Micrometeorites are whirling up the floor of Europe. If you wish to discover life, it’s important to dig a meter deeper or one thing
In the next decade, NASA and ESA will send two special missions to explore Jupiter’s moon Europe. These missions are known as Europa Clipper and JUpiter ICy moons Explorer (JUICE) missions that will fulfill a decades-long dream – searching for possible evidence of life in Europe. Since the 1970s, astronomers have theorized that this satellite contains a warm water ocean that could support life.
The case for living in Europe has only been bolstered by several flyby and observation campaigns that have been carried out since then. According to new research led by the University of Hawaii at Manoa, the best way to look for potential signs of life (aka biosignatures) would be to analyze small impact craters on the surface of Europe. These patches of exposed ice beneath the surface could point the way to life that could exist deeper inside the moon.
Speculation about the possible existence of an inner ocean in Europe began in 1979 after the Voyager 1 and 2 missions flew past Jupiter and its moons on their way to the outer solar system. Data obtained from the Galileo and New Horizons space probes and the Hubble Space Telescope have provided additional clues, including interaction with Jupiter’s magnetic field, tidal models, surface features, and plume activity.
The radiation from Jupiter can destroy molecules on the surface of Europe. Material from Europe’s oceans that lands on the surface is bombarded with radiation, potentially destroying any biosignatures or chemical signs that could indicate the presence of life. Photo credit: NASA / JPL-Caltech
Between resurfacing events and surface clouds coming from within, scientists have speculated that biosignatures – chemicals produced by living organisms – that are the result of life in the European ocean may have made it to the surface as well. However, as Europe orbits in Jupiter’s strong magnetic field, its surface is exposed to high levels of radiation that would destroy all traces of biological material.
This means that any biomolecules that are regularly ejected by plume activity or re-emergence of events would likely only survive beneath the surface. Fortunately, the surface of Europe is covered in small impacts that have occurred over the course of millions of years and are approximately 30 cm (12 inches) deep. These influences would also have led to so-called “impact gardening”, in which material is mixed from above and below.
Led by Emily S. Costello, a postdoctoral fellow at the Hawaii Institute of Geophysics and Planetology (HIGP), which is part of UH Manoa’s School of Ocean and Earth Science and Technology (SOEST), the researchers sought the first comprehensive impact estimate from impact gardening to Europe. Their results are described in a study that was recently published on July 12 in the journal Nature Astronomy.
As Costello emphasized in a recent SOEST press release, the search for potential signs of life on airless bodies like the Europa is a major challenge. “If we hope to find pristine chemical biosignatures, we have to look under the zone where the effects are gardening, ”she said. “Chemical biosignatures in areas shallower than this zone may have been exposed to destructive radiation.”
Artistic concept of a Europa Clipper mission. Photo credit: NASA / JPL
Costello was accompanied by Professor of Planetary Science Paul G. Lucey, who is also a researcher at HIGP; Cynthia B. Phillips, a European scientist at NASA’s Jet Propulsion Laboratory (JPL); and Rebecca Gent, Senior Scientist at the Planetary Science Institute (PSI). Thanks to a program grant from the NASA Solar System Workings (SSW) program, Gent and Costello developed the original Impact Gardening model for this study. As Costello explained in a PSI press release:
“The radiation on the surface of Europe is so intense that it can break down sensitive biomolecules. Impact gardening leads possible biomolecules into the radiation zone. This work, therefore, offers some valuable new constraints on where to look if we are hoping to find evidence of life.
“If we want to find evidence of pristine biomolecules that have not been altered by radiation in Europe’s ice, we either have to dig beyond a depth of about 30 centimeters – deeper in some regions – or find places where fresh material has recently been released Surface was brought. “Impact crater.”
For some time now, astronomers have believed that impact gardening was a likely process on Europe and other airless bodies in the solar system, but this new model offers the most complete picture of that process yet. In addition, for the first time, it takes into account secondary impacts caused by debris falling back on the surface of Europe on first impact.
“This is new because for the first time the impact of impact gardening has been taken into account in predicting where in Europe biomolecules might be found and for the first time impact gardening has been modeled to take into account Europe’s unique icy surface and impactor population in outer solar System, ”said Costello.
Research also suggests that the surface of Europe would be less affected by double impact gardening and radiation around the mid and high latitudes of the moon. In the near future, such research could help NASA and ESA planners develop mission profiles for the Europa Clipper and JUICE. Since both missions will examine Jupiter’s moons for possible signs of life, knowing where they are most likely to be found is critical.
In addition, this research could guide the design of instruments and future missions also dedicated to the search for biosignatures in the “ocean worlds” of the solar system. In addition to Europe and Ganymede, these include Saturn’s moons Titan and Enceladus, Uranus moons Titania and Oberon, Neptune’s largest moon Triton, Pluto, and other icy satellites believed to have inner oceans. Ghent added:
“[I]It also provides a framework for future research with high resolution images of upcoming missions that would help generate more accurate estimates of the depth of gardening in different specific regions. The most important parameters in this study are the impact flow and the crater formation rates. With better estimates of these parameters and higher resolution images resulting from upcoming missions, it will be possible to better predict the depths to which gardening has affected the flat ice in certain regions. ”
Artist’s impression of a possible Europa-Lander mission that would explore the surface of the icy moon in the coming decades. Photo credit :: NASA / JPL-Caltech
“This work broadens our understanding of the fundamental processes on surfaces throughout the solar system,” said Phillips. “If we are to understand the physical properties and general evolution of planets, we need to understand the role gardening plays in reshaping them.” This research is part of a larger, NASA-funded effort to understand the cumulative effects of small impacts on the To examine the surface of Europe in preparation for the Europa Clipper mission.
This mission, expected to start in 2024, will orbit Jupiter as it makes a series of flybys around Europe. Its suite of scientific instruments will include optical and thermal imagers, spectrometers, magnetometers, and radar sounders. These will enable the space probe to measure Europe’s surface, measure its magnetic moment and determine the chemical composition of its ice.
It will also carry a mass spectrometer and dust analyzer to study Europe’s weak atmosphere, plume activity, and study the dust and gases that are being blown up above the surface. The data obtained from these missions could also inform future missions to the surface – such as the Europa-Lander concept – which search directly for biosignatures and could even carry out a sample return.
Further reading: SOEST, PSI, natural astronomy