive 25% of
the planet’s surface. The last probes to enter the atmosphere were Vega 1 and Vega 2, in 1985.
The Soviet probes brought with them landers and balloon explorers, which floated over the surface,
taking measurements from within the middle and most active layer of the Venusian cloud system.
Since the 80s, numerous spacecraft have flown by the second planet,
but visiting there was not the primary goal for most of these missions. There have only
been two dedicated missions in the 21st century so far. Entering orbit around Venus in 2005,
the ESA’s Venus Express carried out a lengthy analysis of the Venusian atmosphere. Originally,
it was intended to operate for 500 days, but was extended multiple times until it ran for
an impressive 9 years. As of writing, there exists only one active mission to Venus: Japan’s Akatsuki
probe, which has been orbiting the planet since 2015. It’s equipped with five cameras,
operating at differing wavelengths, and is focused on analyzing the planet’s atmospheric dynamics.
Fans of Venus should not be upset at its lack of recent attention, as there are plenty of exciting
plans to explore it further. India is planning to put Shukrayaan-1, an atmospheric balloon, into
the planet’s skies. China, Russia and the ESA all have their own orbiters in the works, all expected
to be launched in the next decade. Arguably the most exciting ones coming up are NASA’s VERITAS
and DAVINCI missions, planned to launch in 2029. VERITAS will be an orbiting spacecraft with the
aim of mapping the planet out in the highest resolution yet. DAVINCI is another orbiter,
but will also deploy a probe into the atmosphere to better understand its origin and evolution.
NASA also has a broader goal in mind for these probes: they want to understand the formation
of planets hospitable to life. The morning star remains our most Earth-like neighbor,
and like our own planet resides in the Sun’s goldilocks zone - the sweet spot where liquid
water can exist on a planet’s surface. For all we know, Venus could have been habitable before life
on Earth developed, and the two may have closely resembled each other. If this was the case,
then what happened to change it into the toxic wasteland it is today?
VERITAS intends to answer this question, determining in what way the planet diverged
from its blue twin. The maps it will create are expected to be the most detailed imaging of the
planet to date, and will allow a comprehensive look at areas of high geological activity,
including volcanic eruptions. DAVINCI’s atmospheric probe will get more up close
and personal, taking photos of the surface as it drifts down and lands in a region known as Alpha
Regio. Such ancient highland areas may be the key to learning more about Venus’ past evolution.
Together, the two missions could paint a brand new picture of the planet’s history. Learning
about this history has applications elsewhere, as it will help us understand how planets evolve
in the universe as a whole. We can use this information about the conditions needed for
habitable planets to form in our search for life outside the solar system. Currently,
we’ve discovered over 5,000 exoplanets. Having extensive knowledge about Venus will help us
determine which of these exoplanets are the best candidates for harboring life.
Venus may be Earth’s sister planet in terms of age, size,
and composition. But it diverged long ago down a very different path. These upcoming missions
give us hope that we could one day understand why Earth and Venus became so different - which
will help us decide what to look for in our search for life outside the solar system.
What do YOU think the future holds for Venus? Will we become more interested in this hellish world,
or less? Could humans ever hope to set foot there? There have been some ambitious (and
bizarre) outlines put forward for potential crewed missions in the past, including a theorized bid
to set up bases high in the Venusian atmosphere, above its dense and poisonous clouds. What will
never change is the fact that Venus will never be naturally hospitable to us; for as long as humans
are like we are, and the planet is like it is, there is simply no hope for survival. But, again,
for NASA and the like that’s arguably more reason to investigate this world further. As there are
suggestions that Earth could end up suffering a similar fate to Venus, at some distant time
in its future… it’s certainly worth getting to know this place, rather than ignoring it.
For now, it’s highly unlikely that Venus will rival Mars for our affections, any time soon.
It’s all eyes on the Red Planet, mostly because it seems to offer the most likely route toward
humans actually getting to another world. And, from there, who knows how far across the solar
system (and space) we might be able to reach! But, if nothing else, Venus might yet cement its
place as a cautionary tale for us all to learn about and learn from. It’s this planet’s evil
twin for a reason, and it won’t be ignored. And that’s why NASA is returning to Venus.
What do you think? Is there anything we missed? Let us know in the comments, check out these other
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