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A new milestone has been set for levitated optomechanics as a group of scientists observed the Berry phase of electron spins in nano-sized diamonds levitated in vacuum.

Scientists recently discovered a one-dimensional nanoscale material whose color changes as temperature changes.

Scientists recently discovered a one-dimensional nanoscale material whose color changes as temperature changes.

A new study has found galaxies with more neighbors tend to be larger than their counterparts that have a similar shape and mass, but reside in less dense environments. The team, which used a machine-learning algorithm to analyze millions of galaxies, reports that galaxies found in denser regions of the universe are as much as 25% larger than isolated galaxies. The findings resolve a long-standing debate among astrophysicists over the relationship between a galaxy's size and its environment, but also raise new questions about how galaxies form and evolve over billions of years.

Many times, it’s better to flesh out technologies fully on Earth’s surface before they’re used in space. That is doubly true if that technology is part of the critical infrastructure keeping astronauts alive on the Moon. Since that infrastructure will undoubtedly use in-situ resources – known as in-situ resource utilization (ISRU) – developing test beds here on Earth for those ISRU processes is critical to derisking the technologies before they’re used on a mission. That’s the plan with a test bed designed by researchers at the German Aerospace Center in Bremen – they designed it to improve how well we gather water and oxygen from lunar regolith. Unfortunately, as their work described in a recent paper demonstrates, it will be a challenge to do so.

Water and oxygen are two critical components of any long-term lunar exploration plan. One of the best sources for that on the Moon, other than water ice that might only be available at specific locations, is a mineral called ilmenite. Ilmenite is a combination of iron, titanium, and oxygen—FeTiO3. It’s also the most accessible material to split into its parts using a relatively low-energy chemical reaction with elemental hydrogen as a feedstock. 

After reducing ilmenite with hydrogen, the resulting elements are iron (useful for building materials), titanium dioxide (useful for optical coatings), and water (useful for plenty of things). A further step could reduce the water to oxygen (again, useful for many things, including breathing) and hydrogen, which can be recycled back into the feedstock system for the following processing round. So, in the end, if you have ilmenite, you have access to cheap building materials, rocket fuel, and gas for breathing.

Ilmenite is also mined here on Earth – here’s a model beneficiation plant.
Credit – Christian George

Unfortunately, ilmenite is not particularly common on the lunar surface. While it is somewhat plentiful in the mare regions, it is much less so in the highlands where the first permanent lunar outposts are planned. So, explorers will need a technological solution to find more ilmenite – or at least concentrate it to levels where subjecting it to the reduction process would be energy efficient.

That’s where beneficiation comes in. It is the process of separating valuable materials, such as ilmenite, from the “chaff” that makes up most of the lunar regolith – the most easily accessible resource on the Moon. Given a lack of readily available lunar regolith, the researchers used a regolith simulant when putting their test bed through its paces. That testbed consists of three machines for three main processes: gravitational, magnetic, and electrostatic beneficiation, and the paper goes into detail about each of them.

Before any testing, the regolith simulants were dried for upwards of 48 hours at a temperature of 80 C. Afterwards, they were stored in a sealed container to prevent any additional moisture from entering the system.

Fraser talks about in-situ resource utilization – mining and beneficiating ilmenite is one way of doing so

The gravitational process uses a feeder, which is fed 300g of dried simulant for every test run, and a sieve, which separates particles that are more than 200 micrometers in size. Studies from samples collected by Apollo astronauts showed that most ilmenite grains ranged from about 45-75 micrometers, so most of the ilmenite should make it past this stage. At the same time, larger particles that could hinder the performance of the rest of the system are weeded out.

Next up is the magnetic separator – ilmenite is weakly magnetic due to its iron content and, as such, can be separated from non-magnetic material of a similar density by subjecting it to a magnetic field. The magnetic field is directed such that it would push the particles of ilmenite out of a straight line when falling, directing them into a different hopper. Non-magnetic materials of a similar size would fall directly down and be filtered out by the system.

Finally, the remaining magnetic particles are subjected to massive electric fields using an electrostatic parallel plate separator. Typically used in the oil and gas industry, these devices introduce a gigantic electric field that suspends some particles, slowing their descent and making it possible to sort out materials with specific electrical properties. Characterizing the most effective way to utilize this step was a major focal point of the study.

Isaac Arthur discusses how to mine and refine lunar resources.
Credit – Isaac Arthur YouTube Channel

After all that sifting and sorting, ideally, the users would end up with all the ilmenite in the sample and nothing else, but that doesn’t happen in practice. Realistically, some of the ilmenite present in the sample would be lost as part of the filtering process, and some non-ilmenite particles make their way to the final collection point despite all the various methods to get rid of them. 

In this experiment, the final mixture was about 12% ilmenite by weight, compared to 2.55% before it was beneficiated. The system also recovered around 32% of the total ilmenite available in the sample, and it took about half an hour to run a full 300g sample through the test bed. Further iterations could improve all those numbers – that is what test beds are for. This is only one of numerous steps that have to happen to finally make use of some of the more valuable resources on the Moon. The quicker we’re able to, the better.

Learn More:
Kulkarni et al. – Optimizing lunar regolith beneficiation for ilmenite enrichment
UT – Mysterious Swirls on the Moon Could Be Explained by Underground Magma
UT – Want to Build Structures on the Moon? Just Blast the Regolith With Microwaves
UT – It Should be Possible to Farm on the Moon

Lead Image:
Image of the test bed machine.
Credit – Kulkarni et al.

The post Researchers Developed a Test Bed For Separating Valuable Material on the Moon appeared first on Universe Today.

GPS is ubiquitous on Earth. It guides everything from precision surveying to aircraft navigation. To realize our vision of lunar exploration with a sustained human presence, we’ll need the same precision on the Moon.

That starts with an accurate clock.

The USA’s National Institute of Standards and Technology (NIST) is developing a framework for the precision measurement of lunar time. They’re paving the way for lunar GPS, which could enable the type of precise position finding necessary for lunar navigation and could also contribute to future space missions.

“The proposed framework underpinning lunar coordinate time could eventually enable exploration beyond the Moon and even beyond our solar system.”

Bijunath Patla, physicist, NIST

GPS works because it measures time with extreme precision. Each GPS satellite has an atomic clock. GPS receivers receive signals from multiple GPS satellites at once and then determine their location by the time it takes to receive those signals. All Global Navigation Satellite Systems (GNSS), like the ESA’s Galileo system, work on the same principle.

Future astronauts may use a GPS-like system the same way we use them on Earth. Image Credit: The Ohio State University

But the challenge is creating a lunar GNSS that can coordinate accurately with Earthbound GNSS. Relativity is the sticking point.

Einstein’s relativity tells us that two clocks in different locations will tick at different speeds because of local gravity. An atomic clock on the surface of the Moon would tick faster than one on Earth by about 56 milliseconds per day because gravity is weaker. That’s not a big deal for consumer-level GPS. But when it comes to precision activities like landing a spacecraft, the different clock speed is a problem.

Relativity also tells us that people on Earth experience time differently than people on the Moon. Gravity effects from the Moon orbiting Earth and Earth orbiting the Sun can have a pronounced effect on navigation and communications.

The NIST’s solution to these problems is ‘Master Moon Time.’ It would set a temporal reference point for one location on the Moon, and all other locations would refer to it, similar to how the UTC works on Earth.

Earth is divided into time zones based on UTC. This image shows UTC 00:00. All other zones are offset form it. Image Credit: By Theklan – Own work, CC0, https://commons.wikimedia.org/w/index.php?curid=143021774

The Lunar Positioning System (LPS) would consist of a network of high-precision atomic clocks at various locations on the Moon. A fleet of lunar satellites would also contain atomic clocks. All of these precision clocks would provide the time signals needed for precise navigation.

Atomic clocks are precise because they’re based on the oscillations of atoms, often cesium-133, but also using elements like rubidium or hydrogen. In fact, the official definition of a second is based on the oscillation of cesium-133. Their accuracy is extreme: the most accurate ones can keep time to within one second over one billion years.

Cesium-133 clocks can be heavy compared to other types of atomic clocks, so satellites often use rubidium atomic clocks. The GPS system most commonly uses rubidium, but cesium and hydrogen clocks are used, too, depending on requirements. The ESA’s Galileo system uses both rubidium and hydrogen clocks on the same satellite, with the rubidium clocks serving as backups.

The world’s first cesium atomic clock was built at the UK National Physical Laboratory in 1955. Since then, it has been used to define the length of a second. Image: By National Physical Laboratory – http://www.npl.co.uk/upload/img/essen-experiment_1.jpg, Public Domain, https://commons.wikimedia.org/w/index.php?curid=5543813

“It’s like having the entire Moon synchronized to one ‘time zone’ adjusted for the Moon’s gravity, rather than having clocks gradually drift out of sync with Earth’s time,” said NIST physicist Bijunath Patla.

“This work lays the foundation for adopting a navigation and timing system similar to GPS, which would serve near-Earth and Earth-bound users, for lunar exploration,” said NIST physicist Neil Ashby.

NASA and their partners in the Artemis effort intend to eventually develop a sustained presence on the Moon. There are in-situ resources there that can be used to further the effort, things like water ice and rare earth elements.

With that level of activity, the need for precision navigation is obvious. As the level of complexity in all that activity grows, the need for reliable position-finding and navigation will become acute.

“The goal is to ensure that spacecraft can land within a few meters of their intended destination,” Patla said.

Artist’s illustration of a potential Project Artemis lunar lander. Credit: NASA

The Moon will also eventually serve as a staging area or jumping-off point for missions into the Solar System. As that effort takes shape in the coming decades, precision timing will be needed to coordinate complex missions. The researchers say that atomic clocks in satellites at the Lagrange points can be used to transfer times between the Earth and the Moon.

“The proposed framework underpinning lunar coordinate time could eventually enable exploration beyond the Moon and even beyond our solar system,” Patla said. “Once humans develop the capability for such ambitious missions, of course.”

“This understanding also underpins precise navigation in cislunar space and on celestial bodies’ surfaces, thus playing a pivotal role in ensuring the interoperability of various position, navigation, and timing systems spanning from Earth to the Moon and to the farthest regions of the inner solar system,” the authors write in their paper.

The post What Time is it on the Moon? Lunar GPS Needs to Know appeared first on Universe Today.

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