Last year I discussed two planned missions to Europa. One of them, the Europa Clipper, is NASA’s mission and is scheduled to launch in October 2024. Next year!
Europa is one of several bodies in our solar system deemed of interest regarding the possibility of life. The Europa Clipper is loaded for life – instruments for detecting life supporting conditions.
Europa is one of the Galilean Moons of Jupiter, that is, the four moons Galileo saw when he first looked at Jupiter with a telescope. At 1940 miles in diameter, Europa is a little smaller than our Moon (2500 miles). Europa is called an Ice World, with a water ice surface, and possibly a saltwater ocean beneath. Other notable solar system ice worlds include Jupiter’s Ganymede and Callisto, and Saturn’s Enceladus.
Water is the one common denominator for life’s existence on Earth. From the ices of Antarctica to deep ocean volcanic vents, life not only exists, it flourishes! So, we use the presence of water as a first marker for the possibility of life elsewhere.
What other factors contribute to the conditions for life’s presence?
-The building blocks for living cells need to be present. Earthly life is organic, that is, made of molecules containing carbon bonded to hydrogen, with things like nitrogen, oxygen, and sulfur thrown in. More specifically, most life on Earth is nucleotide based, with amino acids and proteins. Amino acids or their precursors have been found in extraterrestrial objects such as meteorites, comets, and Pluto.
-An energy source is needed. Life on Earth can use various chemicals for energy including but not limited to carbon, nitrogen, sulfur, hydrogen, oxygen, and iron. Notice a resemblance with life itself? Finding any combination of these would be another marker.
-The environment needs to be a safe place to exist – not too much heat, cold, radiation, osmotic gradient. Life can survive, even thrive in harsh environments but too much is too much. And the environment probably needs to be somewhat stable.
Europa Clipper will be examining:
-Europa’s ice shell thickness and thickness variations, and how it interacts with the ocean below.
-Europa’s magnetic fields and how they interact with trapped plasma – to understand the sub-surface ocean.
-Europa’s gravity field to illustrate its internal structure, and its topography, ice structure and thickness.
-Europa’s ice chemical composition via meteorite ejected surface debris and ice frost venting from below.
-Europa’s chemical environment (gasses, liquids, and ices) via a Mass Spectrometer developed by the Southwest Research Institute in San Antonio.
What’s in the Sky?
January 28; dusk; west southwest: See Saturn, Venus, Jupiter, the Moon, and Mars in a line-up from the horizon to overhead.
January 30; night; high overhead: The waxing gibbous Moon occults (hides) Mars again, like in December. Start watching around 10:30pm. Mars should slip behind the Moon a little after 11pm. Use binoculars or telescope if you have one.
Comet C/2022 E3 (ZTF) reaches closest approach to us on February 2. It might be bright enough to see with the naked eye even before then, for sure with binoculars. Tonight it is near the Little Dipper’s cup, south-southeast of Polaris, and heading northwest.