Friday, 12 August 2016

Jupiter’s moon Europa

Jupiter’s moon Europa

Europa Update: The Hubble Telescope took some photos of Europa, that have just been released in Sept 2016.  These appear to show water plumes, emanating from the moon, to a height of about 200 km.  So, that seems to clinch the "water under the ice of Europa" hypothesis.  Plus, it implies that the water is not all that deep below the surface, and that it could be sampled by a probe, to see if chemicals that support life are found in the plume.  So, exciting times for deep space science.


Helena Puumala’s SF Romance series features a planet with seven moons.  This rather unusual setting gives me the opportunity to talk about some of the remarkable moons in our solar system, as I test different moons for the cover of book 2 of the series.

But, more on that at the end of the blog.  Basically, the book gives me the opportunity to do a mini-tour of some of the major moons of our solar system.

This blog is about Europa, one of the four large moons of Jupiter, and one of the most interesting, as there is intense speculation that it could harbor life in its deep ocean.

Here are a few facts about Europa, courtesy of Wiki:

  • It's the smallest of Jupiter’s four Galilean moons, but still the sixth largest in the solar system.
  • As noted above, it is one of the four original moons discovered by Galileo in 1610 (thus, referred to a Galilean moon).
  • It is the second farthest from Jupiter of the four Galilean moons.  It is easy to find in a small telescope.
  • It participates in a 1:2:4 orbital resonance with the two Galilean moons that it is between, Io (closest to Jupiter) and Ganymede(third from Jupiter).  That means, for every one time Ganymede goes around Jupiter, Europa goes around twice and Io goes around four times.
  • Europa’s orbit takes about three and a half days.  It is tidally locked with Jupiter (its rotation rate is the same as its orbit rate), so at a certain point on Europa, Jupiter would always be directly overhead.
  • The orbit is slightly eccentric (non-circular), so sometimes it is a little farther from Jupiter and sometimes it is a little closer.  This causes the planet’s shape to change slightly, elongating when closest to Jupiter and becoming more spherical when farther away.  The flexing of the planet creates heat (friction, basically), which keeps the liquid ocean under the ice from freezing.
  • The orbital resonance with Io “pumps” its orbit, so that it remains elliptical and does not completely circularize over time.  Thus, the moon continues flexing every 3.5 days, supplying a constant source of heat for the buried ocean.
  • An ocean exists many kilometers underneath Europa’s icy crust, which acts as an insulating blanket.   Due to the temperature at the surface (-160 Celsius) that surface ice would be as hard as granite.
  • Some researchers think certain “chaotic” surface features indicate that this ocean may occasionally break through in places to the surface.  This is an area of intense debate.
  • Europa has a small magnetic moment, probably caused by the salty subsurface ocean, which can act a conductor, and induces the magnetic field.
  • Water vapor plumes have been spotted by the Hubble Space Telescope.
  • It is not known exactly how far down the liquid ocean is, but speculations range from a few kilometers to tens of kilometers.
  • Life could cluster around features equivalent to the “black smokers” of Earth’s oceans, where heat and matter from the crust and mantle below escape into the ocean.  Europa might have similar hydrothermal vents.
  • Alternatively, primitive life, like bacterial mats on Earth, might exist near the bottom of this ocean, which would be warmer than the higher levels.
  • There may even be a relatively high oxygen content in this ocean, due to the breakdown of hydrogen peroxide, which seems to exist on the surface.  This could then be absorbed into the ocean below.
  • Free oxygen might also come from water ice being broken down at the surface of Europa, by cosmic rays, that is then absorbed into the deep ocean.
  • A high oxygen content could mean complex life (fish?).
  • Its albedo is about 64% (about 64% of the light falling on it is reflected).  This is one of the highest albedos in the solar system.
  • The surface is smooth and bright, due to the constant reworking of it by the tidal energies noted above. 
  • There are plans to land a probe on Europa and drill into the surface.  That would be difficult and expensive; among other things, the surface has high levels of radiation (via Jupiter’s effect on the solar wind).

Here's a picture of Europa,  taken by a NASA probe.

Here's a recent picture of Europa and some other moons, taken by NASA's Juno probe, on July 5, 2016.  Granted, the moons are pretty small, but this is the first reasonably close-in picture from the new Juno probe.  Hopefully, we will get some more interesting photos of Jupiter’s moons, though I believe the probe’s science mission is mostly focused on Jupiter itself, the atmosphere in particular.



The moon Europa and Love and Intrigue Under the Seven Moves of Kordea

Helena Puumala's SF Romance series features the planet Kordea, home to a race of beautiful and powerful psychic aliens, known as the Witches of Kordea.  The planet has seven moons, an extraordinary arrangement for a terrestrial sized planet in its star's habitable zone.

In fact, the moons of Kordea are a central element in Book 2.  The cover below actually borrows the moon Europa, one of the moons of Jupiter 

The Witches’ Stones Series

The Witches' Stones, Book 1 - Rescue from the Planet of the Amartos

Young Earth woman and spaceship mechanic, Sarah Mackenzie, has unwittingly triggered a vast source of energy, the Witches' Stones,  via her psychic abilities, of which she was unaware.  She becomes the focal point of a desperate contest between the authoritarian galactic power, known as The Organization, and the democratic Earth-based galactic power, known as The Terran Confederation.  The Organization wants to capture her, and utilize her powers to create a super-weapon; the Terra Confederation wants to prevent that at all costs.  The mysterious psychic aliens, the Witches of Kordea also become involved, as they see her as a possible threat, or a possible ally, for the safety of their own world.

A small but fast scout-ship, with its pilot and an agent of the Terra Confederation, Coryn Leigh, are sent to rescue her from a distant planet at the very edge of the galaxy, near space claimed by The Organization.  Battles, physical and mental, whirl around the young woman, as the agent and pilot strive at all costs to keep her from the clutches of the Organization.

The Witches' Stones, Book 2 - Love and Intrigue, Under the Seven Moons of Kordea

Sarah has taken refuge on the planet of Kordea, where she is also learning how to control her psychic abilities, through the tutelage of the Witches of Kordea.  Coryn Leigh has now taken up the position of Confederation diplomat to the Kordeans, but he is also charged with keeping the Mackenzie girl safe at all costs.  During their time on the planet, an attraction between them grows, though they try to deny it, to themselves and each other.
But The Organization has plans of its own, including threatening the destruction of the planet Kordea, via destabalizing the orbit of Lina, one of its many moons.  The Organization proves that its threats are in deadly earnest, so, ultimately Sarah, Coryn and the Witches of Kordea must take the fight to the enemy.  Thus is borne a dangerous mission, to  a planet where their foe has based the weapon that threatens Kordea, and ultimately, the balance of power throughout the galaxy.  Sarah and Coryn agree that the machine must be destroyed, even at the possible cost of their own lives and growing love.

The Witches' Stones, Book 3 - Revenge of the Catspaw

Sarah and Coryn have become married, under the traditions of the Witches of Kordea.  But the marriage is performed by the Eldest of the most important coven, a rare honour, that comes with a blessing and a curse.  The slow working out of this blessing and curse forms the backdrop to the story.

Having come so close to their goal of enhancing their weaponry via Witches' Stone power, The Organization will not give up.  In order to lure Sarah into their trap, and thus have her become their Catspaw (someone who is forced into helping another, against their will) they need bait, and Coryn becomes the bait.  He also comes under the domination of a particularly nasty Elite of The Organization, one "Evil Evilla" Copoz.

Sarah, and a picked group of companions, must re-enter The Organization space, this time to the very heart of the empire, to rescue her husband, as he has done for her in the past.  They do so at great peril, but nothing can stop the terrible Revenge of the Catspaw.

No comments:

Post a Comment