News Feeds

Five days ago I posted a tweet from Richard Dawkins, saying that his Facebook account had been suspended because he had tweeted that Olympic boxers who were biologically male (both of whom have since won gold medals in the welterweight and 57 kg category) should not be boxing in the women’s event.

Here’s his tweet:

Because there didn’t seem to be absolute proof that this was the reason his FB account was suspended, I asked him about this, and he gave me the story, which he’s now posted on his Substack site.

In short, Dawkins was wrong—Facebook said his account had been suspended because it was hacked and had simply been taken down for some kind of repairs, perhaps to strengthen the anti-hacking features. At any rate, he apologized for criticizing Facebook. And I, of course, must also apologize for reproducing what he said because that claim was erroneous. I didn’t do due diligence.

Here’s Dawkins’s apology (click to read)

And here’s the text of his explanation and apology (my bolding):

On July 30th my Facebook account was closed down, with no reason given. Associates of mine got in touch with a kind lawyer (@Steinhoefel), very experienced in exactly this kind of case, and he offered, pro bono, to negotiate with Facebook on my behalf. I appreciated his generosity and accepted his offer. He approached Facebook and received no reply.

Because no reason was given for the shut-down, and no reply to the lawyer’s overtures, I am sorry to say we jumped to the wrong conclusion: might it have some connection with my contemporaneous stand against genetically male boxers fighting women in the Olympics? I then tweeted what turned out to be a false suspicion of Facebook’s motives, and I deeply regret this.

On August 10th , I received an e-mail from an official at Facebook, saying he was looking into the question. He sent me a second e-mail the same day giving a full explanation. Facebook’s records showed, he explained, that one of the admins with access to my account had been hacked as long ago as June 22nd, and the hacker added “a flurry of unauthorized admins”. Their subsequent behaviour alerted Facebook, who closed the account down while they worked on the problem. My Facebook account was restored on August 11th , and I am very grateful.

We knew none of this until August 10 th, eleven days after the account was shut down. Now I am left in the mortifying position of having unjustly imputed an ignoble motive to Facebook. I must say it’s a pity that whoever decided to close my account (certainly not the kind official who eventually was brought in to investigate the problem) omitted to get in touch at the time. Nevertheless I accept responsibility, and publish this to correct the record and apologise.

This is the way a scientist should behave, admitting that he jumped to conclusions, even though he did initially float the possibility that his account hadn’t been taken down because of his tweets. (What made me wary was that I didn’t understand why a Facebook account should be closed because of something said on another and rival platform: Twitter).

Of course the Dawkins haters won’t accept this apology nor acknowledge the gracious admission of error, but how many people on the internet ever admit that they were wrong?

And I too, as I said, must share in this apology. I was wrong to post Dawkins’s tweet without thorough checking, and I accept Facebook’s explanation.

Finally, note that Richard does not retract the implication that there were biologically male boxers competing against women in the Olympics.  I don’t retract what I said, either: that the likelihood is that at least two such boxers were unfairly competing against women in the Olympics. More and more evidence is accumulating that these boxers were indeed XY males, perhaps with a disorder of sex development (see posts by Emma Hilton, Colin Wright, and Carole Hooven).

AI companies hope that feeding ever more data to their models will continue to boost performance, eventually leading to human-level intelligence. Behind this hope is the "transformer", a key breakthrough in AI, but what happens if it fails to deliver?

Should we be concerned about new research linking sugar alcohols like xylitol and erythritol?

The post Are dietary sugar alcohol sweeteners safe? first appeared on Science-Based Medicine.

Congressional hearings about free speech and anti-semitism at Penn, Harvard, MIT and Columbia have now resulted in the resignation of the third of these Presidents. Yes, Columbia President Nemat Shafik, following Presidents Claudine Gay of Harvard and Liz Magill of Penn out the door, has resigned her post. President  President Sally Kornbluth of MIT remains in her job.

The brouhaha began last December when, facing two House panels, three Presidents said that in some cases, depending on context, calls for genocide of the Jews might not violate university regulations. Indeed, this was correct according to a First-Amendment construal of this kind of speech. The problem was that these universities, purporting to adhere to the First Amendment, didn’t really do so for other kinds of speech, so they were really guilty of hypocritical and unequal enforcement.  And their presentations on the Hill were stiff and unempathic. Shafik, grilled this April, angered those who said she’d done very little to curb antisemitism on her campus.

Further, Claudine Gay was later accused of serious and multiple incidents of plagiarism, and, in light of all the bad publicity, Harvard gave Gay the boot. Harvard now has now an interim President, Alan Garber, who will run Harvard for the next two years while it looks for a permanent President.

Click below to read the story. Shafik proved hamhanded in the face of pro-Palestinian and antisemitic behavior on campus, with apparently no students being disciplined, including those who stormed and occupied a Columbia building.

Click to read:

An excerpt:

Columbia University’s president, Nemat Shafik, resigned on Wednesday after months of far-reaching fury over her handling of pro-Palestinian demonstrations and questions over her management of a bitterly divided campus.

She was the third leader of an Ivy League university to resign in about eight months following maligned appearances before Congress about antisemitism on their campuses.

Dr. Shafik, an economist who spent much of her career in London, said in a letter to the Columbia community that while she felt the campus had made progress in some important areas, it had also been a period of turmoil “where it has been difficult to overcome divergent views across our community.”

What she means is that she can’t manage to stop violations of campus rules for encampment and behavior by pro-Palestinian students. This is because Columbia won’t discipline violators.  A lot of the lack of discipline stems from the attitudes of Columbia faculty, many of whom supported the illegal protests and called for Shafik’s resignation after she called the police to dismantle the local encampment. Caught between Jewish faculty and students on one hand and pro-Palestinian faculty on the other, Shafik was rendered powerless. More:

She added that her resignation was effective immediately, and that she would be taking a job with Britain’s foreign secretary to lead a review of the government’s approach to international development.

The university’s board of trustees named Dr. Katrina A. Armstrong, a medical doctor who has been the chief executive of Columbia’s medical center and dean of its medical school since 2022, as the interim president. The board did not immediately announce a timeline for appointing a permanent leader.

. . . But as much as its sudden end, the brevity of Dr. Shafik’s presidency underscores how profoundly pro-Palestinian demonstrations shook her campus and universities across the country.

Facing accusations that she was permitting antisemitism to go unchecked on campus, Dr. Shafik made a conciliatory appearance before Congress in April that ended up enraging many members of her own faculty. She summoned the police to Columbia’s campus twice, including to clear an occupied building. The moves angered some students and faculty, even as others in the community, including some major donors, said she had not done enough to protect Jewish students on campus.

Dr. Shafik’s tenure was among the shortest in Columbia’s 270-year history, and much of it was a sharp reminder of the challenges facing university presidents, who have sometimes struggled recently to lead upended campuses while balancing student safety, free speech and academic freedom.

Few university leaders were as publicly linked to that dilemma as Dr. Shafik, whose school emerged as a hub of the campus protests that began after the Israel-Hamas war erupted last year.

Those protests, as well as accusations of endemic antisemitism, drew the attention of House Republicans, who orchestrated a series of hearings in Washington starting last year.

But make no mistake about it: the protests will continue this next academic year at Columbia and at other schools. The war in Gaza continues, and Israel is still demonized by many academics (remember that the American Association of University Professors just eliminated their two-decade opposition to academic boycotts, undoubtedly to allow boycotts of Israel).

And so Columbia has a color-coded system to indicate the degree of protest occurring on the campus. This is ridiculous:

To prepare for the possibility of renewed protests in the fall, the university announced a new color-coded system to guide the community on protest risk level on campus, similar to a Homeland Security advisory system. The level was recently set from Green to Orange [JAC: there’s also red], the second-highest, meaning “moderate risk.” Only people with Columbia identification are permitted to enter the central campus, which in the past has been open to the public.

College protesters have vowed to come back stronger than ever to push their main demand that Columbia divest from weapons manufacturers and other companies that profit from the occupation of Palestinian territories.

“Regardless of who leads Columbia, the students will continue their activism and actions until Columbia divests from Israeli apartheid,” said Mahmoud Khalil, a student negotiator on behalf of Columbia University Apartheid Divest, the main protest movement. “We want the president to be a president for Columbia students, answering to their needs and demands, rather than answering to political pressure from outside the university.”

I doubt that Columbia, like Chicago and many other schools, will agree to divest, for that is eliminating institutional neutrality in the investment of college funds. As so long as there are calls for divestment, and the universities refuse to divest, the protests will continue.  Coming this fall: Code Red, when almost nobody will be allowed on Columbia’s campus.

Of course free speech, along the lines of the Chicago Prnciples, should reign at all campuses, but there should also be time, place, and manner restrictions so that speech doesn’t impede the functioning of the university (e.g. deplatforming speakers, sit-ins in campus buildings, use of bullhorns during class).  So far these restrictions have largely been ignored by schools like Columbia, loath to have officials or police “lay hands” on protestors since that creates bad “optics.”. But if these illegal protests continue, then we can kiss higher education in America goodbye.  But who cares? The pro-Palestinian protestors aren’t interested in holding universities to their mission. Rather, they want to bend universities to their own ideology, and many, in the end, want to efface the principles of Western democracy.

Experiments in a wind tunnel have revealed why the sling action bowling technique made famous by Sri Lankan cricketer Lasith Malinga is so effective at hoodwinking whoever is batting

Meanwhile, in Dobrzyn, Hili is disgruntled:

A: Why are you lying here? Hili: As an expression of civil protest.

Ja: Czemu tu leżysz?
Hili: W ramach obywatelskiego protestu.

The idea of terraforming Mars, making its atmosphere and environment more Earth-like for human settlement, goes back decades. During that time, many proposed methods have been considered and put aside as “too expensive” or requiring technology well in advance of what we have today. Nevertheless, the idea has persisted and is often considered a part of long-term plans for establishing a human presence on Mars. Given the many plans to establish human outposts on the Moon and then use that infrastructure to send missions to Mars, opportunities for terraforming may be closer than we think.

Unfortunately, any plans for terraforming Mars suffer from unresolved hurdles, not the least of which are the expense, distance, and the need for technologies that don’t currently exist. Triggering a greenhouse effect and warming the surface of Mars would take massive amounts of greenhouse gases, which would be very difficult and expensive to transport. However, a team of engineers and geophysicists led by the University of Chicago proposed a new method for terraforming Mars with nanoparticles. This method would take advantage of resources already present on the Martian surface and, according to their feasibility study, would be enough to start the terraforming process.

The team was led by Samaneh Ansari, a postdoctoral student at the Department of Electrical and Computer Engineering (ECE) at Northwestern University. She was joined by Edwin Kite, an Assistant Professor of Geophysical Sciences at the University of Chicago; Ramses Ramirez, an Assistant Professor with the Department of Physics at the University of Central Florida; Liam J. Steele, a former postdoctoral researcher at UChicago, now with the European Center for Medium-Range Weather Forecasts (ECMWF), and Hooman Mohseni, a Professor of ECE at Northwestern (and Ansari’s postdoc advisor).

As addressed in previous articles, the process of terraforming Mars comes down to a few steps, all of which are complementary. This is to say, progress made in one area will invariably have a positive effect on another. Those steps include:

1. Warming the planet
2. Thickening the atmosphere
3. Melting the water ice

By warming the planet, the polar ice caps and permafrost would melt, releasing liquid water onto the surface and as vapor into the atmosphere. The abundant amounts of dry ice in both ice caps (especially in the southern hemisphere) would also be released, thickening the atmosphere and warming it further. As Robert Zubrin argued in The Case for Mars, this would lead to an atmospheric pressure (atm) of about 300 millibars (30% of Earth’s atm at sea level), which would allow for people to stand outside on the surface without a pressure suit (though they would still need warm clothing and bottled oxygen).

In the past, proposals for terraforming Mars have recommended that the first step be achieved by triggering a greenhouse effect, most notably by introducing additional greenhouse gases. Examples include additional carbon dioxide, methane, ammonia, and chlorofluorocarbons, which would either need to be mined on Mars or imported from Earth (or Venus, Titan, and the outer Solar System). Unfortunately, these options would require a fleet of spacecraft making two-way trips to Mars, Venus, or the outer Solar System and/or heavy mining operations on Mars.

In contrast, the proposal put forth by Ansari and her colleagues involves using engineered dust particles fashioned from local minerals*. Thanks to missions like Curiosity and Perseverance, which have obtained multiple samples of rock and soil for analysis, we know that dust grains on Mars are rich in iron and aluminum. When fashioned into conductive nanorods measuring about 9 micrometers long – the width of a very thin human hair – and arranged in different configurations, these particles could released into the atmosphere, where they would absorb and scatter sunlight.

Image taken by the Viking 1 orbiter in June 1976, showing Mars’ thin atmosphere and dusty, red surface. Credits: NASA/Viking 1

To determine the extent to which these particles would affect Mars’ atmosphere, the team conducted simulations using the Quest high-performance computing cluster at Northwestern University and the Midway 2 computing cluster at the University of Chicago Research Computing Center (RCC). Based on a 10-year particle lifetime, two climate models were simulated where 30 liters (7.9 gallons) of nanoparticles per second were consistently launched into the atmosphere. Their results indicate that this process would warm Mars by more than 30 °C (86 °F), enough to trigger the melting of the polar ice caps.

Based on their simulations, the team found that their method is over 5,000 times more efficient than previous proposals to trigger a greenhouse effect on Mars. In addition, the average temperature increase would make the Martian environment suitable for microbial life, which is vital for plans to ecologically transform Mars. Through the introduction of photosynthetic bacteria (like cyanobacteria), atmospheric carbon dioxide could be slowly converted into oxygen gas. This is precisely how oxygen became an integral part of Earth’s atmosphere, starting 3.5 billion years ago.

As Kite indicated in a UChicago News story, this method would still take decades but would be logistically easier and much cheaper than current plans to terraform Mars:

“This suggests that the barrier to warming Mars to allow liquid water is not as high as previously thought. You’d still need millions of tons to warm the planet, but that’s five thousand times less than you would need with previous proposals to globally warm Mars. This significantly increases the feasibility of the project. This suggests that the barrier to warming Mars to allow liquid water is not as high as previously thought.”

Naturally, a lot of additional research needs to be done before such a method can be field-tested on Mars. Not the least of which are the unresolved questions of how the particles will be affected by atmospheric changes on Mars. Currently, Mars experiences cloud formation and precipitation in the form of dry ice condensing in the atmosphere and falling back toward the surface as CO2 snow. Once the polar ice caps are melted, Mars could experience more cloud cover and precipitation involving water, which could condense around the particles, causing them to fall back to the surface in raindrops.

This artist’s impression shows how Mars may have looked about four billion years ago when much of its surface was covered in liquid water. Credit: ESO/M. Kornmesser

This and other potential climate feedback mechanisms could lead to a myriad of problems. But one of the best aspects of this proposed method is its reversibility. Simply stop producing and releasing the particles into the atmosphere, and the warming effect will end with time. What’s more, the focus of the study only extends to warming the atmosphere to the extent that microbial life could live there and food crops eventually planted. Nevertheless, this study offers terraforming enthusiasts a viable and more affordable option for getting the ball rolling on the whole “Greening of Mars” process. Said Kite:

“Climate feedbacks are really difficult to model accurately. To implement something like this, we would need more data from both Mars and Earth, and we’d need to proceed slowly and reversibly to ensure the effects work as intended. This research opens new avenues for exploration and potentially brings us one step closer to the long-held dream of establishing a sustainable human presence on Mars.”

As the saying goes, “A journey of a thousand miles begins with a single step.” In this case, the first step is perhaps the most daunting, comparable only to the challenges of ensuring that changes in Mars’ climate are maintained in the long run. By offering future generations a viable and (comparatively) cost-effective option, we might achieve the dream of making Mars hospitable to terrestrial life!

*This process is known as In-Situ Resource Utilization (ISRU), a major component of NASA’s Moon to Mars mission architecture and other plans to create a permanent human presence on the Moon and Mars in the coming decades.

Further Reading: University of Chicago News, Nature Advances

The post New Study Shows Mars Could be Terraformed Using Resources that are Already There appeared first on Universe Today.

Many people in a coma seem to think about complex tasks when instructed, which suggests they are aware of what is going on around them

The remarkable affinity of the microbial enzyme iron nitrogenase for the greenhouse gas CO2 makes it promising for future biotechnologies.

A new brain-computer interface translates brain signals into speech with up to 97 percent accuracy. Researchers implanted sensors in the brain of a man with severely impaired speech due to amyotrophic lateral sclerosis (ALS). The man was able to communicate his intended speech within minutes of activating the system.

A new brain-computer interface translates brain signals into speech with up to 97 percent accuracy. Researchers implanted sensors in the brain of a man with severely impaired speech due to amyotrophic lateral sclerosis (ALS). The man was able to communicate his intended speech within minutes of activating the system.

With 2D cameras and space robotics algorithms, astronautics engineers have created a navigation system able to manage multiple satellites using visual data only. They just tested it in space for the first time.

With 2D cameras and space robotics algorithms, astronautics engineers have created a navigation system able to manage multiple satellites using visual data only. They just tested it in space for the first time.

With 2D cameras and space robotics algorithms, astronautics engineers have created a navigation system able to manage multiple satellites using visual data only. They just tested it in space for the first time.

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.