MORE THINGS I LEARNED DURING QUARANTINE--ALIEN LIFE IN AND AROUND THE RINGS OF SATURN

I've taken the enforced quarantine as an opportunity to be productive and learn new things.  The library is closed, but the supermarket is still open.  We visited Mariano's today, and walking around was like playing a game of Pac Man.  If someone was in an aisle, I would quickly turn down a different aisle.  Waiting at the deli counter was like a pas de deux, an elaborate dance to not get too close to anyone.

About 5 years ago, on a long overseas flight, I watched a video on Cosmos that piqued my interest about astronomy and the possibilities of life in the satellites of Saturn.   In college, I had taken an astronomy course, but that was the Dark Ages compared to what we have learned since the Apollo missions.  Our knowledge of Saturn has increased exponentially especially after the success of the Cassini space probe.

RINGS AND MOONS OF SATURN

The Cassini spacecraft (officially Cassini-Huygens) was launched in 1997 by NASA in conjunction with the European Space Agency and the Italian Space Agency--hence the name Cassini--Giovanni, not Oleg.  After making a grand tour of the Solar System, passing close to Venus, Earth, Asteroid 2685 Masursky and Jupiter, the spacecraft began orbiting Saturn in 2004.  It circled Saturn for 13 years before crashing (deliberately) into the planet in 2017 when its useful life was complete.    They ditched the craft to avoid inadvertently contaminating any of Saturn's moons (especially Titan and Enceladus)  with terrestrial microbes which might have somehow survived the trip.  Despite the demise of the spacecraft, the mountains of data it collected are still being analyzed by scientists who will continue to do so for years to come.

We've learned from the probe and recent observations that Saturn has 82 moons, not to mention more than 150 known moonlets.  Astronomers at the Mauna Kea observatory in Hawaii discovered 20 small moons in 2019 of which 17 were retrograde; that is, spinning in the opposite direction from Saturn  When I studied astronomy as a kid, Saturn had only 9 moons.  Incidentally, Jupiter has 79 moons--it had 12 when I grew up. 

Saturn's largest moon, Titan is larger than Mercury or Pluto, but most of the moons are less than 10 km (6 miles) in diameter.  The moonlets, embedded in the Rings are even smaller than that.  If you can envision surf washing over sand on the beach and getting things caught in it, that describes the moonlets..   Some of the moonlets are as small as 400 meters in diameter.  Many of the moons don't even have names yet, and they are soliciting names from the public.  The ones that do have names are named not only for giants of Greek and Roman mythology, but also from Norse, Gallic and Inuit sagas.

Saturn's rings are composed almost entirely of small chunks of water ice, ranging in size from micrometers to several meters.  They are relatively young, geologically speaking.  Scientists estimate their age from 10 million to 100 million years.  They are also slowly disintegrating into the planet by force of gravity.  Time is short; they will be gone in a few hundred million years.

The Rings, which are by and large on the same plane, are classified into at least 154 major subdivisions.  Each one has a name.  We have Rings A through F, though not in alphabetical order.  For example D Ring is the one closest to Saturn (approx. 45,000 miles), followed by C Ring, B Ring, Cassini Division, and then A Ring.  Then comes the Roche Division and then F Ring and various others named after figures from Greek mythology.  The two outermost Rings are E Ring and lastly, Phoebe Ring.   Go figure.  The thickness of the Rings can range from as little as 10 meters up to 1 kilometer. 

The Rings are further subdivided into structures within the Rings themselves.  The 8 structures and gaps within the C Ring alone, have names like Maxwell Gap, Maxwell Ringlet, Bond Gap, Columbo Gap and Titan Ringlet.  They range from 15 km. to 370 km in width.  The Cassini Division has 9 structures and various gaps named after astronomers like Huygens, Herschel and Kuiper.  The Kuiper Gap is only 3 km across. 

The widths of the Rings range from 500 km (300 miles) to 25,000 km (15,500 miles) except for the giant E Ring which is 300,000 km (186,000 mi) across.

POSSIBILITIES OF LIFE

What excites scientists most is the possibility of life on the moons Titan and Enceladus.  Enceladus in particular is intriguing because geysers of water vapor and other materials are constantly erupting in its South polar region.  The spacecraft actually flew through the geysers, probably 50 miles above the surface, and detected organic compounds consisting of carbon and nitrogen as well as amino acids, the building blocks of life.  The indication is that Enceladus has a large subterranean ocean of liquid salt water more than 6 miles thick.  Scientists believe that the ocean covers the entire subsurface of that moon.

Although scientists don't expect intelligent life to appear, they are lobbying for more space missions to determine what types of life, if any, exist there.  They could then compare it to life on Earth in an attempt to determine whether it arose independently or if Earth life and Enceladus life came from a common source in the Universe.  Either way, the results could answer questions we've been asking for generations.  Scientists today still can't answer the question of how life originated on Earth.

For life to exist, there must be an energy source.  On Earth, that energy source generally is the Sun.  But not always.  For example, in recent years, scientists discovered life teeming in extreme environments, the superheated volcanic vents on the ocean floor, far from any energy from the Sun.  They had discovered archaea, an entirely new phylum, totally alien to what we could expect.   Many are one celled creatures distinct from and unrelated to bacteria. 

Scientists speculate that there is no reason why similar life couldn't thrive on (or under) Enceladus.  They don't rule out the fact that alien life could have a different bio-chemistry than Earth life.  We won't know until we can figure out a way to go there or send a probe to find out.  It probably won't happen in our lifetime. 

The spacecraft dispatched the Huygens lander to the surface of Titan in 2005.  The photos aren't much different than those on Mars with many rocks strewn across the surface.  Titan has a thick atmosphere, weather and tidal currents, like we have on Earth.  What's most interesting is the fact that Titan has lakes on the surface, the only lakes in the Solar System other than on Earth.  One Titanian lake, Kraken Mare, is larger than Lake Superior.  You don't want to drink out of it because it is not filled with water but rather liquid hydrocarbons methane and ethane.  Your car might run on it however.

Those lakes sit on top of a subterranean ocean filed with water.  NASA is entertaining the idea of sending a submarine to Titan (I'm not making this up--two different designs have been presented) to search for exotic alien life.