Enceladus, Saturn’s sixth-largest moon, is an interesting place to look to our solar system in the search for evidence of extraterrestrial life, given its habitable oceans and plumes that deposit organic-containing marine material on its surface. It brings you the right opportunities. Organic marine material may be sampled by the Enceladus lander mission. Considering the UV and plasma environment, it is interesting to understand the amount of relatively pure and unaltered organic matter present on the surface.
Enceladus’ tiger stripes are known to be caused by the moon’s icy interior spewing ice into space, creating a cloud of fine ice particles above the moon’s south pole, forming Saturn’s mysterious E ring. It is being This evidence comes from his NASA Cassini spacecraft, which orbited Saturn from 2004 to 2017. Shown here is a high-resolution image of Enceladus taken from a nearby airfield. The tiger stripes appear in a false blue color. Image credit: NASA / ESA / JPL / SSI / Cassini Imaging Team.
“By sending a mission to the surface of Enceladus, we can learn a lot about the biological signatures that may exist in Enceladus’ oceans,” said Amanda Hendricks, a senior scientist at the Planetary Science Institute. .
“Previously, it was thought that sampling the freshest material from Enceladus’ ocean would require flying through the plume and measuring plume particles and gas.”
“But now we know that we can land on the surface, and we are confident that the instrument can measure plume organic matter from the ocean in its relatively natural state.”
“Thanks to measurements from NASA’s Cassini spacecraft, we know that Enceladus’ ocean is habitable,” she added.
“We know that there is liquid water, energy, and chemicals such as carbon, hydrogen, nitrogen, oxygen, phosphorus, and sulfur, which are necessary for life as we know it. It is an ingredient.”
“Enceladus is an oceanic world. Beneath its icy surface is a liquid ocean.”
“There are at least some ocean worlds in our solar system, but Enceladus is special because it is spraying ocean material into space via plumes of water vapor and ice particles at its south pole. This means Cassini’s instruments were able to reveal its signature.” As the spacecraft flew through Enceladus’ plumes, the ocean was visible. ”
“Fortunately, this study found that even though some of the plume particles were ejected into the Saturn system, nearly 90% of the plume particles returned to the Moon’s surface. This is likely due to marine material containing organic matter. But it’s sitting right on the surface.”
Organic molecules found in Enceladus’ plumes include molecules such as methane and ethane, as well as more complex molecules.
Organic matter is processed or chemically transformed by charged particles such as the sun’s ultraviolet photons and electrons.
But if scientists want to know whether ocean-derived biosignatures are present in plume particles, they need these particles to be as pristine as possible and unexposed to ultraviolet light.
An artist’s impression of NASA’s Cassini spacecraft flying through a plume of smoke spewing from Enceladus’ south pole. These plumes are much like geysers, releasing a combination of water vapor, ice grains, salt, methane, and other organic molecules. Image credit: NASA/JPL-Caltech.
In the new study, Dr. Hendricks and fellow Penn State researcher Christopher House use data from NASA/ESA’s Hubble Space Telescope and Cassini to show that ultraviolet photons can be detected on Enceladus’ plume-covered surface. We estimated how deep it could penetrate.
“What we found in this study is that there are places on the surface of Enceladus where a spacecraft can land and collect samples. If we do that, we could measure organic matter in a relatively natural state.” Dr. Hendricks said.
“That’s because the sun’s ultraviolet photons don’t penetrate very deeply into the ice surface.”
“These harmful solar UV photons only penetrate about 100 micrometers into the ice surface. That’s the width of several human hairs!”
“So the topmost surface is exposed to harmful UV photons, but only some of the organic matter is chemically changed, and soon that material is covered by fresher plume material. .”
“And the deeper particles do not undergo further deformation because the ultraviolet photons are prevented from interacting with the deeper material.”
“The newly deposited plume particles act as a shield for the material below. They act like a sunscreen!”
“Ideally, we would like to someday land on the surface of Enceladus and sample organic matter from the relatively pristine ocean.”
“This result is important because the penetration depth of these harmful ultraviolet photons is so shallow that it suggests that there is a lot of relatively primitive organic matter that can be sampled.”
“Slightly deeper particles are less exposed to UV light, meaning the organic matter has a lower age of exposure.”
“Ultraviolet light easily alters organic molecules, so the depth at which such light reaches the surface of the icy world is critical,” Dr House added.
“Because the penetration depth of ultraviolet light was found to be short, our findings confirm that there is sufficient organic material trapped and preserved within Enceladus’ ice that can be traced back to its oceans. Did.”
“It’s awe-inspiring to think that we can easily obtain so much organic matter from habitable extraterrestrial oceans using known techniques.”
of findings It was published in the magazine Communication Earth and Environment.
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AR Hendrix & CH House. 2023. The effective UV exposure age of organic matter on Enceladus’s surface is low. common global environment 4,485; doi: 10.1038/s43247-023-01130-8
Source: www.sci.news
