Europa, is it habitable?
Recently Jupiter’s moon Europa has become a subject of interest. The reason behind this is the discovery of water from the moon shooting into space. Though the first light into this came long back from the evidence of the induced magnetic field as reported by the NASA spacecraft Galileo during its multiple flybys over the Europa. As Europa passes through Jupiter’s magnetic field, its magnetic field changes its direction, which indicates an induced field. This induced field must be due to some conducting material close to Europa’s surface that encompasses the whole planet. The planetary scientists believe that the magnetic field is due to the subsurface salt-water ocean and the icy surface is very thin. The estimated thickness of the floating ice shell surface is about 19 km. So it requires some clever ways to search for ocean material that may have been exposed on the surface.
NASA’s Galileo spacecraft explored the Jupiter system from 1995 to 2003 and made numerous flybys of Europa. The spacecraft was as close as 200 Kilometers from the surface. While re-examining the Galileo data, recently the planetary scientists have come to a conclusion that the bend in the magnetic field could be due to an active geyser from an underground ocean. The scientists believe that the spacecraft travelled through a plume of water and that is the reason for the bend in the recorded magnetic field.
NASA’s Galileo spacecraft explored the Jupiter system from 1995 to 2003 and made numerous flybys of Europa. The spacecraft was as close as 200 Kilometers from the surface. While re-examining the Galileo data, recently the planetary scientists have come to a conclusion that the bend in the magnetic field could be due to an active geyser from an underground ocean. The scientists believe that the spacecraft travelled through a plume of water and that is the reason for the bend in the recorded magnetic field.
The Revelation of Galileo’s findings suggest changes of the icy surface due to heat from within. The Scientific study of spacecraft data also suggests the collapse of the surface in the chaos terrains above lens-shaped lakes embedded within the ice. Most interestingly, in the year 2013, from the findings of the Hubble Space Telescope, the assumption of the water in the moon was confirmed and NASA announced that the moon was geologically active and ejecting water into space (Figure 3 & 4).
While re-examining the images taken by the Galileo spacecraft, scientists found two bumpy features in the disrupted topography of Europa. The chaotic terrain, known as Thera Macula, shows evidence of active resurfacing of ice over a large body of water. Evidence of such terrain of mobile icebergs indicates a geologically active planet and also indicates the possibility of more such terrains. If such lakes with similar collapsing ice shelves exist throughout the shallow regions of Europa’s shell then this is good news for astrobiologists and those who are hopeful for life beneath the surface. Comparisons with similar scenarios in Earth where ice shelves are in motion and volcanoes are found beneath overlying glaciers show an ice-water interaction and diverse morphological and topological structures. This also indicates a chance of the flow of nutrients and energy from the surface to within the subsurface salty water ocean.
Evidence of life support ingredients is quite strong within Europa. Though it is smaller than Earth’s moon, the saltwater ocean beneath its icy crust has at least twice as much water as Earth’s oceans. After the analysis of Hubble Space telescope data. it has been found that many bodies in solar systems either have subsurface water now or it was there in the past. Europa is one of the two places where the ocean water has contact with the rocky sea surface. Another such planet is Saturn’s moon Enceladus. All this evidence have made the satellite the highest priority target for the search of life beyond Earth. NASA’s Science Definition Team (SDT) has also submitted a report in this direction for a future expedition to this planet with the surface lander to explore the possibilities of the existence of life, the habitability of the solar-system neighbors and explore the construction of future robotic exploration blueprint into this satellite of Jupiter.
We have to wait few more years to be sure about the possibility of the moon’s life-supporting and habitability characteristics. Clipper mission to Jupiter is scheduled to be launched in the year 2024 and would cover about 600 million kilometers to reach Jupiter several years later. The travel time of the spacecraft will depend on its mass, type of rocket and trajectory. This may vary from 3 to 6 years. The Voyager spacecraft in a direct trajectory took 2 years to reach the orbit whereas the Galileo mission with the help of gravity assists from Venus and Earth flybys took 6 years to reach the destination of Jupiter’s orbit [8]. This spacecraft will perform 45 flybys of Europa at altitudes varying from 2700 kilometers to 25 kilometers from a long looping orbit around Jupiter. With the help of ice-penetrating radar, it will try to determine the thickness of the moon’s icy shell and search for subsurface lakes. From the measurements of magnitude and direction of the magnetic field, spacecraft mission scientists will try to determine the depth and salinity of its ocean. If everything goes as per schedule, by 2030, we shall know in much more detail about this icy moon and shall know whether it can harbor conditions suitable for life or not.
During the same period of NAS’s clipper mission, European Space Agency is also planning an interplanetary mission, Jupiter Icy Moon Explorer (JUICE), to study the three of Jupiter’s Galilean moons: Ganymede, Callisto and Europa. The voyage is planned for June 2022 and would make two flybys of Europa. Though this spacecraft is scheduled to be an artificial satellite of Ganymede by 2033, during its flybys of Europa it would collect and send critical information of Europa.
