Above a Dark Horizon

The sights one can see in space! I wasn’t quite sure I believed this scene when I first saw it yesterday. From the Cassini space probe, the moon Titan is imaged across the rings of Saturn from just above the dark horizon of Enceladus.

At the Planetary Society blog, Emily Lakdawalla has a time lapse piece of three polar water fountains at Enceladus.

A note: this isn’t what the unaided human eye would see. Cassini is equipped with imaging devices that can closely approximate human vision–and more. This technology also approximates what a decent backyard telescope would show you–if you were flying with Cassini. In actual viewing from Enceladus, Titan would appear as a small orange disk, usually smaller than our moon appears from Earth.

Cassini is there not only to snap pretty pictures–which is does quite well. It detects energy at certain wavelengths that also permit scientists to analyze the chemistry of Saturn and its moons. Astronomy once famously partnered physics, but now adds chemistry as well as geology as companions. A scientific polygamy, but a very moral one, to be sure.

Tuesday’s 270-mile swoop past Enceladus was designed to view the fountains backlit from the sun and detect nitrogen outgassing. Why is that important? Nitrogen is one of the two components of ammonia. When ammonia is dissolved in water, the freezing p0int lowers, and if Enceladus’s internal water has a quantity of ammonia, that would give us a temperature range for the interior we can’t detect directly. When ammonia is heated, the molecular bonds break and gaseous nitrogen is released. Determining how much nitrogen is sputtering from the moon’s south pole will further refine temperature estimates.

Christina Rosetti wrote of a bleak midwinter on Earth:

Earth stood hard as iron, water like a stone.

Her description fits the Saturnian system. On the surface, Enceladus is a bitter 320 degrees below zero, and water is in a permanent solid state, like the stony crust of Earth. But somewhere inside, there’s enough heat to melt ice–just like the Earth’s molten core. Before Cassini, it wasn’t thought that small bodies like Britain-sized Enceladus would be able to maintain a liquid interior. Moons should cool off–like our moon and even the planet Mars. Europa’s subsurface ocean was enough of a surprise, and that one is largely explained by tidal heating from nearby large moons. How can Mars be dead and distant outer solar system moons be geologically alive? Nobody saw that one coming.

Enceladus is much smaller than Europa. And the nearby moons of Saturn in no way rival the size of Io and Ganymede at Jupiter. We will probably have to wait for a probe to plunge directly into these geysers to determine exactly how and why the ice within melts. I’d love to be alive to see the internet feeds on that day. In the meantime, scientists look for whatever clues they can discern to view past the dark horizons of the unknown.


About catholicsensibility

Todd lives in the Pacific Northwest, serving a Catholic parish as a lay minister.
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One Response to Above a Dark Horizon

  1. Tony Barr says:

    My youngest brother, Paul was an astrophysicist, working with the European Space Agency (ESA); I, the eldest, was the theologian in the family. We had awe-inspiring conversations!

    His major area of research was with gamma radiation studies of black holes at the outer extremities of the universe. Although black holes swallow everything in sight (so to speak!), they leave a discernible accretion of matter on their rims. By analyzing these emissions, scientists are able to reveal some of the secrets of the origins of the universe.

    They are able to draw light from, and shed light on, these astronomical phenomena and thus unveil the secrets of the dawn of time.

    His secondary area of research was the polarity of our sun. Shifting patterns at the core of the sun have immediate and dramatic effect on our own planet.

    From the most distant recesses of the universe to the intimate heart of our own galaxy, Paul’s life was a quest for the meaning of life as observed through transmittable light and analytical spectography.

    He died tragically at the age of 50 in 2005, and was honored at his funeral liturgy as being among the top 5 astrophysicists in the world.

    His relentless pursuit of light provoked me to write a setting of ‘Light Eternal’ which I was able to sing with love and courage at his Rite of Commital….

    …. et lux perpetua luceat eis

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