NASA Readies Europa Clipper for First In-Depth Study of Jupiter’s Water Moon Europa

The Europa Clipper will soon be embarking on a mission to Europa — one of the largest natural satellites of Jupiter — on a journey to examine this great ocean moon. This spacecraft, due for launch in 2023, will be the first vehicle ever designed specifically to study the fourth-largest (and potentially, most interesting) moon of Jupiter.

Europa may be one of the best places in the Solar System to search for extraterrestrial life. Beneath its frozen surface lies oceans of liquid water, deeper than any found on the Earth.

“This is a giant step in our search for oases that could support life in our own celestial backyard. We’re confident that this versatile set of science instruments would produce exciting discoveries on a much-anticipated mission,” said Curt Niebur, Europa program scientist at NASA.

Europa Clipper
A 2016 artist’s conception of the Europa Clipper, soaring above its target. Image credit: NASA/JPL-Caltech

Discovered by famed astronomer Galileo Galilei in 1610, Europa has, so far, been visited (quickly) by just five spacecraft – Pioneer 10 and 11, Voyager 1 and 2, and the Galileo orbiter. Pioneer 10 did not get close enough to Europa during its 1973 flyby to record any detail on the surface. Its partner, Pioneer 11, recorded only limited data on the world.

Voyager 1 did not get close enough to the satellite to record significant data from the moon, but Voyager 2 noticed brown stripes in 1979, suggesting cracks in the icy surface of Europa. The Galileo orbiter, which traversed the Jovian system from 1995 to 2003, was the first to provide firm evidence for a significant ocean beneath the icy exterior of this massive moon.

Images taken by the Hubble Space Telescope in 2012 suggest massive plumes of water are erupting from the moon, providing further evidence for a watery environment beneath the ice.

“Like our planet, Europa is thought to have an iron core, a rocky mantle and an ocean of salty water. Unlike Earth, however, Europa’s ocean lies below a shell of ice probably 10 to 15 miles (15 to 25 kilometers) thick and has an estimated depth of 40 to 100 miles (60 to 150 kilometers),” NASA explains on a web page dedicated to the distant moon.

Despite the fact there are oceans on Europa, this is hardly a spot for a summer vacation. At the equator, temperatures never rise above -160 Celsius (-260 Fahrenheit), while the poles see highs peaking out around -220 C (-370F).

In the same way that our Moon is tidally-locked to the Earth, causing the same side of the Moon to eternally face our planet at all times, Europa constantly has one side pointed toward its massive partner. As it orbits Jupiter once every 3.5 days, it is stretched like a model egg, made of rubber. As Europa gets closer to the planet, it lengthens, pointing a little more toward Jupiter. When the distance is greater between the two bodies, the moon returns to a more-rounded shape. This flexing causes heating, melting water ice into liquid.

Europa from Galileo
The best image currently available of Europa. This composite picture was assembled from images acquired by the Galileo spacecraft in the 1990’s. NASA/JPL-Caltech/SETI Institute

The Europa Clipper will be equipped with a bevy of nine instruments with which to explore the geology, composition, and makeup of Jupiter’s fourth-largest moon.

Europa will be mapped in greater detail than ever before with the Europa Imaging System (EIS) instrument aboard the spacecraft. These cameras (both wide- and narrow-angle) will record images of Europa at resolutions as low as 50 meter (164 feet). This is 100 times better than the best images ever recorded.

The Plasma Instrument for Magnetic Sounding (PIMS) will determine the thickness of the ice layer covering Europa, and measure the depths and salinity (salt concentration) of oceans on the body. Working with this device is the Interior Characterization of Europa using Magnetometry (ICEMAG), designed to utilize electromagnetic sounding, in order to determine the magnetic field of Europa, hopefully providing more insights into the size and composition of Europa’s oceans.

A remote examination of the habitability of Europa will be provided by the Mapping Imaging Spectrometer for Europa (MISE) instrument, which will map the positions of organic materials on Europa, along with salts and other materials, and measure the phases of water at different locations on the world.

Ice on Europa will be no match for the Radar for Europa Assessment and Sounding: Ocean to Near-surface (REASON) radar system. This device will map the interior structure of the ice cover of Europa from its surface to the liquid ocean beneath.

The thermal vents of Europa, seen by Hubble, are the targets of The Europa Thermal Emission Imaging System (E-THEMIS). This heat detector will reveal data about these locations where heat is pushing water out from the depths of Europa’s oceans into space. Smaller plumes will be studied utilizing the Ultraviolet Spectrograph/Europa (UVS) instrument.

Above the surface, The MAss SPectrometer for Planetary EXploration/Europa (MASPEX) will study the thin atmosphere of Europa. This device should glean more information about the “air” of this Jovian moon, as well as debris ejected into the tenuous oxygen atmosphere. Material rising into the atmosphere of Europa from the surface will also be examined by researchers using the SUrface Dust Mass Analyzer (SUDA), capable of directly sampling material flying above Europa, during low-altitude flybys.

The Europa Clipper mission is scheduled to last 45 flybys of the satellite, at distances ranging from as close as 25 kilometers (16 miles) out to 2,700 km (1675 miles) from the surface of this little-understood world. The instruments aboard this spacecraft are aimed at studying the mysteries of Europa – especially its oceans, and potential to harbor life – without the need to drill through miles of ice.

The Europa Clipper is primarily designed to study its namesake, but the spacecraft will also make close passes of two other large moons of Jupiter – Ganymede and Callisto, as it shapes its orbit around Europa.

In addition to the Europa Clipper, headed by NASA, The European Space Agency (ESA) is also planning their own journey to the Jovian system, to study Europa and the other moons in that system. The JUpiter ICy moons Explorer (JUICE) program is scheduled for launch in 2022.


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