Scientists have found that the surface of Europa, the moon of Jupiter, on which life can exist, should glow blue and green at night. This should be clearly visible with Europa Clipper cameras and other spacecraft and will help to map surfaces with good resolution. An article with the findings of the researchers was published in the scientific journal Nature Astronomy.
“The surface of Europa is continuously bombarded by electrons and other charged particles, which direct Jupiter’s magnetic field towards it. These particles interact with ice and salt on Europa’s surface, which causes flashes of light in the visible part of the range. This is a green glow, clearly visible to the WAC cameras on board the Europa Clipper can be used to study the composition of its surface,” the researchers write.
Europa is one of the four largest moons of Jupiter discovered by Galileo Galilei in the 17th century. Its surface is covered with ice, under which there is an ocean of liquid water. Planetologists believe that living organisms can exist in this ocean. This is supported by the fact that this ocean exchanges gases and minerals with ice on the surface, as well as the fact that it contains substances that are necessary for the existence of microbes.
It is believed that the ocean on Europa remains liquid due to the fact that its bowels are constantly squeezed and stretched by tidal forces that arise due to the gravitational interactions of Europa and Jupiter. Similar processes, according to planetary scientists, occur in the bowels of three other Galilean satellites – Callisto and Ganymede, in the bowels of which there are also subglacial oceans, and Io, the most volcanic object of the solar system.
The first search for potential traces of this life will be carried out by the Europa Clipper apparatus, which is to be launched into space in 2024. The probe should reach Jupiter’s orbit approximately six years after launch. The Europa Clipper is to take detailed images of Europa’s surface and study the chemistry of its geyser emissions and surface sediments.
Jupiter’s moons shining
One of the main threats to the work of the Europa Clipper, according to one of the co-heads of the mission from the NASA Jet Propulsion Laboratory (USA) Murti Gudipati, will be radiation, the source of which is the powerful magnetic field of Jupiter. Therefore, NASA specialists have been studying the radiation situation in the vicinity of Europe and other satellites of Jupiter for many years.
While working on this, Gudipati and his colleagues pondered how the continuous “bombardment” of Europa’s surface with electrons and other high-energy particles would affect its chemical composition and physical properties. To understand this, scientists recreated the conditions prevailing in Europe in their laboratory and conducted a series of experiments there.
For this, astronomers prepared samples of water ice with a similar composition and structure, cooled them to a temperature of –173 ° C and began to bombard them with electron beams accelerated to near-light speeds.
It turned out that due to such “shelling” the surface of Europa can glow blue-green. At night, this glow should be clearly visible to NASA’s cameras and instruments. Previously, scientists doubted that this was possible, since ground-based telescopes did not record anything like this on the surface of Europa during solar eclipses on it.
Interestingly, the intensity of this glow will very much depend on what substances, besides ice, are on the surface of the satellite.
For example, table salt and organics will weaken it, while deposits of epsomite, a mineral made from magnesium sulfate, will, on the contrary, enhance this glow.
Such a glow could be used to accurately and quickly compile a geological map of the surface of Europe. This can be done by Europa Clipper when it approaches the satellite’s surface. Scientists hope that thanks to this they will be able to understand what substances are in the subglacial ocean of Europe and whether it is suitable for the origin and existence of life.