by The Jupiter Icy Moon Explorer (JUICE) left Earth a year ago, embarking on a mission to closely explore Jupiter’s potential sea moons – Ganymede, Callisto and Europa.
Water is a vital ingredient for life on Earth, so learning more about its distribution on these and other moons, such as Saturn’s moon Enceladus, can tell us whether these ocean worlds can support life — life as we know it, at least. .
Scientists cannot yet drill through the icy crusts of Ganymede, Callisto, and Europa, however, meaning they cannot yet determine the composition and characteristics of their respective bodies of water. In fact, scientists still cannot verify that these oceans exist. On the bright side, with JUICE, there may be a workaround.
Without physical access to the oceans below the surface, SOO relies on radar to look deeper into these icy moons. It is a type of ice-penetrating radar that will provide the next best investigative method to evaluate these buried seas and, therefore, the habitability of these moons. And last week, scientists revealed a little more about the sophisticated ice-penetrating radar system that will be used by the Zoo.
Related: Why will it take the European Zoo’s spacecraft 8 years to get to Jupiter?
“We can use all this information to improve our understanding of the distribution of liquid water in the solar system,” said Elena Pettinelli of the University of Roma Tre in a statement. “There’s a lot more water than we thought 20 or 30 years ago, and it’s very interesting to use this technique to try to understand where the water might be.”
Looking under the ice
Due to arrive at the Jovian system in July 2031, JUICE will observe Jupiter’s magnetic fields and atmosphere, as well as its moons and faint ring system. According to the operators of the spacecraft at the European Space Agency (ESA), the theme of this investigation is the emergence of habitable worlds around the gas giants.
To carry out these operations, JUICE carries a series of 10 cutting-edge scientific instruments. One of these is, of course, the ice penetrating radar. Called the Radar for Icy Moon Exploration (RIME), it can study the subsurface structure of Jupiter’s icy moons down to a depth of about 5.6 miles (9 kilometers). The main aims of RIME are to characterize Ganymede as a planetary object and as a potentially habitable world, to study recently active Europa belts, and to confirm whether Callisto is a remnant of the early Jovian system.
The JUICE team hopes that RIME will also be able to discover the depths of the oceans beneath the ice shells of these moons, and decode the chemistry of any water that may be composed of such liquids. There is a link between these two things, with Pettinelli saying that the depth of radar penetration on the icy moons will depend on the salinity, or salinity, of the water. Salt blocks the transmission of radar signals, meaning it can also reveal important information to the crew in a reverse subtraction fashion.
JUICE is also carrying RIME-like systems, including those already tested here on Earth to detect liquid water. Away from our planet, the first ever planetary subsurface radar, called the Apollo Lunar Sounder Experiment, was tested on the moon during the Apollo 17 mission. Further afield, Pettinelli was part of a team that used radars which was loaded aboard the Mars Exploration Orbiter to discover that there was liquid water at the south pole of Mars.
It is also developing a radar system to be carried to Venus, the second planet from the sun and the hottest world in the solar system, along with the ESA Envision mission. Envision will be the first project to explore Venus from its inner core to its upper atmosphere, looking at interactions between the hellish planet’s various layers, including its atmosphere, surface as well as subsurface and interior. The mission aims to provide a more complete picture of Venus, describing the history, activity and overall climate of the planet.
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— Photos: Galilean Moons in Jupiter
Envision will have two radar systems: The Subsurface Radar Sounder (SRS) and the High Frequency (HF) sounding radar. Both will be used to explore the uppermost 0.6 miles (1 kilometer) of Venus’ subsurface. This should help scientists build a better picture of the climate history of the planet often called “twin worlds.”
Pettinelli presented a more complete picture of the utility of RIME and other planetary radars at the General Assembly of the Union of Geosciences EGU24 on 19 April.
