Buzz Aldrin (left) and his Aldrin’s bootprint in the lunar regolith (right). Credit: NASA
Before the end of this decade, NASA plans to return astronauts to the Moon for the first time since the Apollo Era. But this time, through the Artemis Program, it won’t be a “footprints and flags” affair. With other space agencies and commercial partners, the long-term aim is to create the infrastructure that will allow for a “sustained program of lunar exploration and development.” If all goes according to plan, multiple space agencies will have established bases around the South Pole-Aitken Basin, which will pave the way for lunar industries and tourism.
For humans to live, work, and conduct various activities on the Moon, strategies are needed to deal with all the hazards – not the least of which is lunar regolith (or “moondust”). As the Apollo astronauts learned, moondust is jagged, sticks to everything, and can cause significant wear on astronaut suits, equipment, vehicles, and health. In a new study by a team of Texas A&M engineers, the regolith motion was found to be significantly altered due to inter-particle collisions. Given the many spacecraft and landers that will be delivering crews and cargo to the Moon in the near future, this is one hazard that merits close attention!
Apollo 17 astronaut Harrison Schmitt collecting a soil sample, his spacesuit coated with dust. Credit: NASA
In the coming years, astronauts will be returning to the Moon for the first time since the closing of the Apollo Era. Beyond that, NASA and other space agencies plan to establish the necessary infrastructure to maintain a human presence there. This will include the Artemis Gateway in orbit (formerly the Lunar Gateway) and bases on the surface, like NASA’s Artemis Base Camp and the ESA’s International Moon Village.
This presents a number of challenges. The Moon is an airless body, it experiences extreme variations in temperature, and its surface is exposed to far more radiation than we experience here on Earth. On top of that, there’s the lunar dust (aka. regolith), a fine powder that sticks to everything. To address this particular problem, a team of ESA-led researchers is developing materials that will provide better protection for lunar explorers.
A geological map of the Moon showing different formations and mineral deposits. Credit: NASA/GSFC/USGS
The prospect of mining asteroids and the Moon is on a lot of peoples’ minds lately. Maybe it’s all the growth that’s happened in the commercial aerospace industry in the past few decades. Or perhaps it’s because of Trump’s recent executive order to allow for asteroid and lunar mining. Either way, there is no shortage of entrepreneurs and futurists who can’t wait to start prospecting and harvest the natural bounty of space!
Coincidentally enough, future lunar miners now have a complete map of the lunar surface, which was created by the US Geological Society’s (USGS) Astrogeology Science Center, in collaboration with NASA and the Lunar Planetary Institute (LPI). This map shows the distribution and classification of the mineral deposits on the Moon’s surface, effectively letting us know what its familiar patchwork of light and dark patches the really are.
Apollo Astronaut Alfred Worden (1932-2020). Credit: NASA
Last Wednesday (March 18th), the world was saddened to hear of the death of Apollo astronaut Alfred “Al” Worden, who passed away after suffering a stroke at an assisted living facility in Texas. A former Colonel in the US Marine Corps who obtained his Bachelor of Science from West Point Academy in 1955 and his Master of Science at the University of Michigan in 1963, Worden went on to join NASA.
For decades, scientists have held that the Earth-Moon system formed as a result of a collision between Earth and a Mars-sized object roughly 4.5 billion years ago. Known as the Giant Impact Hypothesis, this theory explains why Earth and the Moon are similar in structure and composition. Interestingly enough, scientists have also determined that during its early history, the Moon had a magnetosphere – much like Earth does today.
However, a new study led by researchers at MIT (with support provided by NASA) indicates that at one time, the Moon’s magnetic field may have actually been stronger than Earth’s. They were also able to place tighter constraints on when this field petered out, claiming it would have happened about 1 billion years ago. These findings have helped resolve the mystery of what mechanism powered the Moon’s magnetic field over time.
Buzz Aldrin's bootprint on the surface of the moon during the Apollo 11 mission on July 20, 1969. Credit: NASA
In the coming years, NASA is going back to the Moon for the first time since the Apollo Era. Rather than being a “footprints and flags” operation, Project Artemis is intended to be the first step in creating a sustainable human presence on the Moon. Naturally, this presents a number of challenges, not the least of which has to do with lunar regolith (aka. moondust). For this reason, NASA is investigating strategies for mitigating this threat.
Lunar footprint from the Apollo missions. Credit: NASA
It’s been over forty years since the Apollo Program wrapped up and the last crewed mission to the Moon took place. But in the coming years and decades, multiple space agencies plan to conduct crewed missions to the lunar surface. These includes NASA’s desire to return to the Moon, the ESA’s proposal to create an international Moon village, and the Chinese and Russian plans to send their first astronauts to the Moon.
For this reason, a great deal of research has been dedicated to what the health effects of long-duration missions to the Moon may be – particularly the effects a lower gravity environment would have on the human body. But in a recent study, a team of pharmacologists, geneticists and geoscientists consider how being exposed to lunar dust could have a serious effect on future astronauts’ lungs.
Geologist and astronaut Harrison Schmitt, Apollo 17 lunar module pilot, pictured using an adjustable sampling scoop to retrieve lunar samples during the Apollo 17 mission in December 1972. Credit: NASA.
Because it has no atmosphere, the Moon’s surface has been pounded by meteors and micrometeroes for billions of years, which have created a fine layer of surface dust known as regolith. In addition, the Moon’s surface is constantly being bombarded by charged particles from the Sun, which cause the lunar soil to become electrostatically charged and stick to clothing.
Indications that lunar dust could cause health problems first emerged during the Apollo missions. After visiting the Moon, astronauts brought lunar soil back with them into the command module as it clung to their spacesuits. After inhaling the dust, Apollo 17 astronaut Harrison Schmitt described having symptoms akin to hay fever, which including sneezing, watery eyes and a sore throat.
While the symptoms were short-lived, researchers wanted to know what the long-term effects of lunar dust could be. There have also been indications that exposure to lunar dust could be harmful based on research that has shown how breathing dust from volcanic eruptions, dust storms and coal mines can cause bronchitis, wheezing, eye irritation and scarring of lung tissue.
Previous research has also shown that dust can cause damage to cells’ DNA, which can cause mutations and eventually lead to cancer. For these reasons, Caston and her colleagues were well-motivated to see what harmful effects lunar soil could have on the human body. For the sake of their study, the team exposed human lung cells and mouse brain cells to samples of simulated lunar soil.
After taking the first boot print photo, Aldrin moved closer to the little rock and took this second shot. The dusty, sandy pebbly soil is also known as the lunar ‘regolith’. Credit: NASA
These simulants were created by using dust samples from Earth that resemble soil found on the Moon’s lunar highlands and volcanic plains, which were then ground to a fine powder. What they found was that up to 90% of human lung cells and mouse neurons died when exposed to the dust samples. The simulants also caused significant DNA damage to mouse neurons, and the human lung cells were so effectively damaged that it was impossible to measure any damage to the cells’ DNA.
The results show that breathing lunar dust (even in minute quantities) could pose a serious health hazard to astronauts traveling to any airless bodies in the future. This includes not only the Moon, but also Mars and other terrestrial bodies like Mercury. Until now, this health hazard has been largely overlooked by space agencies seeking to understand the long-term health risks of space travel.
“There are risks to extraterrestrial exploration, both lunar and beyond, more than just the immediate risks of space itself,” said Rachel Caston. According to Bruce Demple, a biochemist at Stony Brook University School of Medicine and senior author of the new study, their results (coupled with the experience of the Apollo astronauts) indicate that prolonged exposure to lunar dust could impair airway and lung function.
What’s worse, he also indicated that if the dust induces inflammation in the lungs, it could increase the risk of more serious diseases like cancer. “If there are trips back to the Moon that involve stays of weeks, months or even longer, it probably won’t be possible to eliminate that risk completely,” he said.
Long-duration missions to the Moon, which could involve permanent bases, will have to contend with the hazard of breathing lunar dust. Credit: ESA/Foster + Partners
Ergo, any attempts to mitigate the risks of mounting crewed missions to the Moon, Mars, and beyond will have to take into account exposure to not only low-gravity and radiation, but also electrostatically charged soil. Aside from limiting the duration of missions and the number of EVAs, certain protective counter-measures may need to be incorporated into any plans for long-duration missions.
One possibility is to have astronauts cycle through an airlock that would also spray their suits with water or a compound designed to neutralize the charge, thus washing them clean of dust before they enter the main habitat. Otherwise, astronauts working in the International Lunar Village (or any other off-world habitat for that matter) may have to wear breathing masks the entire time they are not in a spacesuit.
Chris Hadfield recently explained how humanity should create a Moon base before attempting to colonize Mars. Credit: Foster + Partners is part of a consortium set up by the European Space Agency to explore the possibilities of 3D printing to construct lunar habitations.
Credit: ESA/Foster + Partners
In the coming decades, NASA has some rather bold plans for space exploration. By the 2030s, they hope to mount their “Journey to Mars“. a crewed mission that will see astronauts traveling beyond Earth for the first time since the Apollo era. At the same time, private companies and organizations like SpaceX and MarsOne are hoping to start colonizing Mars within a decade or so.
According to Chris Hadfield, these mission concepts are all fine and good. But as he explained in a recent interview, our efforts should be focused on renewed exploration of the Moon and the creation of a lunar settlement before we do the same for Mars. In this respect, he is joined by organizations like the European Space Agency (ESA), Roscosmos, the Chinese National Space Agency (CNSA), and others.
When it comes to establishing a base on the Moon, the benefits are rather significant. For starters, a lunar outpost could serve as a permanent research base for teams of astronauts. In the same respect, it would present opportunities for scientific collaboration between space agencies and private companies – much in the same way the International Space Station does today.
On top of that, a lunar outpost could serve as a refueling station, facilitating missions deeper into the Solar System. According to estimates prepared by NexGen Space LLC (a consultant company for NASA), such a base could cut the cost of any future Mars missions by about $10 billion a year. Last, but not least, it would leverage key technologies that have been developed in recent years, from reusable rockets to additive manufacturing (aka. 3D printing).
And as Chris Hadfield stated in an interview with New Scientist, there are also a number of practical reasons for back to the Moon before going to Mars – ranging from distance to the development of “space expertise”. For those interested in science and space exploration, Chris Hadfield has become a household name in recent years. Before becoming an astronaut, he was a pilot with the Royal Canadian Air Force (RCAF) and flew missions for NORAD.
After joining the Canadian Space Agency (CSA) in 1992, he participated in two space missions – STS-74 and STS-100 in 1995 and 2001, respectively – as a Mission Specialist. These missions involved rendezvousing with the Russian space station Mir and the ISS. However, his greatest accomplishment occurred in 2012, when he became the first Canadian astronaut to command an ISS mission – Expedition 35.
During the course of this 148-day mission, Hadfield attracted significant media exposure due to his extensive use of social media to promote space exploration. In fact, Forbes described Hadfield as “perhaps the most social media savvy astronaut ever to leave Earth”. His promotional activities included a collaboration with Ed Robertson of The Barenaked Ladies and the Wexford Gleeks, singing “Is Somebody Singing?“(I.S.S.) via Skype.
Canadian astronaut Chris Hadfield, the first Canadian to serve as commander of the ISS. Credit: CTV
The broadcast of this event was a major media sensation, as was his rendition of David Bowie’s “Space Oddity“, which he sung shortly before departing the station in May 2013. Since retiring from the Canadian Space Agency, Hadfield has become a science communicator and advocate for space exploration. And when it comes to the future, he was quite direct in his appraisal that the we need to look to the Moon first.
According to Hadfield, one of the greatest reasons for establishing a base on the Moon has to do with its proximity and the fact that humans have made this trip before. As he stated:
“With long-haul space exploration there is a whole smorgasbord of unknowns. We know some of the threats: the unreliability of the equipment, how to provide enough food for that length of time. But there are countless others: What are the impacts of cosmic rays on the human body? What sort of spacecraft do you need to build? What are the psychological effects of having nothing in the window for months and months? And going to a place that no one has ever been before, that can’t be discounted.”
In that, he certainly has a point. At their closest – i.e. when it is at “opposition with the Sun”, which occurs approximately every two years – Mars and Earth are still very far from each othre. In fact, the latest closest-approach occurred in 2003, when the two planets were roughly 56 million km (33.9 million miles) apart. This past July, the planets were again at opposition, where they were about 57.6 million km (35.8 million miles) apart.
Using conventional methods, it would take a mission between 150 and 300 days to get from the Earth to Mars. Whereas a more fuel-efficient approach (like ion engines) would cost less but take much longer, a more rapid method like chemical rockets would could cost far more. Even with Nuclear Thermal Propulsion (NTP) or the Variable Specific Impulse Magnetoplasma Rocket (VASIMR) concept, the journey could still take 5 to 7 months.
During this time, astronauts would not only be subjected to a great deal of cosmic radiation, they would have to contend with the affects of microgravity. As studies that have been conducted aboard the ISS that have shown, long-term exposure to a microgravity environment can lead to losses in bone density, muscular atrophy, diminished eyesight, and organ damage.
Recent studies have also shown that exposure to radiation while on the surface of Mars would be quite significant. During its journey to Mars, the Curiosity rover recorded that it was subjected to average dose of 1.8 millisieverts (mSv) per day from inside its spaceship – the Mars Science Laboratory. During its first three hundred days on the surface, it was exposed to about 0.67 millisieverts (mSv) per day.
This is about half and one-fifth (respectively) of what people are exposed to during an average here on Earth. While this falls outside of NASA’s official guidelines, it is still within the guidelines of other space agencies. But to make matter worse, a new study from the University of Nevada, Las Vegas, concluded that exposure to cosmic rays could cause cell damage that would spread to other cells in the body, effectively doubling the risk of cancer.
The risks of going to the Moon, in contrast, are easy to predict. Thanks to the Apollo missions, we know that it takes between two and three days to travel from the Earth to the Moon. The Apollo 11 mission, for example, launched from the Cape Kennedy on July 16th, 1969, and arrived in lunar orbit by July 19th, 1969 – spending a total of 51 hours and 49 minutes in space. Astronauts conducting this type of mission would therefore be subject to far less radiation.
Artist’s impression of a lunar base created with 3-d printing techniques. Credits: ESA/Foster + Partners
Granted, the surface of the Moon is still exposed to significant amounts of radiation since the Moon has no atmosphere to speak of. But NASA estimates that walls which are 2.5 meters in thickness (and made from lunar regolith) will provide all the necessary shielding to keep astronauts or colonists safe. Another good reason to go to the Moon first, according to Hadfield, is because expertise in off-world living is lacking.
“There are six people living on the International Space Station, and we have had people there continuously for nearly 17 years,” he said. “But the reality is we have not yet figured out how to live permanently off-planet. So I think if we follow the historically driven pattern then the moon would be first. Not just to reaffirm that we can get there, but to show that we can also live there.”
But perhaps the best reason to settle the Moon before moving onto Mars has to do with the fact that exploration has always been about taking the next step, and then the next. One cannot simply leap from one location to the next, and expect successful results. What are required is baby-steps. And in time, sufficient traction can be obtained and the process will build up speed, enabling steps that are greater and more far-reaching. Or as Hadfield put it:
“For tens of thousands of years humans have followed a pattern on Earth: imagination, to technology-enabled exploration, to settlement. It’s how the first humans got to Australia 50,000 or 60,000 years ago, and how we went from Yuri Gagarin and Alan Shepherd orbiting Earth to the first people putting footprints on the moon, to people living in orbit.
Based on this progression, one can therefore see why Hadfield and others beleive that the next logical step is to return to the Moon. And once we establish a foothold there, we can then use it to launch long-range missions to Mars, Venus, and beyond. Incremental steps that eventually add up to human beings setting foot on every planet, moon, and larger body in the Solar System.
On the subject of lunar colonization, be sure to check out our series on Building a Moon Base, by Universe Today’s own Ian O’Neill.
A Full Moon, as imaged by NASA's Lunar Reconnaissance Orbiter. Credit: NASA Goddard's Scientific Visualization Studio
Long before the Apollo missions reached the Moon, Earth’s only satellites has been the focal point of intense interest and research. But thanks to the samples of lunar rock that were returned to Earth by the Apollo astronauts, scientists have been able to conduct numerous studies to learn more about the Moon’s formation and history. A key research goal has been determining how much volatile elements the Moon possesses.
Intrinsic to this is determining how much water the Moon possesses, and whether it has a “wet” interior. If the Moon does have abundant sources of water, it will make establishing outposts there someday much more feasible. However, according to a new study by an international team of researchers, the interior of the Moon is likely very dry, which they concluded after studying a series of “rusty” lunar rock samples collected by the Apollo 16 mission.
Collection site of 66095 (bottom left) and the “Rusty Rock” lunar rock sample obtained there (center). Credit: NASA
Determining how rich the Moon is in terms of volatile elements and compounds – such as zinc, potassium, chlorine, and water – is important because it provides insight into how the Moon and Earth formed and evolved. The most-widely accepted theory is that Moon is the result of “catastrophic formation”, where a Mars-sized object (named Theia) collided with Earth about 4.5 billion years ago.
The debris kicked up by this impact eventually coalesced to form the Moon, which then moved away from Earth to assume its current orbit. In accordance with this theory, the Moon’s surface would have been an ocean of magma during its early history. As a result, volatile elements and compounds within the Moon’s mantle would have been depleted, much in the same way that the Earth’s upper mantle is depleted of these elements.
As Dr. Day explained in a Scripps Institution press statement:
“It’s been a big question whether the moon is wet or dry. It might seem like a trivial thing, but this is actually quite important. If the moon is dry – like we’ve thought for about the last 45 years, since the Apollo missions – it would be consistent with the formation of the Moon in some sort of cataclysmic impact event that formed it.”
Cross-polarized light image of a portion of the interior of the lunar ‘Rusty Rock’. Credit: NASA
For the sake of their study, the team examined a lunar rock named “Rusty Rock 66095” to determine the volatile content of the Moon’s interior. These rocks have mystified scientists since they were first brought back by the Apollo 16 mission in 1972. Water is an essential ingredient to rust, which led scientists to conclude that the Moon must have an indigenous source of water – something which seemed unlikely, given the Moon’s extremely tenuous atmosphere.
Using a new chemical analysis, Day and his colleagues determined the levels of istopically light zinc (Zn66) and heavy chlorine (Cl37), as well as the levels of heavy metals (uranium and lead) in the rock. Zinc was the key element here, since it is a volatile element that would have behaved somewhat like water under the extremely hot conditions that were present during the Moon’s formation.
Ultimately, the supply of volatiles and heavy metals in the sample support the theory that volatile enrichment of the lunar surface occurred as a result of vapor condensation. In other words, when the Moon’s surface was still an ocean of hot magma, its volatiles evaporated and escaped from the interior. Some of these then condensed and were deposited back on the surface as it cooled and solidified.
This would explain the volatile-rich nature of some rocks on the lunar surface, as well as the levels of light zinc in both the Rusty Rock samples and the previously-studied volcanic glass beads. Basically, both were enriched by water and other volatiles thanks to extreme outgassing from the Moon’s interior. However, these same conditions meant that most of the water in the Moon’s mantle would have evaporated and been lost to space.
Near-infrared image of the Moon’s surface by NASA’s Moon Mineralogy Mapper on the Indian Space Research Organization’s Chandrayaan-1 mission Image credit: ISRO/NASA/JPL-Caltech/Brown Univ./USGS
This represents something of a paradox, in that it shows how rocks that contain water were formed in a very dry, interior part of the Moon. However, as Day indicated, it offers a sound explanation for an enduring lunar mystery:
“I think the Rusty Rock was seen for a long time as kind of this weird curiosity, but in reality, it’s telling us something very important about the interior of the moon. These rocks are the gifts that keep on giving because every time you use a new technique, these old rocks that were collected by Buzz Aldrin, Neil Armstrong, Charlie Duke, John Young, and the Apollo astronaut pioneers, you get these wonderful insights.”
These results contradict other studies that suggest the Moon’s interior is wet, one of which was recently conducted by researchers at Brown University. By combining data provided by Chandrayaan-1 and the Lunar Reconnaissance Orbiter (LRO) with new thermal profiles, the Brown research team concluded that lots of water exists within volcanic deposits on the Moon’s surface, which could also mean there are vast quantities of water in the Moon’s interior.
To these, Day emphasized that while these studies present evidence that water exists on the lunar surface, they have yet to offer a solid explanation for what mechanisms deposited it on the surface. Day and his colleague’s study also flies in the face of other recent studies, which claim that the Moon’s water came from an external source – either by comets which deposited it, or from Earth during the formation of the Earth-Moon system.
Other studies indicate that evidence from ancient volcanic deposits suggests that lunar magma contained substantial amounts of water, hinting at water in the interior. Credit: Olga Prilipko Huber
Those who believe that lunar water was deposited by comets cite the similarities between the ratios of hydrogen to deuterium (aka. “heavy hydrogen”) in both the Apollo lunar rock samples and known comets. Those who believe the Moon’s water came from Earth, on the other hand, point to the similarity between water isotopes on both the Moon and Earth.
In the end, future research is needed to confirm where all of the Moon’s water came from, and whether or not it exists within the Moon’s interior. Towards this end, one of Day’s PhD students – Carrie McIntosh – is conducting her own research into the lunar glass beads and the composition of the deposits. These and other research studies ought to settle the debate soon enough!
And not a moment too soon, considering that multiple space agencies hope to build a lunar outpost in the upcoming decades. If they hope to have a steady supply of water for creating hydrazene (rocket fuel) and growing plants, they’ll need to know if and where it can be found!
Astronaut Alan Shepard poses next to the American flag on the Moon during the Apollo 14 mission. Credit: NASA
For decades, scientists have been of the belief that the Moon, Earth’s only natural satellite, was four and a half billion years old. According to this theory, the Moon was created from a fiery cataclysm produced by a collision between the Earth with a Mars-sized object (named Theia) roughly 100 million years after the formation of primordial Earth.
But according to a new study by researchers from UCLA (who re-examined some of the Apollo Moon Rocks), these estimates may have been off by about 40 to 140 million years. Far from simply adjusting our notions of the Moon’s proper age, these findings are also critical to our understanding of the Solar System and the formation and evolution of its rocky planets.
This study, titled “Early formation of the Moon 4.51 billion years ago“, was published recently in the journal Science Advances. Led by Melanie Barboni – a professor from the Department of Earth, Planetary, and Space Sciences at UCLA – the research team conducted uranium-lead dating on fragments of the Moon rocks that were brought back by the Apollo 14 astronauts.
Artist’s concept of a collision that is believed to have taken place in the HD 172555 star system between a moon-sized object and a Mercury-sized planet. Credit: NASA/JPL-Caltech
These fragments were of a compound known as zircon, a type of silicate mineral that contains trace amounts of radioactive elements (like uranium, thorium, and lutetium). As Kevin McKeegan, a UCLA professor of geochemistry and cosmochemistry and a co-author of the study, explained, “Zircons are nature’s best clocks. They are the best mineral in preserving geological history and revealing where they originated.”
By examining the radioactive decay of these elements, and correcting for cosmic ray exposure, the research team was able to get highly precise estimates of the zircon fragments ages. Using one of UCLA’s mass spectrometers, they were able to measure the rate at which the deposits of uranium in the zircon turned into lead, and the deposits of lutetium turned into hafnium.
In the end, their data indicated that the Moon formed about 4.51 billion years ago, which places its birth within the first 60 million years of the Solar System or so. Previously, dating Moon rocks proved difficult, mainly because most of them contained fragments of many different kinds of rocks, and these samples were determined to be tainted by the effects of multiple impacts.
However, Barboni and her team were able to examine eight zircons that were in good condition. More importantly, these silicate deposits are believed to have formed shortly after the collision between Earth and Theia, when the Moon was still an unsolidified mass covered in oceans of magma. As these oceans gradually cooled, the Moon’s body became differentiated between its crust, mantle and core.
Zircon deposits found in the Moon rocks returned by the Apollo 17 mission. Credit: NASA//Nicholas E. Timms.
Because zircon minerals were formed during the initial magma ocean, uranium-lead dating reaches all the way back to a time before the Moon became a solidified mass. As Edward Young, a UCLA professor of geochemistry and cosmochemistry and a co-author of the study, put it, “Mélanie was very clever in figuring out the Moon’s real age dates back to its pre-history before it solidified, not to its solidification.”
These findings have not only determined the age of the Moon with a high degree of accuracy (and for the first time), it also has implications for our understanding of when and how rocky planes formed within the Solar System. By placing accurate dates on when certain bodies formed, we are able to understand the context in which they formed, which also helps to determine what mechanisms were involved.
And this was just the first revelation produced by the research team, which hopes to continue studying the zircon fragments to see what they can learn about the Moon’s early history.
