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Throughout Earth’s history, the planet’s surface has been regularly impacted by comets, meteors, and the occasional large asteroid. While these events were often destructive, sometimes to the point of triggering a mass extinction, they may have also played an important role in the emergence of life on Earth. This is especially true of the Hadean Era (ca. 4.1 to 3.8 billion years ago) and the Late Heavy Bombardment, when Earth and other planets in the inner Solar System were impacted by a disproportionately high number of asteroids and comets.

These impactors are thought to have been how water was delivered to the inner Solar System and possibly the building blocks of life. But what of the many icy bodies in the outer Solar System, the natural satellites that orbit gas giants and have liquid water oceans in their interiors (i.e., Europa, Enceladus, Titan, and others)? According to a recent study led by researchers from Johns Hopkins University, impact events on these “Ocean Worlds” could have significantly contributed to surface and subsurface chemistry that could have led to the emergence of life.

The team was led by Shannon M. MacKenzie, a planetary scientist, and her colleagues at Johns Hopkins University Applied Physics Laboratory (JHUAPL). They were joined by researchers from Dartmouth’s Thayer School of Engineering, the University of Western Ontario, Curtin University’s School of Earth and Planetary Sciences, the Planetary Habitability Laboratory (PHL) at UPR at Arecibo, Jacobs Technology, NASA’s Jet Propulsion Laboratory, and the Astromaterials Research and Exploration Science (ARES) at NASA Johnson Space Center. The paper that details their findings recently appeared in The Planetary Science Journal.

Voyager 1 image of Valhalla, a multi-ring impact structure 3,800 km (2,360 mi) in diameter.
Credit: NASA/JPL Exogenesis

As indicated in their paper, impacts from asteroids, comets, and large meteors are more often associated with destruction and extinction-level events. However, multiple lines of evidence indicate that these same types of impacts may have supported the emergence of life on Earth roughly 4 billion years ago. These events not only delivered volatiles (such as water, ammonia, and methane) and organic molecules, but modern research indicates that they also created new substrates and compounds essential to life.

Moreover, they created a variety of environments that were essential to the emergence and sustainment of life on Earth. As they wrote:

“Exogenously delivered materials have been estimated to be an important source of organics on early Earth. Shockwaves could provide the energy for organic synthesis of important precursors like HCN or amino acids. The iron and heat from very large impactors can facilitate the reducing atmospheric conditions necessary for abundant HCN production. Impacts fracture and, in typical terrestrial events, melt the target: the more permeable substrates and excavation of deeper rock layers promote hydrothermal activity and endolithic habitats.”

According to the latest fossilized evidence, the earliest life forms emerged on Earth roughly 4.28 billion years ago. These fossils were recovered from hydrothermal vent precipitates in the Nuvvuagittuq Greenstone Belt in northern Quebec, Canada, confirming that hydrothermal activity played a vital role in the emergence of life on Earth. But what about the many “Ocean Worlds” that reside in the outer Solar System? This includes bodies like Europa, Ganymede, Enceladus, and Titan, as well as Uranus’ moons Ariel and Titania, Neptune’s moon Triton, and Trans-Neptunian bodies like Pluto, Charon, and possibly more.

Ocean Worlds

This term refers to bodies predominantly composed of volatile elements such as water and differentiated between an icy crust and a rocky and metallic core. At the core-mantle boundary, tidal flexing (the result of gravitational interaction with another body) causes a buildup of heat and energy released via hydrothermal vents into the ice. This allows these worlds to maintain oceans of liquid water in their interiors. In short, these worlds have all the necessary ingredients for life: water, the requisite chemical compounds, and energy.

Impact velocity and first contact pressure estimates for potential icy and rocky impactors on “Ocean Worlds.” Credit: Mackenzie, S.M. et al. (2024)

Furthermore, data from the NASA/ESA Cassini–Huygens mission confirmed that the plumes regularly erupting from Enceladus’ southern polar region contain organic molecules. Last but not least, the presence of surface craters indicates that these bodies have experienced surface impacts throughout their history. The question naturally arises: could impacts have delivered the necessary building blocks of life to “Ocean Worlds” the same way they delivered them to the inner Solar System? And if so, what does that mean about their potential habitability today? As the team wrote in their paper:

“Impact processes are likely an important part of the answers to these questions, as impacts can drive exchange through the ice crust—either through direct seeding or flushing through the crust—and therefore drive episodic influxes of organic and inorganic materials from the surface and/or from the impactor itself. Impacts can also generate ephemeral microcosms: any liquid water melted during impact freezes out over timescales commensurate with the impact energy.”

“The exciting potential for chemistry within these pockets has been established, from concentrating salts to driving amino acid synthesis. Furthermore, shock-driven chemistry of icy, sometimes organic-rich (in the case of Titan especially) target materials may generate new “seed” compounds (e.g., amino acids or nucleotides) in the melt pool.”

Investigation

The first step for MacKenzie and her team was to investigate the initial shock levels created by the most common impacts for Ocean Worlds—comets that likely originated from the Kuiper Belt and Oort Cloud. To do this, the team calculated the velocities and maximum pressure that would be achieved by impacts involving icy and rocky bodies. They also considered how this would vary based on different families (primary or secondary impacts) and which systems were involved – i.e., Jupiter or Saturn. Whereas primary impacts involve comets or asteroids, secondary impacts are caused by the ejecta they create.

In the case of the Jupiter and Saturn systems, secondary impactors may be icy or rocky depending on where they originated (an icy body like Europa, Enceladus, and Titan, a rocky body like Io and larger asteroids). Whereas primary impacts have higher velocities and produce larger melt volumes), secondary impacts are more frequent. To determine melt sizes, the team consulted observed crater sizes on Europa, Enceladus, and Titan, and dynamic models that calculate the cumulative rate of cratering over time. They then compared the peak pressures at impact to thresholds for the survivability of elements essential to life, organic molecules, amino acids, and even microbes identified in previous studies.

Cumulative cratering rates assuming heliocentric, cometary impactors. Credit: Mackenzie, S.M. et al. (2024)

From this, they determined that most impacts at Europa and Enceladus experience peak pressures greater than what bacterial spores can survive. However, they also determined that a significant amount of material still survives these impacts and that higher first-contact pressures could also facilitate the synthesis of organic compounds in the meltwater that fills the craters. Meanwhile, on average, Titan and Enceladus experienced impacts with lower impact velocities, creating peak pressures that fall within the tolerance range for both bacterial spores and amino acids.

The next step was to consider how long fresh craters would survive and whether this would be sufficient for synthesizing biological materials. Based on the observed crater sizes on Enceladus and Europa, they determined that the longest-lived craters last only a few hundred years, whereas Titan could take centuries to tens of thousands of years for fresh craters to freeze. While Europa and Enceladus experience more high-velocity impacts (due to Titan’s dense atmosphere), the long-lived nature of Titan’s craters means that all three bodies have a chance for organic chemistry experiments to occur.

They also considered resurfacing rates on Europa, Enceladus, and Titan and how these would cycle biological material to their interiors. In all three cases, the satellites have relatively “young” terrain, implying regular resurfacing events.

Results

Based on these considerations, Mackenzie and her team determined that melts produced by comet impacts on Europa, Enceladus, and Titan have been frequent and long-lived enough to be of astrobiological interest. However, this varies based on the composition of the comets and the surface ice in question. As they summarized:

“At Europa and Enceladus, the survival and deposition of impactor organics is more important as there are fewer surface organics within the ice crust to seed the melt pool. On Titan, the survival of elements like phosphorous may be more important. Thus, even the small, more frequent impact events contribute to the astrobiological potential by delivering less modified compounds to the surface that are available either for immediate reaction if melt is produced or for future processing (including in subsequent impact events).”

Total melt production for observed craters on Enceladus (cyan) and Titan (orange), binned by observed crater diameter. Credit: Mackenzie, S.M. et al. (2024)

For instance, they found that a comet impacting Europa at the average impact velocity would create a 15 km (9.3 mi) crater and provide ~1 km3 (0.24 mi3)of meltwater. Based on the abundance of glycine (an essential amino acid) found on the comet 67P Churyumov–Gerasimenko, they determined that several parts per million would survive – roughly three orders of magnitude higher than what has been observed forming around hydrothermal vents here on Earth. “Thus, impactors seed whatever chemistry happens in the melt, providing organic and other essential elements depending on the impactor composition,” they added.

While this does not necessarily mean that these and other “Ocean Worlds” are currently habitable or actively support life, they demonstrate potential for future study. In the coming years, missions like the ESA’s JUpiter ICy moons Explorer (JUICE), and NASA’s Europa Clipper and Dragonfly missions will reach Ganymede, Europa, and Titan (respectively). There are also plans to create an Enceladus Orbiter to pick up where the Cassini-Huygens probe left off by examining Enceladus’ plume activity more closely.

Therefore, conducting in-situ sampling and analysis on these moons could provide powerful insight into prebiotic chemical pathways and determine under what conditions life can emerge. These sample studies will also address the larger question of whether or not life could exist in the interiors of “Ocean Worlds,” providing a preview of what future missions prepared to explore beneath the ice will find.

Further Reading: The Planetary Science Journal

The post Could Comets have Delivered the Building Blocks of Life to “Ocean Worlds” like Europa, Enceladus, and Titan too? appeared first on Universe Today.

When you walk across your lawn or down the street, you move on the surface of a surprisingly layered world. Some of those layers are rock, others are molten. A surprising amount of water is mixed into those layers, as well. It turns out that most planets have more of it “deep down” than we imagined.

Most of a planet’s water isn’t on the surface, even though we see oceans, lakes, and rivers here on Earth. The heart of our planet is iron, and covered by silicate rock layers. Scientists have long used our planet’s makeup as a sort of “model” for rocky exoplanets around other stars. That model may be outdated and too simplistic, according to Professor Caroline Dorn at ETH Zurich. “It is only in recent years that we have begun to realize that planets are more complex than we had thought,” she said. Dorn has been collaborating with Haiyang Luo and Jie Deng from Princeton University to understand the distribution of water mixed with silicates and iron inside a planet. They used computer simulations to come up with a robust model of the distribution of water on exoplanets.

Recent investigations of Earth’s water content triggered the team’s work. It turned out that our oceans contain only a small fraction of the overall water budget. The interior could be hiding the equivalent of 80% of the surface oceans. That raised a big question: could other planets have similarly hidden reservoirs?

Planets and Water

To answer that question, the science team simulated how water behaves in the conditions present when planets are young. Many known exoplanets orbit close to their stars, which means they’re likely to be hot worlds. They probably have oceans of molten magma that haven’t yet solidified to make silicate bedrock mantles.

Artist’s impression of a lava world. The exoplanet K2-141b is so close to its host star that it likely has magma oceans and surface temperatures over 3000 degrees. Water may be mixed in with the magma. c. ESO

As it turns out water dissolves very well in these magma oceans. The iron core takes time to develop,” she said. “A large share of the iron is initially contained in the hot magma soup in the form of droplets,” she explained, noting that water sequestered in this soup combines with the iron droplets and sinks with them to the core. “The iron droplets behave like a lift that is conveyed downwards by the water,” Dorn said.

That kind of mixing of iron and water happened in the moderate pressure environment in Earth’s interior. Larger planets with higher interior pressures presented a challenge to understand. It turns out they mix water and iron, too. “The larger the planet and the greater its mass, the more the water tends to go with the iron droplets and become integrated in the core,” said Dorn. “Under certain circumstances, iron can absorb up to 70 times more water than silicates. However, owing to the enormous pressure at the core, the water no longer takes the form of H2O molecules but is present in hydrogen and oxygen.”

Evolving Planets over Time

This result is a big deal if you want to understand how planets form and develop. That’s because the water never escapes the planet’s core. However, under the right conditions, water mixed in with the magma ocean can “de-gas” under the right conditions. Essentially, it separates and rises to the surface as the magma cools and forms the mantle. “So if we find water in a planet’s atmosphere, there is probably a great deal more in its interior,” explained Dorn.

That gives a lot of new information to use as scientists search for planets around other stars and look for habitable worlds. In particular, astronomers using the JWST can track the types of molecules in exoplanet atmospheres and use that information to find habitable worlds. “Only the composition of the upper atmosphere of exoplanets can be measured directly,” said Dorn. “Our group wishes to make the connection from the atmosphere to the inner depths of celestial bodies.”

TOI-270d appears to be a super-Earth or Earth-type planet, as shown in this artists’ concept. Could it have water hidden in its core that could boost its habitability. Courtesy Martin Vargic CC BY 3.0

Currently, the team studies exoplanet TOI-270d. “Evidence has been collected there of the actual existence of such interactions between the magma ocean in its interior and the atmosphere,” said Dorn. It’s at the top of her list of interesting objects to examine more closely for water, along with another one called K2-18b. It seems to be a promising candidate for habitability as well.

So, Does Deep Water Imply Life or Habitability?

Since water is important in the search for life-bearing worlds, looking for wet Earth-type and super-Earth worlds is the next step in searching out life. Dorn’s team found that planets with these deep water layers are likely to be fairly rare. That’s because most of their water is not on the surface. In other words, they may not be ocean worlds, but places with water trapped in their cores.

That’s not all bad. The science team assumes that even planets with a relatively high water content could have the potential to develop Earth-like habitable conditions. Dorn’s team may give scientists new ways to look for water-abundant worlds.

For More Information

Planets Contain More Water Than Thought
The Interior as the Dominant Water Reservoir in Super-Earths and Sub-Neptunes

The post There’s More Water Inside Planets Than We Thought appeared first on Universe Today.

Popular science history paints a picture of the Greek geocentric model dominating astronomical thought beginning around the 3rd century BCE, and being the favored model for ~1,500 years. Then, suddenly (it suggests), astronomical thought was overhauled at the birth of the Renaissance by brilliant astronomers such as Copernicus, Kepler, and Galileo, all of whom rejected placing the Earth at the center of the cosmos.

But these sources are generally quiet on why this shift occurred. If mentioned at all, sources generally suggest that it was because the Ptolemaic geocentric model was too complicated – overly burdened with epicycle and equants. Heliocentrism, in comparison, was simple – elegant, even.

Yet, Copernicus’ heliocentric model was still rooted in the Greek philosophical principles of uniform circular motion. Thus, it too was forced to adopt many of the complications we’re regularly told were the reason for rejecting Ptolemy’s model – epicycles included.

So, why then, did Copernicus actually turn his back on over 1,500 years of astronomical thought?

The answers are an interesting glimpse into the astronomical paradigm of the 16th century.

To find out Copernicus’ thoughts, we can examine the first book of his masterwork, De Revolutionibus.

The Force Needed to Sustain Geocentrism

The first reason he gives applies to the forces involved:

Surely if [Ptolemy’s reasoning for the geocentric model] were tenable, the magnitude of the heavens would extend infinitely. For the farther the movement is borne upward by the vehement force, the faster will the movement be, on account of the ever-increasing circumference which must be traversed every twenty-four hours.

– Copernicus, De Revolutionibus, Book I, Chapter 8

Copernicus’ writing of De Revolutionibus predated Newton’s Principa by over 140 years. The notion that “an object in motion tends to stay in motion” was, therefore, not yet one in the scientific consciousness.

Instead, natural philosophers believed that the natural tendency of objects was that of rest and the only way an object could be kept in motion was through an application of force.

In the Ptolemaic geocentric model, the Earth did not rotate on an axis. Instead, the stars were all affixed to the surface of a sphere at an immense distance which rotated about the Earth every day along with the rest of the cosmos. Copernicus criticizes the absurd amount of force he supposed would be necessary since, “things to which force or violence is applied get broken up and are unable to subsist for a long time.”

In other words, Copernicus believed that the force that should keep Ptolemy’s geocentric model going would necessarily destroy it.

The heliocentric model avoids this by making the motion of the stars and planets around the sky every night not actual motion, but apparent motion caused by the rotation of the Earth about its poles. This would require a far smaller force since the Earth is smaller than the stellar sphere. Indeed, this completely removes the need for the motion of the stellar sphere, and now the planets and Sun can move far more slowly, and thus would have a much reduced force on them.

To be fair, various astronomers had considered the possibility that the cosmos was geocentric, but did allow for the Earth to rotate on its axis. However, the Ptolemaic cosmos with its static Earth was still the predominant model of the day, which is why Copernicus attacks it with little mention of other authors.

But, if you’re willing to accept that the Earth rotates on its axis, why wouldn’t you accept that it has other motions too?

Early Musings on Gravity

I myself think that gravity or heaviness is nothing except a certain natural appetency implanted in the parts by the divine providence of the universal Artisan, in order that they should unite with one another in their oneness and wholeness and come together in the form of a globe. It is believable that this affect is present in the sun, moon, and the other bright planets and that through its efficacy they remain in the spherical figure in which they are visible, though they nevertheless accomplish their circular movements in many different ways.

-Copernicus, De Revolutionibus, Book I, Chapter 9

To understand this, we should briefly examine Ptolemy’s thinking on gravity. In the Almagest, Ptolemy opines that there is some point in the universe towards which all things fall unless they are supported. Thus, the Earth, being unsupported by a celestial sphere, must fall towards this point and thus, is the center of the cosmos; ergo, geocentrism.

Copernicus suggests that, perhaps gravity is just an innate force, and it would have the property to make things round. And since the Sun and moon are obviously round, perhaps they too have gravity. This removes the need for the central point to the cosmos that Ptolemy relies on, undercutting Ptolemy’s argument.

Elongation of Inferior vs Superior planets

How unconvincing is Ptolemy’s argument that the sun must occupy the middle position between those planets which have the full range of angular elongation from the sun [i.e., Mercury and Venus] and those which do not [i.e., Mars, Jupiter, and Saturn] is clear from the fact that the moon’s full range of angular elongation proves its falsity.

– Copernicus, De Revolutionibus, Book I, Chapter 10

Here, Copernicus is taking aim at the argument that the Sun must be between Venus and Mars due to a division in the angular elongation (the distance from the Sun) inferior and superior planets are able to have. Specifically, Mercury and Venus are never more than 24º and 45º away from the Sun respectively. Meanwhile, Mars, Jupiter, and Saturn can be any angular distance from the Sun (although they are always found along the ecliptic).

Ptolemy explains this by matching the mean (or average) speeds of Mercury and Venus to that of the Sun. Therefore, their getting ahead of and falling behind the Sun’s motion is due only to their epicycles. The other three planets had mean speeds unrelated to the Sun, allowing their centers of motion to drift anywhere along the ecliptic relative to the Sun.

The Ptolemaic order of the planets was largely correct; Ptolemy had ordered them according to speed. Ignoring the Sun and moon momentarily, this meant the planets, in increasing distance from the Earth, were ordered Mercury, Venus, Mars, Jupiter, and Saturn.

The Sun was inserted between Venus and Mars, again based on its speed. But, this conveniently meant that the Sun’s sphere provided a division between planets which were fixed to the Sun (Mercury and Venus), and those that could obtain any elongation (Mars, Jupiter, and Saturn). And astronomers of the day used this division as evidence that that positioning of the Sun among the planets must be correct.

But the moon, Copernicus tells us, upends this argument, because the moon is the innermost sphere and it is able to have any elongation, just like the outer planets.

Keep in mind, the nature of the moon, Sun, and planets was still quite uncertain at this time. Quite frequently, the term “planet” can include all of them. Hence why Copernicus considered their nature all together in this point.

Apogee & Perigee are Aligned with the Sun

For, it is manifest that the planets are always nearer the Earth at the time of their evening rising, i.e., when they are opposite to the sun and the Earth is in the middle between them and the sun. But, they are farthest away from the Earth at the time of their evening setting, i.e., when they are occulted in the neighbourhood of the sun, namely when we have the sun between them and the Earth. All that shows clearly enough that their center is more directly related to the sun and is the same as that to which Venus and Mercury refer their revolutions.

– Copernicus, De Revolutionibus, Book I, Chapter 10

Copernicus’ next argument has to do with the position of the planets when at their farthest points to Earth versus their closest points. These are known as apogee and perigee, respectively.

What Copernicus is indicating is that planets always seem to have their apogee when they are nearest to the Sun. This is a natural consequence of a heliocentric model (because the planet is on the opposite side of the Sun), but the geocentric model has no special cause for this.

This is easiest to understand if we think about a superior planet, like Mars, in the context of the heliocentric model. If we think of the closest Mars can be to Earth (perigee), it occurs when the Sun, Earth, and Mars are all in a straight line, in that order. When that occurs, Mars would be rising in the evening, being highest in the sky around midnight.

Conversely, the furthest Mars could be from us, is when it is on the opposite side of the Sun. It’s still on a straight line, but this time the order would be Mars, Sun, then Earth. When this occurs, Mars is setting in the evening (although we couldn’t see it because it would be too close to the Sun to be visible).

What Copernicus is pointing out is that this is true for every planet – they’re all tied to the Sun in this manner. Thus, he tells us, the Sun clearly has some special privilege.

Venus’ Massive Epicycle

Moreover, there is the fact that the diameter of the epicycle of Venus – by reason of which Venus has an angular distance of approximately 45º on either side of the sun – would have to be six times greater than the distance from the center of the Earth to its perigee, as will be shown in the proper place. Then what will they say is contained in all this space, which is so great as to take in the Earth, air, ether, moon, and Mercury, and which moreover the vast epicycle of Venus would occupy if it revolved around the immovable Earth?

– Copernicus, De Revolutionibus, Book I, Chapter 10

Epicycles are often cited as one of the biggest problems with the Ptolemaic geocentric model. And that is precisely what Copernicus is taking aim at here. That’s not to say that Copernicus was fundamentally against epicycles. Indeed, his own adherence to uniform circular motion forced him to include epicycles in his model. But what Copernicus is criticizing here is the size demanded by the Ptolemaic model for Venus in particular.

As discussed above, the mean motion of Venus is tied to that of the Sun. So it can only deviate from that position based on its epicycle. Thus, to get 45º away from the Sun, it was going to need a massive epicycle. One so large, it would take Venus crashing through the spheres of both Mercury and the Moon. The latter was particularly problematic because of a belief about the nature of matter.

The natural philosophy of the time was still alchemical, with four terrestrial elements (earth, fire, air, and water) and one celestial element (æther, or quintessence). It was held that the celestial element was eternal and unchanging. “Incorruptible,” as they would phrase it, which is why the heavens were so pure and consistent. It was only on Earth that we had the other four classical elements, which were “mutable” or “corruptible”. But where does that division between the incorruptible and corruptible take place? Greek astronomers placed it at the sphere of the moon which was the closest to Earth in the geocentric model.

Conclusion

However, because Venus’ epicycle would be so big, it would cross into this realm. Thus, there becomes a logical contradiction as you’d have the celestial matter diving in and out of the terrestrial realm which was not something that was considered acceptable.

Ultimately, these arguments were only partially convincing to astronomers of the time. We know that Copernicus’ work was widely read. However, it was not quickly adopted.

Even after Kepler revised it, sweeping away the Ptolemaic equants and epicycles and replacing them with ellipses, geocentrism still took quite a bit of time to be fully dislodged. Newton’s theory of gravity gave a compelling theoretical reason to give centrality to the larger object, but it was the discovery of the aberration of starlight and the parallaxes of stars that finally disproved the geocentric model.

The post Why Did Copernicus Reject Geocentrism? appeared first on Universe Today.

It seems that on some posts some readers are violating the posting Roolz with impunity, as if these commenters are for some reason immune to the Roolz I’ve set forth here.   So, once again I politely ask commenters to read and follow the posting rules at the link I just gave. Please read especially Roolz #6-#9 and #23.

I am doing the best I can to run this site during these fraught times, and also when I’m not in Chicago. By all means hash things out, but please keep things civil.  I have to add, though, that I will not alter the mix of topics, stop commenting on the excesses of the “progressive” left until the election is over, or change the slant of this site simply because there’s an election impending.

On another note, if you wish to contact me by email, preferably to send me wildlife photos (but also if I’ve made typos or arrant errors of fact), you can find my email address by clicking on “about the author” at the upper right and then on “contact information” at the bottom of the “about the author” link.

I’ve long urged all colleges and universities, including private ones, to adopt a speech code that adheres as closely as possible to the First Amendment of the Constitution.  The few exceptions, like specifying the “time, place, and manner” of protests, are made simply to avoid demonstrations from disrupting the main business of colleges: teaching and learning.

The University of Chicago and its “Free Expression” policy has now been adopted by 110 American universities, but there are many more who haven’t yet (there are roughly 4,000 colleges and universities in America).

Further, fewer than a dozen schools have adopted the principle of institutional neutrality embodied in Chicago’s “Kalven Report”, which prevents the university and its units from making any political, ideological, or moral statement—with the rare exception that statements are permitted when they bear directly on the teaching, learning, and research mission of the university. A neutrality principle is important because it prevents the university from taking official ideological positions that might chill the speech of those who dissent from such positions.

A similar defense of the neutrality principle, for scholarly associations, by the way, just appeared as an op-ed in the WSJ, written by our former provost Daniel Diermeier, now Chancellor (aka President) of Vanderbilt University. You can read it by clicking below, or find it archived here:

A quote:

The American Association of University Professors sparked a firestorm in higher education last month by reversing its longstanding opposition to academic boycotts. As wrongheaded as that move was—and as poorly received as it was by many, including the group representing America’s leading research universities—the real trouble with the AAUP began in February, when the organization signed on to a petition from organized labor calling for a cease-fire in Israel’s war in Gaza.

It is inappropriate for the AAUP to take a position at all on the war in the Middle East. Here is an important guardian of academic freedom—the essential rights of professors to study, write and say what they like—espousing a particular ideological position, thereby sending the message to its members that there is only one correct way to think about the war.

. . . This is a problem for several reasons. There is the chilling effect on debate, and the potential silencing of dissenting members, that occurs when a professional association declares there is only one right way to think about an issue. There is the risk of eroding the organization’s legitimacy and effectiveness by turning it into one more political player or advocacy group. And there is the undermining of respect for earned and credentialed expertise, the foundation of academia, that results when leaders of an association whose discipline is unrelated to the topic at hand opine on the issue nonetheless. But what concerns me most are the damaging consequences that position-taking by academic associations can have on the careers of individual faculty members.

But I digress, for the topic at hand is Sunstein’s op-ed. I just happen to agree nearly completely with both pieces, which lay the ground work for free speech and academic freedom.

At any rate, Cass Sunstein, a professor of law at Harvard (and formerly at the University of Chicago), has written a NYT op-ed emphasizing that yes, colleges and universities should follow the free speech guidelines of the First Amendment as they have been interpreted by the courts. You can read the article by clicking on the headline below, or you can find it archived her.

I’ll add the Sunstein is of Jewish descent given his statements about speech that may be anti-Semitic.  His introduction:

Last spring, protests at numerous American universities, prompted by the ongoing conflict in the Middle East, produced fierce debates over freedom of speech on campus.

Colleges and universities struggled mightily over how to mount an appropriate response. The University of Pennsylvania refused to allow a screening of a movie that was sharply critical of Israel. Brandeis University barred a pro-Palestinian student group in response to inflammatory statements made by its national chapter.

At Columbia, police officers arrested more than 100 students in an effort to empty the school’s pro-Palestinian encampment; classes were later moved online. But at Northwestern, the administration entered into a deal with protesters in which almost all of their tents were removed in return for multiple commitments by the university, including an agreement to provide the “full cost of attendance for five Palestinian undergraduates to attend Northwestern for the duration of their undergraduate careers.”

There have been intense debates about whether antisemitic speech, as such, should be banned on campus and about the right definition of antisemitic speech. With the new academic year starting alongside a looming presidential election, we can expect protest activity on a host of issues, raising fresh questions about free speech on campus.

To answer those questions, we should turn to the First Amendment of the U.S. Constitution, which states that Congress “shall make no law … abridging the freedom of speech.” Those words provide the right foundation for forging a new consensus about the scope and importance of free speech in higher education.

. . . It is true that the First Amendment, as framed, does not apply to private colleges and universities — only to public officials and institutions. If Harvard, Stanford, Baylor, Vanderbilt, Pomona or Colby wants to restrict speech, the First Amendment usually does not stand in the way (though a state might choose to apply First Amendment requirements to colleges and universities, as California has in fact done).

Still, most institutions of higher learning, large or small, would do well to commit themselves to following the First Amendment of their own accord.

As a rallying cry, that consensus should endorse the greatest sentence ever written by a Supreme Court justice. In 1943, Justice Robert H. Jackson wrote, “Compulsory unification of opinion achieves only the unanimity of the graveyard.”

Agreed, and remember, as Sunstein emphasizes, the courts have placed limits on free expression: no defamation, no false advertising, no sexual harassment, no speech intended to provoke imminent and lawless violence. The last one, and several others, are relevant to the abrogations of speech likely to occur on campus this year:

If students want to take over a building or to destroy university property, the First Amendment will not help them. The Constitution does not forbid universities from enforcing the law of trespass.

Nor does the First Amendment protect criminal conspiracy. If a group of students or professors conspires to violate the law, it is not protected merely because the conspiracy consists of speech.

More subtly, the First Amendment allows universities to punish speech that is intended to incite, and is likely to invite, “imminent lawless action.” Under this standard, students or professors can be punished for inciting an angry crowd to take over the president’s office.

But they cannot be punished for saying, “The United States is a racist country” or “Capitalism Is Rape” or “Israel is committing genocide” or “Abortion is Murder.”

The First Amendment protects speech that is angry, unpatriotic, insulting, hateful, hurtful, offensive — or even harmful.

Sunstein then quickly lays out a program of what speech should be permitted (and again, he’s talking largely about campuses, for this is where the problem has become most acute, at least for academics).  Colleges should not ban speech because of its viewpoint. Colleges should not restrict speech based on its content—unless that content inhibits the mission of the college (for example, if a professor in an evolution class starts fulminating about politics).  Here’s another sensible exception:

It follows that even if colleges and universities choose to follow the First Amendment, they can impose restrictions that would not be permissible elsewhere. They can direct professors to treat their students respectfully in class. If a teacher of physics says he believes it is hopeless to try to teach physics to women, he can probably be disciplined; it is hard to teach physics if you are on record as saying that your female students are incapable of learning.

Most important, colleges and universities should not (and public ones cannot) forbid “hate speech”, for that’s a slippery term that, unless designed to incite imminent and predictable violence, could encompass any statements that people find offensive, including criticism of affirmative action or religion.  I, for example, should be free to stand in the middle of the University of Chicago campus and shout “gas the Jews!”. (If you’re shouting it to a group of Jews who could enact violence, however, that is banned speech.) Such words are reprehensible, of course, and I’d never say them, but I would defend those who would.  And for sure that’s “hate speech”.

Sunstein shouldn’t have to write such an op-ed, as the value of the First Amendment is obvious, especially on campus, where the clash of ideas, many of them “offensive,” is supposed to take place as the way to sort out good ideas from bad, truth from falsehood. But each generation of students needs to learn this anew, which is why our University, and many others, will be giving entering students a short introduction to the meaning and application of the First Amendment.  As Sustein concludes,

. . . freedom always deserves the benefit of the doubt. The educational mission does not give colleges and universities a green light to punish speech that their alumni, their donors or influential politicians abhor or perceive as harmful. As Justice Oliver Wendell Holmes Jr. put it, “we should be eternally vigilant against attempts to check the expression of opinions that we loathe and believe to be fraught with death.”

Colleges and universities exist for one reason above all: to promote learning. They are democracy’s greatest arsenal. They do not need the unanimity of the graveyard. They need the noisy, teeming pluralism of living communities that search for truth.

Katie Herzog is still doing the TGIF columns at the Free Press, which, when Nellie Bowles wrote them, was one of the best reasons to subscribe (Bowles is the Bill Maher of print journalism).  Since Bowles has taken maternity leave, the column has been written by others, including nepo baby Suzy Weiss and, this week, Katie Herzog again.  The replacements have been good, but Nellie is The Queen, and nobody can really replace her. We’re told she’ll be back in two weeks.

Anyway, since I can’t do a proper Hili column when I’m traveling, here at least are three article stolen from Herzog’s latest column, called “TGIF: Foreign Interference.” Click below to read the whole thing:

→ Iranian writer sentenced to prison over dot: Hossein Shanbehzadeh, an Iranian writer and activist, has been sentenced to 12 years in prison by the Tehran Revolutionary Court after he tweeted a period at the Supreme Leader. Officially, NPR reports, “Shanbehzadeh was sentenced to five years for alleged pro-Israel propaganda activity, four years for insulting Islamic sanctities, two years for spreading lies online and an additional year for anti-regime propaganda.” Suspicious. . . this was my exact penalty in college for attending Shabbat services.

Shanbehzadeh’s one-character tweet, which was in response to a photo posted by Ayatollah Ali Khamenei of himself with the national volleyball team, received more likes than the Ayatollah’s post. He basically got 12 years for ratioing. Which, if that’s a crime, I guess I’ll be going in for twenty to life any day now.

→ Now, maybe you’re telling yourself: This could never happen in the U.S. Thank Allah and the Founding Fathers for the First Amendment! And you’re probably right: Tweeting a period at President Harris and/or Trump is unlikely to get you thrown in jail, and American citizens enjoy more speech protections than probably any other people on Earth. But don’t let your Bill of Rights throw pillow woo you into complacency. I mean, we’re not some tyrannical shit hole like the UK, where people are being charged for mean tweets, but government censorship does exist here. The last few years has seen huge surges in book banning and protest crackdowns, and just last week, Mark Zuckerberg admitted that Meta caved to Biden administration pressure to censor content posted by users on Facebook.

This week, Reason reported on the case of a “citizen journalist” who goes by the name Lagordiloca, or “the fat, crazy lady” (catchy), who was arrested by police in Laredo, Texas, after she broke stories obtained by a confidential source from within that same department. And vice presidential hopeful Tim Walz said in a recently resurfaced interview that misinformation and hate speech aren’t protected by the First Amendment. Now, he’s wrong about that, which you’d think a former high school social studies teacher would know (you actually are allowed to be a prick and a liar in America, thank God), but it’s a troubling statement from someone who could soon occupy the little closet down the hall from the Oval Office where they stow the VP.

→ Arrest-Me-Not: The darling of Sweden, Greta Thunberg, was arrested at Copenhagen University while protesting the school’s connection to Israel, namely that they have an exchange program where Israeli students come to study there. Thunberg sent a dispatch via Instagram from the front lines of her battle against. . . climate? Israel? At this point I can’t tell. She wrote: “Students Against the Occupation and I are at the University of Copenhagen’s administration building. Police have been called, violently entered the building with a ram wearing assault rifles. They are evicting everyone as we speak.” I love the new use of eviction where it’s just when someone tells you to leave the place that you aren’t allowed to be in. I swear I’ve been evicted from many pools in my neighborhood by people who don’t know me, and dozens of Denny’s parking lots after closing. . . it’s honestly a travesty. Meanwhile, a bunch of people were arrested outside of Citibank headquarters in New York while protesting fossil fuels, a throwback to a sweet time when environmental activists organized around the environment.

Whatever happened to Greta? Although I’ve always found her somewhat irritating, I also was on her side in the climate-change controversy. But I guess she’s found herself a new cause, BDS:

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A post shared by Students Against the Occupation (@studerendemodbesaettelsen)

Speaking of violations of freedom of speech by colleges, here’s a letter to the “faculty community” of Mount Holyoke College (a high-class women’s liberal arts school), telling professors that they have to report certain types of speech. Note that these violations, however, are apparently in line with the Biden Administration’s recent rewriting of the Title IX guidelines, so federal money could be withheld from schools who don’t comply. In that sense, it’s the Biden administration itself who is responsible for policing “hate speech” and creating these new—and in my view mostly harmful—regualations (Note that as a private school, Mt. Holyoke needn’t abide by the First Amendment, but, like all nonreligious and nonmilitary schools, it certainly should.)

The new rules are laid out in this email sent to the Mount Holyoke faculty by the College President and another administrator, with the text taken from a tweet by Steve McGuire (bolding is mine):

Dear Faculty Community,

Welcome to the start of another academic year at Mount Holyoke College! As you may have learned in President Danielle R. Holley’s email communication on August 20th, the College has created a new compliance department as of this past summer. To ensure that Mount Holyoke is a safe and inclusive campus for our community as well as compliant with ever-changing regulations, two new positions were created: Assistant Vice President for Compliance and Director of Civil Rights and Community Standards.

Some of you recently heard from the Assistant Vice President for Compliance, Shannon Lynch, regarding your responsibilities as Mandated Reporters at the College. Per our Sex Discrimination and Sex-Based Harassment Policy, all College employees who are not designated as Confidential must disclose to the Title IX Coordinator when they have information that may reasonably constitute a violation of the Policy.

On August 1, Title IX Regulations expanded to include misgendering, deadnaming, and mispronouning as prohibited acts and thus expanded the set of prohibited activities of concern to mandated reporters. Because faculty have a unique role in creating classrooms as spaces of mutual trust, respect, and concern—a role that lives alongside their responsibilities under Title IX—we would like to provide some guidance regarding faculty observations of misgendering in their classrooms. It is the expectation of the College that faculty report when misgendering occurs in the following ways:

• when the misgendering has created a hostile environment;

• when there is open mocking of our Pronoun Policy or an individual’s choice of pronouns;

• or when a student reports being misgendered, deadnamed, or has been subject to incorrect use of their pronouns.

Shannon will follow up with all parties named in a report, offering resources and support, as well as procedural options if the policies’ definitions and standards have been met.

The scope of Title IX has shifted, but Mount Holyoke’s overarching commitment to education, care, and support of our gender diverse community of students, faculty and staff remains unchanged. Faculty can continue to look to the Office of Diversity, Equity, and Inclusion, as well as the Teaching and Learning Initiative (TLI) for additional resources and support. We also want to highlight the upcoming TGNC10 programming, which will provide opportunities for education, discussion, and community related to our 10 years as a gender diverse campus. [Although Mt. Holyoke is a women’s school, about a decade ago they decided to allow transgender women to enroll.]

Additional resources related to our Title IX policies can be found here. You may also visit the College Title IX webpage to learn more about our policies and procedures, as well as support and resources available to our campus community.

Should you have any questions or concerns regarding your responsibilities listed above, please contact Shannon Lynch at shannonlynch@mtholyoke.edu for more information.

Thank you and we wish you a successful semester ahead! =

Shannon Lynch
AVP for Compliance

Lisa M. Sullivan
Provost and Dean of Faculty
Mount Holyoke College

You can see how Title IX has changed for the worse under Biden, which, beyond changes highlighted above, also removed protections for students accused of sexual harassment or assault when their cases were being adjudicated by colleges. These protections, like the right to cross-examine witnesses, are inherent in the legal system when sexual harassment or assault is judged in the courts, and were reinstated by Betsy DeVos, but dismantled again by the Biden administration. The protections accused students enjoy when they are judged in college hearings are far weaker than when they’re judged in the courts.

And there’s more, but they’re saving these changes until after the election, presumably because they’ll be unpopular:

Absent is a proposal on transgender participation on specific men and women athletics teams, which is anticipated after the November election.

You can read about that rule at the link to the WaPo article above, which describes a proposal apparently applying to all secondary schools through high school:

[The rule] would outlaw blanket state bans but gives schools a road map for how they can bar transgender girls from competing in certain circumstances, particularly in competitive sports.

But allowing transgender females to compete against biological women isn’t a popular view, and so the administration, in an act of duplicity and mendacity, put it off:

. . . . Nonetheless, issuing such a rule risks injecting the issue into an election year in which President Biden faces a close contest with former president Donald Trump, who has promised to ban trans women from women’s sports if reelected.

“Folks close to Biden have made the political decision to not move on the athletics [regulation] pre-election,” said one person familiar with the administration’s thinking. “It seems to be too much of a hot topic.”

Seriously, how is it okay to adopt a policy that’s unpopular with the public, but not publicize it or put it into force until the three-month period between the election and the inauguration of a new administration?

At any rate, I agree with Mt. Holyoke’s first point above: misgendering should not be allowed to create a hostile climate for a given student by repeatedly harassing that student directly, although criticizing the general notion of going along with someone’s pronoun preference is simply freedom of speech to criticize compelled speech.

Ditto for “open mocking of our pronoun policy”, which again prevents someone from criticizing a policy that is debatable. That mockery, too, is in line with the First Amendment.  Finally, deadnaming or pronoun “misuse” not used to harass a student directly seems to me in line with the First Amendment as well. (Still, if a student hears about it and reports it, that too has become a violation.) I suspect that if this issue gets to the courts, some of the provisions of the new Title IX provisions will be struck down.

Here’s a tweet about this from Nicholas Christakis, who along with his wife Erika had their own speech run-in at Yale University:

A college that prohibits “mocking” a policy (not a person) simply does not have academic freedom nor understand freedom of expression. Who are these administrative apparatchiks overrunning our universities? https://t.co/zV3PrBEc4G

— Nicholas A. Christakis (@NAChristakis) September 5, 2024

While NASA’s Mars Sample Return mission has experienced a setback, China is still moving forward with their plans to bring home a piece of the Red Planet. This week, officials from the China National Space Administration (CNSA) announced their sample return mission, called Tianwen-3, will blast off for Mars in 2028. It will land on the surface, retrieve a sample, and then take off again, docking with a return vehicle in orbit. They also announced another mission, Tianwen-4 will head off to Jupiter in 2030 as well as unveiling a conceptual plan for China’s first mission to test defenses against a near-Earth asteroid.

The announcements were made this week at the second International Deep Space Exploration Conference, also known as the Tiandu Forum, held in China. China says the conference promotes international cooperation for future large-scale missions.

As reported by CGTN, the English-language news channel of state-run China Global Television Network, the chief designer of the Mars sample return mission, Liu Jizhong said the Tianwen-3 mission will include international payloads, and China plans to share samples and data from the mission with scientists around the world.  Liu also said the primary scientific goal of the Mars sample return mission will be searching for signs of life.

A wireless camera took this ‘group photo’ of China’s Tianwen-1 lander and rover on Mars’ surface. Credit: Chinese Space Agency

China’s first Mars exploration mission, Tianwen-1 arrived at Mars in February 2021 and included an orbiter, a lander, and a rover named Zhurong. The orbiter imaged the entire surface of Mars and the rover found hydrated minerals which are likely associated with groundwater. Its success made China the third nation to successfully land a spacecraft on the surface of Mars.

While the reporting on Liu’s speech didn’t disclose many details of the proposed mission to Mars, a paper published in the fall of 2023 by the China Academy of Space Technology proposed a quadcopter similar to NASA’s Ingenuity that would be capable of collecting a sample weighing up to 100 grams and return it to a lander.  Since the Zhurong rover mission has concluded and it was not capable of collecting samples for Earth return, the new Tianwen-3 mission would need to include the entire collection of spacecraft that would land, collect, and store the samples; then launch to orbit to return and dock to an orbiting spacecraft which would then head back to Earth and somehow drop off or land the samples.

A Chinese flag flies next to the Chang’e-6 sample return capsule after its landing in Inner Mongolia. (Credit: CCTV / CNSA via Weibo)

But China recently achieved this feat at the Moon with their Chang’e-6 mission, which launched in early May, becoming the first robotic mission to land and lift off again from the Moon’s far side, and also the first mission to bring dirt and rocks from the far side back to Earth. They also placed a lander on the near side of the Moon and brought back samples with Chang’e 5.

Meanwhile, NASA’s proposal for a Mars sample return mission have been shelved for now, as costs were increasing and timescales were slipping creating a budget challenge. NASA is now reworking their plan for a simpler, less expensive and less risky alternative. The Perseverance rover has already collected and cached several samples for return.

This graphic outlines China’s Lunar Exploration Program. Image Credit: CASC

China has been actively sharing their plans for upcoming space missions, including the asteroid mission, the Mars sample return and the mission to Jupiter. Along with their ambitious robotic missions, the CNSA announced in 2021 that they plan to send its first crewed mission to Mars in 2033 with goal to send regular missions to Mars and eventually build a base there. China also has their Tiangong space station which currently houses three astronauts on six-months stays.

Liu did say the efforts to include international payloads, and sample and data sharing — as well as joint planning for future missions — are “expected to enhance global synergy in the realm of deep space exploration.”

China has approved four missions for planetary exploration, set to be completed within 10 to 15 years. The Tianwen-2 mission to a currently unnamed asteroid is scheduled for launch around 2025, and Tianwen-4 for Jupiter exploration is set for launch around 2030.

The post China Will Launch its Mars Sample Return Mission in 2028 appeared first on Universe Today.

SGU Celebrates 1000 Episodes; A Skeptical Retrospective: Global Warming, Solar Panels, Cold and Hot Fusion, Medical Quackery, UFOs; Science or Fiction

Meanwhile, in Dobrzyn, Hili is not an unreliable narrator:

Hili: I’m a responsible editor.
A: Why are you saying this?
Hili: So that there are no doubts.

Hili: Jestem redaktorem odpowiedzialnym.
Ja: Dlaczego to mówisz?
Hili: Żeby nie było wątpliwości.

Where would be the most ideal landing site for the Artemis III crew in SpaceX’s Human Landing System (HLS)? This is what a recent study submitted to Acta Astronautica hopes to address as an international team of scientists investigated plausible landing sites within the lunar south pole region, which comes after NASA selected 13 candidate landing regions in August 2022 and holds the potential to enable new methods in determining landing sites for future missions, as well.

Here, Universe Today discusses this research with Dr. Juan Miguel Sánchez-Lozano from the Technical University of Cartagena and Dr. Eloy Peña-Asensio from the Politecnico di Milano regarding the motivation behind the study, significant findings, the reasons for determining the final landing site, location to Shackleton Crater, and if a lander smaller than HLS would have changed the outcome? Therefore, what was the motivation behind the study?

Dr. Sánchez-Lozano tells Universe Today, “Our motivation was to contribute to the selection process for the Artemis III landing site by introducing methods that are well-established in other fields of study to the context of space exploration for the first time. Specifically, we identified that Geographic Information Systems combined with Multi-Criteria Decision-Making (GIS-MCDM) methodologies could provide significant value in evaluating and prioritizing the candidate landing sites. Therefore, we aimed to demonstrate the utility of these methods to NASA and apply them in practice by identifying and recommending the most suitable landing locations.”

For the study, the researchers used these methods to analyze 1,247 locations within the 13 candidate landing regions near the lunar south pole previously identified by NASA to ascertain the most precise landing sites for HLS. They accomplished this by combining their GIS-MCDM methodologies with a Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS) algorithm to analyze specific criteria: lunar surface visibility, line of sight for HLS astronauts, Permanently Shadows Regions (PSRs), sunlight exposure, direct communication with Earth, geological units, and abundance of mafic (volcanic rock high in iron or magnesium) materials. Therefore, what were the most significant findings from this study?

Dr. Peña-Asensio tells Universe Today, “In addition to demonstrating the applicability of MCDM to these challenges, our analysis identified Site DM2 (Nobile Rim 2) as the optimal landing site based on criteria such as visibility, solar illumination, direct communication with Earth, geological diversity, and the presence of mafic materials. The best nine locations identified in our study are all situated within this region. Surprisingly, this site is not among the most favored regions within the scientific community.”

Site DM2 is one of the furthest landing regions within the 13 candidate landing regions, located approximately 250 kilometers (150 miles) from Shackleton Crater, the latter of which has a portion located directly on the lunar south pole. The researchers identified the exact location of the optimal landing site being 84°12’5.61” S and 60°41’59.61” E, which is located near a PSR crater. The reason PSR craters are of exploration importance is due to the craters being so deep that no sunlight has reached their depths in possibly billions of years, potentially resulting in their potential housing of water ice deposits. Therefore, what were the specific reasons for selecting Site DM2 and what are some potential backup landing sites?

Dr. Sánchez-Lozano tells Universe Today, “Site DM2 offers exceptional performance across several key criteria, including the highest percentage of solar illumination, optimal proportions of explorable ice-hosting areas, and extended communication windows with Earth. The strength of the decision-making methodology we employed, particularly the TOPSIS technique, lies in its compensatory nature. This approach allows criteria with merely acceptable values to be offset by others with excellent values, resulting in a comprehensive ranking of alternatives. Consequently, adjacent landing sites to the optimal location may also present highly viable options with a high degree of acceptability.”

Regarding back sites, Dr. Peña-Asensio tells Universe Today, “As potential backup sites, we consider DM1 (Amundsen Rim) particularly compelling, as it offers locations with consistently high averages across all evaluated parameters. We also highlight Site 004, centered at the edge of the Shackleton Crater, which our analysis identifies as one of the best landing sites.”

As noted, one of the primary criteria for determining the most optimal landing site is HLS, which will attempt to land the first humans on the lunar surface for the first time since Apollo 17 in 1972. However, the height of HLS is almost ten times greater than the Apollo lander at 50 meters (160 feet) and 5.5 meters (17.9 feet), respectively, which means landing a larger spacecraft carries its own benefits and challenges.

For context, the original spacecraft design for Apollo called for landing a large spacecraft on the lunar surface known as direct ascent, which Wernher von Braun was initially in favor of using. However, the direct ascent technique was scrapped in favor of the Lunar Orbit Rendezvous (LOR) technique, which argued to be less risky due to a smaller spacecraft needing to land on the lunar surface. Therefore, if a smaller lander than HLS (i.e., Apollo-sized) was being used, how would this influence the landing site selection?

Dr. Peña-Asensio tells Universe Today, “This would directly impact our results, as we considered criteria such as the lander’s solar illumination received for energy recharging, visibility from the lander windows to help astronaut extravehicular activities and to allow intravehicular science, and direct communication with Earth. A lower lander could intensify the challenges posed by local topography, obstructing sight lines and the sunlight. However, it might also offer increased stability for the lander (by reducing its center of mass height), potentially decreasing the terrain slope safety restrictions and thereby opening up new landing site options for exploration.”  

As landing sites for the Artemis III mission continue to be debated, NASA is currently scheduled to launch Artemis II late next year with a four-person crew whose mission will be to orbit the Moon and return to the Earth like Apollo 8 in December 1968. Additionally, the commercial space industry is taking their own shots at landing near the lunar south pole with the upcoming IM-2 mission courtesy of Intuitive Machines, which earlier this year successfully landed the first American spacecraft on the Moon for the first time since 1972.

This study demonstrates that a plethora of methods can be used to determine optimal landing sites for the Artemis missions and potentially other missions to other planetary bodies throughout the solar system, specifically the use of mapping and machine learning algorithms. Therefore, as we approach the Artemis III mission and the first human landing since Apollo 17, these methods will continue to evolve and improve to develop enhanced landing methods as humanity continues its journey into the cosmos.

Dr. Sánchez-Lozano tells Universe Today, “This research demonstrates how methodologies from the field of engineering projects and the business world, such as multi-criteria decision-making techniques, can be applied to solve decision problems of interest to the international astronomical community, such as the proposed case study: the selection of the optimal landing site for the Artemis III mission.”

Where will Artemis III ultimately land near the lunar south pole and how will landing site selection methods improve in the coming years and decades? Only time will tell, and this is why we science!

As always, keep doing science & keep looking up!

The post Artemis III Landing Sites Identified Using Mapping and Algorithm Techniques appeared first on Universe Today.

Scientists have identified and demonstrated a method to process a plant-based material called nanocellulose that reduced energy needs by a whopping 21%, using simulations on the lab's supercomputers and follow-on analysis.

Physicists directly observed ultracold atoms in an 'edge state,' flowing along a boundary without resistance. The research could help physicists manipulate electrons to flow without friction in materials that could enable super-efficient transmission of energy and data.

What is the shortest route to the next stop or the agreed meeting point? Global positioning systems (GPS) have become a routine part of everyday life for most people. Until now, however, the minimum number of GPS satellites needed to determine the exact position of a mobile phone or other navigation device has remained a matter of conjecture. Researchers have now proved that a precise location can be determined in most cases with five or more satellites. At present, we can generally be sure of having contact to only four satellites.

What is the shortest route to the next stop or the agreed meeting point? Global positioning systems (GPS) have become a routine part of everyday life for most people. Until now, however, the minimum number of GPS satellites needed to determine the exact position of a mobile phone or other navigation device has remained a matter of conjecture. Researchers have now proved that a precise location can be determined in most cases with five or more satellites. At present, we can generally be sure of having contact to only four satellites.

Few scientists doubt that Mars was once warm and wet. The evidence for a warm, watery past keeps accumulating, and even healthy skepticism can’t dismiss it. All this evidence begs the next question: what happened to it?

Mars bears the marks of a past when water flowed freely across its surface. There are clear river channels, lakes, and even shorelines. NASA’s Perseverance rover is working its way around Jezero Crater, an ancient paleolake, and finding minerals that can only form in water’s presence. MSL Curiosity has found the same in Gale Crater.

The water that created these landscape features is gone now. Some of it has retreated to the polar caps, where it remains frozen. But aside from that, there are only two places where the remainder of Mars’ ancient water could’ve gone: underground or into space.

Scientists think that there’s water under Mars’ surface. In 2018, researchers found evidence of a large subglacial lake about 1.5 km beneath the southern polar region, though these results have been met with some skepticism. Even if the lake is real, there’s nowhere near enough water there to account for all of Mars’ lost water.

In new research in Science Advances, a team of scientists using data from the Hubble Space Telescope and NASA’s Mars Atmosphere and Volatile EvolutioN (MAVEN) orbiter explain how Mars lost much of its water to space. The research is “Martian atmospheric hydrogen and deuterium: Seasonal changes and paradigm for escape to space.” The lead author is John Clarke, a Professor of Astronomy and the Director of the Center for Space Physics at Boston University.

“Overall, the results presented here offer strong supporting evidence for a warm and wet period with an abundance of water on early Mars and a large amount of water loss into space over the lifetime of the planet.”

John Clarke, Director, Center for Space Physics at Boston University.

“There are only two places water can go. It can freeze into the ground, or the water molecule can break into atoms, and the atoms can escape from the top of the atmosphere into space,” explained Clarke in a press release. “To understand how much water there was and what happened to it, we need to understand how the atoms escape into space.”

The research focuses on two types of hydrogen: what we can call ‘regular’ hydrogen (H) and deuterium (D). Deuterium is hydrogen with a neutron in its nucleus. Water is H2O—two hydrogen atoms bonded to one oxygen atom—and water molecules can contain either hydrogen or deuterium. The neutron contributes additional mass and makes deuterium twice as heavy as hydrogen.

Ultraviolet light from the Sun can split water molecules apart into their constituent hydrogen and oxygen atoms. In an escape-to-space scenario, more of the heavier deuterium is likely to be left behind than hydrogen.

As time passed on Mars and hydrogen kept escaping into space, more of the heavier deuterium was left behind. Over time, this preferential retention shifted the ratio of hydrogen to deuterium in the atmosphere. In this research, Clarke and his co-researchers used MAVEN to see how both atoms escape from Mars currently.

NASA launched MAVEN in 2013, and it reached Martian orbit in 2014. Since then, the capable spacecraft has been observing the Martian atmosphere, making it the first spacecraft dedicated to the task. Its overarching goal is to determine how Mars lost its atmosphere. One of its specific goals is to measure the rate of gas loss from the planet’s upper atmosphere to space and what factors and mechanisms govern the loss.

NASA’s MAVEN spacecraft is depicted in orbit around an artistic rendition of planet Mars, which is shown in transition from its ancient, water-covered past to the cold, dry, dusty world that it has become today. Credit: NASA

MAVEN’s instrument suite contains eight powerful instruments. However, every mission has its tradeoffs, and where MAVEN is concerned, it’s unable to monitor deuterium emissions throughout the entire Martian year. Mars’s orbit is more elliptical than Earth’s. During Martian winter, it travels further from the Sun compared to a circular orbit. During that period, the deuterium emissions are very faint.

This is where the Hubble Space Telescope comes in. It contributed observations from its two high spectral resolution UV instruments, the Goddard High Resolution Spectrograph (GHRS) and the Space Telescope Imaging Spectrograph (STIS). By combining the Hubble observations and the MAVEN data, Clarke and his team monitored deuterium escape for three complete Martian years.

Hubble also contributed data that predates the MAVEN mission. Hubble’s data is critical because the Sun drives the atmospheric escape, and its effect changes throughout the Martian year. The closer Mars is to the Sun, the more rapidly water molecules rise through the atmosphere, where they split apart at high altitudes.

These Hubble images of Mars at aphelion (top) and perihelion (bottom) show how its atmosphere is brighter and more extended when Mars is closer to the Sun. Image Credit: NASA, ESA, STScI, John T. Clarke (Boston University); Processing: Joseph DePasquale (STScI)

The Sun’s effect on the Martian atmosphere is striking.

“In recent years scientists have found that Mars has an annual cycle that is much more dynamic than people expected 10 or 15 years ago,” explained Clarke. “The whole atmosphere is very turbulent, heating up and cooling down on short timescales, even down to hours. The atmosphere expands and contracts as the brightness of the Sun at Mars varies by 40 percent over the course of a Martian year.”

Prior to this research, Mars scientists thought that hydrogen and deuterium atoms slowly diffused upward through the thin atmosphere until they were high enough to escape. But these results change that perspective.

These results show that when Mars is close to the Sun, water molecules rise very rapidly and release their atoms at high altitudes.

“H atoms in the upper atmosphere are lost rapidly by thermal escape in all seasons, and the escape flux is limited by the amount diffusing upward from the lower atmosphere so that the escape flux effectively equals the upward flux,” the authors explain in their research.

It’s different for deuterium atoms, though. “The D escape flux from thermal escape is negligible, in which case an upward flux with the water-based D/H ratio would result in a large surplus of D in the upper atmosphere,” the authors write.

For the D/H ratio to be restored to the measured equilibrium with H near aphelion and to be consistent with observed faster changes in D density near perihelion, something has to boost the escape of D atoms. “In this scenario, the fractionation factor becomes much larger, consistent with a large primordial reservoir of water on Mars,” the authors write. “We consider this to be the likely scenario, while more work is needed to understand the physical processes responsible for superthermal atoms and their escape.”

“Overall, the results presented here offer strong supporting evidence for a warm and wet period with an abundance of water on early Mars and a large amount of water loss into space over the lifetime of the planet,” Clarke and his colleagues write.

The research also reached another conclusion. The upper Martian atmosphere is cold, so most of the atoms need a boost of energy to become superthermal and escape Mars’ gravity. This research shows that solar wind protons can enter the atmosphere and collide with atoms to provide the kick. Sunlight can also provide an energy boost through chemical reactions in the upper atmosphere.

This research doesn’t answer all of our questions about Mars’s lost water, but it makes significant progress, and that’s always welcome.

“The trends reported here represent substantial progress toward understanding the physical processes that govern the escape of hydrogen into space at Mars and our ability to relate these to the isotopic fractionation of D/H and the depth of primordial water on Mars,” the authors write.

How Mars lost its water is one of the big questions in space science right now. It’s about more than just Mars; it can help us understand Earth, Venus, and the rocky exoplanets we find in other habitable zones and how they evolve.

To put it bluntly, Mars lost its water, and Earth didn’t. Why?

We’re inching toward the answer.

The post One Step Closer to Solving the Mystery of Mars’ Lost Water appeared first on Universe Today.

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