This is Venera 4
A Soviet space probe moments away from attempting the first landing on another planet.
Venus.
At the time, very little was known about this mysterious planet
but scientists believed that under its thick layer of cloud
was a world not too different from Earth
with a similar one bar atmosphere and earthlike temperatures.
But little did they know what kind of world this poor little space probe was about to enter.
As it hit the atmosphere at 40,000 km per hour, its parachute deployed and the antenna started sending back data.
At first the atmospheric pressure was similar to Earth's and the temperature was around 30° C
but as it descended further into the atmosphere the readings started to go crazy.
One atmosphere quickly became ten
Ten became 20
and the temperature was well over 200° when suddenly
the space probe cracked open and all communication was lost.
The last bit of data it sent back revealed an atmosphere that was 22 times thicker and 250° hotter than Earth
but now that the Soviets knew just how harsh Venus really was
they were even more determined to get there.
We modeled these incredible space probes to show you how the Soviets finally managed to land
take pictures and record audio on the surface of our most dangerous planet.
The early space probes had a relatively simple design.
The lander was a 1 m wide titanium sphere pressurized inside to around 25 atmospheres
It had a handful of scientific instruments to analyze the atmosphere
and a battery to power it during descent.
The lander had no thrusters and instead used its own drag and a series of parachutes to bring it down to the ground.
But with Venus's thick atmosphere this turned out to be a problem.
Instead of quickly falling through the atmosphere in a matter of minutes, Venera 4 hit the atmosphere like a brick wall
and quickly slowed down to just 18 km per hour, much slower than expected.
This meant that the spacecraft had to endure 90 minutes inside Venus's atmosphere
constantly being exposed to the heat and pressure until it was crushed.
The Soviets realized that once they entered Venus's atmosphere, time way limited
and so they would have to pass through the atmosphere before it had time to crush or melt the lander.
And so the Soviets completely rethought their approach to Venus.
They sent a fax to NASA asking for a special heat resistant material
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In order to reach the surface of Venus before being destroyed
the Soviets redesigned the space probe to make it fall through the atmosphere more quickly.
They added a cord to the parachute that would stop it from opening, allowing Venera to fall much faster.
It was made of a material that would melt at 200°
and so the parachute wouldn't open until the probe was much closer to the surface.
Since the pressure on the surface was still unknown, the engineers went overkill with Venera's protection.
The walls were two times thicker and the space probe could now withstand a pressure of 180 atmospheres.
The Soviets were ready to put Venera 7 through hell.
As it hit the atmosphere the lander slowed all the way down and deployed its parachute.
The cord did its thing and allowed the space probe to quickly fall through Venus's thick atmosphere.
The probe was now much closer to the surface than any of the previous missions
until, with just 3 km to go, the parachute tore itself apart and the probe started plummeting to the ground
slamming into the surface at 60 km an hour.
The Soviets had another failure on their hands
or so they thought.
A few weeks later when reviewing the data, they noticed that a very weak signal had actually been transmitting
for 23 minutes after the lander hit the surface.
As it turned out the lander actually survived but it had been knocked onto its side
making the antenna's signal to Earth extremely weak.
Incredibly, the last bit of data it sent out showed that the temperature at the surface was a mind-boggling 500° C
Since temperature was now the main problem limiting their time on the surface
the engineers came up with a genius but simple cooling solution for Venera 8.
Inside the space probe were blocks of lithium nitrate
a salt-like substance which has a very high heat of fusion.
This is the amount of energy required to turn it from a solid into a liquid.
In order to heat this material up by 1° it takes just under 2 joules of energy per gram
but when it reaches its melting point crossing that boundary from a solid into a liquid
takes almost 300 joules of energy.
And so this change from a solid to a liquid absorbs a large amount of heat energy
which is effectively stored in the material.
And so blocks were placed inside the lander to absorb heat and take it away from the electrical components.
This system worked extremely well and Venera 8 successfully made it to Venus
and survived for an entire hour on the surface.
The Soviets had now mastered the art of getting to Venus
but the world still had no idea what this crazy world actually looked like.
And so it was up to Venera 9 to take the first pictures of Venus.
The Lander was completely redesigned once more.
Instead of using parachutes for the final descent, Venera 9 had a large air brig to slow it down
and a set of landing legs to absorb the impact.
But the most important feature on Venera 9 was the camera system.
It had two movable cameras on either side of the lander
that could take a 360° panorama of the surrounding landscape
but designing a camera that could survive the intense pressure and temperature of Venus was yet another challenge.
The cameras were placed inside the lander's pressure vessel and two periscopes stuck out
into the super thick pressure window.
At the end of the periscope was a small lens that could rotate and scan the 180° view of the surface.
The light would travel down the periscope and through a lens
that would correct the effect of the thick pressure window.
Each of the two cameras had large lens caps
that were designed to pop off once the probe had landed.
On Venera 9 only one of these worked.
This was the very first picture taken on Venus.
On future missions the cameras were improved
eventually taking higher definition color images.
On Venera 14 a microphone was placed on board.
The following is real audio of the probe landing on the surface and an instrument drilling into the surface.
All in all the Soviets landed on Venus eight times with each Mission sending
back incredible images and scientific data about this mysterious planet.
An achievement we are yet to repeat some 50 years later.
And now for the Primal Space giveaway.
The winner of the previous giveaway is David. Congrats! In the next video we'll be
giving away this custom Primal Space Venera poster to one lucky winner.
All you need to do is sign up at the link below, like the video and leave a comment saying what you think about the Venera space probes.
Thank you very much for watching and I'll see you in the next video.