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I have about three wildlife-photo submissions in reserve, so we’re going to run out soon. If you have some good photos (not blurry or small!), please send them to me. Thanks!

Today is Sunday, and we’re resuming John Avise‘s series on the birds of Hawaii; this is the last installment. John’s captions are indented, and you can enlarge his photos by clicking on them.

Birds in Hawaii, Part 4 

This week we conclude our 4-part photographic journey into native and introduced bird species that you might encounter on a natural-history tour of the Hawaiian Islands.

Red-vented Bulbul (Pycnonotus cafer) (native to the Indian subcontinent):

Red-whiskered Bulbul (Pycnonotus jocosus) (native to Asia):

Salmon-crested Cockatoo (Cacatua moluccensis) (native to Indonesia):

Spotted Dove (Spilopelia chinensis) (native to the Indian subcontinent and southeast Asia):

Wedge-tailed Shearwater (Ardenna pacifica) (widespread in tropical Pacific and Indian oceans):

Western Meadowlark (Sturnella neglecta) (native to North America):

White Tern (Gygis alba) (widespread in the world’s tropical oceans):

White Tern flying:

 White-rumped Shama (Copsychus malabaricus), male in bird-bander’s hand (native to India and southeast Asia):

White-rumped Shama female:

Yellow-fronted Canary (Serinus mozambicus) (native to Africa):

Zebra Dove (Geopelia striata) (native to southeast Asia):

Here’s the beginning of Wikipedia’s entry for Kathleen Hagerty, the Provost of Northwestern University here in Evanston, Illinois. It’s a screenshot, and I’ve marked it:

I don’t find any discussion about “antisemite” in the “history” section of the entry, so this description must have been in the original post created in August, 2020.

Now why would this description of Hagerty be added to her entry?  One thing I recall is that Northwestern was one of the few universities to actually bargain and strike a deal with the pro-Palestinian protestors at her school.  I find this from The Minnesota Lawyer (bolding is mine):

The Wisconsin Institute for Law & Liberty (WILL) has filed a federal Title VI complaint against Northwestern University on behalf of the Young America’s Foundation, which has an active chapter on the university’s campus.

The complaint documents the university’s plan to offer nearly $1.9 million in scholarship funds, faculty positions, and student-organization space to Palestinian students and staff. As a recipient of federal funds, Northwestern University is subject to Title VI of the Civil Rights Act of 1964, which prohibits discrimination “on the grounds of race, color, or national origin,” WILL said.

Northwestern University officials have struck a deal with pro-Palestinian protesters who set up an encampment on campus. In exchange for removal of the encampment, Northwestern agreed to provide a facility for Muslim student activities and fundraise for scholarships going to Palestinian undergraduates.

According to WILL attorney Skylar Croy, that deal violates federal law.

“You just can’t go get scholarships based on ethnicity because they rioted it and demanded it,” Croy said.

According to WILL, on April 29, 2024, University officials entered into an agreement with anti-Israel demonstrators occupying a space on campus called Deering Meadow. The officials involved in the agreement are University President Michael Schill, Provost Kathleen Hagerty, and Vice President Susan Davis.

Pursuant to the terms of the agreement, the University promised to provide the “full cost of attendance for five Palestinian undergraduates to attend Northwestern for the duration of their undergraduate careers.”

The agreement provides “funding two faculty per year for two years,” with the provision that these faculty will be “Palestinian faculty.”

Additionally, Northwestern University agreed to “provide immediate temporary space for MENA/Muslim students.” MENA is an acronym for “Middle Eastern and North African” individuals.

According to WILL, as a recipient of federal funds, the University is subject to Title VI of the Civil Rights Act of 1964, which prohibits discrimination “on the grounds of race, color, or national origin.” By providing nearly $1.9 million in scholarships, two faculty positions, and “immediate temporary space” based on an individual’s status as Palestinian or MENA, the University is intentionally discriminating against non-Palestinian or non-MENA individuals on the grounds of race, color, or national origin.

WILL noted, as the United States Supreme Court recently held in a case applying Title VI, race and national origin may never operate as a “negative” or a “stereotype.” Students for Fair Admissions, Inc. v. President & Fellows of Harvard Coll., 600 U.S. 181, 218 (2023). Discrimination in favor of Palestinians or MENA individuals is, in turn, discrimination against individuals not within those categories and is therefore illegal under federal law.

Did some pro-Israel editor stick “antisemite” in there somehow to reflect this bargain? If so, it’s not in the history of the entry. I don’t find the word in the entry for Northwestern President Michael Shill, and VP Susan Davis doesn’t have a Wikipedia entry.

But I expect that, now that I’ve called attention to it, this noun will be gone by the end of the day. Still, this deal is almost certainly illegal, but that doesn’t warrant such pejorative.

h/t: Peggy

Voyager 1 was launched waaaaaay back in 1977. I would have been 4 years old then! It’s an incredible achievement that technology that was built THAT long ago is still working. Yet here we are in 2024, Voyager 1 and 2 are getting older. Earlier this week, NASA had to turn off one of the radio transmitters on Voyager 1. This forced communication to rely upon the low-power radio. Alas technology around 50 years old does sometimes glitch and this was the result of a command to turn on a heater. The result was that Voyager 1 tripped into fault protection mode and switch communications! Oops. 

Voyager 1 is a NASA space probe launched on September 5, 1977, as part of the Voyager program to study the outer planets and beyond. Initially, Voyager 1’s mission focused on flybys of Jupiter and Saturn, capturing incredible images before traveling outward. In 2012, it became the first human-made object to enter interstellar space, crossing the heliopause—the boundary between the influence of the Sun and interstellar space. It now continues to  to send data back to Earth from over 22 billion km  away, helping scientists learn about the interstellar medium. There is also a “Golden Record” onboard which contains sounds and images of life on Earth, Voyager 1 serves as a time capsule, intended to articulate the story of our world to any alien civilizations that may encounter it.

The Ringed Planet Saturn

Just a few days ago on 24 October, NASA had to reconnect to Voyager 1 on its outward journey because one of its radio transmitters had been turned off! Alien intervention perhaps! Exciting though that would be, alas not. 

The transmitter seems to have been turned off as a result of one of the spacecraft fault protection systems. Any time there is an issue with onboard systems the computer will flip the systems into protection mode to protect any further damage. If the spacecraft draws too much power from the batteries, the same system will turn off less critical systems to conserve power. When the fault protection system kicks in, it’s then the job of engineers on the ground fixing the fault.

Artist rendition of Voyager 1 entering interstellar space. (Credit: NASA/JPL-Caltech)

There are challenges here though. Due to the immense distance to Voyager 1, now about 24 billion km away, any communications to or from takes almost 23 hours to arrive. A request for data for example means a delay of 46 hours before the request arrives and the data returned! Undaunted, the team sent commands to Voyager 1 on the 16 October to turn on a heater but, whilst the probe should have had enough power, the command triggered the system to turn off a radio transmitter to conserve power. This was discovered on 18 October when the Deep Space Network was no longer able to detect the usual ping from the spacecraft. 

The engineers correctly identified the likely cause of the problem and found Voyager pinging away on a different frequency using the alternate radio transmitte. This one hadn’t been used since the early 19080’s! With the fault identified, the team did not switch immediately back to the original transmitter just yet in case the fault triggered again. Instead,they are now working to understand the fault before switching back. 

Until then, Voyager 1 will continue to communicate with Earth using the lower power transmitter as it continues its exploration out into interstellar space. 

Source : After Pause, NASA’s Voyager 1 Communicating With Mission Team

The post Voyager 1 is Forced to Rely on its Low Power Radio appeared first on Universe Today.

Perhaps the greatest tool astronomers have is the ability to look backward in time. Since starlight takes time to reach us, astronomers can observe the history of the cosmos by capturing the light of distant galaxies. This is why observatories such as the James Webb Space Telescope (JWST) are so useful. With it, we can study in detail how galaxies formed and evolved. We are now at the point where our observations allow us to confirm long-standing galactic models, as a recent study shows.

This particular model concerns how galaxies become chemically enriched. In the early universe, there was mostly just hydrogen and helium, so the first stars were massive creatures with no planets. They died quickly and spewed heavier elements, from which more complex stars and planets could form. Each generation adds more elements to the mix. But as a galaxy nurtures a menagerie of stars from blue supergiants to red dwarfs, which stars play the greatest role in chemical enrichment?

One model argues that it is the most massive stars. This makes sense because giant stars explode as supernovae when they die. They toss their enriched outer layers deep into space, allowing the material to mix within great molecular clouds from which new stars can form. But about 20 years ago, another model argued that smaller, more sunlike stars played a greater role.

The Cat’s Eye nebula is a remnant of an AGB star. Credit: ESA, NASA, HEIC and the Hubble Heritage Team, STScI/AURA

Stars like the Sun don’t die in powerful explosions. Billions of years from now, the Sun will swell into a red giant star. In a desperate attempt to keep burning, the core of a sun-like star heats up significantly to fuse helium, and its diffuse outer layers swell. On the Hertzsprung-Russell diagram, they are known as asymptotic giant branch (AGB) stars. While each AGB star might toss less material into interstellar space, they are far more common than giant stars. So, the model argues, AGB stars play a greater role in the enrichment of galaxies.

Both models have their strengths, but proving the AGB model over the giant star model would prove difficult. It’s easy to observe supernovae in galaxies billions of light years away. Not so much with AGB stars. Thanks to the JWST, we can now test the AGB model.

Using JWST the study looked at the spectra of three young galaxies. Since the Webb’s NIRSpec camera can capture high-resolution infrared spectra, the team could see not just the presence of certain elements but their relative abundance. They found a strong presence of carbon and oxygen bands, which is common for AGB remnants, but also the presence of more rare elements such as vanadium and zirconium. Taken altogether, this points to a type of AGB star known as thermally pulsing AGBs, or TP-AGBs.

Many red giant stars enter a pulsing phase at the end of their lives. The hot core swells the outer layers, things cool down a bit, and gravity compresses the star a bit, which heats the core, and the whole process starts over. This study indicates that TP-AGBs are particularly efficient at enriching galaxies, thus confirming the 20-year-old model.

Reference: Lu, Shiying, et al. “Strong spectral features from asymptotic giant branch stars in distant quiescent galaxies.” Nature Astronomy (2024): 1-13.

The post Webb Confirms a Longstanding Galaxy Model appeared first on Universe Today.

Neutron stars are extraordinarily dense objects, the densest in the Universe. They pack a lot of matter into a small space and can squeeze several solar masses into a radius of 20 km. When two neutron stars collide, they release an enormous amount of energy as a kilonova.

That energy tears atoms apart into a plasma of detached electrons and atomic nuclei, reminiscent of the early Universe after the Big Bang.

Even though kilonova are extraordinarily energetic, they’re difficult to observe and study because they’re transient and fade quickly. The first conclusive kilonova observation was in 2017, and the event is named AT2017gfo. AT stands for Astronomical Transient, followed by the year it was observed, followed by a sequence of three letters that are assigned to uniquely identify the event.

New research into AT2017gfo has uncovered more details of this energetic event. The research is “Emergence hour-by-hour of r-process features in the kilonova AT2017gfo.” It’s published in the journal Astronomy and Astrophysics, and the lead author is Albert Sneppen from the Cosmic Dawn Center (DAWN) and the Niels Bohr Institute, both in Copenhagen, Denmark.

A kilonova explosion creates a spherical ball of plasma that expands outward, similar to the conditions shortly after the Big Bang. Plasma is made up of ions and electrons, and the intense heat prevents them from combining into atoms.

However, as the plasma cools, atoms form via nucleosynthesis, and scientists are intensely interested in this process. There are three types of nucleosynthesis: slow neutron capture (s-process), proton process (p-process), and rapid neutron capture (r-process). Kilonovae form atoms through the r-process and are known for forming heavier elements, including gold, platinum, and uranium. Some of the atoms they form are radioactive and begin to decay immediately, and this releases the energy that makes a kilonova so luminous.

This study represents the first time astronomers have watched atoms being created in a kilonova.

“For the first time we see the creation of atoms.”

Rasmus Damgaard, co-author, PhD student at Cosmic DAWN Center

Things happen rapidly in a kilonova, and no single telescope on Earth can watch as it plays out because the Earth’s rotation removes it from view.

“This astrophysical explosion develops dramatically hour by hour, so no single telescope can follow its entire story. The viewing angle of the individual telescopes to the event is blocked by the rotation of the Earth,” explained lead author Sneppen.

This research is based on multiple ground telescopes that each took their turn watching the kilonova as Earth rotated. The Hubble also contributed observations from its perch in low-Earth orbit.

“But by combining the existing measurements from Australia, South Africa and The Hubble Space Telescope, we can follow its development in great detail,” Sneppen said. “We show that the whole shows more than the sum of the individual sets of data.”

As the plasma cools, atoms start to form. This is the same thing that happened in the Universe after the Big Bang. As the Universe expanded and cooled and atoms formed, light was able to travel freely because there were no free electrons to stop it. AT2017gfo produced

The research is based on spectra collected from 0.5 to 9.4 days after the merger. The observations focused on optical and near-infrared (NIR) wavelengths because, in the first few days after the merger, the ejecta is opaque to shorter wavelengths like X-rays and UV. Optical and NIR are like open windows into the ejecta. They can observe the rich spectra of newly-formed elements, which are a critical part of kilonovae.

This figure from the research shows how different telescopes contributed to the observations of AT2017gfo. Image Credit: Sneppen et al. 2024.

The P Cygni spectral line is also important in this research. It indicates that a star, or in this case, a kilonova, has an expanding shell of gas around it. It’s both an emission line and an absorption line and has powerful diagnostic capabilities. Together, they reveal velocity, density, temperature, ionization, and direction of flow.

Strontium plays a strong role in this research and in kilonovae. It produces strong emission and absorption features in Optical/NIR wavelengths, which also reveal the presence of other newly formed elements. These spectral lines do more than reveal the presence of different elements. Along with P Cygni, they’re used to determine the velocity of the ejecta, the velocity structures in the ejecta, and the temperature conditions and ionization states.

The spectra from AT2017gfo are complex and anything but straightforward. However, in all that light data, the researchers say they’ve identified elements being synthesized, including Tellurium, Lanthanum, Cesium, and Yttrium.

“We can now see the moment where atomic nuclei and electrons are uniting in the afterglow. For the first time we see the creation of atoms, we can measure the temperature of the matter and see the micro physics in this remote explosion. It is like admiring the cosmic background radiation surrounding us from all sides, but here, we get to see everything from the outside. We see before, during and after the moment of birth of the atoms,” says Rasmus Damgaard, PhD student at Cosmic DAWN Center and co-author of the study.

“The matter expands so fast and gains in size so rapidly, to the extent where it takes hours for the light to travel across the explosion. This is why, just by observing the remote end of the fireball, we can see further back in the history of the explosion,” said Kasper Heintz, co-author and assistant professor at the Niels Bohr Institute.

The kilonova produced about 16,000 Earth masses of heavy elements, including 10 Earth masses of the elements gold and platinum.

Neutron star mergers also create black holes, and AT2017gfo created the smallest one ever observed, though there’s some doubt. The gravitational wave GW170817 is associated with the kilonova and was detected by LIGO in August 2017. It was the first time a GW event was seen in conjunction with its electromagnetic counterpart. Taken together, the GW data and other observations suggest that a black hole was created, but overall, there’s uncertainty. Some researchers think a magnetar may be involved.

This artist’s illustration shows a neutron star collision that, in addition to the radioactive fire cloud, leaves behind a black hole and jets of fast-moving material from its poles. Illustration: O.S. SALAFIA, G. GHIRLANDA, CXC/NASA, GSFC, B. WILLIAMS ET AL

Kilonovae are complex objects. They’re like mini-laboratories where scientists can study extreme nuclear physics. Kilonovae are important contributors of heavy elements in the Universe, and researchers are keen to model and understand how elements are created in these environments.

The post The Aftermath of a Neutron Star Collision Resembles the Conditions in the Early Universe appeared first on Universe Today.

Today’s photos are from California tidepools and were taken by UC Davis math professor Abigail Thompson, a recognized “hero of intellectual freedom.” Abby’s notes and IDs are indented, and you can enlarge the photos by clicking on them.

September-October tidepools (Northern California).

September and October tides are not as extreme as the tides of midsummer, and by mid-October the lowest tides occur after sunset, which altogether makes finding creatures and taking pictures a bit more challenging.  As usual I got help with some of the IDs from people on inaturalist.

Phyllocomus hiltoni: this Doctor-Suessian marine worm washed up on the beach in a clump of eelgrass.    It was tiny; the photo is through a microscope.     I already thought it was amazing, but then (see the next picture) as a bonus it also sprouted tentacles:

Phyllocomus hiltoni with frills!

Porychthis notatus: these tiny fish showed up when I turned over a rock. They were very small, I assume newly-hatched:

Porychthis notatus: close-up:

Anthopleura sola (starburst anemone), one of the more spectacular sea anemones:

Phragmatopoma californica (California sandcastle worm): These worms often live in groups and form large conglomerations of the tubes they live in (the “sandcastles”).    The black shell-like thing on the left is the worm’s operculum, like a lid to close off the top of the tube when the worm withdraws.  The next picture is a close-up of the operculum:

Operculum close-up:

Triopha maculata: nudibranch; this one looks like he’s eating the pink bryozoan, but he may just be passing over it, I’m not sure what this species eats (nudibranchs are very picky eaters):

Epiactis prolifera (brooding anemone: probably): there are a few species of Epiactis sea anemones along the California coast; prolifera is the most common:

Halosydna brevisetosa: Eighteen-scaled worm, found on the underside of a rock.   There are 18 pairs of scales, with a close-up of them in the next picture.

Close-up of scales:

Low tide on this day was about an hour after sunset, which is a lovely time to be out on the beach:

Camera info:  Mostly Olympus TG-7, in microscope mode, pictures taken from above the water.  The first picture was taken with my iphone through the eyepiece of a microscope.

Think of the Moon and most people will imagine a barren world pockmarked with craters. The same is likely true of Mars albeit more red in colour than grey! The Earth too has had its fair share of craters, some of them large but most of the evidence has been eroded by centuries of weathering. Surprisingly perhaps, Venus, the second planet from the Sun does not have the same weathering processes as we have on Earth yet there are signs of impact craters, but no large impact basins! A team of astronomers now think they have secured a new view on the hottest planet in the Solar System and revealed the missing impact sites. 

Venus is the second planet from the Sun and, whilst it’s often called Earth’s sister planet, the reality is really they differ in many ways. The term comes from similarities in size and composition yet the conditions on Venus are far more hostile. Surface temperatures far exceed the boiling point of water, the dense atmosphere exerts a pressure on the surface equivalent to being 3,000 feet under water and there is sulphuric acid rain in the atmosphere! Most definitely not a nice place to head to for your next vacation. 

Venus

If you were to stand on the surface of Venus you would see beautifully formed craters. Looking down on the planet from orbit you would see none due to the thick, dense atmosphere. Yet if you could gaze through the obscuring clouds you would see a distinct lack of larger impact basins of the sort we are familiar with on the Moon. Now, a team of researchers mostly from the Planetary Science Institute believe they solve the mystery of the missing craters. 

The Moon. Credit: NASA

They have mapped a region of Venus known as Haastte-baad Tessera using radar technology and the results were rather surprising. The region is thought to be one of the oldest surfaces on Venus and is classed as tessera terrain. This type of feature is complex and is characterised by rough, intersecting ridges to create a tile like pattern thought to be the result of a thin but strong layer of material forming over a weak layer which can flow and convect energy just like boiling water. Images from the area in question reveal a set of concentric rings over 1,400 km across at their widest. The team propose that the feature is the result of two back-to-back impact events. “Think of pea soup with a scum forming on top,” said Vicki Hansen,  Planetary Science Institute Senior Scientist. 

Obviously there is no pea soup on Venus but instead, the thin crust layer formed upon a layer of molten lava. Venus of today has a thick outer shell called a lithosphere which is about 112 km thick but when Venus was younger, its thought it was just 9km thick! If an impactor struck the hot young Venus then it’s very likely it would have fractured the lithosphere allowing molten lava to seep through and eventually solidify to create the tesserae we see today. 

Confusing things slightly however is that features like this have been seen on top of flat, raised plateaus where the lithosphere is likely much thicker. The researchers have an answer for this though, “When you have vast amounts of partial melt in the mantle that rushes to the surface, what gets left behind is something called residuum. Solid residuum is much stronger than the adjacent mantle, which did not experience partial melting.” said Hansen. “What may be surprising is that the solid residuum is also lower density than all the mantle around it. So, it’s stronger, but it’s also buoyant. You basically have an air mattress sitting in the mantle beneath your lava pond, and it’s just going to rise up and raise that tessera terrain.”

The features found by the time seem to show that two impact events happened one after the other with the first creating the build up of lava and the second creating the ring structure seen today. 

Source : Impact craters were hiding in plain sight, say researchers with a new view of Venus

The post New View of Venus Reveals Previously Hidden Impact Craters appeared first on Universe Today.

Quickie with Bob: Predicting Earthquakes; News Items: Cell Phones and Brain Cancer, Gold from Earthquakes, Plastic in the Brain, Quantum Neural Network, Marmosets have Names; Your questions and E-mails: Beetles; Name That Logical Fallacy; Science or Fiction

In a few years, as part of the Artemis Program, NASA will send the “first woman and first person of color” to the lunar surface. This will be the first time astronauts have set foot on the Moon since the Apollo 17 mission in 1972. This will be followed by the creation of permanent infrastructure that will allow for regular missions to the surface (once a year) and a “sustained program of lunar exploration and development.” This will require spacecraft making regular trips between the Earth and Moon to deliver crews, vehicles, and payloads.

In a recent NASA-supported study, a team of researchers at the University of Illinois Urbana-Champaign investigated a new method of sending spacecraft to the Moon. It is known as “multimode propulsion,” a method that integrates a high-thrust chemical mode and a low-thrust electric mode – while using the same propellant. This system has several advantages over other forms of propulsion, not the least of which include being lighter and more cost-effective. With a little luck, NASA could rely on multimode propulsion-equipped spacecraft to achieve many of its Artemis objectives.

The paper describing their investigation, “Indirect optimal control techniques for multimode propulsion mission design,” was recently published in Acta Astronautica. The research was led by Bryan C. Cline, a doctoral student in the Department of Aerospace Engineering at the University of Illinois Urbana-Champaign. He was joined by fellow aerospace engineer and PhD Candidate Alex Pascarella, and Robyn M. Woollands and Joshua L. Rovey – an assistant professor and professor with the Grainger College of Engineering (Aerospace Engineering).

Artist’s impression of the ESA LISA Pathfinder mission. Credit: ESA–C.Carreau

To break it down, a multimode thruster relies on a single chemical monopropellant – like hydrazine or Advanced Spacecraft Energetic Non-Toxic (ASCENT) propellant – to power chemical thrusters and an electrospray thruster (aka. colloid thruster). The latter element relies on a process known as electrospray ionization (ESI), where charged liquid droplets are produced and accelerated by a static electric field. Electrospray thrusters were first used in space aboard the ESA’s LISA Pathfinder mission to demonstrate disturbance reduction.

By developing a system that relies on both that can switch as needed, satellites will be able to perform propulsive manuevers using less propellant (aka. minimum-fuel transfers). As Cline said in a Grainger College of Engineering press release:

“Multimode propulsion systems also expand the performance envelope. We describe them as flexible and adaptable. I can choose a high-thrust chemical mode to get someplace fast and a low-thrust electrospray to make smaller maneuvers to stay in the desired orbit. Having multiple modes available has the potential to reduce fuel consumption or reduce time to complete your mission objective.”

The team’s investigation follows a similar study conducted by Cline and researchers from NASA’s Goddard Spaceflight Center and the aerospace advisory company Space Exploration Engineering, LLC. In a separate paper, “Lunar SmallSat Missions with Chemical-Electrospray Multimode Propulsion,” they considered the advantages of multimode propulsion against all-chemical and all-electric approaches for four design reference missions (DRMs) provided by NASA. For this latest investigation, Cline and his colleagues used a standard 12-unit CubeSat to execute these four mission profiles.

.Earth–Mars minimum-fuel trajectory when the CubeSat is coasting, as well as in mode 1-low thrust and mode 2-high thrust. Credit: UIU-C

“We showed for the first time the feasibility of using multimode propulsion in NASA-relevant lunar missions, particularly with CubeSats,” said Cline. “Other studies used arbitrary problems, which is a great starting point. Ours is the first high-fidelity analysis of multimode mission design for NASA-relevant lunar missions.”

Multimode propulsion is similar in some respects to hybrid propulsion, where two propulsion systems are combined to achieve optimal thrust. A good example of this (though still unrealized) is bimodal nuclear propulsion, where a spacecraft relies on a nuclear-thermal propulsion (NTP) and nuclear-electric propulsion (NEC) system. While an NTP system relies on a nuclear reactor to heat hydrogen or deuterium propellant and can achieve a high rate of acceleration (delta-v), an NEC system uses the reactor to power an ion engine that offers a consistent level of thrust.

A key advantage multimode propulsion has over a hybrid system is a drastic reduction in the dry mass of the spacecraft. Whereas hybrid propulsion systems require two different propellants (and hence, two separate fuel tanks), bimodal propulsion requires only one. This not only saves on the mass and volume of the spacecraft, but makes them cheaper to launch. “I can choose to use high-thrust at any time and low-thrust at any time, and it doesn’t matter what I did in the past,” said Cline. “With a hybrid system, when one tank is empty, I can’t choose that option.”

To complete each of the design reference missions for this project, the team made all decisions manually – i.e., when to use high-thrust and low-thrust. As a result, the trajectories weren’t optimal. This led Cline to develop an algorithm after completing the project that automatically selects which mode would lead to an optimal trajectory. This allowed Cline and his team to solve a simple two-dimensional transfer between Earth and Mars and a three-dimensional transfer to geostationary orbit that minimizes fuel consumption. As Cline explained:

“This was an entirely different beast where the focus was on the development of the method, rather than the specific results shown in the paper. We developed the first indirect optimal control technique specifically for multimode mission design. As a result, we can develop transfers that obey the laws of physics while achieving a specific objective such as minimizing fuel consumption or transfer time.”

“We showed the method works on a mission that’s relevant to the scientific community. Now you can use it to solve all kinds of mission design problems. The math is agnostic to the specific mission. And because the method utilizes variational calculus, what we call an indirect optimal control technique, it guarantees that you’ll get at least a locally optimal solution.”

Artist rendering of an Artemis astronaut exploring the Moon’s surface during a future mission. Credit: NASA

The research is part of a project led by Professor Rovey and a multi-institutional team known as the Joint Advanced Propulsion Institute (JANUS). Their work is funded by NASA as part of a new Space and Technology Research Institute (STRI) initiative. Rovey is responsible for leading the Diagnostics and Fundamental Studies team, along with Dr. John D. Williams, a Professor of Mechanical Engineering and the Director of the Electric Propulsion & Plasma Engineering Laboratory at Colorado State University (CSU).

As Cline indicated, their work into multimode propulsion could revolutionize how small spacecraft travel between Earth and the Moon, Mars, and other celestial bodies:

“It’s an emerging technology because it’s still being developed on the hardware side. It’s enabling in that we can accomplish all kinds of missions we wouldn’t be able to do without it. And it’s enhancing because if you’ve got a given mission concept, you can do more with multimode propulsion. You’ve got more flexibility. You’ve got more adaptability.

“I think this is an exciting time to work on multimode propulsion, both from a hardware perspective, but also from a mission design perspective. We’re developing tools and techniques to take this technology from something we test in the basement of Talbot Lab and turn it into something that can have a real impact on the space community.”

Further ReadingL University of Illinois Urbana-Champaign, Acta Astronautica

The post Multimode Propulsion Could Revolutionize How We Launch Things to Space appeared first on Universe Today.

China has a fabulously rich history when it comes to space travel and was among the first to experiment in rocket technology. The invention of the rocket is often attributed to the Sung Dynasty (AD 960-1279.) Since then, China has been keen to develop and build its own space industry. The Chinese National Space Administration has already successfully landed probes on the Moon but is preparing for their first human landers. Chinese astronauts are sometimes known as taikonauts and CNSA has just confirmed their fourth batch of taikonauts are set for a lunar landing. 

The Chinese National Space Administration (CNSA) is China’s equivalent to NASA. It was founded in 1993 to oversee the country’s space aspirations. Amazing results have been achieved over the last twenty years including the landmark Chang’e lunar missions. In 2019 Chang’e-4 landed on the far side of the Moon, the first lunar lander to do so and in 2021 became the third country to land a rover on Mars. In 2021 the first modules for CNSA’s Tiangong space station were launched, it’s now operational and working with other space agencies, is working on a number of scientific research projects. 

China has announced that it successfully completed its latest selection process in May. The CNSA are striving to expand their team of taikonauts. Ten were chosen from all the applicants including 8 experienced space pilots and two payload specialists. The team will now begin their program of training in August covering over 200 subject areas designed to prepare them for future missions to the Moon and other Chinese space initiatives. 

The training covers an extensive range of skills It will include training for living and working in microgravity, to learn about physical and mental health in space and specialist training in extravehicular activities. They will also learn maintenance techniques for advanced spacecraft systems and in hands-on training for undertaking experiments in microgravity. 

On her 2007 mission aboard the International Space Station, NASA astronaut Peggy Whitson, Expedition 16 commander, worked on the Capillary Flow Experiment (CFE), which observes the flow of fluid, in particular capillary phenomena, in microgravity. Credits: NASA

The program is designed to expand and fine tune the skills of the taikonauts in preparation for future crewed lunar missions. Specialist training for lunar landings include piloting spacecraft under different gravitational conditions, manoeuvring lunar rovers, training in celestial navigation and stellar identification. 

Not only will they learn about space operations but they will have to learn skills to support scientific objectives too. This will include how to conduct geological surveys and how to operate tools and manoeuvre in the micro-gravitational environments. 

Source : China’s fourth batch of taikonauts set for lunar landings

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It was 1969 that humans first set foot on the Moon. Back then, the Apollo mission was the focus of the attempts to land on the Moon but now, over 50 years on, it looks like we are set to head back. The Artemis project is the program that hopes to take us back to the Moon again and it’s going from strength to strength. The plan is to get humans back on the Moon by 2025 as part of Artemis III. As a prelude to this, NASA is now turning its attention to the possible landing sites. 

The Artemis Project is NASA’s program aimed at returning humans to the Moon and establishing a permanent base there. Ultimately with a view to paving the way for missions to Mars. With the first launch in 2017, Artemis intends to land “the first woman and the next man” on the lunar surface by 2025.  The program began with Artemis I and an uncrewed mission which orbited the Moon. Arte is II will take astronauts on an orbit of the Moon and finally Artemis III will land humans back on the Moon by 2025. At the heart of the program is the giant Space Launch System (SLS) rocket and the Orion spacecraft. 

NASA’s Space Launch System rocket carrying the Orion spacecraft launches on the Artemis I flight test, Wednesday, Nov. 16, 2022, from Launch Complex 39B at NASA’s Kennedy Space Center in Florida. Credit: NASA/Joel Kowsky.

As the plans ramp up for the first crewed landing, NASA are now analysing possible landing sites and have identified nine potential spots. They are all near the South Pole of the Moon and will provide Artemis III with landing sites near to potentially useful resources. Further investigations will be required to further assess them for their suitability. 

The team working upon the analysis is the Cross Agency Site Selection Analysis team and they will work with other science and industry partners. The teams will explore each possible site for science value and suitability for the mission including the availability of water ice. The final list so far, and in no particular order, are;

• Peak near Cabeus B
• Haworth
• Malapert Massif
• Mons Mouton Plateau
• Mons Mouton
• Nobile Rim 1
• Nobile Rim 2
• de Gerlache Rim 2
• Slater Plain

The South Polar region was chosen as a region was chosen chiefly because it has water locked up deep in the shadowed craters. The Apollo missions never visited that region of the Moon either so it is a great opportunity for humans to explore this aged region of the lunar surface. To settle on these 9 areas, the team assessed various regions of the south polar region using potential launch window suitability, terrain suitability, communication capability and even lighting levels. The geology team also looked at the landing sites to assess their scientific value 

Apollo 17 astronaut Harrison Schmitt collecting a soil sample, his spacesuit coated with dust. Credit: NASA

NASA will finally settle on the appropriate landing site based upon the decision for the launch date. Once that has been confirmed it will determine the transfer trajectories to the Moon, the orbital paths and the surface environment. 

Source : NASA Provides Update on Artemis III Moon Landing Regions

The post NASA Focusses in on Artemis III Landing Sites. appeared first on Universe Today.

The discovery of the accelerated expansion of the Universe has often been attributed to the force known as dark energy. An intriguing new theory was put forward last year to explain this mysterious force; black holes could be the cause of dark energy! The theory goes on to suggest as more black holes form in the Universe, the stronger the pressure from dark energy. A survey from the Dark Energy Spectroscopic Instrument (DESI) seems to support the theory. The data from the first year of operation shows the density of dark energy increases over time and seems to correlate with the number and mass of black holes! 

Cast your mind back 4 billion years to the beginning of the Universe. Just after the Big Bang, the moment when the Universe popped into existence, there was a brief period when the Universe expanded faster than the speed of light. Before you argue that nothing can travel faster than the speed of light we are talking of the very fabric of space and time expanding faster than the speed of light. The speed of light limit relates to travel through the fabric of space, not the fabric of space itself! This was the inflationary period. 

This illustration shows the “arrow of time” from the Big Bang to the present cosmological epoch. Credit: NASA

The energy that drove the expansion in the early Universe shared similarities with dark energy, the repulsive force that seems to permeate the Universe and is driving the current day accelerated expansion of the Universe.

What is dark energy though? It is thought to make up around 68% of the Universe and, unlike normal matter and energy seems to have a repulsive force rather than attractive. The repulsive nature was first inferred from observations in the late 1990’s when astronomers deduced the rate of acceleration when observing distant supernova. As to the nature of dark energy, no-one really knows what it is or what it comes from, that is, until now. 

Artist’s illustration of a bright and powerful supernova explosion. (Credit: NASA/CXC/M.Weiss)

A team of researchers from the University of Michigan and other institutions have published a paper in the Journal of Cosmology and Astroparticle Physics. In their paper they propose that black holes are the source of dark energy. Professor Gregory Tarle said ‘Where in the later Universe do we see gravity as strong as it was at the beginning of the Universe?’ The answer, Tarle goes on to describe is the centre of black holes. Tarle and team propose that what happened during the inflation period runs in reverse during the collapse of a massive star. When this happens, the matter could conceivably become dark energy. 

The team have used data from the Dark Energy Spectroscopic Instrument (DESI) which is mounted upon the 4m Mayall telescope at Kitt Peak National Observatory. The instrument is essentially 5,000 computer controlled fibre optics which cover an area of the sky equal to about 8 square degrees. The evidence of dark energy is achieved by studying tens of millions of galaxies. The galaxies are so far way their light takes billions of years to reach us. We can use the information to determine how fast the Universe is expanding with unprecedented precision. 

Stu Harris works on assembling the focal plane for the Dark Energy Spectroscopic Instrument (DESI), which involves hundreds of thousands of parts, at Lawrence Berkeley National Laboratory on Wednesday, 6 December, 2017 in Berkeley, Calif.

The data shows evidence that dark energy has increased with time. This is not perhaps in itself surprising but it seems to accurately mirror the increase in black holes over time too. Now that DESI is operational, more observations are required to hunt down the black holes and try to quantify their growth over time to see if there really is merit in this new exciting hypothesis. 

Source : Evidence mounts for dark energy from black holes

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A bird flu virus that has been circulating in dairy cattle for months has now been found in a pig in the US for the first time, raising the risk of the virus evolving to become more dangerous to people

Inside a hunk of a material called a semimetal, scientists have uncovered signatures of bizarre particles that sometimes move like they have no mass, but at other times move just like a very massive particle

Soil is full of an uncountable number of viruses, and scientists are only beginning to understand just how substantial their role in the carbon cycle may be

If there are alien civilizations in the Universe, some of them could be super advanced. So advanced that they can rip apart planets and create vast shells surrounding a star to capture all its energy. These Dyson spheres should be detectable by modern telescopes. Occasionally astronomers find an object that resembles such an alien megastructure, but so far, they’ve all turned out to be natural objects. As best we can tell, there are no Dyson spheres out there.

And when you think about it, building a Dyson sphere is the cosmic endgame of a capitalist dystopia. In the never-ending quest to capture and consume every last bit of energy, your civilization rips worlds asunder, moving heaven and earth to create an orbitally unstable, unlivable engine. If you can traverse light-years and transform planets, why not just move Earth-like planets and moons into a star’s habitable zone and have a nice cluster of comfy planets to live on? If this kind of stellar-punk civilization is out there, could astronomers detect it? This is the question behind a study on the arXiv.

The authors begin by noting that when Freeman Dyson proposed the idea in 1960, our solar system was the only known planetary system. Star systems were thought to be rare at the time, but now we know better. Most stars have planets, and even our solar system has a dozen water-rich moons that could be made habitable with a shift of their orbits and a bit of terraforming. Since this would be much easier than building a Dyson sphere, the authors argue that modified systems should be much more common. The only question is how to detect them.

One way would be to look for planetary systems that don’t seem to have formed naturally. For example, if you find a system with a dozen worlds in a star’s habitable zone and few other planets, that isn’t likely to have happened by chance. Less obvious would be to look for systems that are orbitally unusual. Perhaps the planets have orbital resonances that aren’t stable in the long term, or have unusually perfect orbits. Maybe the chemical composition of some worlds don’t match that of the system as a whole. Anything that stands out might be worth a closer look.

Using lasers to change a planet’s orbit. Credit: Narasimha, et al

Another way would be to look for signs of systems under construction. The authors note that planets could be moved or captured slowly over time using high-power directional lasers to accelerate them. Stray light from those lasers would be visible across light years. If we detect monochromatic laser light coming from a potentially habitable star, it could be aliens building a better home.

It’s not likely that we’ll find this kind of evidence, but the idea is no stranger than those of giant alien megastructures. Besides, it’s fun to think about just how many habitable planets you could pack into a single star system. It turns out to be quite a lot!

Reference: Narasimha, Raghav, Margarita Safonova, and C. Sivaram. “Making Habitable Worlds: Planets Versus Megastructures.” arXiv preprint arXiv:2309.06562 (2023).

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Enough landmines are buried underground worldwide to circle Earth twice at the equator, but the identification and removal of these explosives is costly and time-consuming. New research could help solve the problem.

Biomedical engineers have invented a 3D printing system, or bioprinter, capable of fabricating structures that closely mimic the diverse tissues in the human body, from soft brain tissue to harder materials like cartilage and bone.

SURD, an algorithm, reveals causal links in complex systems. Applications may include forecasting climate to projecting population growth to designing efficient aircraft.

Despite ongoing efforts to curb CO2 emissions with electric and hybrid vehicles, other forms of transportation remain significant contributors of greenhouse gases. To address this issue, old technologies are being revamped to make them greener, such as the reintroduction of sailing vessels in shipping and new uses for hydrogen in aviation. Now, researchers have used computer modeling to study the feasibility and challenges of hydrogen-powered aviation.