What type of mission would be ideal for sampling the plumes of Saturn’s oceanic moon, Enceladus, to ascertain whether this fascinating celestial body contains the necessary components to support life? This is the question under consideration. recent study Presented at the 56th Lunar and Planetary Science Conference LPSC 2025 The aim is to tackle through a study conducted by a group of researchers exploring the advantages and disadvantages of an orbiter or flyby mission to collect samples from Enceladus’ geysers.
This research could assist scientists, engineers, and mission designers in crafting the most scientifically fruitful expedition to Enceladus aimed at assessing its potential for being inhabitable.
In this discussion from Universe Today, Dr. Morgan Cable, a research scientist within the Laboratory Studies team at the NASA Jet Propulsion Laboratory, addresses the reasons driving the investigation, key findings, comparisons between this suggested mission and Cassini, future developments for such an endeavor, and potential life forms we could discover on Enceladus. Consequently, what prompted the study’s initiation?
Dr. Cable explains to Universe Today: “What makes Enceladus special is that we can access materials from its underground ocean directly without having to excavate, bore holes, or even touch down.” She adds, “No other celestial body allows such direct exploration, which is made possible due to the geysers erupting from four large cracks near the moon’s southern pole. By conducting a flyby through these plumes—whether from an orbit around Saturn or one circling Enceladus—a probe could gather gases and icy particles and conduct analyses to assess the potential livability of this subterranean sea as well as look for signs of biological activity.”
In the study, the researchers explored the motivations and multiple factors explaining why sampling Enceladus’ plumes could yield the most significant scientific insights into this icy moon with an subsurface ocean. They examined the advantages of focusing on a plume-centric mission compared to one involving landing or other types of exploration missions. Additionally, they considered how information gathered by NASA’s Cassini spacecraft has informed recent findings about Enceladus. Lastly, they weighed the merits of conducting a flyby against those of deploying an orbiter around Enceladus, along with addressing the complexities involved in executing such a bold endeavor.
The conversation was enhanced as the researchers shared models from prior investigations which predicted the amount of salt within the particles that might possibly be gathered from Enceladus’ jets. One investigation anticipated obtaining highly salty particles, whereas another forecasted acquiring grains with lower salinity levels.
By merging the findings of these two studies, the investigators of this new research determined that they must collect 100 times more samples than initially anticipated to gather adequate information about the makeup of Enceladus’ subterranean sea. Consequently, what are the key insights derived from their work?
Enceladus stands as the sole verified celestial object in our solar system where we can directly sample fresh matter from what may be a life-sustaining underground sea," explains Dr. Cable to Universe Today. "Moreover, humanity has reached a pivotal moment; we now possess scientific tools compact enough for space probes and powerful enough to identify even a solitary extraterrestrial organism present within an icy particle of the moon’s jet, should such a discovery await us.
Although our quest to look for life beyond Earth began with the Viking missions to Mars, we might now be entering the golden age of searching for life right here in our solar neighborhood.
Although Cassini officially held the title of an orbiter for having circled Saturn multiple times and performing numerous close passes by its various satellites—such as making 11 approaches to Enceladus—it never actually entered into orbit around Enceladus itself to thoroughly examine this oceanic moon and its features. Other spacecrafts like Pioneer 11 along with Voyagers 1 and 2 also made brief visits to study Saturn and its moons through flyby maneuvers without entering extended orbits.
As mentioned earlier, this research relies on information gathered during NASA's Cassini mission, which carried out pioneering investigations for more than 13 years from 2004 until 2017 as it orbited Saturn and its numerous satellites. Throughout this period, Cassini detected the geysers emanating from Enceladus and passed through these jets multiple times, collecting details about their chemical makeup and particle dimensions.
Although these plume samples indicated the existence of organic compounds, carbon monoxide, carbon dioxide, water vapor, and various gaseous substances, Cassini’s equipment was unable to perform a comprehensive examination of the ice particles. Thus, what differences might we expect from the findings of the upcoming orbiter/flyby mission compared to those obtained during Cassini's passes through Enceladus’ plumes?
Dr. Cable explains to Universe Today, “The equipment onboard Cassini represented cutting-edge technology when the spacecraft was designed and deployed; however, these tools weren’t intended to look for signs of life or intricate organic compounds.” She continues, “Contemporary devices allow us to pinpoint both simple molecules and sophisticated organics—ranging from lipids and polypeptides all the way to nucleic acids like DNA or RNA. The reason lies in their superior mass accuracy, enhanced resolution capabilities, improved sensitivity which allows detection despite low concentrations, and an increased capacity to manage interfering substances effectively.”
NASA missions usually require multiple years to progress from an idea to their launch and can take even longer after that to start yielding significant scientific data. As an illustration, although Cassini took off in 1997, it was initially proposed back in 1982 by a collaboration involving the National Academy of Sciences and the European Science Foundation. This explains why Cassini became a cooperative effort among NASA, the European Space Agency (ESA), as well as the Italian Space Agency.
Over the following years, numerous discussions took place along with encountering various political challenges as the U.S. Congress nearly terminated the mission; however, NASA managed to convince them otherwise. Launched in 1997, Cassini embarked on an almost seven-year journey towards Saturn, ultimately reaching orbit in 2004. It then continued to gather unprecedented scientific data about Saturn and its multitude of moons up until 2017. Consequently, what should be the subsequent phases for designing this prospective spacecraft capable of both orbital maneuvers and flybys aimed at sampling Enceladus’ geysers?
Dr. Cable informs Universe Today, “The latest Planetary Science and Astrobiology Decadal Survey suggests including Enceladus among destinations under the New Frontiers Program and proposes an Enceladus Orbilander following the Uranus Orbiter and Probe (UOP), which should become the top priority flagship mission afterward. Hence, I anticipate submission of one or multiple mission proposal concepts aimed at exploring Enceladus when the upcoming opportunity for the New Frontiers program arises; selection could make this venture highly thrilling. Otherwise, considerable backing exists within the scientific community advocating for another flagship project post-Uranus exploration.”
Enceladus stands out among the most fascinating and enigmatic celestial bodies in our solar system due to jets of water ice spewing from fractures near its southern pole, originating from an underground ocean beneath its surface. However, what sparks the utmost curiosity is this hidden ocean because, similar to Earth’s demonstration, liquid water appears to be essential for sustaining life as we understand it, supporting countless marine organisms across various forms and dimensions.
A comparison between what scientists might discover on Enceladus and conditions on Earth would be analogous to hydrothermal vents located near underwater areas where volcanoes are active. These vents typically come in two types: black smokers and white smokers, both releasing distinct sets of minerals and supporting various ecosystems. Examples of organisms living around these vents encompass creatures like crabs, shrimp, tubeworms, and mussels. Given this information, what kind of life does Dr. Cable believe we might encounter on Enceladus?
According to Dr. Cable’s explanation for Universe Today, “Given what we know about the level of energy present in the ocean, it seems unlikely that biomass would be particularly dense.” He further elaborates, “Within Earth's oceans—where sunlight serves as our main energy supply—we typically observe cellular densities ranging from approximately 100,000 to 1,000,000 cells per milliliter of seawater; this abundance supports larger creatures like fish, sharks, and whales. However, in settings with limited energy availability, similar to those found beneath Antarctic ice sheets—which lack exposure to sunlight—the observed cell counts usually hover around just 100 to 1,000 cells per milliliter.”
Dr. Cable goes on to say, “This scenario seems more plausible for Enceladus since sunlight would not reach the subsurface ocean beneath its icy crust; instead, the main energy supply is expected to come from hydrothermal activity along the seafloor. However, this does not imply that we will encounter solely microorganisms. Here on Earth, around hydrothermal vents located at our own seafloor, complex ecosystems have been observed which consist of various species such as shrimp, octopuses, and other multi-cellular creatures. Therefore, we shouldn’t dismiss the possibility of discovering similar life forms. Regardless of what we ultimately discover, I believe we’ll still be thrilled.”
Various captivating ocean worlds also encompass Saturn’s biggest satellite, Titan; Jupiter’s satellites—Europa, Ganymede, and Callisto; Uranus’ satellites such as Ariel, Umbriel, Oberon, and Titania; Neptune’s satellite, Triton; along with the dwarf planets Pluto and Ceres. The European Space Agency's upcoming mission, Europa Clipper, will investigate the underground oceans of Europa, complementing ongoing studies conducted by NASA's Juno spacecraft which examines both Europa and the remaining Galilean moons. As for Titan, NASA plans to dispatch the Dragonfly drone in 2028, projecting its arrival at Titan by 2034.
At present, a potential mission to Enceladus remains at the conceptual stage, with the proposed Enceladus Orbilander being the most eagerly awaited project aimed at investigating Enceladus and its underground ocean. Meanwhile, scientists are still considering whether forms of life, known or unknown to us, might inhabit these submerged waters.
Dr. Cable informs Universe Today, “A fascinating aspect of my research involves collaborating and engaging with individuals across various fields, including chemistry, geophysics, marine biology, and oceanography. Therefore, it’s crucial to understand that even though your area of focus might be quite distant from astrophysics or astronomy, you could still contribute valuable insights as part of an expedition team tackling major cosmic mysteries.”
More information: The Enceladus Plume: An Unparalleled Chance to Tackle Astrobiology Queries Through Orbital Missions or Flybys. www.hou.usra.edu/meetings/lpsc2025/pdf/2404.pdf
Provided by Universe Today
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