Tag Archives: regolith

Nitrogen-fixing bacteria could make farming possible even in Martian soils

New research is investigating the role bacteria could play in future efforts to grow food on planets such as Mars. While such an approach has been shown to boost the growth of clover plants, more work needs to be done to determine exactly how to proceed with off-world farming.

Image credits Kathleen Bergmann.

Nitrogen is a key nutrient for plant growth, one which typically acts as a bottleneck here on Earth. Nitrogen itself cannot be directly assimilated by plants or animals, despite it being available in the atmosphere. Nature has found a workaround to this issue through the formation of symbiotic relationships between the roots of plants and nitrogen-fixing bacteria. These supply essential compounds to the roots that, in turn, feed the bacterial nodules.

Martian soil, or regolith, also lacks essential nutrients, including nitrogen compounds, which would severely limit our ability to grow food in space. In a bid to understand whether we could enrich alien dirt with the aid of Earth-born bacteria, a new study reports on efforts to grow clover in simulated regolith.

Clover for good luck

“Nodule forming bacteria Sinorhizobium meliloti has been shown to nodulate in Martian regolith, significantly enhancing the growth of clover (Melilotus officinalis) in a greenhouse assay. This work increases our understanding of how plant and microbe interactions will help aid efforts to terraform regolith on Mars,” the study reads.

For the study, the team planted clover plants in a man-made regolith substitute that closely resembles that found on Mars. Some of the plants were inoculated with nitrogen-fixing, nodule-forming bacteria, while the others were left to fend for themselves. Sinorhizobium meliloti is a common bacterium on Earth that naturally forms symbiotic relationships with clover plants. Previous research has shown that clover plants can grow in regolith substitutes, the authors explain, but didn’t explore the effects of nitrogen-fixing bacteria on their growth rate.

One of the key findings of the study was that inoculated plants experienced a significantly higher rate of growth than the controls. They recorded 75% more growth in the roots and shoots of these plants compared to clovers which didn’t have access to the bacteria.

Although the bacteria had a positive effect on the plants themselves, the team also reports not seeing any increase in ammonium (NH4) levels in the regolith. In other words, the soil itself did not become enriched in any meaningful way in key nitrogen compounds that other plants could tap into. Furthermore, the symbiotic relationship between bacteria and clovers planted in regolith showed some functional differences compared to those of clovers planted in potting soil.

This suggests that even with the benefit of nitrogen-fixing bacteria on their side, crops sown in alien soils might still develop at different rates to crops on Earth.

All in all, however, the research proves that there is a case to be made for growing crops on alien worlds. Although there are still many unknowns regarding this topic, and even considering a lower yield rate, it remains an attractive proposition. Shuttling materials to outer space remains extremely expensive. It’s also a very long trip to Mars. Both of these factors make it impractical to rely on food transports from Earth to feed a potential colony.

But we are making strides towards offering space explorers greater autonomy. For example, we’re exploring new ways to produce building materials from astronauts’ own bodies and waste. We’re also working on ways to obtain water from regolith.

We’re likely not ready to grow crops in space, however, and the authors note that more research is needed to understand exactly how such a process should be handled. Chief among these, they want to expand their research to other types of crops, and to address possible issues of plant toxicity in regolith.

The paper “Soil fertility interactions with Sinorhizobium-legume symbiosis in a simulated Martian regolith; effects on nitrogen content and plant health” has been published in the journal PLOS ONE.

This company’s weird mission: turning moon dust into oxygen

Humans haven’t been on the moon for about 50 years, since the Apollo Era. But that’s soon about to change. Several ambitious lunar missions are underway, including the Artemis Gateway in orbit, and even planned bases on the surface of the moon, like NASA’s Artemis Base Camp and the ESA’s International Moon Village.

The logistic challenges for establishing a moonbase are enormous. It’s a completely different endeavor from just sending people there and hauling them back. You need infrastructure, food, water, and even air — and you need to produce many of these things using what’s already on the moon.

The bad news is that there’s not that much on the moon. The good news is that even what little is available can be useful. Case in point: a British company has just won a European Space Agency contract to develop the technology that turns moon dust into oxygen, leaving behind useful elements like aluminium and iron.

A proposed design for a lunar base. Image from ESA.

The dust has not settled

The practice of extracting oxygen and metals from lunar dust is simple in principle and very challenging in practice. The main idea is that you take oxidated regolith (which is what lunar dust is called) and break it into pure oxygen and other constituents.

Analyses of this rock showed that oxygen makes about 45% of this dust by weight — encouraging if you want to produce breathing air. But actually extracting it is a very challenging job.

In work published one year ago, researchers at the European Space Agency (ESA), the University of Glasgow, and British company Metalysis, showed that it could be done: up to 96% of the oxygen from lunar soil could be extracted through an electrochemical process developed in 1997 by Cambridge researchers. The process, called the ‘FFC Cambridge process‘, typically takes place at over 900 °C.

Lunar dust before (left) and after (right) the FFC Cambridge process. Image credits: ESA.

The gateway to the solar system

The process is already used here on Earth, but it is typically used as a way to extract metal, with the oxygen being discarded and eliminated as a byproduct. Now, ESA has funded Metalysis for 9 months to tweak the process to also trap and store the oxygen. The oxygen can then be used to produce breathable air, as well as rocket propellant, which could be manufactured on the moon. In addition, the de-oxidized metals will also be useful.

“Anything you take from Earth to the moon is an added weight that you don’t want to carry, so if you can make these materials in situ it saves you a lot of time, effort and money,” said Ian Mellor, the managing director of Metalysis, which is based in Sheffield.

Metalysis will also try to perfect the process and make it ‘moon-proof’, and if it goes according to plan, the next step will be to demonstrate it on the moon. They have 9 months to get to this point.

Mark Symes, one of the researchers working on the process at the University of Glasgow, said moon rock represents “an enormous potential source of oxygen” which could support exploration not only on the moon, but even further in the solar system.

“Oxygen is useful not only for astronauts to breathe, but also as an oxidizer in rocket propulsion systems,” he said. “There is no free oxygen on the moon, so astronauts would have to take all their own oxygen with them to the moon, for life support and to enable their return journey, and this adds considerably to the weight and hence expanse of rocket launches bound for the moon.”

So far, our farthest exploration station has been the International Space Station — which is impressive enough. But building a moon base could serve as a gateway to the rest of the solar system, allowing us to venture even farther away from Earth. For now, the first thing to do is to see how we can produce oxygen on the moon. For now, it all hinges on dust.

Lunar dirt can be broken down into oxygen and metals

New research from the University of Glasgow is working out how to squeeze metal and oxygen from dry rock; dry moon rocks that is.

Image credits Beth Lomax, University of Glasgow.

Samples of regolith (dirt) retrieved from the Moon revealed that the material is made up of between 40% to 45% oxygen by weight. Essentially, this vital (for us) gas is the single most abundant element in the lunar soil. A group of researchers plans to draw the oxygen out of the dirt, in order to give astronauts and colonists a reliable and plentiful source of breathable air and metals.

Rise from the dirt

“This oxygen is an extremely valuable resource, but it is chemically bound in the material as oxides in the form of minerals or glass, and is therefore unavailable for immediate use,” explains researcher Beth Lomax of the University of Glasgow, whose Ph.D. work is being supported through the European Space Agency’s (ESA) Networking and Partnering Initiative.

The approach involves the use of molten salt electrolysis to pry apart the Oxygen and metallic atoms in regolith. The team reports that this is the first “direct powder-to-powder processing of solid lunar regolith simulant” that can extract all the oxygen in such a sample. Alternative methods, they add, either achieve much lower yields or require extreme temperatures (in excess of 1600°C) to work.

The team placed powdered regolith in a mesh-lined basket, mixing in molten calcium chloride salt as an electrolyte. Then they baked everything up to 950°C. While the regolith is still solid at this temperature, the team explains that pushing current through it causes the oxygen atoms to migrate across the molten salt and build-up at the anode.

The technique takes around 50 hours to pull 96% of the oxygen from a sample, but around 75% of the total is extracted in the first 15 hours.

“This research provides a proof-of-concept that we can extract and utilise all the oxygen from lunar regolith, leaving a potentially useful metallic by-product,” adds Lomax.

“This work is based on the FCC process — from the initials of its Cambridge-based inventors — which has been scaled up by a UK company called Metalysis for commercial metal and alloy production.”

Going forward, the team plans to continue cooperating with Metalysis and ESA to ready the process for a lunar context. The process would give lunar settlers access to oxygen for fuel and life support, and raw material (metals) for on-site manufacturing. Exactly what metals they would obtain, the team says, would depend on where on the Moon they land.

Furthermore, the same approach could likely work on Mars as well, materials engineer Advenit Makaya told Phys. The findings also tie in nicely with previous research that developed an approach to extract water out of lunar regolith. Future colonists, it seems, will have ample resources at their disposal.

The paper “Proving the viability of an electrochemical process for the simultaneous extraction of oxygen and production of metal alloys from lunar regolith” has been published in the journal Planetary and Space Science.

Moon.

Solar wind plus moon soil plus meteorite impacts create water on the Moon, researchers report

Researchers are smartening up to a new mechanism of water formation, one which can explain how the liquid got to the Moon.

Moon.

Image credits Patricia Alexandre.

A cross-disciplinary group of researchers has shown chemical, physical, and material evidence for water formation on the moon. The research is the product of two teams of researchers from the University of Hawaiʻi at Mānoa working together — physical chemists at the UH Mānoa Department of Chemistry’s W.M. Keck Research Laboratory in Astrochemistry and planetary scientists at the Hawai’i Institute of Geophysics and Planetology (HIGP).

Their findings could help explain recent findings of water ice being present on the moon, as revealed by data from the Lunar Prospector and the hard lander Lunar Crater Observation and Sensing Satellite.

Actually squeezing water from a stone

“Overall, this study advances our understanding on the origin of water as detected on the moon and other airless bodies in our solar system such as Mercury and asteroids and provides, for the first time, a scientifically sound and proven mechanism of water formation,” says Jeffrey Gillis-Davis, who led the HIGP team.

Data beamed back by the two craft does indeed suggest the existence of water ice on the moon’s poles, but where this water came from was far from clear. It’s an especially interesting question for bodies such as NASA, because lunar water represents one of the key requirements for establishing a permanent colony on the moon. Water can be broken down into breathable air or hydrogen fuel, used to grow food, and is, obviously, in high demand with parched spacefarers.

Chemistry Professor Ralf I. Kaiser and HIGP’s Jeffrey Gillis-Davis designed a series of experiments to understand how the liquid got all the way to the moon. Their working hypothesis was that interactions between solar wind, the minerals in lunar soils, and/or micrometeorite impacts, might hold the key. However, due to a lack of available lunar material to work with, the team substituted it with samples of irradiated olivine, a dry mineral that is a good proxy for lunar regolith (soil). The team simulated solar wind — mainly protons — with a flow of deuterium ions.

At first, the study seemed to be a bust. Experiments using only deuterium and the irradiated samples “did not reveal any trace of water formation, even after increasing the temperature to lunar mid-latitude daytime temperatures,” explains Cheng Zhu, a UH Manoa postdoctoral fellow and lead author of the paper.

“But when we warmed the sample, we detected molecular deuterium, suggesting that deuterium—or hydrogen—implanted from the solar wind can be stored in the lunar rock.”

“Therefore, another high-energy source might be necessary to trigger water formation within the moon’s minerals followed by its release as a gas that can be detected,” Kaiser added.

The second round of testing involved more of the same — bombarding the sample with the ions, then heating them up to temperatures that would be seen on the moon — but the team subsequently blasted the sample with powerful laser pulses. This step was meant to simulate the thermal effects of micrometeorite impacts. Analysis of the gas produced by the laser showed that water was indeed present in the sample at this time.

“Water continued to be produced during laser pulses after the temperature was increased, suggesting that the olivine was storing precursors to heavy water that were released by laser heating,” said Zhu.

Hope Ishii and John Bradley from the HIGP used focused ion beam–scanning electron microscopy and transmission electron microscopy to image these processes as they were unfurling. They observed sub-micrometer-sized surface pits, some partially covered by lids, suggesting that water vapor builds up under the surface until it bursts, releasing water from lunar silicates upon micrometeorite impact.

The paper “Untangling the formation and liberation of water in the lunar regolith,” has been published in the journal Proceedings of the National Academy of Sciences.

Moon.

Future Moon colonists could produce water from regolith and sunlight

Future moon settlers could produce all the water they need — by capturing solar winds.

Moon.

Image via Pixabay.

Streams of charged particles propelled from the surface of the sun (known as ‘solar wind’) slam into the Moon’s surface every day. It’s not a gentle process — these particles reach speeds in excess of 450 kilometers per second (nearly 1 million miles per hour) — but it does enrich the lunar surface with the building blocks of water, a new study reports.

Water from a stone

“We think of water as this special, magical compound,” said William M. Farrell, a plasma physicist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, one of the study’s co-authors. “But here’s what’s amazing: every rock has the potential to make water, especially after being irradiated by the solar wind.”

The team ran a computer simulation to see what chemical changes take place in lunar rocks under the effect of solar winds.

Solar wind is basically a flow of protons. It continually blasts the Moon’s surface, breaking the bonds among molecules in regolith — lunar soil — pulling apart the atoms of silica (SiO2, basically sand) and iron oxides found within the majority of the Moon’s soil. Some of these protons also grab onto electrons in the lunar surface, producing hydrogen atoms. These atoms then work their way up through the regolith leeching the released oxygen. Together, hydrogen and oxygen make the molecule hydroxyl (OH), which is two-thirds of the water (H2O) molecule.

The findings should help further our goal of sending humans up to the Moon to establish a permanent presence there, says Orenthal James Tucker, a physicist at Goddard who led the research.

“We’re trying to learn about the dynamics of transport of valuable resources like hydrogen around the lunar surface and throughout its exosphere, or very thin atmosphere, so we can know where to go to harvest those resources,” he explains.

The research drew on infrared measurements performed on the lunar surface by several spacecraft — including NASA’s Deep Impact spacecraft NASA’s Cassini spacecraft, and India’s Chandrayaan-1. These readings offered us insight into the chemistry of the lunar surface, all of them finding evidence that water or its components — hydrogen and hydroxyl — were present in the regolith.

Exactly how such compounds wound up on the moon, however, was still a matter of debate. It was possible that they arrived on the back of meteorites impacting its surface, or that these impacts initiated the chemical reactions that created hydrogen, hydroxyl, and water. Tucker’s simulation, which traces the life cycle of hydrogen atoms on the Moon, supports the solar wind hypothesis.

“From previous research, we know how much hydrogen is coming in from the solar wind, we also know how much is in the Moon’s very thin atmosphere, and we have measurements of hydroxyl in the surface,” he says. “What we’ve done now is figure out how these three inventories of hydrogen are physically intertwined.”

The findings also helped us understand why spacecraft have found fluctuations in the amount of hydrogen in different regions of the Moon. All the hydrogen atoms created by solar wind bombardment eventually escape into space (since it’s much less dense than all other compounds). However, hydrogen tends to accumulate predominantly in the Moon’s colder areas since it gets energized by sunlight, making it escape much faster.

“The whole process is like a chemical factory,” Farrell said.

A key implication of the findings, Farrell said, is that every exposed body of silica in space — from the Moon down to a small dust grain — has the potential to create hydroxyl and thus become a chemical factory for water.

The paper ” Solar Wind Implantation Into the Lunar Regolith: Monte Carlo Simulations of H Retention in a Surface With Defects and the H 2 Exosphere” has been published in the Journal of Geophysical Research.

University creates Mars-like soil — and you can buy it dirt cheap

While we’re still a long way from making manned missions to Mars a reality, there’s now a way to bring a piece of Mars back to you — kind of. In a new study, researchers describe a new method to create Mars-like soil, which is very much like the real thing, and costs only $20 / kg (2.2 pounds).

Curiosity’s tracks on Martian soil. Image credits: NASA / JPL.

A Red puzzle

Martian soil is essentially fine regolith — a layer of loose, unconsolidated material which typically includes dust, soil, flakes of rock, and other related materials. We have a lot of regolith on Earth, but Martian regolith is quite different from ours. For instance, on our planet, “soil” is generally considered to include organic components — which is not the case on Mars (even if organic matter does exist on Mars, it’s much rarer than on Earth). So on Mars, we need a different definition for soil — generally, this refers to all unconsolidated material, from small rocks to fine grains, small enough to be moved around by wind.

We know quite a bit about this Martian soil, but the information is disparate; think of it as a puzzle, where we vaguely see the big picture, even though some of the pieces are missing.

For instance, remote sensing has shown that our neighbor features vast expanses of sand and dust and its surface is littered with rocks and boulders. The Martian dust is very fine, and when it remains suspended in the atmosphere, it gives the sky a reddish hue — presumably due to rusting iron minerals formed billions of years ago, when Mars still had vast quantities of water. More modern soil might also be red, due to a different type of oxide. The Phoenix lander showed Martian soil to be slightly alkaline, containing elements such as magnesium, sodium, potassium, and chlorine.

The Curiosity rover brought our understanding of Martian soil even further, discovering minerals such as feldspar, pyroxenes, and olivine — all of which are found on Earth, particularly in basaltic soils (weathered basaltic soils, to be more precise).

However, Curiosity never brought any samples back to Earth, and although a few return missions have, that’s not nearly enough for thorough experimentation. Armed with these samples and many more pieces of information, scientists from the University of Central Florida set out to develop realistic Martian soil, which they call “simulant.”

Constructing soil

Comparison of martian simulants. Image credits: Cannon et al. Icarus.

The reasoning is simple: much like in the movie The Martian, scientists are also considering growing crops on Mars, and seeing what its properties are and what the soil can be used for is key to such pursuits.

“The simulant is useful for research as we look to go to Mars,” said Physics Professor Dan Britt, a member of UCF’s Planetary Sciences Group. “If we are going to go, we’ll need food, water and other essentials. As we are developing solutions, we need a way to test how these ideas will fare.”

Britt works at the confluence of geology and physics, you could hardly imagine someone better suited for developing this project. In the new study, he says that the new simulant “offers vast improvements over previous simulants” and can be used for a myriad of lab tests.

“The composition and physical properties of martian regolith are dramatically better understood compared to just a decade ago, particularly through the use of X-ray diffraction by the Curiosity rover,” the study reads.

“Cooking” the Mars simulant. Image credits: University of Central Florida.

Developing the simulant is somewhat similar to cooking: if you know the chemical makeup (the ingredients) and the process to subject them to (how to cook), you can control your end product — and in this case, the end product looks and acts very much like the real thing. The best part about it? It only costs $20 per kilogram (2.2 pounds) plus shipping — which means it could be easily sent to labs and universities across the world, where a number of experiments can be carried out. NASA’s Kennedy Space Center has already reportedly placed an order for a ton.

“I expect we will see significant learning happening from access to this material,” Britt says.

Cannon also believes it will help accelerate our exploration of the solar system and democratize access to this exploration, as demonstrated by investments already being made by Space X, Blue Origin, and other private companies.

However, this is just one type of simulant — Martian soil comes in many variations, featuring different percentages of clays, sand, and salty dirt. Kevin Cannon, the paper’s lead author and a post-doctoral researcher who works with Britt at UCF, says the team is already working on developing new varieties, which they plan to make commercially available for similarly low prices.

Cannon is in Montana to collect ingredients for a moon simulant this week — the moon also features a regolith soil, though with significant differences from the Martian one.

The study is published and freely available at Icarus.