As you probably know, NASA recently announced
plans to send a mission to Jupiter’s moon
Europa.
If all goes well, the Europa Clipper will
blast off for the world in the 2020s, and
orbit the icy moon to discover all its secrets.
And that’s great and all, I like Europa
just fine.
But you know where I’d really like us to
go next?
Titan.
Titan, as you probably know, is the largest
moon orbiting Saturn.
In fact, it’s the second largest moon in
the Solar System after Jupiter’s Ganymede.
It measures 5,190 kilometers across, almost
half the diameter of the Earth.
This place is big.
It orbits Saturn every 15 hours and 22 days,
and like many large moons in the Solar System,
it’s tidally locked to its planet, always
showing Saturn one side.
Before NASA’s Voyager spacecraft arrived
in 1980, astronomers actually thought that
Titan was the biggest moon in the Solar System.
But Voyager showed that it actually has a
thick atmosphere, that extends well into space,
making the true size of the moon hard to judge.
This atmosphere is one of the most interesting
features of Titan.
In fact, it’s the only moon in the entire
Solar System with a significant atmosphere.
If you could stand on the surface, you would
experience about 1.45 times the atmospheric
pressure on Earth.
In other words, you wouldn’t need a pressure
suit to wander around the surface of Titan.
You would, however, need a coat.
Titan is incredibly cold, with an average
temperature of almost -180 Celsius.
For you Fahrenheit people that’s -292 F.
The coldest ground temperature ever measured
on Earth is almost -90 C, so way way colder.
You would also need some way to breathe, since
Titan’s atmosphere is almost entirely nitrogen,
with trace amounts of methane and hydrogen.
It’s thick and poisonous, but not murderous,
like Venus.
Titan has only been explored a couple of times,
and we’ve actually only landed on it once.
The first spacecraft to visit Titan was NASA’s
Pioneer 11, which flew past Saturn and its
moons in 1979.
This flyby was followed by NASA’s Voyager
1 in 1980 and then Voyager 2 in 1981.
Voyager 1 was given a special trajectory that
would take it as close as possible to Titan
to give us a close up view of the world.
Voyager was able to measure its atmosphere,
and helped scientists calculate Titan’s
size and mass.
It also got a hint of darker regions which
would later turn out to be oceans of liquid
hydrocarbons.
The true age of Titan exploration began with
NASA’s Cassini spacecraft, which arrived
at Saturn on July 4, 2004.
Cassini made its first flyby of Titan on October
26, 2004, getting to within 1,200 kilometers
or 750 miles of the planet.
But this was just the beginning.
By the end of its mission later this year,
Cassini will have made 125 flybys of Titan,
mapping the world in incredible detail.
Cassini saw that Titan actually has a very
complicated hydrological system, but instead
of liquid water, it has weather of hydrocarbons.
The skies are dotted with methane clouds,
which can rain and fill oceans of nearly pure
methane.
And we know all about this because of Cassini’s
Huygen’s lander, which detached from the
spacecraft and landed on the surface of Titan
on January 14, 2005.
Here’s an amazing timelapse that shows the
view from Huygens as it passed down through
the atmosphere of Titan, and landed on its
surface.
Huygens landed on a flat plain, surrounded
by “rocks”, frozen globules of water ice.
This was lucky, but the probe was also built
to float if it happened to land on liquid
instead.
It lasted for about 90 minutes on the surface
of Titan, sending data back to Earth before
it went dark, wrapping up the most distant
landing humanity has ever accomplished in
the Solar System.
Although we know quite a bit about Titan,
there are still so many mysteries.
The first big one is the cycle of liquid.
Across Titan there are these vast oceans of
liquid methane, which evaporate to create
methane clouds.
These rain, creating mists and even rivers.
Is it volcanic?
There are regions of Titan that definitely
look like there have been volcanoes recently.
Maybe they’re cryovolcanoes, where the tidal
interactions with Saturn cause water to well
up from beneath crust and erupt onto the surface.
Is there life there?
This is perhaps the most intriguing possibility
of all.
The methane rich system has the precursor
chemicals that life on Earth probably used
to get started billions of years ago.
There’s probably heated regions beneath
the surface and liquid water which could sustain
life.
But there could also be life as we don’t
understand it, using methane and ammonia as
a solvent instead of water.
To get a better answer to these questions,
we’ve got to return to Titan.
We’ve got to land, rove around, sail the
oceans and swim beneath their waves.
Now you know all about this history of the
exploration of Titan.
It’s time to look at serious ideas for returning
to Titan and exploring it again, especially
its oceans.
And I’ll explain all about that in a second,
but first I’d like to thank Deepak, George
Greene, Steve Dalton, Matt Douglass, and the
rest of our 696 patrons for their generous
support.
If you love what we’re doing and want to
help out, head over to patreon.com/universetoday.
Planetary scientists have been excited about
the exploration of Titan for a while now,
and a few preliminary proposals have been
suggested, to study the moon from the air,
the land, and the seas.
First up, there’s the Titan Saturn System
Mission, a mission proposed in 2009, for a
late 2020s arrival at Titan.
This spacecraft would consist of a lander
and a balloon that would float about in the
atmosphere, and study the world from above.
Over the course of its mission, the balloon
would circumnavigate Titan once from an altitude
of 10km, taking incredibly high resolution
images.
The lander would touch down in one of Titan’s
oceans and float about on top of the liquid
methane, sampling its chemicals.
As we stand right now, this mission is in
the preliminary stages, and may never launch.
In 2012, Dr. Jason Barnes and his team from
the University of Idaho proposed sending a
robotic aircraft to Titan, which would fly
around in the atmosphere photographing its
surface.
Titan is actually one of the best places in
the entire Solar System to fly an airplane.
It has a thicker atmosphere and lower gravity,
and unlike the balloon concept, an airplane
is free to go wherever it needs powered by
a radioactive thermal generator.
Although the mission would only cost about
$750 million or so, NASA hasn’t pushed it
beyond the conceptual stage yet.
An even cooler plan would put a boat down
in one of Titan’s oceans.
In 2012, a team of Spanish engineers presented
their idea for how a Titan boat would work,
using propellers to put-put about across Titan’s
seas.
They called their mission the Titan Lake In-Situ
Sampling Propelled Explorer, or TALISE.
Propellers are fine, but it turns out you
could even have a sailboat on Titan.
The methane seas have much less density and
viscosity than water, which means that you’d
only experience about 26% the friction of
Earth.
Cassini measured windspeeds of about 3.3 m/s
across Titan, which half the average windspeed
of Earth.
But this would be plenty of wind to power
a sail when you consider Titan’s thicker
atmosphere.
And here’s my favorite idea.
A submarine.
This 6-meter vessel would float on Titan’s
Kraken Mare sea, studying the chemistry of
the oceans, measuring currents and tides,
and mapping out the sea floor.
It would be capable of diving down beneath
the waves for periods, studying interesting
regions up close, and then returning to the
surface to communicate its findings back to
Earth.
This mission is in the conceptual stage right
now, but it was recently chosen by NASA’s
Innovative Advanced Concepts Group for further
study.
If all goes well, the submarine would travel
to Titan by 2038 when there’s a good planetary
alignment.
Okay?
Are you convinced?
Let’s go back to Titan.
Let’s explore it from the air, crawl around
on the surface and dive beneath its waves.
It’s one of the most interesting places
in the entire Solar System, and we’ve only
scratched the surface.
If I’ve done my job right, you’re as excited
about a mission to Titan as I am.
Let’s go back, let’s sail and submarine
around that place.
Let me know your thoughts in the comments.
People always want to know if I believe in
aliens.
That’s actually a pretty complicated question,
and I’ve got a complicated answer.
I’ll get into it in the next episode.
Now you know my thoughts on a mission to Titan.
Here’s an episode all about a potential
mission to Europa, which looks more and more
like it’ll be a reality.
