Behold, directly overhead, a certain strange star was suddenly seen...
Amazed, and as if astonished and stupefied, I stood still.

— Tycho Brahe

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China’s First Space Station Crew is Back From Orbit

Universe Today - Tue, 09/28/2021 - 8:08pm

On Friday, Sept. 17th, three Chinese astronauts returned safely from space following a three-month stay aboard the new Tiangong space station. This was a major milestone for the Chinese Manned Space (CMS) program, which beats its previous record for the longest crewed mission to space. Whereas the Shenzhou 11 mission (2016) lasted 33 days, the crew of Tang Hongbo, Nie Haisheng, and Liu Boming spent a total of 92 days in orbit.

The astronauts successfully landed in their Shenzou 12 capsule at the Dongfeng Landing Site, located in the Gobi Desert in the autonomous region of Inner Mongolia. According to a statement issued by the CMS, the astronauts safely exited the capsule and were in good physical condition. They were then flown to Beijing on a mission plane, where they were greeted by Li Shangfu, the commander of China’s crewed space project and the project leaders.

The search and rescue team inspecting the Shenzhou 12 capsule after the astronauts exited the vehicle. Credit: Xinhua

As the state-run Xinhua News Agency stated in a recent press release:

“Three Chinese astronauts, the first sent to orbit for space station construction, have completed their three-month mission and returned to Earth safely on Friday. The return capsule of the Shenzhou-12 manned spaceship, carrying astronauts Nie Haisheng, Liu Boming, and Tang Hongbo, touched down at the Dongfeng landing site in north China’s Inner Mongolia Autonomous Region, according to the China Manned Space Agency (CMSA).”

The three astronauts launched in June and were the first of four planned crewed missions to the station during the construction period (which is expected to be complete sometime in 2022). This was China’s first crewed mission to space in five years and represented multiple milestones for the China National Space Administration (CNSA). For one, the astronauts conducted several important station-related tasks while aboard the station.

“During the orbiting flight, two astronaut out-of-vehicle activities were carried out, and a series of space science experiments and technical tests were carried out,” said the CMS in another statement. “In orbit, the key technologies for the construction and operation of space stations such as rail repairs [sic]. The complete success of the Shenzhou 12 manned mission has laid a solid foundation for the construction and operation of the subsequent space station.”

The Shenzhou 12 space capsule landing in the Gobi desert. Credit: Xinhua

This mission was also the first time personnel were dispatched from the Dongfeng Landing Field to perform a search and recovery mission involving a crewed spacecraft. But most importantly, this was the first mission to the Tiangong (“Heavenly Palace”) space station since it was launched in April of 2021. This third-generation habitat builds on the experiences learned from the Tiangong-1 and Tiangong-2 stations.

The space station currently consists of the Tianhe Core Module (“Harmony of the Heavens”), which will be augmented with the addition of the Laboratory Cabin Modules (LCMs). These consist of the Wentian (“Quest for the Heavens”) and Mengtian (“Dreaming of the Heavens”) modules, which are scheduled to launch during the summer of 2022. Once these are integrated, China hopes to conduct a full range of scientific experiments and research in orbit.

These activities are meant to rival those that have been conducted aboard the International Space Station (ISS), which has been in orbit for 22 years and is due to be decommissioned by 2024 at the earliest. While it is unclear if the Tiangong space station will remain in orbit that long (or after the ISS retires), it is clear that China plans to maintain a space station in orbit indefinitely.

Further Reading: digitaltrends, Xinhua

The post China’s First Space Station Crew is Back From Orbit appeared first on Universe Today.

Categories: Astronomy

It’s now easier to run trials testing CRISPR-edited crops in England

New Scientist Space - Space Headlines - Tue, 09/28/2021 - 8:01pm
The UK government has lifted licensing hurdles that laboratories face when starting a field trial of gene-edited crops in England
Categories: Astronomy

It’s now easier to run trials testing CRISPR-edited crops in England

New Scientist Space - Cosmology - Tue, 09/28/2021 - 8:01pm
The UK government has lifted licensing hurdles that laboratories face when starting a field trial of gene-edited crops in England
Categories: Astronomy

NASA's record-breaking Lucy asteroid mission gearing up for October launch

Space.com - Tue, 09/28/2021 - 6:37pm
Lucy is scheduled to launch Oct. 16, kicking off a landmark mission that will see the probe get up close and personal with eight different space rocks over the next dozen years.
Categories: Astronomy

3D-printed rocket engines: The technology driving the private sector space race

Space.com - Tue, 09/28/2021 - 6:00pm
The volatile nature of space rocket engines means that many early prototypes end up embedded in dirt banks or decorating the tops of any trees that are unfortunate enough to neighbor testing sites.
Categories: Astronomy

The Early Solar System was Messier and More Violent Than Previously Believed

Universe Today - Tue, 09/28/2021 - 5:45pm

Our conventional models of planet formation may have to be updated, according to a pair of new papers.

Accretion is the keyword in current planet formation theory. The idea is that the planets formed out of the solar nebula, the material left over after the Sun formed. They did this through accretion, where small particles accumulate into more massive objects. These massive boulder-sized objects, called planetesimals, continued to merge together into larger entities, sometimes through collisions. Eventually, through repeated mergers and collisions, the inner Solar System was populated by four rocky planets.

But the new research suggests that the collisions played out much differently than thought and that objects collided with each other several times, in a series of hit and runs, before merging. This research fills some stubborn holes in our current understanding.

The two new papers are published in The Planetary Science Journal. The first one looks at hit-and-runs in the late formation stages of Earth and Venus. It’s titled “Collision Chains among the Terrestrial Planets. II. An Asymmetry between Earth and Venus.” The lead author is Alexandre Emsenhuber, who was at the University of Arizona’s Lunar and Planetary Laboratory at the time this work was done.

The researchers relied on 3d simulations of giant impacts, and machine learning based on those impacts. They found that hit-and-runs or collision chains are as common as accretion events in the later stages of planetary formation, at least for Venus and Earth. And they also found that Earth acted as a kind of vanguard for Venus, helping to shepherd impactors into Venus.

The authors propose a hit-and-run-and-return model for the terrestrial planets, and have evidence to back it up. They say that the pre-planetary bodies would have spent a long time crashing into each, bouncing off, and returning to crash into each other again. Since the initial collision would have slowed them down, they’d be more likely to stick together in succeeding collisions. While the accretion model is often compared to a snowman with each snowball sticking to him, this model is more like billiards. There are successive collisions, with each collision at reduced velocities, until things calm down.

The central takeaway from the research is that giant impacts are not efficient planet-forming events.

“We find that most giant impacts, even relatively ‘slow’ ones, are hit-and-runs. This means that for two planets to merge, you usually first have to slow them down in a hit-and-run collision,” said Erik Asphaug, co-author from LPL at the University of Arizona. “To think of giant impacts, for instance the formation of the moon, as a singular event is probably wrong. More likely it took two collisions in a row.”

The first of the two papers focuses on Venus and Earth, often called “sister planets.” But for sister planets, there are some puzzling differences between the two when it comes to composition, geology, and satellite formation. The researchers think they know why.

“We think that during solar system formation, the early Earth acted like a vanguard for Venus.”

Alexandre Emsenhuber, Lead Author.

The early Solar System was a chaotic time, with objects smashing into each other. The new model shows that Earth and Venus had an unusual relationship. They say that Earth acted as a kind of vanguard for Venus. As objects struck Earth and bounced off they, many of them were sent toward Venus at a lower velocity. In this way, Venus accreted more objects from the outer Solar System.

“The Earth acts as a shield, providing a first stop against these impacting planets,” Asphaug said. “More likely than not, a planet that bounces off of Earth is going to hit Venus and merge with it.” Part of the reason for this is that the Solar System is like a gravity well. The closer an object gets to the Sun, the more likely it is to stay there. Since Venus is closer, more objects stuck to it after hitting Earth and bouncing off. “…an impactor that collides with Venus is pretty happy staying in the inner solar system, so at some point it is going to hit Venus again,” Asphaug explained.

Earth, Venus, Mars, and Mercury. According to ‘late stage accretion’ theory, Mars and Mercury (front left and right) are what’s left of an original population of colliding embryos, and Venus and Earth grew in a series of giant impacts. New research focuses on the preponderance of hit-and-run collisions in giant impacts, and shows that proto-Earth would have served as a ‘vanguard’, slowing down planet-sized bodies in hit-and-runs. But it is proto-Venus, more often than not, that ultimately accretes them, meaning it was easier for Venus to acquire bodies from the outer solar system. Image Credit: Lsmpascal – Wikimedia Commons

But Earth has no vanguard. There’s nothing to slow down interloping objects from the outer Solar System. As a result, many objects just bounced off. And since objects are drawn to the center of the gravity well, they’re not likely to encounter Earth again. Instead they encounter Venus. This discrepancy could account for the differences between Venus and Earth. In low-velocity hit-and-runs “… the runner is an identifiable remnant of the projectile (eg a mantle-stripped core, sometimes barely so)…” the authors write.

“The prevailing idea has been that it doesn’t really matter if planets collide and don’t merge right away, because they are going to run into each other again at some point and merge then,” Emsenhuber said. “But that is not what we find. We find they end up more frequently becoming part of Venus, instead of returning back to Earth. It’s easier to go from Earth to Venus than the other way around.”

In most hit-and-runs, most of the projectile survives the impact. But its velocity can be greatly reduced, and its trajectory changed. If the runner is slowed down enough, then both bodies can stay gravitationally bound to one another. In that case, the researchers call it a graze-and-merge.

The paper reached four related conclusions.

  1. The terrestrial planets weren’t isolated from each other during the later stages of planetary formation. Escaping runners from a hit-and-run with one planet are likely to collide with another planet.
  2. Long collision chains are less likely because the projectile needs such a high initial velocity, and high velocity runners are less likely to return.
  3. Earth served as a vanguard for Venus, slowing late stage projectiles and sending them toward Venus. Earth only accreted about half of the projectiles, at most, that collided with it.
  4. Runners from Earth are about equally as likely to collide with Venus as they are to return to Earth. But Venus retains the majority of its runners.
The Moon

The second paper deals with the Moon and its formation. It’s title is “Collision Chains among the Terrestrial Planets. III. Formation of the Moon.” It’s also published in The Planetary Science Journal. The lead author is Erik Asphaug, of the LPL at the University of Arizona.

The prevailing theory says that the young Earth was struck by a planet named Theia about 4.5 billion years ago. Earth has a larger core than it should have for its size, and that came from Theia. The impact destroyed Theia, and much of its mass was sent into orbit around Earth. Eventually it coalesced into the Moon.

But there are some unresolved problems in this scenario. The collision velocity would have to be very low, and the isotope composition of the Earth and the Moon are almost identical. A single low-velocity impact wouldn’t allow all the material to be mixed up enough for the isotope compositions to be so similar.

“The standard model for the moon requires a very slow collision, relatively speaking,” Asphaug said, “and it creates a moon that is composed mostly of the impacting planet, not the proto-Earth, which is a major problem since the moon has an isotopic chemistry almost identical to Earth.”

“The “graze-and-merge” collision strands a fraction of Theia’s mantle into orbit, while Earth accretes most of Theia and its momentum,” the authors write in their paper. “However, a Moon that derives mostly from Theia’s mantle, as angular momentum dictates, is challenged by the fact that O, Ti, Cr, radiogenic W, and other elements are indistinguishable in Earth and lunar rocks.”

The moon is thought to be the aftermath of a giant impact. According to a new theory, there were two giant impacts in a row, separated by about 1 million years, involving a Mars-sized ‘Theia’ and proto-Earth. In this image, the proposed hit-and-run collision is simulated in 3D, shown about an hour after impact. A cut-away view shows the iron cores. Theia (or most of it) barely escapes, so a follow-on collision is likely. Image Credit: A. Emsenhuber/University of Bern/University of Munich.

In the team’s new model, there’s not a single collision, but two. When Theia collides with Earth, it’s moving a bit faster, and bounces off Earth in a hit-and-run. About one million years later it returns. It collides with Earth again, in a giant impact similar to the existing model.

“The double impact mixes things up much more than a single event,” Asphaug said, “which could explain the isotopic similarity of Earth and moon, and also how the second, slow, merging collision would have happened in the first place.”

This figure from the study illustrates the hit-and-run and return scenario for the formation of the Moon. On the left is the first hit-and-run impact. Eventually Earth and Theis encounter each other again, in about one million years, and merge into one disk. The Earth and the Moon form from that homogenized disk. This model explains the near-identical isotopic composition of the Earth and the Moon. Image Credit: Asphaug et al 2021.

This new model of hit-and-run impacts and chains of collisions has the potential to explain some puzzling things about the terrestrial planets. If the standard accretion model is correct, why are the inner planets so different? Why doesn’t Venus have a moon of its own? Why does Earth have a strong magnetic shield and Venus such a weak one?

Asphaug says their research helps explain how these difference could have arisen.

“In our view, Earth would have accreted most of its material from collisions that were head-on hits, or else slower than those experienced by Venus,” he said. “Collisions into the Earth that were more oblique and higher velocity would have preferentially ended up on Venus.”

Common sense suggests that Earth would have more material from the outer Solar System because its closer to it than Venus is. But this research suggests the opposite. Projectiles from the outer Solar System would be likely travelling faster, so would bounce off Earth in a hit-and-run. Many of those projectiles would have found their way to Venus and become part of that planet. So Venus’ differences could be chalked up to its greater component of outer Solar System material.

“You would think that Earth is made up more of material from the outer system because it is closer to the outer solar system than Venus. But actually, with Earth in this vanguard role, it makes it actually more likely for Venus to accrete outer solar system material,” Asphaug said.

This research could also explain why Venus has no Moon, even though this hypothesis makes it more likely for the planet to acquire one. “While Venus may have been more likely than Earth to have acquired a massive satellite by our hypothesis, it may also have been more likely to have lost one,” the authors write. “For the same reason that Venus reaccretes a greater fraction of its runners, compared to Earth, it also reaccretes a greater fraction of its giant impact debris, of which it produces more for a given projectile.” Since Venus’ orbit is smaller than Earth, impact debris will collide with it sooner. All that returning debris could erode or even destroy any natural satellite that Venus may have acquired.

Overall, this research suggests a greater interconnectedness among the terrestrial planets. A greater understanding of the Moon’s geology, layering, and solidification could help confirm the new model. So could surface samples from Venus.

But that’s a ways off in the future.

More:

The post The Early Solar System was Messier and More Violent Than Previously Believed appeared first on Universe Today.

Categories: Astronomy

57 per cent of elephants at Thai tourist facilities have nervous tics

New Scientist Space - Space Headlines - Tue, 09/28/2021 - 5:19pm
An investigation of elephants at 20 Thai tourist facilities show that more than half of the captive animals show repetitive behaviour like swaying or head bobbing, which may be signs of anxiety or boredom
Categories: Astronomy

57 per cent of elephants at Thai tourist facilities have nervous tics

New Scientist Space - Cosmology - Tue, 09/28/2021 - 5:19pm
An investigation of elephants at 20 Thai tourist facilities show that more than half of the captive animals show repetitive behaviour like swaying or head bobbing, which may be signs of anxiety or boredom
Categories: Astronomy

Stuffed cow guards China's space station ahead of Shenzhou 13 crew arrival next month

Space.com - Tue, 09/28/2021 - 4:47pm
A stuffed cow is currently a lone occupant of the Chinese Tianhe space station, waiting to be joined by the crew of the upcoming Shenzhou 13 mission.
Categories: Astronomy

NASA Mars missions facing 2-week communications blackout as sun blocks Red Planet

Space.com - Tue, 09/28/2021 - 4:36pm
NASA plans to pause most of its Martian work in October for safety reasons associated with the Red Planet's position in space.
Categories: Astronomy

What Is a Quasar?

Sky & Telescope Magazine - Tue, 09/28/2021 - 2:57pm

A quasar is a supermassive black hole gorging on gas in the heart of a distant galaxy.

The post What Is a Quasar? appeared first on Sky & Telescope.

Categories: Astronomy

Life on Venus may have only been possible for its first billion years

New Scientist Space - Space Headlines - Tue, 09/28/2021 - 2:06pm
Previous research suggested Venus may have been habitable for 2 to 3 billion years, but that didn’t take into account the lack of plate tectonics, which affects CO2 levels and narrows the window for life on Venus
Categories: Astronomy

Life on Venus may have only been possible for its first billion years

New Scientist Space - Cosmology - Tue, 09/28/2021 - 2:06pm
Previous research suggested Venus may have been habitable for 2 to 3 billion years, but that didn’t take into account the lack of plate tectonics, which affects CO2 levels and narrows the window for life on Venus
Categories: Astronomy

NASA’s Lucy Mission Prepares for Launch to Trojan Asteroids

NASA - Breaking News - Tue, 09/28/2021 - 1:59pm
NASA has tested the functions of Lucy, the agency’s first spacecraft to study Jupiter’s Trojan asteroids, filled it with fuel, and is preparing to pack it into a capsule for launch Saturday, Oct. 16.
Categories: NASA

Watch live: NASA previews Lucy asteroid mission @ 2 pm ET

Space.com - Tue, 09/28/2021 - 1:47pm
NASA will hold a news conference today (Sept. 28) to preview the upcoming launch of its Lucy mission.
Categories: Astronomy

Exoplanet in a triple star system may orbit all three at once

New Scientist Space - Space Headlines - Tue, 09/28/2021 - 1:27pm
Astronomers have spotted hints of a planet that orbits a distant system of three stars – if confirmed, it will be the first time such a world has been found
Categories: Astronomy

Exoplanet in a triple star system may orbit all three at once

New Scientist Space - Cosmology - Tue, 09/28/2021 - 1:27pm
Astronomers have spotted hints of a planet that orbits a distant system of three stars – if confirmed, it will be the first time such a world has been found
Categories: Astronomy

Chinese commercial satellite has been spotting meteors and aurora

Space.com - Tue, 09/28/2021 - 1:00pm
A small Chinese commercial satellite has been detecting meteors impacting the atmosphere and even filming the aurora.
Categories: Astronomy

Ariane 6 launch complex inaugurated at Europe’s Spaceport

ESO Top News - Tue, 09/28/2021 - 12:40pm

The new launch complex built for Europe’s upcoming Ariane 6 rocket is inaugurated at Europe’s Spaceport in French Guiana.

Categories: Astronomy

NASA Transfers Air Traffic Management Tool Updates to FAA

NASA - Breaking News - Tue, 09/28/2021 - 12:07pm
As part of an effort aimed at making aviation more sustainable, NASA has transferred findings from an air traffic management project to the Federal Aviation Administration (FAA) for nationwide implementation, the two agencies announced at a media briefing Tuesday.
Categories: NASA