NASA’s Galileo spacecraft captured a colorful view of Jupiter’s moon Europa in the late 1990s. Scientists study the processes that affect the surface as they prepare to explore icy bodies. Credit: NASA/JPL-Caltech/SETI Institute
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Jupiter’s moon Europa and its global environment may have had conditions suitable for life today. Scientists study processes on the surface of the ice as they prepare for exploration.
It’s easy to see the impact of space debris on our moon, where the old, damaged surface is covered in craters and scars. Europa, Jupiter’s icy moon, suffered a similar defeat – along with very intense radiation. When the icy moon’s upper surface ripples, the material brought to the surface is emitted by Jupiter’s accelerated high-energy electronic radiation.
NASA-funded scientists are studying the cumulative effects of minor impacts on Europa’s surface as they prepare to explore the distant moon with the Europa Clipper mission and examine prospects for future landing missions. Europa is of great scientific interest because its salty seas, which lie beneath a thick layer of ice, may currently have conditions suitable for life today. This water can reach the ice crust and onto the surface of the moon.
New research and modeling estimates the extent of this disturbance on the surface through a process called the “horticultural effect.” The work, published July 12 in Nature Astronomy, estimates that Europa’s surface was affected by impacts from small to medium depths of about 12 inches (30 cm) over tens of millions of years. And any molecule that could be considered a potential biological signature, including the chemical signatures of life, could be affected at this depth.
In this enlarged image of Europa’s surface, taken by NASA’s Galileo mission, a thin, light layer, visible above the cliff in the center, shows the type of area affected by the horticultural effect. Credit: NASA/JPL-Caltech
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This is because the effect would cause some of the material to move to the surface, where the radiation would likely break the bonds of potentially sensitive large molecules produced by biology. Meanwhile, some of the material on the surface will be pushed down, so it can mix with what’s below the surface.
“If we’re hoping to find a purely biochemical signature, we’ll have to look under the region where the horticultural impact is,” said lead researcher Emily Costello, a planetary research scientist at the University of Hawaii at Manoa. “The biochemical fingerprints in shallow areas of the region may have been exposed to the devastating radiation.”
go deeper
While it has long been understood that horticultural impacts are likely to occur in Europe and other airless bodies in the Solar System, the new model provides the most comprehensive picture of the process. In fact, it is the first to account for the secondary effects caused by debris falling on Europa’s surface after the initial impact kicked it. Research shows that middle to high latitudes in Europe will be less affected by the double hit of the effects of horticulture and radiation.
“This work expands our understanding of fundamental processes at the surface throughout the solar system,” said Cynthia Phillips, a European scientist at NASA’s Jet Propulsion Laboratory in Southern California and a co-author of the study. “If we want to understand the physical properties and how the planet generally evolves, we need to understand the role horticulture has played in reshaping it.”
The Europa Clipper, which JPL operates for NASA, will help advance this understanding. The spacecraft, which is targeted for launch in 2024, will make a series of flights close to Europa as it orbits Jupiter. This will bring instruments to observe the moon precisely, as well as take samples of dust and gas kicked above the surface.
More about mission
Missions like the Europa Clipper contribute to the field of astrobiology, interdisciplinary research into variables and conditions in distant worlds that could host life as we know it. While the Europa Clipper is not a life-detection mission, it will conduct a detailed survey of Europa and examine whether the icy moon, with its oceans beneath its surface, has the potential to support life. Understanding the habitability of Europe will help scientists better understand how life evolved on Earth and the possibility of finding life beyond our planet.
The Jet Propulsion Laboratory, operated by the California Institute of Technology in Pasadena, California, is directing the development of the Europa Clipper mission in partnership with APL for NASA’s Science Mission Directorate in Washington. The Planetary Mission Program Office at NASA’s Marshall Space Flight Center in Huntsville, Alabama, manages the Europa Clipper mission program.
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