Researchers develop dustbuster for the moon

A team led by the University of Colorado Boulder is pioneering a new solution to the problem of spring cleaning on the moon: Why not zap away the grime using a beam of electrons?

The research, published recently in the journal Acta Astronautica, marks the latest to explore a persistent, and perhaps surprising, hiccup in humanity’s dreams of colonizing the moon: dust. Astronauts walking or driving over the lunar surface kick up huge quantities of this fine material, also called regolith.

“It’s really annoying,” said Xu Wang, a research associate in the Laboratory for Atmospheric and Space Physics (LASP) at CU Boulder. “Lunar dust sticks to all kinds of surfaces — spacesuits, solar panels, helmets — and it can damage equipment.”

So he and his colleagues developed a possible fix — one that makes use of an electron beam, a device that shoots out a concentrated (and safe) stream of negatively-charged, low-energy particles. In the new study, the team aimed such a tool at a range of dirty surfaces inside of a vacuum chamber. And, they discovered, the dust just flew away.

“It literally jumps off,” said lead author Benjamin Farr, who completed the work as an undergraduate student in physics at CU Boulder.

The researchers still have a long way to go before real-life astronauts will be able to use the technology to do their daily tidying up. But, Farr said, the team’s early findings suggest that electron-beam dustbusters could be a fixture of moon bases in the not-too-distant future.

Spent gunpowder

The news may be music to the ears of many Apollo-era astronauts. Several of these space pioneers complained about moon dust, which often resists attempts at cleaning even after vigorous brushing. Harrison “Jack” Schmitt, who visited the moon as a member of Apollo 17 in 1972, developed an allergic reaction to the material and has said that it smelled like “spent gunpowder.”

The problem with lunar dust, Wang explained, is that it isn’t anything like the stuff that builds up on bookshelves on Earth. Moon dust is constantly bathed in radiation from the sun, a bombardment that gives the material an electric charge. That charge, in turn, makes the dust extra sticky, almost like a sock that’s just come out of the drier. It also has a distinct structure.

“Lunar dust is very jagged and abrasive, like broken shards of glass,” Wang said.

The question facing his group was then: How do you unstick this naturally clingy substance?

Electron beams offered a promising solution. According to a theory developed from recent scientific studies of how dust naturally lofts on the lunar surface, such a device could turn the electric charges on particles of dust into a weapon against them. If you hit a layer dust with a stream of electrons, Wang said, that dusty surface will collect additional negative charges. Pack enough charges into the spaces in between the particles, and they may begin to push each other away — much like magnets do when the wrong ends are forced together.

“The charges become so large that they repel each other, and then dust ejects off of the surface,” Wang said.

Electron showers

To test the idea, he and his colleagues loaded a vacuum chamber with various materials coated in a NASA-manufactured “lunar simulant” designed to resemble moon dust.

And sure enough, after aiming an electron beam at those particles, the dust poured off, usually in just a few minutes. The trick worked on a wide range of surfaces, too, including spacesuit fabric and glass. This new technology aims at cleaning the finest dust particles, which are difficult to remove using brushes, Wang said. The method was able to clean dusty surfaces by an average of about 75-85%.

“It worked pretty well, but not well enough that we’re done,” Farr said.

The researchers are currently experimenting with new ways to increase the cleaning power of their electron beam.

But study coauthor Mihály Horányi, a professor in LASP and the Department of Physics at CU Boulder, said that the technology has real potential. NASA has experimented with other strategies for shedding lunar dust, such as by embedding networks of electrodes into spacesuits. An electron beam, however, might be a lot cheaper and easier to roll out.

Horányi imagines that one day, lunar astronauts could simply leave their spacesuits hanging up in a special room, or even outside their habitats, and clean them after spending a long day kicking up dust outside. The electrons would do the rest.

“You could just walk into an electron beam shower to remove fine dust,” he said.

Other coauthors on the new research include John Goree of the University of Iowa and Inseob Hahn and Ulf Israelsson of the Jet Propulsion Laboratory.

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Higher concentration of metal in Moon’s craters provides new insights to its origin

Life on Earth would not be possible without the Moon; it keeps our planet’s axis of rotation stable, which controls seasons and regulates our climate. However, there has been considerable debate over how the Moon was formed. The popular hypothesis contends that the Moon was formed by a Mars-sized body colliding with Earth’s upper crust which is poor in metals. But new research suggests the Moon’s subsurface is more metal-rich than previously thought, providing new insights that could challenge our understanding of that process.

Today, a study published in Earth and Planetary Science Letters sheds new light on the composition of the dust found at the bottom of the Moon’s craters. Led by Essam Heggy, research scientist of electrical and computer engineering at the USC Viterbi School of Engineering, and co-investigator of the Mini-RF instrument onboard NASA Lunar Reconnaissance Orbiter (LRO), the team members of the Miniature Radio Frequency (Mini-RF) instrument on the Lunar Reconnaissance Orbiter (LRO) mission used radar to image and characterize this fine dust. The researchers concluded that the Moon’s subsurface may be richer in metals (i.e. Fe and Ti oxides) than scientists had believed.

According to the researchers, the fine dust at the bottom of the Moon’s craters is actually ejected materials forced up from below the Moon’s surface during meteor impacts. When comparing the metal content at the bottom of larger and deeper craters to that of the smaller and shallower ones, the team found higher metal concentrations in the deeper craters.

What does a change in recorded metal presence in the subsurface have to do with our understanding of the Moon? The traditional hypothesis is that approximately 4.5 billion years ago there was a collision between Earth and a Mars-sized proto-planet (named Theia). Most scientists believe that that collision shot a large portion of Earth’s metal-poor upper crust into orbit, eventually forming the Moon.

One puzzling aspect of this theory of the Moon’s formation, has been that the Moon has a higher concentration of iron oxides than the Earth — a fact well-known to scientists. This particular research contributes to the field in that it provides insights about a section of the moon that has not been frequently studied and posits that there may exist an even higher concentration of metal deeper below the surface. It is possible, say the researchers that the discrepancy between the amount of iron on the Earth’s crust and the Moon could be even greater than scientists thought, which pulls into question the current understanding of how the Moon was formed.

The fact that our Moon could be richer in metals than the Earth challenges the notion that it was portions of Earth’s mantle and crust that were shot into orbit. A greater concentration of metal deposits may mean that other hypotheses about the Moon’s formation must be explored. It may be possible that the collision with Theia was more devastating to our early Earth, with much deeper sections being launched into orbit, or that the collision could have occurred when Earth was still young and covered by a magma ocean. Alternatively, more metal could hint at a complicated cool-down of an early molten Moon surface, as suggested by several scientists.

According to Heggy, “By improving our understanding of how much metal the Moon’s subsurface actually has, scientists can constrain the ambiguities about how it has formed, how it is evolving and how it is contributing to maintaining habitability on Earth.” He further added, “Our solar system alone has over 200 moons — understanding the crucial role these moons play in the formation and evolution of the planets they orbit can give us deeper insights into how and where life conditions outside Earth might form and what it might look like.”

Wes Patterson of the Planetary Exploration Group (SRE), Space Exploration Sector (SES) at Johns Hopkins University Applied Physics Laboratory, who is the project’s principal investigator for Mini-RF and a co-author of the study, added, “The LRO mission and its radar imager Mini-RF are continuing to surprise us with new insights into the origins and complexity of our nearest neighbor.”

The team plans to continue carrying out additional radar observations of more crater floors with the Mini-RF experiment to verify the initial findings of the published investigation.

This research project was funded through the University of Southern California under NASA award NNX15AV76G.

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Planetary exploration rover avoids sand traps with ‘rear rotator pedaling’

The rolling hills of Mars or the moon are a long way from the nearest tow truck. That’s why the next generation of exploration rovers will need to be good at climbing hills covered with loose material and avoiding entrapment on soft granular surfaces.

Built with wheeled appendages that can be lifted and wheels able to “wiggle,” a new robot known as the “Mini Rover” has developed and tested complex locomotion techniques robust enough to help it climb hills covered with such granular material — and avoid the risk of getting ignominiously stuck on some remote planet or moon.

Using a complex move the researchers dubbed “rear rotator pedaling,” the robot can climb a slope by using its unique design to combine paddling, walking, and wheel spinning motions. The rover’s behaviors were modeled using a branch of physics known as terradynamics.

“When loose materials flow, that can create problems for robots moving across it,” said Dan Goldman, the Dunn Family Professor in the School of Physics at the Georgia Institute of Technology. “This rover has enough degrees of freedom that it can get out of jams pretty effectively. By avalanching materials from the front wheels, it creates a localized fluid hill for the back wheels that is not as steep as the real slope.

The rover is always self-generating and self-organizing a good hill for itself.”

The research will be reported on May 13 as the cover article in the journal Science Robotics. The work was supported by the NASA National Robotics Initiative and the Army Research Office.

A robot built by NASA’s Johnson Space Center pioneered the ability to spin its wheels, sweep the surface with those wheels and lift each of its wheeled appendages where necessary, creating a broad range of potential motions. Using in-house 3D printers, the Georgia Tech researchers collaborated with the Johnson Space Center to re-create those capabilities in a scaled-down vehicle with four wheeled appendages driven by 12 different motors.

“The rover was developed with a modular mechatronic architecture, commercially available components, and a minimal number of parts,” said Siddharth Shrivastava, an undergraduate student in Georgia Tech’s George W. Woodruff School of Mechanical Engineering. “This enabled our team to use our robot as a robust laboratory tool and focus our efforts on exploring creative and interesting experiments without worrying about damaging the rover, service downtime, or hitting performance limitations.”

The rover’s broad range of movements gave the research team an opportunity to test many variations that were studied using granular drag force measurements and modified Resistive Force Theory. Shrivastava and School of Physics Ph.D. candidate Andras Karsai began with the gaits explored by the NASA RP15 robot, and were able to experiment with locomotion schemes that could not have been tested on a full-size rover.

The researchers also tested their experimental gaits on slopes designed to simulate planetary and lunar hills using a fluidized bed system known as SCATTER (Systematic Creation of Arbitrary Terrain and Testing of Exploratory Robots) that could be tilted to evaluate the role of controlling the granular substrate. Karsai and Shrivastava collaborated with Yasemin Ozkan-Aydin, a postdoctoral research fellow in Goldman’s lab, to study the rover motion in the SCATTER test facility.

“By creating a small robot with capabilities similar to the RP15 rover, we could test the principles of locomoting with various gaits in a controlled laboratory environment,” Karsai said. “In our tests, we primarily varied the gait, the locomotion medium, and the slope the robot had to climb. We quickly iterated over many gait strategies and terrain conditions to examine the phenomena that emerged.”

In the paper, the authors describe a gait that allowed the rover to climb a steep slope with the front wheels stirring up the granular material — poppy seeds for the lab testing — and pushing them back toward the rear wheels. The rear wheels wiggled from side-to-side, lifting and spinning to create a motion that resembles paddling in water. The material pushed to the back wheels effectively changed the slope the rear wheels had to climb, allowing the rover to make steady progress up a hill that might have stopped a simple wheeled robot.

The experiments provided a variation on earlier robophysics work in Goldman’s group that involved moving with legs or flippers, which had emphasized disturbing the granular surfaces as little as possible to avoid getting the robot stuck.

“In our previous studies of pure legged robots, modeled on animals, we had kind of figured out that the secret was to not make a mess,” said Goldman. “If you end up making too much of a mess with most robots, you end up just paddling and digging into the granular material. If you want fast locomotion, we found that you should try to keep the material as solid as possible by tweaking the parameters of motion.”

But simple motions had proved problematic for Mars rovers, which got stuck in granular materials. Goldman says the gait discovered by Shrivastava, Karsai and Ozkan-Aydin might be able to help future rovers avoid that fate.

“This combination of lifting and wheeling and paddling, if used properly, provides the ability to maintain some forward progress even if it is slow,” Goldman said. “Through our laboratory experiments, we have shown principles that could lead to improved robustness in planetary exploration — and even in challenging surfaces on our own planet.”

The researchers hope next to scale up the unusual gaits to larger robots, and to explore the idea of studying robots and their localized environments together. “We’d like to think about the locomotor and its environment as a single entity,” Goldman said. “There are certainly some interesting granular and soft matter physics issues to explore.”

Though the Mini Rover was designed to study lunar and planetary exploration, the lessons learned could also be applicable to terrestrial locomotion — an area of interest to the Army Research Laboratory, one of the project’s sponsors.

“Basic research is revealing counter-intuitive principles and novel approaches for locomotion and granular intrusion in complex and yielding terrain,” said Dr. Samuel Stanton, program manager, Army Research Office, an element of the U.S. Army Combat Capabilities Development Command’s Army Research Laboratory. “This may lead to novel, terrain-aware platforms capable of intelligently transitioning between wheeled and legged modes of movement to maintain high operational tempo.”

Beyond those already mentioned, the researchers worked with Robert Ambrose and William Bluethmann at NASA, and traveled to NASA JSC to study the full-size NASA rover.

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3D Printing Industry

Tuskegee set to help develop NASA’s Artemis lunar lander using 3D printing

NASA’s ambitious Artemis program will see two astronauts returning to the surface of the moon for the first time since Apollo 17 touched down in December of 1972. To achieve this by 2024, the U.S. space agency has commissioned three private aerospace companies to design and manufacture human landing systems (HLS) for the mission. SpaceX, […]

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Author: Kubi Sertoglu


Possibly active tectonic system on the Moon

Researchers have discovered a system of ridges spread across the nearside of the Moon topped with freshly exposed boulders. The ridges could be evidence of active lunar tectonic processes, the researchers say, possibly the echo of a long-ago impact that nearly tore the Moon apart.

“There’s this assumption that the Moon is long dead, but we keep finding that that’s not the case,” said Peter Schultz, a professor in Brown University’s Department of Earth, Environmental and Planetary Sciences and co-author of the research, which is published in the journal Geology. “From this paper it appears that the Moon may still be creaking and cracking — potentially in the present day — and we can see the evidence on these ridges.”

Most of the Moon’s surface is covered by regolith, a powdery blanket of ground-up rock created by the constant bombardment of tiny meteorites and other impactors. Areas free of regolith where the Moon’s bedrock is exposed are vanishingly rare. But Adomas Valantinas, a graduate student at the University of Bern who led the research while a visiting scholar at Brown, used data from NASA’s Lunar Reconnaissance Orbiter (LRO) to spot strange bare spots within and surrounding the lunar maria, the large dark patches on the Moon’s nearside.

“Exposed blocks on the surface have a relatively short lifetime because the regolith buildup is happening constantly,” Schultz said. “So when we see them, there needs to be some explanation for how and why they were exposed in certain locations.”

For the study, Valantinas used the LRO’s Diviner instrument, which measures the temperature of the lunar surface. Just as concrete-covered cities on Earth retain more heat than the countryside, exposed bedrock and blocky surfaces on the Moon stays warmer through the lunar night than regolith-covered surfaces. Using nighttime observations from Diviner, Valantinas turned up more than 500 patches of exposed bedrock on narrow ridges following a pattern across the lunar nearside maria.

A few ridges topped with exposed bedrock had been seen before, Schultz says. But those ridges were on the edges of ancient lava-filled impact basins and could be explained by continued sagging in response to weight caused by the lava fill. But this new study discovered that the most active ridges are related to a mysterious system of tectonic features (ridges and faults) on the lunar nearside, unrelated to both lava-filled basins and other young faults that crisscross the highlands.

“The distribution that we found here begs for a different explanation,” Schultz said.

Valantinas and Schultz mapped out all of the exposures revealed in the Diviner data and found an interesting correlation. In 2014, NASA’s GRAIL mission found a network of ancient cracks in the Moon’s crust. Those cracks became channels through which magma flowed to the Moon’s surface to form deep intrusions. Valantinas and Schultz showed that the blocky ridges seemed to line up just about perfectly with the deep intrusions revealed by GRAIL.

“It’s almost a one-to-one correlation,” Schultz said. “That makes us think that what we’re seeing is an ongoing process driven by things happening in the Moon’s interior.”

Schultz and Valantinas suggest that the ridges above these ancient intrusions arestill heaving upward. The upward movement breaks the surface and enables regolith to drain into cracks and voids, leaving the blocks exposed. Because bare spots on the Moon get covered over fairly quickly, this cracking must be quite recent, possibly even ongoing today. They refer to what they’ve found as ANTS, for Active Nearside Tectonic System.

The researchers believe that the ANTS was actually set in motion billions of years ago with a giant impact on the Moon’s farside. In previous studies, Schultz and a co-worker proposed this impact, which formed the 1500-mile South Pole Aitken Basin, shattered the interior on the opposite side, the nearside facing the Earth. Magma then filled these cracks and controlled the pattern of dikes detected in the GRAIL mission. The blocky ridges comprising the ANTS now trace the continuing adjustments along these ancient weaknesses.

“This looks like the ridges responded to something that happened 4.3 billion years ago,” Schultz said. “Giant impacts have long lasting effects. The Moon has a long memory. What we’re seeing on the surface today is testimony to its long memory and secrets it still holds.”

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One small grain of moon dust, one giant leap for lunar studies

Back in 1972, NASA sent their last team of astronauts to the Moon in the Apollo 17 mission. These astronauts brought some of the Moon back to Earth so scientists could continue to study lunar soil in their labs. Since we haven’t returned to the Moon in almost 50 years, every lunar sample is precious. We need to make them count for researchers now and in the future. In a new study in Meteoritics & Planetary Science, scientists found a new way to analyze the chemistry of the Moon’s soil using a single grain of dust. Their technique can help us learn more about conditions on the surface of the Moon and formation of precious resources like water and helium there.

“We’re analyzing rocks from space, atom by atom,” says Jennika Greer, the paper’s first author and a PhD student at the Field Museum and University of Chicago. ” It’s the first time a lunar sample has been studied like this. We’re using a technique many geologists haven’t even heard of.

“We can apply this technique to samples no one has studied,” Philipp Heck, a curator at the Field Museum, associate professor at the University of Chicago, and co-author of the paper, adds. “You’re almost guaranteed to find something new or unexpected. This technique has such high sensitivity and resolution, you find things you wouldn’t find otherwise and only use up a small bit of the sample.”

The technique is called atom probe tomography (APT), and it’s normally used by materials scientists working to improve industrial processes like making steel and nanowires. But its ability to analyze tiny amounts of materials makes it a good candidate for studying lunar samples. The Apollo 17 sample contains 111 kilograms (245 pounds) of lunar rocks and soil — the grand scheme of things, not a whole lot, so researchers have to use it wisely. Greer’s analysis only required one single grain of soil, about as wide as a human hair. In that tiny grain, she identified products of space weathering, pure iron, water and helium, that formed through the interactions of the lunar soil with the space environment. Extracting these precious resources from lunar soil could help future astronauts sustain their activities on the Moon.

To study the tiny grain, Greer used a focused beam of charged atoms to carve a tiny, super-sharp tip into its surface. This tip was only a few hundred atoms wide — for comparison, a sheet of paper is hundreds of thousands of atoms thick. “We can use the expression nanocarpentry,” says Philipp Heck. “Like a carpenter shapes wood, we do it at the nanoscale to minerals.”

Once the sample was inside the atom probe at Northwestern University, Greer zapped it with a laser to knock atoms off one by one. As the atoms flew off the sample, they struck a detector plate. Heavier elements, like iron, take longer to reach the detector than lighter elements, like hydrogen. By measuring the time between the laser firing and the atom striking the detector, the instrument is able to determine the type of atom at that position and its charge. Finally, Greer reconstructed the data in three dimensions, using a color-coded point for each atom and molecule to make a nanoscale 3D map of the Moon dust.

It’s the first time scientists can see both the type of atoms and their exact location in a speck of lunar soil. While APT is a well-known technique in material science, nobody had ever tried using it for lunar samples before. Greer and Heck encourage other cosmochemists to try it out. “It’s great for comprehensively characterizing small volumes of precious samples,” Greer says. “We have these really exciting missions like Hayabusa2 and OSIRIS-REx returning to Earth soon — uncrewed spacecrafts collecting tiny pieces of asteroids. This is a technique that should definitely be applied to what they bring back because it uses so little material but provides so much information.”

Studying soil from the moon’s surface gives scientists insight into an important force within our Solar System: space weathering. Space is a harsh environment, with tiny meteorites, streams of particles coming off the Sun, and radiation in the form of solar and cosmic rays. While Earth’s atmosphere protects us from space weathering, other bodies like the Moon and asteroids don’t have atmospheres. As a result, the soil on the Moon’s surface has undergone changes caused by space weathering, making it fundamentally different from the rock that the rest of the Moon is composed of. It’s kind of like a chocolate-dipped ice cream cone: the outer surface doesn’t match what’s inside. With APT, scientists can look for differences between space weathered surfaces and unexposed moon dirt in a way that no other method can. By understanding the kinds of processes that make these differences happen, they can more accurately predict what’s just under the surface of moons and asteroids that are too far away to bring to Earth.

Because Greer’s study used a nanosized tip, her original grain of lunar dust is still available for future experiments. This means new generations of scientists can make new discoveries and predictions from the same precious sample. “Fifty years ago, no one anticipated that someone would ever analyze a sample with this technique, and only using a tiny bit of one grain,” Heck states. “Thousands of such grains could be on the glove of an astronaut, and it would be sufficient material for a big study.”

Greer and Heck emphasize the need for missions where astronauts bring back physical samples because of the variety of terrains in outer space. “If you only analyze space weathering from the one place on the Moon, it’s like only analyzing weathering on Earth in one mountain range,” Greer says. We need to go to other places and objects to understand space weathering in the same way we need to check out different places on Earth like the sand in deserts and outcrops in mountain ranges on Earth.”

We don’t yet know what surprises we might find from space weathering. “It’s important to understand these materials in the lab so we understand what we’re seeing when we look through a telescope,” Greer says. “Because of something like this, we understand what the environment is like on the Moon. It goes way beyond what astronauts are able to tell us as they walk on the Moon. This little grain preserves millions of years of history.

The results from this study convinced NASA to fund the Field Museum and Northwestern team and colleagues from Purdue for the next three years to study different types of lunar dust with APT to quantify its water content and to study other aspects of space weathering.

Funding for this work was provided by the TAWANI Foundation, the National Science Foundation, the Office of Naval Research, Northwestern University and the Field Museum’s Science and Scholarship Funding Committee.

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IEEE Spectrum

NASA Begins Testing Next Moon Rover

NASA has decided that humans are going back to the Moon. That’s great! Before that actually happens, a whole bunch of other things have to happen, and excitingly, many of those things involve robots. As a sort of first-ish step, NASA is developing a new lunar rover called VIPER (Volatiles Investigating Polar Exploration Rover). VIPER’s job is to noodle around the permanently shaded craters at the Moon’s south pole looking for water ice, which can (eventually) be harvested and turned into breathable air and rocket fuel.


How moon jellyfish get about

With their translucent bells, moon jellyfish (Aurelia aurita) move around the oceans in a very efficient way. Scientists at the University of Bonn have now used a mathematical model to investigate how these cnidarians manage to use their neural networks to control their locomotion even when they are injured. The results may also contribute to the optimization of underwater robots. The study has already been published online in the journal eLife; the final version will appear soon.

Moon jellyfish (Aurelia aurita) are common in almost all oceans. The cnidarians move about in the oceans with their translucent bells, which measure from three to 30 centimeters. “These jellyfish have ring-shaped muscles that contract, thereby pushing the water out of the bell,” explains lead author Fabian Pallasdies from the Neural Network Dynamics and Computation research group at the Institute of Genetics at the University of Bonn.

Moon jellyfish are particularly efficient when it comes to getting around: They create vortices at the edge of their bell, which increase propulsion. Pallasdies: “Furthermore, only the contraction of the bell requires muscle power; the expansion happens automatically because the tissue is elastic and returns to its original shape.”

Jellyfish for research into the origins of the nervous system

The scientists of the research group have now developed a mathematical model of the neural networks of moon jellyfish and used this to investigate how these networks regulate the movement of the animals. “Jellyfish are among the oldest and simplest organisms that move around in water,” says the head of the research group, Prof. Dr. Raoul-Martin Memmesheimer. On the basis of them and other early organisms, the origins of the nervous system will now be investigated.

Especially in the 50s and 80s of the last century, extensive experimental neurophysiological data were obtained on jellyfish, providing the researchers at the University of Bonn with a basis for their mathematical model. In several steps, they considered individual nerve cells, nerve cell networks, the entire animal and the surrounding water. “The model can be used to answer the question of how the excitation of individual nerve cells results in the movement of the moon jellyfish,” says Pallasdies.

The jellyfish can perceive their position with light stimuli and with a balance organ. If a moon jellyfish is turned by the ocean current, the animal compensates for this and moves further to the water surface, for example. With their model, the researchers were able to confirm the assumption that the jellyfish uses one neural network for swimming straight ahead and two for rotational movements.

Wave-shaped propagation of the excitation

The activity of the nerve cells spreads in the jellyfish’s bell in a wave-like pattern. As experiments from the 19th century already show, the locomotion even works when large parts of the bell are injured. Scientists at the University of Bonn are now able to explain this phenomenon with their simulations: “Jellyfish can pick up and transmit signals on their bell at any point,” says Pallasdies. When one nerve cell fires, the others fire as well, even if sections of the bell are impaired.

However, the wave-like propagation of the excitation in the jellyfish’s bell would be disrupted if the nerve cells fired randomly. As the researchers have now discovered on the basis of their model, this risk is prevented by the nerve cells not being able to become active again so quickly after firing.

The scientists hope that further research will shed light on the early evolution of the neural networks. At present, underwater robots are also being developed that move on the basis of the swimming principle of jellyfish. Pallasdies: “Perhaps our study can also help to improve the autonomous control of these robots.”

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IEEE Spectrum

Aerospace Companies Compete to Build Lunar Landers for NASA’s Project Artemis

After 50 years of lamenting that America had abandoned the moon, astronauts are in a rush again, trying to go back within five—and NASA has asked aerospace companies to design the lunar landers that will get them there. The project is called Artemis, and the agency is now reviewing proposals to build what it calls the Human Landing System, or HLS. In January, it says, it will probably select finalists.

NASA had said a landing was possible by 2028. Then, the White House said to do it by 2024.

“Urgency must be our watchword,” said U.S. Vice President Mike Pence when he announced the new deadline in March 2019. “Now, let’s get to work.”


NASA’s treasure map for water ice on Mars

NASA has big plans for returning astronauts to the Moon in 2024, a stepping stone on the path to sending humans to Mars. But where should the first people on the Red Planet land?

A new paper published in Geophysical Research Letters will help by providing a map of water ice believed to be as little as an inch (2.5 centimeters) below the surface.

Water ice will be a key consideration for any potential landing site. With little room to spare aboard a spacecraft, any human missions to Mars will have to harvest what’s already available for drinking water and making rocket fuel.

NASA calls this concept “in situ resource utilization,” and it’s an important factor in selecting human landing sites on Mars. Satellites orbiting Mars are essential in helping scientists determine the best places for building the first Martian research station. The authors of the new paper make use of data from two of those spacecraft, NASA’s Mars Reconnaissance Orbiter (MRO) and Mars Odyssey orbiter, to locate water ice that could potentially be within reach of astronauts on the Red Planet.

“You wouldn’t need a backhoe to dig up this ice. You could use a shovel,” said the paper’s lead author, Sylvain Piqueux of NASA’s Jet Propulsion Laboratory in Pasadena, California. “We’re continuing to collect data on buried ice on Mars, zeroing in on the best places for astronauts to land.”

Buried Treasure on Mars

Liquid water can’t last in the thin air of Mars; with so little air pressure, it evaporates from a solid to a gas when exposed to the atmosphere.

Martian water ice is locked away underground throughout the planet’s mid-latitudes. These regions near the poles have been studied by NASA’s Phoenix lander, which scraped up ice, and MRO, which has taken many images from space of meteor impacts that have excavated this ice. To find ice that astronauts could easily dig up, the study’s authors relied on two heat-sensitive instruments: MRO’s Mars Climate Sounder and the Thermal Emission Imaging System (THEMIS) camera on Mars Odyssey.

Why use heat-sensitive instruments when looking for ice? Buried water ice changes the temperature of the Martian surface. The study’s authors cross-referenced temperatures suggestive of ice with other data, such as reservoirs of ice detected by radar or seen after meteor impacts. Data from Odyssey’s Gamma Ray Spectrometer, which is tailor-made for mapping water ice deposits, were also useful.

As expected, all these data suggest a trove of water ice throughout the Martian poles and mid-latitudes. But the map reveals particularly shallow deposits that future mission planners may want to study further.

Picking a Landing Site

While there are lots of places on Mars scientists would like to visit, few would make practical landing sites for astronauts. Most scientists have homed in on the northern and southern mid-latitudes, which have more plentiful sunlight and warmer temperatures than the poles. But there’s a heavy preference for landing in the northern hemisphere, which is generally lower in elevation and provides more atmosphere to slow a landing spacecraft.

A large portion of a region called Arcadia Planitia is the most tempting target in the northern hemisphere. The map shows lots of blue and purple in this region, representing water ice less than one foot (30 centimeters) below the surface; warm colors are over two feet (60 centimeters) deep. Sprawling black zones on the map represent areas where a landing spacecraft would sink into fine dust.

What’s Next?

Piqueux is planning a comprehensive campaign to continue studying buried ice across different seasons, watching how the abundance of this resource changes over time.

The more we look for near-surface ice, the more we find,” said MRO Deputy Project Scientist Leslie Tamppari of JPL. “Observing Mars with multiple spacecraft over the course of years continues to provide us with new ways of discovering this ice.”

JPL manages the MRO and Mars Odyssey missions for NASA’s Science Mission Directorate in Washington. Lockheed Martin Space in Denver built both orbiters. JPL built and operates the Mars Climate Sounder instrument. THEMIS was built and is operated by Arizona State University in Tempe. The Gamma Ray Spectrometer was built and is operated by the University of Arizona in Tucson.

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