Could microbes survive in the permanently shadowed regions (PSRs) of the Moon? This is what a recent study presented at the 56^th Lunar and Planetary Science Conference hopes to address as a team of researchers from the United States and Canada investigated the likelihood of long-term survival for microbes in the PSR areas of the Moon, which are craters located at the poles that don’t see sunlight due to the Moon’s small axial tilt. This study has the potential to help researchers better understand unlikely locations where they could find life as we know it throughout the solar system.

Here, Universe Today discusses this incredible research with Dr. John Moores, who is an associate professor in the Centre for Research in Earth and Space Science at York University and lead author of the study, regarding the motivation behind the study, significant results, how these findings could influence human exploration to the PSRs, possible contamination from human exploration, and how any microbes could have arrived at the PSRs. Therefore, what was the motivation behind the study?

“A few years ago in 2019, I participated in a study looking at the potential for the Moon to preserve microbial contamination on spacecraft, led by University of Florida researcher Dr. Andrew Schuerger,” Dr. Moores tells Universe Today. “At the time, we did not consider the PSRs because of the complexity of modelling the ultraviolet radiation environment here. However, in the years since, a former student of mine, Dr. Jacob Kloos at the University of Maryland, had developed a sophisticated illumination model. Furthermore, with the renewed interest in PSR exploration, we decided to take another look at these regions and realized we had all the pieces of the puzzle we needed to understand their ability to preserve terrestrial microbial contamination.”

For the study, the researchers conducted a series of models to ascertain if the reduced amount of ultraviolet (UV) radiation and increased temperatures within the PSRs could enable the possible survival of microorganisms within two PSR craters, Shackleton and Faustini. The researchers chose these two craters based on previous studies involving the modeling of light entering the craters and both craters are also current landing site targets for the upcoming Artemis missions.

As noted, the lunar PSRs are devoid of sunlight due to the Moon’s axial tilt, which is approximately 1.5 degrees with respect to Sun. For context, the Earth’s axial tilt is approximately 23.5 degrees with respect to the Sun, resulting in the seasons we experience as Earth orbits the Sun. As a result from this small axial tilt, certain lunar PSRs crater like Shackleton and Faustini have not received sunlight in potentially billions of years. While the Moon lacks an atmosphere and is exposed to the vacuum of space, this creates very cold pockets that the researchers propose could preserve microbes for long periods of time. Therefore, what are the most significant results from this study?

“In space, microbes are typically killed by high heat and ultraviolet radiation,” Dr. Moores tells Universe Today. “However, the PSRs are very cold and very dark and, as a result, they are one of the most protective environments in the solar system for the kinds of microbes that are typically present on spacecraft. To be clear, those microbes cannot metabolize, replicate or grow here, but they likely remain viable for decades until their spores are killed by the effects of vacuum. The organic molecules that make up their cells likely would persist far longer.”

As noted, the lunar PSRs are currently targeted landing sites for the upcoming NASA Artemis program, most notably Shackleton, due to the potential pockets of water ice that are trapped within the PSR craters that future astronauts could use for water, fuel, and oxygen. However, all space missions run the risk of bringing unwanted microbes to the target location, thus potentially and unnecessarily contaminating an otherwise pristine location devoid of microbes. This could result in faulty data being collected and inaccurate results after analyzing the data, potentially leading to inaccurate findings regarding finding life beyond Earth.

This is especially true for human missions to the Moon, as humans are naturally dirty creatures that carry a myriad of microbes that could travel with them to the Moon. Thus, whatever microbes that could exist within the PSRs could become influenced by human microbes, possibly killing them off.

To combat this, the NASA Planetary Protection office is tasked with overseeing that outgoing spacecraft are sterilized and clean of microbes prior to launch but also tasked with ensuring returned spacecraft did not carry unwanted microbes from outside the Earth. Therefore, how can the findings from this study influence human exploration in lunar PSRs?

Dr. Moores tells Universe Today, “While we can clean robotic spacecraft fairly well, it is more difficult to decontaminate equipment and spacesuits used in human exploration. As a result, humans walking into the PSRs will likely carry considerably more contamination with them, some of which will be left behind and be preserved far longer than anywhere else on the moon.”

Additionally, the study notes that “care should be taken in their exploration” regarding the PSRs, but is this referring to planetary protection?

Dr. Moores tells Universe Today, “It is less a question of planetary protection than of preserving the PSRs in as close to a pristine state as possible for future scientific analyses. The question then is to what extent does this contamination matter? This will depend on the scientific work being done within the PSRs. One possible goal is to retrieve samples of water ice from within the PSRs to better understand their origins and how they came to be found here. Part of that analysis could include looking at organic molecules present in the ice that are known to occur in other places, for instance within comets. That analysis will be easier if contamination from terrestrial sources is minimized.”

If there are microbes at the lunar PSRs, the question then becomes how they arrived there. Given the heavily-craters surface of the Moon, they could have arrived from an impacting body from elsewhere in the solar system, or beyond. However, humans have also sent a number of spacecraft that have impacted the lunar surface, including the Ranger spacecraft that occurred leading up to the Apollo missions, but these spacecraft crashed near the Moon’s equator and far from the poles.

In 2009, NASA’s Lunar Crater Observation and Sensing Satellite (LCROSS) mission to the Moon intentionally crashed its Centaur upper stage into Cabeus crater, which is a PSR crater located approximately 100 kilometers (62 miles) from the lunar south pole, with the goal of measuring the amount of water produced from the ejecta plume. But, how could microbes have arrived in lunar PSRs and what can this teach us about the Moon’s formation and evolution?

“The chance that there is already terrestrial microbial contamination in the PSRs is low but not zero,” Dr. Moores tells Universe Today. “Several spacecraft have impacted within or near the PSRs. Though they all did so at high speed, past research by others has suggested that small numbers of spores can survive simulated impacts into regolith-like materials. If any microbes survived those impacts, they would have been widely dispersed.”

What new discoveries about potential microbes living on the Moon will researchers make in the coming years and decades? Only time will tell, and this is why we science!

• As always, keep doing science & keep looking up!

What can a sample return mission from Jupiter’s volcanic moon, Io, teach scientists about planetary and satellite (moon) formation and evolution? This is what a recent study presented at the 56^th Lunar and Planetary Science Conference hopes to address as an international team of more than two dozen scientists discussed the benefits and challenges of a mission to Io with the goal of sampling its volcanic plumes that eject from its surface on a regular basis.

Here, Universe Today discusses this incredible research with Aanu Adeloye, who is a PhD Candidate in Aerospace, Aeronautical, and Astronautical Engineering at the University of Texas at Austin and lead author of the study, regarding the motivation behind the study, significant takeaways, next steps for making a sample return a reality, and the importance of returning Io samples to Earth. Therefore, what was the motivation behind the study?

“This study was sponsored by the Keck Institute for Space Studies (KISS) at the California Institute of Technology as part of a two-part workshop series titled ‘Sample Return from All across the Solar System’,” Adeloye tells Universe Today. “The primary objective was to evaluate both the scientific case for and the feasibility of returning samples from the surface, atmosphere, or plumes of diverse planetary bodies—from Mercury to Kuiper Belt Objects beyond Pluto’s orbit. Through this workshop, we developed a prioritized list of solar system targets for sample return missions over the coming decades, based on expected scientific yield and technological readiness. Io emerged as one of the key targets on this list.”

Image of Io’s nightside and dayside taken by NASA’s Juno spacecraft.

(Credit: NASA/JPL-Caltech/SwRI/MSSS Image processing by Emma Wälimäki © CC BY)

For the study, the researchers discussed the reasons behind choosing Io for their sample return mission, vital questions that returned samples could answer about volcanism and Io’s formation and evolution, the mission design, and the scientific impact on the planetary science community. The researchers emphasized how a sample return mission to Io could build off previous spacecraft missions to the Jovian (Jupiter) system, including Galileo, New Horizons (flyby en route to Pluto), and Juno (currently active).

Potential questions a sample return mission could address include Io’s geologic and isotopic composition, plume source and composition, geologic similarities to Europa, and Io’s interaction with Jupiter’s massive magnetic field. For mission design, the researchers propose a fast-moving spacecraft that would travel through the plumes while collecting samples, highlighting the importance of not needing to land on the surface. They estimate the total mission length from launch to return would be approximately 9.4 years based on proposed propulsion technologies. Finally, the researchers emphasized how a sample return mission could help planetary scientists gain greater insight into planetary formation and evolution, specifically Jupiter and its moons. Therefore, what were the most significant takeaways from the study?

“Io stands out as the most volcanically active body in our solar system, boasting hundreds of active volcanoes that emit plumes of gas and dust reaching heights of up to 400 km [250 miles] and spanning widths as large as 1500 km [930 miles],” Adeloye tells Universe Today. “Positioned at the boundary between the outer and inner Solar System, Io occupies a unique location that makes it an ideal target for sample return missions. Analyzing samples from Io promises to shed light on many enduring questions about the origins and evolution of the Solar System.”

NASA missions typically take years, and sometimes decades, to go from a concept to returning relevant scientific data. They are typically designated specific mission types based on budget and scope of the mission, including Discovery, New Frontiers, Solar System Exploration, and large strategic missions (formerly called Flagship). This also includes whether the mission will be a flyby, orbiter, lander, or rover. For this Io sample return mission, the researchers have designated it as a flyby since it will fly through Io’s plumes without stopping and returning to Earth with the collected samples.

Image of plumes erupting from Io’s surface taken by NASA’s Galileo spacecraft in June 1997.

(Credit: NASA/JPL/University of Arizona)

The NASA selection process for each mission typically consists of several phases involving concept, designs, testing hardware in a laboratory or ground setting, re-designs, more tests for specific systems, integrating all systems together, more tests, launch, cruise, arrival, and finally data collection. Therefore, what are the next steps for making an Io plume sample return mission a reality?

“The Io sample return study evaluated both the scientific rationale and the technological requirements needed for such a mission,” Adeloye tells Universe Today. “We concluded that, with current technology, a ‘New-Frontiers-style’ mission could feasibly perform a fly-through of one of Io’s volcanic plumes to collect gas and dust ejected from its crust. This concept is achievable using today’s propulsion and sample collection systems.”

Adeloye continues, “Furthermore, our ability to develop sophisticated simulations of Io’s plumes will greatly aid in mission planning and execution. Although further improvements in laboratory techniques are needed to optimize the analysis and yield of returned samples, we expect these challenges to be addressed over time. The next step is to assemble a team of leading scientists and engineers to develop and present detailed concept missions to the scientific community.”

As noted, Io is the most volcanically active planetary body in the solar system, boasting hundreds of volcanoes that eject magma and other materials hundreds of kilometers into space. This volcanic activity results from a phenomenon known as tidal heating, which occurs when the gravity of a much larger body tugs on a smaller body, causing it to stretch and compress during the latter’s orbit. In Io’s case, Jupiter’s intense gravity tugs on the much smaller moon as the latter orbits in an elliptical (oval-shaped) pattern, meaning Io is closer to Jupiter at some points during its orbit and farther away at other points.

Io’s volcanic activity was first discovered by Voyager 1 when it and its sister spacecraft, Voyager 2, conducted flybys of Jupiter and its moons in 1979. This was the first time that active volcanism was observed on another planetary body aside from Earth, opening new understandings into the complex and unique nature of the solar system. Therefore, what is the importance of returning Io plume samples to Earth for further analysis?

“Io occupies a unique position within both the Jovian system and the broader Solar System,” Adeloye tells Universe Today. “Its dynamic, transient atmosphere and vigorous volcanic activity continually renew its surface, effectively mitigating the space-weathering effects seen on more geologically inactive bodies. Consequently, Io's distinctive properties have preserved its surface materials in a relatively pristine state. Collecting samples from Io thus offers an unparalleled opportunity to probe early Solar System materials in a way that samples from more weathered bodies cannot.”

What will sampling Io’s volcanic plumes teach scientists about planetary formation and evolution in the coming years and decades? Only time will tell, and this is why we science!

• As always, keep doing science & keep looking up!