A Gamma-ray Burst Disturbed the Earth’s Ionosphere
by Carolyn Collins Petersen on November 30, 2023 at 2:50 am
You’d think that something happening billions of light-years away wouldn’t affect Earth, right? Well, in 2002, a burst of gamma rays lasting 800 seconds actually impacted our planet. They came from a powerful and very distant supernova explosion. Its gamma-ray bombardment disturbed our planet’s ionosphere and activated lightning detectors in India.
This particular gamma-ray burst (GRB) occurred in a galaxy almost 2 billion light-years away (and took two billion years to reach us). Not only did ground-based detectors record the bombardment, but satellites sensitive to high-energy outbursts “saw” it, too. That included the European Space Agency’s International Gamma-Ray Astrophysics Laboratory (INTEGRAL) mission. It typically records gamma-ray bursts on a daily basis, but this one—named GRB 221009A—outshone all the rest.
GRBs this strong happen (on average) about once every 10,000 years, so this was one that caught everyone’s attention. “It was probably the brightest gamma-ray burst we have ever detected,” says Mirko Piersanti, University of L’Aquila, Italy, and lead author of a paper analyzing the event.
How The Gamma-ray Burst Affected the Ionosphere
Most of the time, radiation from the Sun bombards our planet. That’s often strong enough to affect the ionosphere. That’s an atmospheric layer that bristles with electrically charged gases called plasma. It stretches from around 50 km to 950 km in altitude above the surface. There’s a “top-side ionosphere” (which lies above 350 km) and a “bottom-side ionosphere”) which lies below that. Scientists are pretty familiar with how the Sun treats this region of the atmosphere, particularly during periods of heavy solar activity.
This GRB blast triggered instruments generally reserved for studying the immense explosions in the Sun’s atmosphere known as solar flares. “Notably, this disturbance impacted the very lowest layers of Earth’s ionosphere, situated just tens of kilometers above our planet’s surface, leaving an imprint comparable to that of a major solar flare,” says Laura Hayes, research fellow and solar physicist at ESA. That imprint basically was an increase in ionization in the bottom-side ionosphere. It left an imprint in low-frequency radio signals that move between Earth’s surface and the lowest levels of the ionosphere. “Essentially, we can say that the ionosphere ‘moved’ down to lower altitudes, and we detected this in how the radio waves bounce along the ionosphere,” explained Laura.
Gamma Ray Bursts in the Data
Past GRBs bothered the bottom-side ionosphere but didn’t always disturb the topside. Scientists just assumed that by the time it reached Earth, the blast from a GRB didn’t have the “oomph” to change that part of the ionosphere. GRB 221009A proved that idea wrong. Thanks to data from the orbiting China Seismo-Electromagnetic Satellite (CSES), scientists saw a strong disturbance in the upper ionosphere. It created a strong electric field variation and was the first time scientists saw this connected to a GRB. The result is the first-ever top-side ionospheric measurement of electric field variations triggered by a gamma-ray outburst at cosmic distances.
INTEGRAL and other spacecraft continually record GRBs from around the Universe. Have they all affected our ionosphere in some way? Is there a way to find out? Now that scientists know what ionospheric effects to look for, they can search the data to find answers. Data from INTEGRAL, and CSES will be particularly useful. They should be able to correlate it with other GRBs seen since 2018. That’s when CSES was launched.
Evidence of ionospheric disturbances from GRBs goes back as far as 1988. That’s when the effects of a 1983 gamma-ray burst were first reported. Scientists now have an array of ground-based and space-based detectors—such as Swift, Fermi, MAXI, AGILE, INTEGRAL, and CSES—gave strong detections of the emissions from GRB221009A.
Implications for Future GRB Effects on Earth
This kind of disturbance from a very distant event poses a question: what would happen if such an explosion happened “closer to home”? A supernova in our own galaxy, for example, releasing a huge burst of gamma rays, could very well “reach out and touch” Earth in a drastic way. “There has been a great debate about the possible consequences of a gamma-ray burst in our own galaxy,” says Mirko Piersanti.
For one thing, a close-by and strong GRB would have drastic effects on our ionosphere, much stronger than a typical solar flare. It could also do some significant damage to the ozone layer (which provides a protective shield against radiation from the Sun). That would allow a lot more ultraviolet (UV) to reach the surface than we’re accustomed to experiencing. It’s possible (although not proven) that some of Earth’s past extinction events could be related to an increase in UV radiation on the surface.
Gamma-ray Bursters and Extinctions
Earth’s ozone layer is a first-line defense mechanism against radiation, which is why people stopped using gases such as chlorofluorocarbons. They were destroying the ozone layer, allowing in more UV radiation. This affected the atmosphere as well as people, plants, and animals. At least one research paper looked at ozone depletion by GRBs by studying what happens over the polar regions. Increased UV radiation produces changes in the middle atmosphere, including the creation of ground-level ozone, which can damage life in high concentrations. A burst that sent radiation into the south polar regions is suggested as one reason that the Ordovician extinction happened around 445 million years ago. An estimated 85 percent of species alive at that time were wiped out.
If a nearby GRB was involved, that might explain the Ordovician event and may offer insight into other mass extinctions. It’s not far-fetched to think that some of them may have had cosmic triggers. Those could have affected life on Earth more powerfully than the two-billion-year-old bombardment from GRB 221009A.
For More Information
Blast from the Past: Gamma-ray Burst Strikes Earth from Distant Exploding Star
Evidence of an Upper Ionospheric Electric Field Perturbation Correlated with a Gamma Ray Burst
How Deadly Would a Gamma-ray Burst Be?
The post A Gamma-ray Burst Disturbed the Earth’s Ionosphere appeared first on Universe Today.
Should We Send Humans to Venus?
by Laurence Tognetti on November 30, 2023 at 2:11 am
NASA is preparing to send humans back to the Moon with the Artemis missions in the next few years as part of the agency’s Moon to Mars Architecture with the long-term goal of landing humans on the Red Planet sometime in the 2030s or 2040s. But what about sending humans to other worlds of the Solar System? And, why not Venus? It’s closer to Earth than Mars by several tens of millions of kilometers, and despite its extremely harsh surface conditions, previous studies have suggested that life could exist in its clouds. In contrast, we have yet to find any signs of life anywhere on the Red Planet or in its thin atmosphere. So, should we send humans to Venus?
“Yes, we should send humans to Venus,” Dr. Paul Byrne, who is an Associate Professor of Earth, Environmental, and Planetary Sciences at Washington University in St. Louis, tells Universe Today. “But first, let’s talk about what ‘sending humans to Venus’ actually means. The surface of Venus is hellish, so nobody would last long there nor volunteer to go. Above the clouds, the temperature and pressure are almost like a nice spring day here on Earth, so aside from tiny sulphuric acid cloud droplets you’d be okay (with a breathing apparatus).”
These “hellish” conditions that Dr. Byrne alludes to are the extreme conditions across the surface of Venus, including surface pressures 92 times that of Earth’s surface and average surface temperatures of approximately 464 degrees Celsius (867 degrees Fahrenheit). In contrast, Earth’s average surface temperatures are a calm 15 degrees Celsius (59 degrees Fahrenheit). These extreme pressures and temperatures have made landing on the surface of Venus even more difficult, as the former Soviet Union continues to be the only nation to have successfully landed on Venus’ surface, having accomplished this feat with several of their Venera and Vega missions. However, the longest mission duration for the lander was only 127 minutes (Venera 13), which also conducted the first sound recording on another planet.
“If we were to send humans to Venus, they’d be going in a spacecraft that would fly by the planet en route somewhere else,” Dr. Byrne tells Universe Today. “If we were to one day send humans actually to Venus itself for science and engineering purposes, then a cloud-based habitat is the way to go. Getting humans onto the Venus surface is going to require so much technology and expense that, for the foreseeable future, I don’t think anyone will think it worth doing.”
A 2015 study presented at the AIAA Space and Astronautics Forum and Exposition outlined a NASA study for the High Altitude Venus Operational Concept (HAVOC) mission that would involve a 30-day crewed mission using an airship equipped with solar panels within the upper atmosphere of Venus. This is because Venus’ upper atmosphere at approximately 50 kilometers (30 miles) above the surface exhibits much more hospitable conditions, including temperatures between 30 to 70 degrees Celsius (86 to 158 degrees Fahrenheit) and pressures very close to that of Earth. However, Dr. Byrne refers to HAVOC as an “unbelievably expensive concept”.
As for using Venus while en route to another location in the Solar System, Venus has been used on several occasions to slingshot spacecraft to the outer Solar System as well as for exploration of the inner Solar System, such as Mercury and the Sun. For example, NASA’s Galileo and Cassini spacecraft used gravity assists at Venus while en route to Jupiter and Saturn, respectively, while NASA’s MESSENGER and the European Space Agency’s (ESA) BepiColombo spacecraft used gravity assists at Venus while en route to Mercury. Additionally, NASA’s Parker Solar Probe and the ESA Solar Orbiter used gravity assists at Venus for orbital adjustments to explore the Sun.
“Once within close proximity to Venus, astronauts could remotely operate spacecraft, landers, or even aircraft to conduct valuable science before moving out of range again,” Dr. Byrne tells Universe Today. “But to be clear, the real value for such a mission would be as part of learning how to live and work in deep space en route to distant destinations, i.e., Mars. That’s something I don’t think we’re talking enough about yet when we think about sending humans, one day, to the Red Planet.”
Will we ever send humans to Venus? Will it be a cloud or surface mission, and what can we learn from doing it? Only time will tell, and this is why we science!
As always, keep doing science & keep looking up!
Odyssey Gives Us a Cool New View of Mars
by Matt Williams on November 30, 2023 at 12:35 am
Chances are that you’ve seen images of Earth from space, thanks to the astronauts aboard the International Space Station (ISS), who regularly share stunning photos of our planet. These images provide us regularly with breathtaking views of cities, oceans, storms, eruptions, clouds, the curvature of the planet, and the way the atmosphere glows against the horizon. Thanks to NASA’s Mars Odyssey Orbiter, which has been in orbit for over 22 years, we now have an equally breathtaking view of Mars from orbit that captured what its curvature and atmosphere look like from space.
The images were taken back in May when the orbiter was at an altitude of 400 km (250 mi) above the surface, the same altitude that the ISS orbits Earth. The spacecraft took ten pictures in total, which were stitched together to create a panoramic image showing the curving Martian landscape below a hazy layer of dust and clouds, as well as Mars’ smaller satellite Phobos. The THEMIS camera is ideally suited to capturing what’s happening in Mars’ atmosphere, as its sensitivity to infrared (heat) enables it to map ice, rock, sand, dust, and temperature changes on the planet’s surface.
Because THEMIS is fixed to the bottom of the orbiter, adjusting the camera’s angle requires that the entire spacecraft be reoriented. In this case, the team needed to rotate the orbiter about 90 degrees while making sure the solar panels were still pointed at the right angle so they could continue to draw power from the Sun. At the same time, they had to ensure that the orbiter’s sensitive instruments would not overheat. This included the THEMIS camera itself since external heat would cause extreme interference with its readings.
This required that the orbiter’s antenna be pointed away from Earth, which meant that the mission team could not communicate with Earth until the operation was complete. Preparing for this maneuver took three months and involved engineers at NASA’s Jet Propulsion Laboratory and Lockheed Martin Space, which together manage the mission and lead its day-to-day operations. Jonathon Hill, Arizona State University, is the operations lead for Odyssey’s camera, the Thermal Emission Imaging System (THEMIS). As he explained in a NASA press release, the image is reminiscent of what astronauts may see someday:
“If there were astronauts in orbit over Mars, this is the perspective they would have. No Mars spacecraft has ever had this kind of view before. We got a different angle and lighting conditions of Phobos than we’re used to. That makes it a unique part of our Phobos dataset,” he said. “I think of it as viewing a cross-section, a slice through the atmosphere,” added Jeffrey Plaut, Odyssey’s project scientist at JPL. “There’s a lot of detail you can’t see from above, which is how THEMIS normally makes these measurements.”
The resulting panorama is not only impressive to look at but will provide scientists with new insights into the composition and dynamics of the Martian atmosphere. Seeing where layers of water-ice clouds and dust are (and how they are stacked) in relation to each other is essential to improving models of Mars’ atmosphere. The mission team hopes to take similar images in the future that capture seasonal changes in the Martian atmosphere. The spacecraft also captured images of Phobos, which is the seventh time the mission has pointed THEMIS towards Phobos in the 22 years it has been orbiting Mars.
The latest imagery shows temperature variations across the moon’s surface and provides insight into the composition and physical properties of the moon. These images will also be helpful to the Odyssey scientists who are also working on the joint NASA-JAXA sample-return mission to Phobos and Deimos – the Mars Moon eXplorer (MMX). It is hoped this mission will finally settle the long-standing debate about whether Phobos is a captured asteroid or a chunk of Mars that was blasted into orbit by a past impact.
Further Reading: NASA
We Should Hit Peak Solar Activity Next Year
by Mark Thompson on November 30, 2023 at 12:08 am
You may be familiar with the solar cycle that follows a 22 year process shifting from solar minimum to maximum and back again. It’s a cycle that has been observed for centuries yet predicting its peak has been somewhat challenging. The Sun’s current cycle is approaching maximum activity which brings with it higher numbers of sunspots on its surface, more flares and more coronal mass ejections. A team from India now believe they have discovered a new element of the Sun’s magnetic field allowing them to predict the peak will occur early in 2024.
The Sun is a gigantic sphere of plasma or electrically charged gas. One of the features of plasma is that if a magnetic field passes through it, the plasma moves with it. Conversely if the plasma moves, the magnetic field moves too. This magnetic field is just like Earth and is known as a dipole magnetic field. You can visualise it if you can remember your school science days with a bar magnet and iron filings.
A dipole magnetic field has two opposite but equal charges and at the start of the Sun’s cycle the field lines effectively run from the north pole to the south. As the Sun rotates, with the equator rotating faster than the polar regions, then the plasma drags the magnetic field lines with it, winding them tighter and tighter.
The field lines become stretched causing the magnetic field to loop up and through the visible surface of the Sun. This localised event prevents the convection of super heated gas from underneath and appears as a cooler area of the surface which appears dark. As the solar cycle starts, these sunspots appear around the polar regions and slowly migrate toward the equator as it progresses with peak activity occurring when the sunspots fade away as we head toward the start of another cycle.
On occasions the magnetic field of sunspots are disrupted and we can experience flares or coronal mass ejections hurling vast amounts of charged particles out into space. If they reach us here on Earth they give rise to the beautiful aurora displays but they do also have a rather negative impact to satellites, power grids and telecommunications systems.
Deep inside the Sun, a dynamo mechanism is driving all this. It is created by the energy from the movement of plasma and it is this that is responsible for the flipping of the Sun’s magnetic poles where the north pole becomes south and the south pole becomes north which happens every 11 years or so. It’s another aspect of the solar cycle.
It’s been known since the 1930’s that the rate of rise the sunspot cycle relates to its strength with stronger cycles taking less time to reach peak. In the paper published in the Monthly Notices of the Royal Astronomical Society Letters; Priyansh Jaswal, Chitradeep Saha and Dibyendu Nandy from the Indian Institutes of Science Education and Research announced their findings. They discovered that the rate of decrease in the Sun’s dipole magnetic field also seems to relate to the rise of the present cycle.
The team have looked back through archives and have shown how the observation of the dipole decrease rate along with observations of sunspots can predict the peak of activity with better accuracy than before. They conclude the current cycle is expected to peak somewhere between early 2024 and September next year. Being able to better predict the peak of activity will help understand the likely intensity of space weather events here on Earth providing us more warning to be able to prepare.
It Doesn’t Take Much to Get Tilted Planets
by Evan Gough on November 29, 2023 at 10:39 pm
Chinese and Indian astronomers were the first to measure Earth’s axial tilt accurately, and they did it about 3,000 years ago. Their measurements were remarkably accurate: in 1120 BC, Chinese astronomers pegged the Earth’s axial tilt at 24 degrees. Now we know that all of the planets in the Solar System, with the exception of Mercury, have some tilt.
While astronomers have puzzled over why our Solar System’s planets are tilted, it turns out it’s rather normal.
Now that astronomers have observed so many other solar systems, they’ve learned that axial tilt is to be expected, even in so-called “pristine” solar systems. Pristine refers to the precise mathematical relationship between planets.
New research in The Astronomical Journal explains why some axial tilt is to be expected. It’s titled “Evidence for Low-level Dynamical Excitation in Near-resonant Exoplanet Systems.” The lead author is Malena Rice, an assistant professor of astronomy at Yale’s Faculty of Arts and Sciences.
The orbital resonance concept is at the heart of this research.
As planets orbit a star, they can exert regular and periodic gravitational influence on one another. When they do, astronomers say they’re in resonance with one another. It also happens in moon systems around planets with many moons. Some resonant systems can be self-stabilizing, while others can become unstabilized over time.
Early in a solar system’s history, planets are more likely to be in resonance with one another.
“This type of configuration, where one planet’s orbit is precisely ordered with another in an exact integer ratio of orbital periods, is likely common to find in a solar system early in its development,” said Rice. “It’s a gorgeous configuration — but only a small percentage of systems retain it.”
“Given that near-resonant systems have likely experienced minimal dynamical disruptions, the spin-orbit orientations of these systems inform the typical outcomes of quiescent planet formation, as well as the primordial stellar obliquity distribution,” the authors write in their research. The spin-orbit orientation is the tilt of companion planets’ orbits relative to the host star’s spin axis.
What that boils down to is that in a system that’s suffered few disruptions, like migrating planets, for example, the spin-orbit and axial tilt of the planets in the system should be largely unchanged from the time of formation. But the problem is astronomers haven’t rigorously measured the spin-orbit orientations of near-resonant systems.
“To date, only a handful of near-resonant systems have had spin-orbit angles measured to characterize the tilts of their constituent planetary orbits,” the authors explain in their research.
In this work, the researchers started out by examining a warm Jupiter named TOI-2202 b. It’s a near-resonant planet that’s only slightly less massive than Jupiter. It orbits a K-type star about 770 light-years away. TOI-2202 b is tight to its star, only 0.09564 AU away, and it completes an orbit in only 11.9 days. For comparison, Mercury is 0.387098 AU away from the Sun.
TOI-2202 b is in a pristine solar system, and it’s in a 2:1 mean-motion resonance with another planet further from the star. The researchers compared it to archival data and new observations of the exoplanet from multiple telescopes. They arrived at a spin-orbit angle of about 31 degrees. Then they compared that to the full census of other similar planets in pristine systems found in NASA’s Exoplanet Archive.
“To place this measurement into context, we examined the full set of transiting exoplanet systems with (1) a sky-projected spin-orbit measurement and (2) evidence that the transiting planet lies near a low-order mean-motion resonance with a neighbouring companion,” the authors explain in their research.
They found that planets in these pristine systems exhibit a typical spin-orbit angle of around 20 degrees. So even “quiet” solar systems have axial tilt. TOI-2202 b was one of the most strongly tilted planets in the sample. “The measured spin-orbit angle of TOI-2202 b, together with the full census of spin-orbit measurements for near-resonant exoplanets, indicates that even quiescently formed systems may experience low-level dynamical excitation that produces some dispersion in their spin-orbit orientations,” the authors write.
This told the researchers that our Solar System’s tilted planets are the norm rather than an oddball outlier.
“It’s reassuring,” Rice said. “It tells us that we’re not a super-weird solar system. This is really like looking at ourselves in a funhouse mirror and seeing how we fit into the bigger picture of the universe.”
Our Solar System does contain one oddball, though: Uranus. Uranus’s tilt angle is 97.77 degrees, nearly parallel to the Solar System’s plane. Astronomers aren’t certain, but a collision with an Earth-sized protoplanet in the Solar System’s early days is likely the cause.
One of Rice’s research areas concerns hot Jupiters and why they exhibit such pronounced axial tilts. “I’m trying to figure out why systems with hot Jupiters have such extremely tilted orbits,” Rice said. “When did they get tilted? Can they just be born that way? To find that out, I first need to find out what types of systems are not so dramatically tilted.”
That search continues.
A Protoplanetary Disc Has Been Found… in Another Galaxy!
by Nancy Atkinson on November 29, 2023 at 10:28 pm
Astronomers have imaged dozens of protoplanetary discs around Milky Way stars, seeing them at all stages of formation. Now, one of these discs has been found for the first time — excitingly — in another galaxy. The discovery was made using the Atacama Large Millimeter/Submillimeter Array (ALMA) in Chile along with the , which detected the telltale signature of a spinning disc around a massive star in the Large Magellanic Cloud, located 160,000 light-years away.
“When I first saw evidence for a rotating structure in the ALMA data I could not believe that we had detected the first extragalactic accretion disc, it was a special moment,” said Anna McLeod, an associate professor at Durham University in the UK and lead author of the study published in Nature. “We know discs are vital to forming stars and planets in our galaxy, and here, for the first time, we’re seeing direct evidence for this in another galaxy.”
McLeod and her fellow researchers were doing a follow-up study on a system named HH 1177, which was located deep inside a gas cloud in the Large Magellanic Cloud LMC). In 2019, the researchers reported that in using the Very Large Telescope, they observed a jet emitted by a fledgling but massive star with a mass 12 times greater than our Sun. This was the first time such a jet has been observed in visible light outside the Milky Way, as they are usually obscured by their dusty surroundings. However, the relatively dust-free environment of the LMC allowed for HH 1177 to be observed at visible wavelengths. At nearly 33 light-years in length, it is one of the longest such jets ever observed.
“We discovered a jet being launched from this young massive star, and its presence is a signpost for ongoing disc accretion,” McLeod said in an ESO press release. But to confirm that such a disc was indeed present, the team needed to measure the movement of the dense gas around the star.
The gas motion indicated that there is a radial flow of material falling onto a central disk-like structure. In their new observations, the team found that the disk exhibits signs of Keplerian rotation – which is a disk of material that obey’s Kepler’s laws of motion due to the dominance of a massive body at its center. Their observations revealed that “the rotating toroid [was] feeding an accretion disk and thus the growth of the central star,” the McLeod and team wrote in their paper. “The system is in almost all aspects comparable to Milky Way high-mass YSOs (young stellar objects) accreting gas from a Keplerian disk.
As matter is pulled towards a growing star, it cannot fall directly onto it; instead, it flattens into a spinning disc around the star. Closer to the center, the disc rotates faster, and this difference in speed is the clear evidence to show astronomers an accretion disc is present.
“The frequency of light changes depending on how fast the gas emitting the light is moving towards or away from us,” said Jonathan Henshaw, a research fellow at Liverpool John Moores University in the UK, and co-author of the study, in the ESO press release. “This is precisely the same phenomenon that occurs when the pitch of an ambulance siren changes as it passes you and the frequency of the sound goes from higher to lower.”
Massive stars like HH 1177 live fast and die hard. In the Milky Way, stars like this are challenging to observe because they are often clouded from view by the dusty material from which they form — which also obscures the disc that might be shaping around them.
“They form in heavily embedded regions full of gas and dust, such that the accretion phase typically occurs before the star has time to become exposed due to stellar feedback, whether internal or external,” the team wrote in their paper. “The primary reason for the lack of observations of extragalactic accretion disks around forming stars has been the limited spatial resolution of both ground- and space-based observatories.”
But the Large Magellanic Cloud is fundamentally different from because the stars that form there have a lower dust content than in the Milky Way. Because of that HH 1177 is no longer cloaked in its early dust cloud, providing astronomers an unobstructed view, even though it is so far away.
The researchers said the instruments on ALMA enables the high-sensitivity and high-angular-resolution observations needed to detect and resolve rotating circumstellar gas in the LMC.
“We are in an era of rapid technological advancement when it comes to astronomical facilities,” McLeod says. “Being able to study how stars form at such incredible distances and in a different galaxy is very exciting.”
The post A Protoplanetary Disc Has Been Found… in Another Galaxy! appeared first on Universe Today.
There are Myterious Polygons Beneath the Surface of Mars
by Nancy Atkinson on November 29, 2023 at 9:09 pm
China’s Zhurong rover was equipped with a ground-penetrating radar system, allowing it to peer beneath Mars’s surface. Researchers have announced new results from the scans of Zhurong’s landing site in Utopia Planitia, saying they identified irregular polygonal wedges located at a depth of about 35 meters all along the robot’s journey. The objects measure from centimeters to tens of meters across. The scientists believe the buried polygons resulted from freeze-thaw cycles on Mars billions of years ago, but they could also be volcanic, from cooling lava flows.
The Zhurong rover landed on Mars on May 15, 2021, making China the second country ever to successfully land a rover on Mars. The cute rover, named after a Chinese god of fire, explored its landing site, sent back pictures — including a selfie with its lander, taken by a remote camera – studied the topography of Mars, and conducted measurements with its ground penetrating radar (GPR) instrument. Zhurong had a primary mission lifetime of three Earth months but it operated successfully for just over one Earth year before entering a planned hibernation. However, the rover has not been heard from since May of 2022.
Researchers from the Institute of Geology and Geophysics under the Chinese Academy of Sciences who worked with Zhurong’s data said the GPR provides an important complement to orbital radar explorations from missions such as ESA’s Mars Express and China’s own Tianwen-1 orbiter. They said in-situ GPR surveying can provide critical local details of shallow structures and composition within approximately 100-meter depths along the rover’s traverse.
Utopia Planitia is a large plain within Utopia, the largest recognized impact basin on Mars (also in the Solar System) with an estimated diameter of 3,300 km. In total, the rover traveled 1,921 meters during its lifetime.
The researchers, led by Lei Zhang, wrote in their paper published in Nature, that the rover’s radar detected sixteen polygonal wedges within about 1.2?kilometers distance, which suggests a wide distribution of similar terrain under Utopia Planitia. These detected features probably formed 3.7 – 2.9 billion years ago during the Late Hesperian–Early Amazonian epochs on Mars, “possibly with the cessation of an ancient wet environment. The palaeo-polygonal terrain, either with or without being eroded, was subsequently buried” by later geological processes.
While polygon-type terrain has been seen across several areas of Mars from many previous missions, this is the first time there has been indications of buried polygon features.
The buried polygonal terrain requires a cold environment, the researchers wrote, that might be related to water/ice freeze–thaw processes in southern Utopia Planitia on early Mars.
“The possible presence of water and ice required for the freeze–thaw process in the wedges may have come from cryogenic suction-induced moisture migration from an underground aquifer on Mars, snowfall from the air or vapor diffusion for pore ice deposition,” the paper explains.
Earlier research from Zhurong’s radar data indicated that multiple floods during that same time frame created several layers beneath the surface of Utopia Planitia.
While the new paper indicates that the most likely possible formation mechanisms would be soil contraction from wet sediments that dried, producing mud-cracks, however, contraction from cooling lava could have also produced thermal contraction cracking.
Either way, they note that a huge change in Mars’ climate was responsible for the polygon’s formation.
“The subsurface structure with the covering materials overlying the buried palaeo-polygonal terrain suggests that there was a notable palaeoclimatic transformation some time thereafter,” the researchers wrote. “The contrast above and below about-35-meter depth represented a notable transformation of water activity or thermal conditions in ancient Martian time, implying that there was a climatic upheaval at low-to-mid latitudes.”
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Contact Binary Asteroids are Common, but We’ve Never Seen One Form. So Let’s Make One
by Andy Tomaswick on November 29, 2023 at 8:21 pm
Ever want to play a game of cosmic billiards? That’s commonly how the DART mission was described when it successfully changed the orbit of a near-Earth asteroid last year. If you want an idea of how it works, just Google it and an Easter egg from the search giant will give you a general idea. But DART was more like trying to brute force a billiards break – there are many other things you can do with a set of asteroids and impactors on the galactic stage. One of the more interesting is to try to force two asteroids together to form a “contact binary” – the goal of a mission design put forward by a group of scientists from Cornell in a recent paper in Acta Astronautica.
Colby Merill and his colleagues at Cornell’s Mechanical and Aerospace Engineering department first explain why such a mission would be a good idea. Contact binaries are defined as a system when two objects are so close together that their surfaces touch. Typically, astronomers think of the objects as a pair of stars, but asteroids can also form contact binaries.
Recent estimates put the total number of contact binaries as high as 30% of all small solar system bodies, including famous ones like Arrokoth and 67P/Churyumov-Gersasimenko. That means if there are any potentially hazardous asteroids we aren’t yet aware of, there’s a fair chance it’s actually a contact binary.
Such a configuration presents a problem for planetary defense operators. Understanding where to hit a binary to deflect it makes the math much harder. Moreover, we’ve never seen one of these systems form to understand its underlying mechanisms. The standard model of this process is known as the Binary Yarkovsky-O’Keefe-Radzievskii-Paddack (BYORP) effect, by which the two asteroids, which usually begin in a standard, non-touching binary system, end up having their gravities draw each other together and touch without the catastrophic impact that would be typical of large bodies at higher speeds.
Setting up a contact binary through the BYORP effect would require a separate mission design. According to the paper, a good first effort would be to smack the asteroids into each other using an impactor. There are several advantages to this. A big one is flight heritage – the mission could use a slightly modified version of DART and a coupled observer satellite that could watch the slow-motion impact.
How slow that impact is will have a significant impact on the success of the mission. Hit the billiard ball too hard, and it will smash into its companion and cause a potentially devastating chain reaction. Hit it too softly, and there might not be enough force to push the two objects together. Plenty of math, including simulations of the forces of ejecta fragments, would go into the planning stage of any such mission.
Those simulations require you to know some features of the planned targets, though, and the Cornell researchers have identified one. Known in strikingly formal near-asteroid parlance as (350751) 2002 AW, this system’s primary comes in at about 230 m, with a secondary partner measuring about 50 m. One potential advantage of a mission to this system is that the 50 m size of its smaller object is the minimum size limit for possible future planetary defense missions, allowing the mission to emulate a potential real planetary defense scenario.
Plenty of observation will need to take place to effectively plan where best to hit the pair, though, and with how much force to do so. The paper requests plenty of ground-based observational support, including density and orbital measurements. However, it’s unclear if there’s enough interest in the project yet to warrant diverting those resources to this new effort.
There’s also additional work to do, including developing a plan for how the observational satellite could avoid the debris cloud that will form after the impact. Another potential research area is initiating a contact using a gravity tug to force a sped-up BYORP effect.
For now, these ideas remain on the drawing board. But it’s nice to see how successful missions like DART can inspire even more ambitious ones in the future. Maybe someday, our skill at cosmic billiards will grow to include an ability to do trick shots, too.
Merill et al. – Creating a contact binary via spacecraft impact to near-Earth binary asteroid (350751) 2002 AW
UT – DART Had a Surprising Impact on its Target
UT – After DART Smashed Into Dimorphos, What Happened to the Larger Asteroid Didymos?
UT – Remember the DART impact? Hubble Made a Movie of the Debris
Images of three contact asteroids – Arrokoth (right), 67P/Churyumov-Gerasimenko (middle), and Itokawa (left)
Credit – NASA, ESA, and JAXA
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China’s Space Station, Seen from Orbit
by Evan Gough on November 29, 2023 at 5:44 pm
When the Space Age dawned in 1957, there were only two players: the USA and the USSR. The USA won the space race by being first to the Moon, though the USSR enjoyed its own successes. But here we are only a few decades later, and the USSR appears to be fading away while China is surging ahead.
Nothing’s more emblematic of China’s surge than its Tiangong space station.
China is sometimes secretive about its space activities. But not when it comes to Tiangong. China is sharing some images of the space station captured by their taikonauts on Shenzhou-16. Shenzhou is the spacecraft that transports crew to and from the space station, and 16 is the current mission.
These are our first high-resolution images of Tiangong, and the China Manned Space Agency released them at a press conference on Tuesday, November 28th.
China began launching different modules to the space station in 2021, starting with the Tianhe core module. Tianhe provides life support and living quarters for the space station’s crew, as well as navigation, guidance, and orientation for the station.
Three more modules follow the Tianhe core: Wentian (2022), Mengtian (2022), and Xuntian in 2024. Wentian contains a laboratory and also fulfills other functions. Mengtian also contains research facilities, while Xuntian is the Chinese Survey Space Telescope (CSST). The CSST is an optical-ultraviolet telescope that China says will outperform the Hubble.
The CSST will co-orbit with Tiangong and will periodically dock with the space station.
The China Manned Space Agency (CMSA) released the images at a press conference in Hong Kong. At the conference, the Chief Executive of the Hong Kong Special Administrative Region, John Lee, spoke about the CMSA and Tiangong.
“It has made history by realizing the Chinese nation’s millennium-long dream of flying to the stars, of which we, as Chinese, are all profoundly proud. Through the delegation’s visit, Hong Kong people can share the nation’s pride in China’s manned space development from close range and develop a deeper understanding of the country’s developments in aerospace technologies. The visit exemplifies the affection and support of the Central People’s Government for the Hong Kong Special Administrative Region,” Lee said.
China needs its own space station in part because the US Congress banned China from playing any role in the ISS. In fact, Congress prohibited any official American contact with the entire Chinese space program. That was due to “National Security” concerns, which often means spying but could mean anything. So, China built their own.
China’s list of reasons for building a space station mirrors any nation’s list of reasons: to gain experience in spacecraft rendezvous, permanent human operations in orbit, long-term autonomous spaceflight of the space station, regenerative life support technology and autonomous cargo and fuel supply technology. It’s also a platform for developing technologies for further exploration of the Solar System.
China is inviting private space companies to take part in the Tiangong mission to help drive innovation and the development of their own space industry. They’re also considering space tourism.
Yang Liwei, China’s first taikonaut in space, says it’s just a matter of time before tourists will be able to visit Tiangong. “It is not a matter of technology but of demand,” Yang told Chinese media last year. “And it can be realized within a decade as long as there is such demand.”
For there to be space tourists, there have to be people with a lot of money. But communism is supposed to prevent the accumulation of wealth, and everything is supposed to belong to everyone. But that’s a political discussion.
China has earned the right to boast about and enjoy its success. Decades ago, during the space race, China was mired in trouble. The Cultural Revolution was in full swing, and Mao Zedong was purging the remnants of capitalism from China. There was chaos, armed struggles, and political upheaval.
Fast forward to now, and China, for all intents and purposes, is a different country. It’s an industrial and economic powerhouse, and we have to acknowledge that space is open to all nations with the resources to reach it. China is making great strides with Tiangong and all their other efforts aimed at the Moon and Mars. Once they have their own space telescope, will they really be playing catch up anymore?
The space race between the USA and the USSR helped define the age we live in. But the page has turned on that. Now it’s the USA and China that are vying for supremacy.
Tiangong is not only a symbol of China’s rise, but a functioning technological artifact of it.
A Detailed Design for a Space Station at Sun-Earth L2
by Andy Tomaswick on November 29, 2023 at 5:22 pm
New ideas in space exploration come from all corners, and, by and large, the community welcomes anybody interested in the field. Having just read A City on Mars, it seems that even people who disagree with the idea that the age of space settlement is imminent will be accepted into the fold by enthusiasts. Now, a new entrant has joined – Daniel Akinwumi is a Nigerian graduate student at the University of Strathclyde who recently published his Master’s thesis detailing the design of the “intergalactic hub,” or I-HUB.
The introductory section of the thesis lays out many of the challenges familiar to those interested in space habitats. These include the importance of robots, a completely closed-loop recycling system, and novel radiation shielding. Mr. Akinwumi also provides a thorough literature search and mentions several other design concepts similar to the I-HUB.
One crucial design choice is how to get the system into space. As of the time of writing, I-HUB will use Starship, the largest rocket ever developed, which is still being tested. Many of the other selected systems for the I-HUB would utilize technologies developed elsewhere, such as NASA’s ECLSS life support system or standard RTGs for a power source.
Food is essential for any long-term habitat, and the paper looks closely at different food-production systems for use in space. NASA’s Vegetable Production System is one of the most highly developed and could be used on the I-HUB with little modification. Propulsion is another key system, with I-HUB being designed behind an extensive solar electric propulsion system that would allow it to research its deep-space destination of the Earth/Sun L2 point.
Ideally, the system would be built in order, but plenty of work on robotic assemblers must take place before that will be a possibility. Any such assembly would also have to occur near Earth, as sending an army of assemblers to the L2 point would be prohibitively expensive. But the views from L2 would be spectacular, as the paper points out the site could be a helpful platform for scientific inquiry – it already houses several large-scale telescopes, including Euclid.
Once installed, the intent of I-HUB isn’t to remain static but to continue to grow by adding additional modules over time to increase both its physical and operational capacity. Modular designs of the modules that would connect would be critical to this feature and would be similar to how the different modules connect on the ISS.
Some of the modules might even rotate to decrease microgravity’s harmful effects on the long-term health of I-HUB’s residents. It will also have an integrated communication system and, as mentioned above, a closed-looped resource recycling/life support system.
Mr. Akinwumi also detailed budgets for various systems, such as power and mass, and the expected overall cost of the station. In his analysis, he fleshed out some of the inherent risks in the system and detailed how they could be mitigated with future development work. Some of these would include multiple redundancies of the life-support systems and various layers of radiation shielding.
Overall, the plan for I-HUB seems reasonable and weighs in at a hefty 71 pages – probably a little above average for an MS thesis. However, those pages have little new ideation details; it’s more a collection of ideas already detailed in other resources and in much more detail than even this thesis would allow. It’s a good start on a promising research line, and hopefully, Mr. Akinwumi will continue with his PhD and can delve further into the details of his I-HUB idea.
Daniel Akinwumi – Design and Analysis of the Technical Infrastructure for a Self-Sufficient and Sustainable Intergalactic Hub
UT – A New Paper Shows How To Change An Asteroid Into A Space Habitat – In Just 12 Years
UT – Check out This Amazing Fly-through of a Futuristic Space Habitat
UT – Lockheed Martin Shows off its new Space Habitat
Artist’s depiction of the location of the I-HAB space habitat.
Credit – Daniel Akinwumi
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