Saturday 24 August 2019

The Mission to Jupiter’s Moon Europa (Clipper)


The Mission to Jupiter’s Moon Europa (Clipper)

Some time back (2017), I blogged about NASA’s upcoming decision about a possible mission to Jupiter’s moon Europa.  You can check out that blog with the link below, which also has a lot of general information about Europa.


Europa is one of the preferred targets for the search for non-Earth life within the solar system, as there is every indication of a watery ocean below a permanent layer of ice, though we don’t yet know how thick the ice actually is.  The possibility of there being such an ocean was noted from results of the Voyager missions, during the last century.  Since then, the evidence for ice and water has only grown stronger (e.g. images and measurements from other probes, Hubble photos that seem to have spotted water plumes being thrown high above the surface, etc.).

That’s important, as NASA has a “follow the water” strategy, in its search for life.  The tidal disruptions that keep the moon’s ocean from freezing may also provide energy for life, and the chemicals that may be found at the ocean/crust boundary might provide the needed raw materials for life.
The ultimate mission would include a lander, and some sort of vehicle to access that ocean beneath the ice, to search for signs of life directly. Although that mission is still some time in the future, it seems as if a preliminary mission, a series of close encounters with Europa called “Clipper” is moving ahead to the next stage (as many as 45 flybys, one every couple of weeks).  The mission is scheduled for sometime in the 2020s.

The Clipper mission will carry out detailed reconnaissance of Europa, via a number of close fly-bys of the moon.  It will have an eccentric orbit around Jupiter, which will allow it to remain a safe distance from Jupiter’s intense magnetic field for much of the time.  That’s important, as the magnetic field traps highly charged and highly energetic particles from the solar wind, which are destructive to highly sensitive instruments, such as Clipper will carry.  Then, once each orbit, the spacecraft will swoop down towards Europa, on a fast and close flyby, and collect close-in scientific data.

The probe will carry a number of scientific instruments, including:

  • High resolution cameras, to take very detailed pictures of the surface, including “chaotic” features which may actually be where water has broken through the ice in the fairly recent past.
  • Spectrometers, which will help to determine the composition of the surface, by measuring the tenuous atmosphere and/or particles there, as well as the spectra of light coming from the surface.
  • A Dust Analyser, to investigate the properties of dust that may be in the high atmosphere of Europa, presumably ejected by the moon.
  • Ice penetrating radar, to estimate the depth of the ice (i.e. the distance to the under-ice ocean).
  • Magnetometers, to measure the strength and direction of Europa’s magnetic field in detail, which will also help discover important facts about the ocean, such as its level of salinity (salt in the water acts as an electrical conductor, which induces a magnetic field).
  • A Thermal Instrument (ultra-sophisticated infra-red camera?) to identify warm spots on the ice, where the water has “outcropped” in the recent past, or is still escaping to the surface.  If plumes are detected, it may be possible to sample them directly, and gain information about the under-ice ocean.

At this stage of the process, NASA has selected a number of research teams to propose and build the scientific payload described above (possibly other instruments as well).  After that (assuming the necessary funding is given) the instrumentation will be finalized and built and the details of the mission’s launch, flight path, orbit, etc. will be worked out.

Then, the mission itself (2020s), hopefully followed by the proposed Europa Lander mission, a few years later (2030s).


Sources:

1 – Proposed Europa Mission, from 2017
2 – Facts about Europa
3 – NASA site, regarding the Clipper mission
 
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Now that you have read some real science (astronomy and astrophysics), you should read some science fiction.  The Witch’s Stones series would be an excellent choice.  Alternatively, you could try the short story “The Magnetic Anomaly”, a SF story which includes plenty of interesting geophysics, including magnetic fields. 

The Witches’ Stones

You might prefer, the trilogy of the Witches’ Stones (they’re psychic aliens, not actual witches), which follows the interactions of a future Earth confederation, an opposing galactic power, and the Witches of Kordea.  It features Sarah Mackenzie, another feisty young Earth woman (they’re the most interesting type – the novelist who wrote the books is pretty feisty, too).

The Magnetic Anomaly: A Science Fiction Story

“A geophysical crew went into the Canadian north. There were some regrettable accidents among a few ex-military who had become geophysical contractors after their service in the forces. A young man and young woman went temporarily mad from the stress of seeing that. They imagined things, terrible things. But both are known to have vivid imaginations; we have childhood records to verify that. It was all very sad. That’s the official story.” 


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