The satellite of the gas giant Jupiter Europa is of great scientific interest. Under the ice crust of the moon is a vast ocean, in which there may be even more water than any earthly one. The presence of water is one of the indicators of the possible presence of life. Scientists have been looking at Europe for a long time and are thinking about how to land some kind of research apparatus there. But, apparently, this will be even more difficult than previously thought. According to the findings of a new study by planetary scientists, published in the journal Nature Geoscience, Europa's surface is covered with huge, sharp ice spikes, which will significantly complicate landing.
In the new work, scientists have modeled how ice structures form on Europa's surface. Researchers claim that the satellite is covered with a forest of ice needles, which reach a height of 15 meters. They are formed as a result of sublimation - a process in which ice turns immediately into water vapor, bypassing the liquid phase. For their formation, special conditions are necessary: a lot of light, as well as a very cold, dry environment with no movement of air currents.
There are similar formations on Earth - they are called kalgaspores or "repentant snow", and are found in the dry and cold highlands of the Andes. The initial irregularities on the ice surface act as positive feedback - the grooves are slightly darker, absorb light more efficiently and melt faster, while the bulges remain bright and reflect most of the radiation. As a result, high and thin ice rises are formed.
Small calgaspores in the Atacama Desert (Mexico). Similar structures are present on the surface of Europa, but they are much higher.
According to the authors of the study, the conditions for the formation of giant kalgaspores on the surface of Europe are ideal. First, the surface itself is a solid ice cap. Secondly, it is very cold there (temperatures down to - 165 degrees Celsius). Combined with other factors, an ideal sublimation environment is created.
Scientists note that they did not see the kalgaspore directly on Europe (the quality of the obtained photographs of the satellite's surface from orbit is not enough to be seen), but indirect evidence speaks of their presence.
Using previously collected observational data, the researchers calculated the level of sublimation in different regions of the surface of Europe, which made it possible to establish the size and distribution of calgaspores. Taking into account the various erosion processes in Europe, such as the fall of small meteorites and the irradiation of charged particles, astronomers use their model to predict that these objects could be 15 meters high, and they could be located about 7 meters from each other. At the same time, scientists note that, most likely, these objects are found in the equatorial regions of Europe. The presence of kalgaspor can be confirmed by energy anomalies that scientists noted earlier during studies of the satellite's surface using radars.
The researchers note that new observations with more modern scientific instruments are needed to confirm the presence of calgaspores on the surface of Europe. Fortunately, such an opportunity may indeed come out pretty soon. Aerospace agency NASA is developing the Europa Clipper mission, which should be launched sometime between 2022 and 2025.
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An orbital probe equipped with the latest instruments will be able to approach the satellite surface at an altitude of 25 kilometers and from there look for kalgaspores. It is assumed that, in general, the results of the Europa Clipper mission will become the starting point for the preparation of a further mission to land a spacecraft on the surface of Europe. This device will be able to drill through the ice surface of the satellite and look into the dark under-ice world of its ocean. Nevertheless, the presence of thorns on the surface will significantly complicate this task, unless of course you take into account the very technical complexity of such a mission.
Nikolay Khizhnyak