Several days ago the National Academies of Sciences Engineering and Medicine released
their decadal survey for Planetary Science and Astrobiology outlining a plan for what
to prioritize for the period of 2023 to 2032.
These decadal surveys are sought by NASA to determine which missions should take priority
as far as funding.
While not bound to the survey, NASA usually follows through and this particular survey
prioritized two surprising, but extremely cool missions.
Coming in at the top is a mission to study Uranus over a period of years using a spacecraft
in orbit of that ice giant.
It will include an atmospheric probe that will drop into Uranus’ atmosphere and an
orbiter that will study the planet and its moons.
The concept is not unlike that of the Cassini mission to Saturn.
While Uranus isn’t the first on the list you might think of as far as interesting planets
to visit, it’s actually one of the planets we know least about.
And Uranus, and Neptune, represent a whole class of planet, the ice giants, that may
be a very common type of planet in the universe.
Other areas of the plan are to continue support for a Mars sample return mission, continued
support for lunar exploration and other pre-existing efforts.
But most notably, coming in at priority number two is a very interesting, and ambitious mission
to determine directly if Enceladus has life.
Known as the The Enceladus Orbilander Mission, this mission not only will study enceladus
from space, but also land directly on it.
This will very much be a first as far as space exploration goes.
We’ve landed on only a few moons in the solar system, including our own.
It seems that our next will be one of the most mysterious and interesting moons in the
solar system, on level with Titan which we have already landed on.
Enceladus is up there with Europa as the penultimate ice shell moons, very clearly indicating a
liquid water ocean existing under a shell of ice.
But Enceladus is particularly interesting because its ocean actually interacts with
space through enormous plumes of ice originating from the ocean below being spewed into space
constantly through fissures in the ice.
Those plumes and the fissures indicate that the moon’s core is heating a liquid water
ocean beneath, and there is also evidence that supports the idea of geothermal vents
on the ocean floor.
Such vents here on earth are a very good home to life, providing energy, nutrients and basically
everything you need for life to thrive.
This could also be the case with Enceladus, or indeed any of the numerous ice shell moons
in the solar system.
Unlike many missions since the 70’s that ask questions about habitability and never
a direct search for life itself, The Enceladus Orbilander is specifically design to do just
that.
Find out if Enceladus has life, or does not.
Sometimes direct searches aren’t very direct, microbial life is difficult to detect remotely,
and attempts to directly detect life on the surface of Mars with the Viking landers gave
ambiguous positive results that are in question to this day.
So it’s difficult to find opportunities to directly look for life and get a clear
answer.
But, we may be able to do that at Enceladus.
We now have sufficiently advanced technology to sample Enceladus’ plumes, and unlike
previous proposals for an Enceladus mission, none of those were envisioned as flagship
missions, rather lower cost Discovery or New Frontiers programs.
This one is a flagship, with an estimated price tag of 2.5 billion US dollars.
If pursued, here’s how the mission would work.
The spacecraft will function as both an orbiter, and a lander, hence Orbilander and would spend
about 200 days orbiting Enceladus.
The gravitational elephant in the room known as Saturn will wreak havoc on this process,
so frequent station keeping maneuvers will be needed.
One of the things it will be doing is sampling the plumes by passing through them.
But the material in the plumes isn’t very dense, it can be likened to the droplets in
clouds, and the very high speed of the spacecraft will make collection and analysis tricky,
but possible.
While performing that task along with other scientific studies, scientists will look at
data and imagery from the spacecraft to determine just where to land when the time comes.
When the science team decides on a location it will use a similar landing and navigation
system to the Osiris-Rex mission that landed on and sampled the asteroid Bennu.
Incidentally, those asteroid samples will be arriving back here to earth in September
of 2023.
While we already know quite a bit about asteroid geology from our meteorite collections, pristine
sealed material directly from an asteroid should yield plenty of interesting science.
Once a landing site for Orbilander is found, it will perform an orientation maneuver to
position it to become a lander.
It would then land and begin operations.
Spacecraft going to the outer solar system such as the Voyagers and this one, must use
RTGs for power, there just isn’t enough sunlight out there for solar power.
RTGs use the heat from the decay of plutonium for energy, and Orbilander will have two of
them.
But plutonium decays, and RTG’s eventually stop providing enough power to the instrumentation
of their spacecraft, so Orbilander’s lifetime on the surface of Enceladus will only be about
a year and a half.
Given that Orbilander’s specific mission is to search for life, it will have a very
complex instrument package.
As was shown with Viking, you need more than just one experiment to determine if life is
indeed present.
Rather you need a suite of them along with general science instruments to study enceladus
itself.
Planned instruments include equipment to search for the stuff of life, such as amino acids
and lipids with a mass spectrometer, a microscope to directly look for microbes themselves,
which is really amazing if you think about it.
That could, in a best case scenario, give us our first picture of alien life.
Also included will be equipment for sequencing the DNA of anything that might be found, a
seismometer to get data on Enceladus moving ice and geology, plus general cameras for
photographing the surface of enceladus.
Imagine for a moment what that will be like, having pictures from the surface of an ice
shell moon.
We’ve never seen anything like that on any of the solar system bodies we’ve landed
on, and it could be one of the most alien looking landscapes in the solar system.
Just the idea of the possibility of photographing the surface of an ice shell moon, and even
imaging any life that might be there makes this particular mission one of the most exciting
that have ever been proposed, at least for me.
But why Enceladus and not Europa or any of the other ice shells?
It’s the plumes, Enceladus is constantly emitting material and that makes for easy
access.
You don’t have to drill through the ice and thereby possibly contaminate the subsurface
ocean.
And with so many experiments to perform regarding life detection, the results should be unambiguous.
And ideally, there are two ways to study the plumes, from orbit passing through them, and
on the surface as the material settles back down, sort of like a very fine particle diffuse
snow falling constantly.
No launch date as been set for the Enceladus Orbilander, and it still has to be approved
by NASA to fly, and after that it takes a long time to get to Saturn from Earth, on
the order of 12 years, so we may not see this mission arrive at Saturn until 2040 or possibly
2050.
But it remains an exciting development, and could advance astrobiology from a branch of
science with nothing yet to study, to a full blown discipline with the discovery of a second
genesis of life in the solar system.
Thanks for listening!
I am futurist and science fiction author John Michael Godier currently hoping the life at
Enceladus is still microbial and hasn’t advanced to macroscopic space sharks capable
of eating landers, or ejecting a shark out of a fissure.
It would be very sad indeed if our first detection of alien life is a frozen space shark impact
destroying our Enceladus probe.
Very worrying and be sure to check out my books at your favorite online book retailer
and subscribe to my channels for regular, in-depth explorations into the interesting,
weird and unknown aspects of this amazing universe in which we live.