Astronomy and Planetary Science Thread

Candidate Tidal Disruption Event AT2019fdr Coincident with a High-Energy Neutrino

ABSTRACT
The origins of the high-energy cosmic neutrino flux remain largely unknown. Recently, one high-energy neutrino was associated with a tidal disruption event (TDE). Here we present AT2019fdr, an exceptionally luminous TDE candidate, coincident with another high-energy neutrino. Our observations, including a bright dust echo and soft late-time x-ray emission, further support a TDE origin of this flare. The probability of finding two such bright events by chance is just 0.034%. We evaluate several models for neutrino production and show that AT2019fdr is capable of producing the observed high-energy neutrino, reinforcing the case for TDEs as neutrino sources.


 
Observation of a strange pentaquark, a doubly charged tetraquark and its neutral partner.

Today, at the CERN seminar, the LHCb Collaboration reported the observation of a strange pentaquark, a doubly charged tetraquark and its neutral partner. These results will also be presented at the ICHEP 2022 International Conference on High Energy Physics in Bologna, Italy, starting tomorrow.


 
Observation of a strange pentaquark, a doubly charged tetraquark and its neutral partner.

Today, at the CERN seminar, the LHCb Collaboration reported the observation of a strange pentaquark, a doubly charged tetraquark and its neutral partner. These results will also be presented at the ICHEP 2022 International Conference on High Energy Physics in Bologna, Italy, starting tomorrow.



Well done CERN, Is this the first discovery of the Supersymmetry particles that theoretical physicist's have been getting extremely excited about since the discovery of the Higgs Boson ten years ago?
 
Sub-second periodicity in a fast radio burst

Abstract
Fast radio bursts (FRBs) are millisecond-duration flashes of radio waves that are visible at distances of billions of light years1. The nature of their progenitors and their emission mechanism remain open astrophysical questions2. Here we report the detection of the multicomponent FRB 20191221A and the identification of a periodic separation of 216.8(1) ms between its components, with a significance of 6.5σ. The long (roughly 3 s) duration and nine or more components forming the pulse profile make this source an outlier in the FRB population. Such short periodicity provides strong evidence for a neutron-star origin of the event. Moreover, our detection favours emission arising from the neutron-star magnetosphere3,4, as opposed to emission regions located further away from the star, as predicted by some models5.


A fast radio burst (FRB) dubbed FRB 20191221A persists for up to three seconds, about 1,000 times longer than the average FRB; within this window, astronomers from the CHIME/FRB Collaboration detected bursts that repeat every 217 ms in a clear periodic pattern, similar to a beating heart.

 
Early crustal processes revealed by the ejection site of the oldest martian meteorite

Abstract
The formation and differentiation of the crust of Mars in the first tens of millions of years after its accretion can only be deciphered from incredibly limited records. The martian breccia NWA 7034 and its paired stones is one of them. This meteorite contains the oldest martian igneous material ever dated: ~4.5 Ga old. However, its source and geological context have so far remained unknown. Here, we show that the meteorite was ejected 5–10 Ma ago from the north-east of the Terra Cimmeria—Sirenum province, in the southern hemisphere of Mars. More specifically, the breccia belongs to the ejecta deposits of the Khujirt crater formed 1.5 Ga ago, and it was ejected as a result of the formation of the Karratha crater 5–10 Ma ago. Our findings demonstrate that the Terra Cimmeria—Sirenum province is a relic of the differentiated primordial martian crust, formed shortly after the accretion of the planet, and that it constitutes a unique record of early crustal processes. This province is an ideal landing site for future missions aiming to unravel the first tens of millions of years of the history of Mars and, by extension, of all terrestrial planets, including the Earth.

 

The way ice covers the surface of Saturn’s moon Enceladus suggests that the oceans trapped beneath it may be only a little less salty than Earth’s oceans. The finding adds to the possibility that this moon might be able to sustain life.
...

Samples taken by the Cassini spacecraft of geyser-like jets of water from Enceladus’s surface previously showed that there is some organic matter that could sustain potential life on the icy moon.
...

The researchers found that saltier subsurface oceans correspond to thicker ice on a planet’s poles than over its equator and vice versa for less salty water. On Enceladus, the ice over the poles is thinner than the ice over the equator. The specific variation in thickness suggests that the ocean’s salinity could be as high as 30 grams of salt in a kilogram of water. For comparison, Earth’s oceans have a salinity of 35 grams of salt per kilogram of water.
...

The team found that some heat emanates from the bottom of Enceladus’s ocean, possibly indicating the existence of heat vents in the ocean floor. Kang says that some astrobiologists have previously suggested that, like on Earth, such hydrothermal vents could be where life is found in the future.
 

The US and Europe are remodelling their plans to bring rock samples back from Mars, for study in Earth laboratories.
They hope to simplify the process, cut risk and cost using helicopters instead of a British-built "fetch rover".

"The architecture is evolving right now and nothing is absolutely finalised," European Space Agency human and robotic exploration director, Dr David Parker, told BBC News.
"But Perseverance is there and being very effective - and the reliability analysis suggests Perseverance will keep on working. And that would allow us to streamline the programme and remove the fetch rover, taking out the need for another [risky] landing on Mars."

If Perseverance breaks down, mini-helicopters could be asked to do the job.
Perseverance's own drone, Ingenuity, has proven conclusively that aircraft work in Mars' thin atmosphere.
"So, maybe, we can use helicopters, one or two of them, as insurance," Dr Parker said.
 
Why Jupiter doesn’t have substantial rings like Saturn.

The Dynamical Viability of an Extended Jupiter Ring System

Planetary rings are often speculated as being a relatively common attribute of giant planets, partly based on their prevalence within the Solar System. However, their formation and sustainability remain a topic of open discussion, and the most massive planet within our planetary system harbors a very modest ring system. Here, we present the results of a N-body simulation that explores dynamical constraints on the presence of substantial ring material for Jupiter. Our simulations extend from within the rigid satellite Roche limit to 10\% of the Jupiter Hill radius, and include outcomes from 106 and 107 year integrations. The results show possible regions of a sustained dense ring material presence around Jupiter that may comprise the foundation for moon formation. The results largely demonstrate the truncation of stable orbits imposed by the Galilean satellites, and dynamical desiccation of dense ring material within the range ∼3--29 Jupiter radii. We discuss the implications of these results for exoplanets, and the complex relationship between the simultaneous presence of rings and massive moon systems.

 
Potential hints of weird new particles in a dark matter detector have evaporated with new data.

Following up on a beguiling result from its predecessor experiment, the XENONnT experiment found no sign of extra blips that could point to new particles or another phenomenon, scientists report July 22 in Vienna at the International Conference on Identification of Dark Matter.

 
What did you do with the extra 1.59 milliseconds on Wednesday, June 29, 2022?

As reported by TimeAndDate.com, on that date our planet set a new fastest record—as far as scientists can tell—for completing one rotation.

Hang on! Earth takes exactly 24 hours to rotate once on its axis, right? Almost, yes, but not exactly.

 
Tonga Eruption Blasted Unprecedented Amount of Water Into Stratosphere

The huge amount of water vapor hurled into the atmosphere, as detected by NASA’s Microwave Limb Sounder, could end up temporarily warming Earth’s surface.

When the Hunga Tonga-Hunga Ha’apai volcano erupted on Jan. 15, it sent a tsunami racing around the world and set off a sonic boom that circled the globe twice. The underwater eruption in the South Pacific Ocean also blasted an enormous plume of water vapor into Earth’s stratosphere – enough to fill more than 58,000 Olympic-size swimming pools. The sheer amount of water vapor could be enough to temporarily affect Earth’s global average temperature.

“We’ve never seen anything like it,” said Luis Millán, an atmospheric scientist at NASA’s Jet Propulsion Laboratory in Southern California. He led a new study examining the amount of water vapor that the Tonga volcano injected into the stratosphere, the layer of the atmosphere between about 8 and 33 miles (12 and 53 kilometers) above Earth’s surface.

In the study, published in Geophysical Research Letters, Millán and his colleagues estimate that the Tonga eruption sent around 146 teragrams (1 teragram equals a trillion grams) of water vapor into Earth’s stratosphere – equal to 10% of the water already present in that atmospheric layer. That’s nearly four times the amount of water vapor that scientists estimate the 1991 Mount Pinatubo eruption in the Philippines lofted into the stratosphere.

Millán analyzed data from the Microwave Limb Sounder (MLS) instrument on NASA’s Aura satellite, which measures atmospheric gases, including water vapor and ozone. After the Tonga volcano erupted, the MLS team started seeing water vapor readings that were off the charts. “We had to carefully inspect all the measurements in the plume to make sure they were trustworthy,” said Millán.

A Lasting Impression

Volcanic eruptions rarely inject much water into the stratosphere. In the 18 years that NASA has been taking measurements, only two other eruptions – the 2008 Kasatochi event in Alaska and the 2015 Calbuco eruption in Chile – sent appreciable amounts of water vapor to such high altitudes. But those were mere blips compared to the Tonga event, and the water vapor from both previous eruptions dissipated quickly. The excess water vapor injected by the Tonga volcano, on the other hand, could remain in the stratosphere for several years.

This extra water vapor could influence atmospheric chemistry, boosting certain chemical reactions that could temporarily worsen depletion of the ozone layer. It could also influence surface temperatures. Massive volcanic eruptions like Krakatoa and Mount Pinatubo typically cool Earth’s surface by ejecting gases, dust, and ash that reflect sunlight back into space. In contrast, the Tonga volcano didn’t inject large amounts of aerosols into the stratosphere, and the huge amounts of water vapor from the eruption may have a small, temporary warming effect, since water vapor traps heat. The effect would dissipate when the extra water vapor cycles out of the stratosphere and would not be enough to noticeably exacerbate climate change effects.

The sheer amount of water injected into the stratosphere was likely only possible because the underwater volcano’s caldera – a basin-shaped depression usually formed after magma erupts or drains from a shallow chamber beneath the volcano – was at just the right depth in the ocean: about 490 feet (150 meters) down. Any shallower, and there wouldn’t have been enough seawater superheated by the erupting magma to account for the stratospheric water vapor values Millán and his colleagues saw. Any deeper, and the immense pressures in the ocean’s depths could have muted the eruption.

The MLS instrument was well situated to detect this water vapor plume because it observes natural microwave signals emitted from Earth’s atmosphere. Measuring these signals enables MLS to “see” through obstacles like ash clouds that can blind other instruments measuring water vapor in the stratosphere. “MLS was the only instrument with dense enough coverage to capture the water vapor plume as it happened, and the only one that wasn’t affected by the ash that the volcano released,” said Millán.

The MLS instrument was designed and built by JPL, which is managed for NASA by Caltech in Pasadena. NASA’s Goddard Space Flight Center manages the Aura mission.

Jane J. Lee / Andrew Wang
Jet Propulsion Laboratory, Pasadena, Calif.
818-354-0307 / 626-379-6874
jane.j.lee@jpl.nasa.gov / andrew.wang@jpl.nasa.gov

2022-112

 
We found some strange radio sources in a distant galaxy cluster. They’re making us rethink what we thought we knew.

The universe is littered with galaxy clusters – huge structures piled up at the intersections of the cosmic web. A single cluster can span millions of light-years across and be made up of hundreds, or even thousands, of galaxies.

However, these galaxies represent only a few percent of a cluster’s total mass. About 80% of it is dark matter, and the rest is a hot plasma “soup”: gas heated to above 10,000,000℃ and interwoven with weak magnetic fields.

We and our international team of colleagues have identified a series of rarely observed radio objects – a radio relic, a radio halo and fossil radio emission – within a particularly dynamic galaxy cluster called Abell 3266. They defy existing theories about both the origins of such objects and their characteristics.


Related paper:

Radio fossils, relics, and haloes in Abell 3266: cluster archaeology with ASKAP-EMU and the ATCA

ABSTRACT
Abell 3266 is a massive and complex merging galaxy cluster that exhibits significant substructure. We present new, highly sensitive radio continuum observations of Abell 3266 performed with the Australian Square Kilometre Array Pathfinder (0.8–1.1 GHz) and the Australia Telescope Compact Array (1.1–3.1 GHz). These deep observations provide new insights into recently reported diffuse non-thermal phenomena associated with the intracluster medium, including a ‘wrong-way’ relic, a fossil plasma source, and an as-yet unclassified central diffuse ridge, which we reveal comprises the brightest part of a large-scale radio halo detected here for the first time. The ‘wrong-way’ relic is highly atypical of its kind: it exhibits many classical signatures of a shock-related radio relic, while at the same time exhibiting strong spectral steepening. While radio relics are generally consistent with a quasi-stationary shock scenario, the ‘wrong-way’ relic is not. We study the spectral properties of the fossil plasma source; it exhibits an ultrasteep and highly curved radio spectrum, indicating an extremely aged electron population. The larger scale radio halo fills much of the cluster centre, and presents a strong connection between the thermal and non-thermal components of the intracluster medium, along with evidence of substructure. Whether the central diffuse ridge is simply a brighter component of the halo, or a mini-halo, remains an open question. Finally, we study the morphological and spectral properties of the multiple complex radio galaxies in this cluster in unprecedented detail, tracing their evolutionary history.

 
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Supergiant Betelgeuse had a never-before-seen massive eruption

The red supergiant Betelgeuse, a colossal star in the Orion constellation, experienced a massive stellar eruption -- the likes of which have never been seen before, according to astronomers.

Now, astronomers have analyzed data from the Hubble Space Telescope and other observatories, and they believe the star experienced a titanic surface mass ejection, losing a substantial part of its visible surface.

"We've never before seen a huge mass ejection of the surface of a star. We are left with something going on that we don't completely understand," said Andrea Dupree, an astrophysicist at the Center for Astrophysics | Harvard & Smithsonian in Cambridge, Massachusetts, in a statement.

"It's a totally new phenomenon that we can observe directly and resolve surface details with Hubble. We're watching stellar evolution in real time."

The amount of mass lost is incredible.

But the surface mass ejection Betelgeuse experienced released more than 400 billion times as much mass as a typical coronal mass ejection from the sun.

 
If you find yourself in Bristol in the next month or so...


 
Initial dating evidence shows it maybe around the same age of Chicxulub, plus or minus a million years. So they might be related.

An asteroid from space slammed into the Earth's surface 66 million years ago, leaving a massive crater underneath the sea and wreaking havoc with the planet.

No, it's not that asteroid, the one that doomed the dinosaurs to extinction, but a previously unknown crater 248 miles off the coast of West Africa that was created right around the same time. Further study of the Nadir crater, as it's called, could shake up what we know about that cataclysmic moment in natural history.
Uisdean Nicholson, an assistant professor at Heriot-Watt University in Edinburgh, happened on the crater by accident -- he was reviewing seismic survey data for another project on the tectonic split between South America and Africa and found evidence of the crater beneath 400 meters of seabed sediment.
"While interpreting the data, I (came) across this very unusual crater-like feature, unlike anything I had ever seen before," he said.

 
A one-two punch from contact binaries? OT..will Webb be able to study Gliese 710?
 
The discovery of the 528.6 Hz accreting millisecond X-ray pulsar MAXI J1816-195

We present the discovery of 528.6 Hz pulsations in the new X-ray transient MAXI J1816-195. Using NICER, we observed the first recorded transient outburst from the neutron star low-mass X-ray binary MAXI J1816-195 over a period of 28 days. From a timing analysis of the 528.6 Hz pulsations, we find that the binary system is well described as a circular orbit with an orbital period of 4.8 hours and a projected semi-major axis of 0.26 light-seconds for the pulsar, which constrains the mass of the donor star to 0.10−0.55M⊙. Additionally, we observed 15 thermonuclear X-ray bursts showing a gradual evolution in morphology over time, and a recurrence time as short as 1.4 hours. We did not detect evidence for photospheric radius expansion, placing an upper limit on the source distance of 8.6 kpc.

 
Discovery Alert: Intriguing New ‘Super-Earth' Could Get a Closer Look

The discovery: Planet TOI-1452 b.

Key facts: Using observations from NASA’s Transiting Exoplanet Survey Satellite (TESS), backed up by ground-based telescopes, an international team led by the University of Montreal announced the discovery of a “super-Earth” – a planet that is potentially rocky like ours, but larger – orbiting a red-dwarf star about 100 light-years away. Further investigation could shed light on an intriguing possibility: that the planet might be a “water world.”

Details: Ocean planets are long imagined but difficult to confirm, and TOI-1452 b is no different. About 70% larger than Earth, and roughly five times as massive, its density could be consistent with having a very deep ocean. But more follow-up will be needed. The planet also might be a huge rock, with little or no atmosphere. It could even be a rocky planet with an atmosphere of hydrogen and helium.

If TOI-1452 b were shown to be an ocean world, that ocean could be quite deep indeed. While Earth’s surface is 70% water, our sea of blue makes up less than 1% of Earth’s mass. One simulation of TOI-1452 b, created by computer modeling specialists on the discovery team, showed that water could make up as much as 30% of its mass. That proportion is comparable to watery moons in our solar system – Jupiter’s Ganymede and Callisto, or Saturn’s Titan and Enceladus – believed to hide deep oceans under shells of ice.

TOI-1452 b makes a complete orbit of its star every 11 days – a “year” on TOI-1452 b. But because the red-dwarf star is smaller and cooler than our Sun, the planet receives a similar amount of light from its star as Venus does from our Sun. Liquid water might exist on the planet’s surface, despite its close orbit. The star, by the way, is one of a pair; its gravitational partner also is a red dwarf, estimated to be in a 1,400-year orbit.

Fun facts: Planet TOI-1452 b seems perfectly positioned for further investigation by the James Webb Space Telescope, now delivering science observations from its perch about a million miles (1.6 million kilometers) from Earth. The planet’s distance of 100 light-years is, in astronomical terms, fairly close. Its relatively bright star should allow Webb to capture a spectrum of starlight shining through its atmosphere, a kind of fingerprint of atmospheric components. It also appears in a part of the sky, in the constellation Draco, that Webb can observe almost any time of year. Researchers on the discovery team say they will seek to schedule time on Webb to take a closer look.

The discoverers: The international team that found the planet was led by Charles Cadieux, a Ph.D. student at the University of Montreal. Read the University’s press release. http://www.exoplanetes.umontreal.ca/an-extrasolar-world-covered-in-water/?lang=en

 
TOI-836: A super-Earth and mini-Neptune transiting a nearby K-dwarf

We present the discovery of two exoplanets transiting TOI-836 (TIC 440887364) using data from TESS Sector 11 and Sector 38. TOI-836 is a bright (T=8.5 mag), high proper motion (∼200 mas yr−1), low metallicity ([Fe/H]≈−0.28) K-dwarf with a mass of 0.68±0.05 M⊙ and a radius of 0.67±0.01 R⊙. We obtain photometric follow-up observations with a variety of facilities, and we use these data-sets to determine that the inner planet, TOI-836 b, is a 1.70±0.07 R⊕ super-Earth in a 3.82 day orbit, placing it directly within the so-called 'radius valley'. The outer planet, TOI-836 c, is a 2.59±0.09 R⊕ mini-Neptune in an 8.60 day orbit. Radial velocity measurements reveal that TOI-836 b has a mass of 4.5±0.9 M⊕ , while TOI-836 c has a mass of 9.6±2.6 M⊕. Photometric observations show Transit Timing Variations (TTVs) on the order of 20 minutes for TOI-836 c, although there are no detectable TTVs for TOI-836 b. The TTVs of planet TOI-836 c may be caused by an undetected exterior planet.

 
200,000 images combined, 174 megapixels. Colour-enhanced. Reddish areas are rich in iron and feldspar, while more blue areas are rich in titanium.


ezgif-3-cd792b9870.jpg
 
Detection of new pulsars at the frequency 111 MHz

The pulsar search was started at the radio telescope LPA LPI at the frequency 111~MHz. The first results deals of a search for right ascension 0h−24h and declinations +21∘−+42∘ are presented in paper. The data with sampling 100 ms and with 6 frequency channals was used. It were found 34 pulsars. Seventeen of them previously been observed at radio telescope LPA LPI, and ten known pulsars has not previously been observed. It were found 7 new pulsars.

 
Abstract
Planet 9 is an hypothetical object in the outer Solar system, which is as yet undiscovered. It has been speculated that it may be a terrestrial planet or gas/ice giant, or perhaps even a primordial black hole (or dark matter condensate). State-of-the-art models indicate that the semimajor axis of Planet 9 is ∼400 AU. If the location of Planet 9 were to be confirmed and pinpointed in the future, this object constitutes an interesting target for a future space mission to characterize it further. In this paper, we describe various mission architectures for reaching Planet 9 based on a combination of chemical propulsion and flyby maneuvers, as well as more advanced options (with a ∼100 kg spacecraft payload) such as nuclear thermal propulsion (NTP) and laser sails. The ensuing mission duration for solid chemical propellant ranges from 45 years to 75 years, depending on the distance from the Sun for the Solar Oberth maneuver. NTP can achieve flight times of about 40 years with only a Jupiter Oberth maneuver whereas, in contrast, laser sails might engender timescales as little as 7 years. We conclude that Planet 9 is close to the transition point where chemical propulsion approaches its performance limits, and alternative advanced propulsion systems (e.g., NTP and laser sails) apparently become more attractive.

 
SPECULOOS discovers a potentially habitable super-Earth

An international team of scientists, led by Laetitia Delrez, astrophysicist at the University of Liège, has just announced the discovery of two 'super-Earth' type planets orbiting LP 890-9. Also known as TOI-4306 or SPECULOOS-2, this small, cool star located about 100 light-years from our Earth is the second coolest star around which planets have been detected, after the famous TRAPPIST-1. This important discovery is published in the journal Astronomy & Astrophysics.


Related paper:

 
Abstract
Planet 9 is an hypothetical object in the outer Solar system, which is as yet undiscovered. It has been speculated that it may be a terrestrial planet or gas/ice giant, or perhaps even a primordial black hole (or dark matter condensate). State-of-the-art models indicate that the semimajor axis of Planet 9 is ∼400 AU. If the location of Planet 9 were to be confirmed and pinpointed in the future, this object constitutes an interesting target for a future space mission to characterize it further. In this paper, we describe various mission architectures for reaching Planet 9 based on a combination of chemical propulsion and flyby maneuvers, as well as more advanced options (with a ∼100 kg spacecraft payload) such as nuclear thermal propulsion (NTP) and laser sails. The ensuing mission duration for solid chemical propellant ranges from 45 years to 75 years, depending on the distance from the Sun for the Solar Oberth maneuver. NTP can achieve flight times of about 40 years with only a Jupiter Oberth maneuver whereas, in contrast, laser sails might engender timescales as little as 7 years. We conclude that Planet 9 is close to the transition point where chemical propulsion approaches its performance limits, and alternative advanced propulsion systems (e.g., NTP and laser sails) apparently become more attractive.

Planet 9... from outer space ?
 
Abstract
Planet 9 is an hypothetical object in the outer Solar system, which is as yet undiscovered. It has been speculated that it may be a terrestrial planet or gas/ice giant, or perhaps even a primordial black hole (or dark matter condensate). State-of-the-art models indicate that the semimajor axis of Planet 9 is ∼400 AU. If the location of Planet 9 were to be confirmed and pinpointed in the future, this object constitutes an interesting target for a future space mission to characterize it further. In this paper, we describe various mission architectures for reaching Planet 9 based on a combination of chemical propulsion and flyby maneuvers, as well as more advanced options (with a ∼100 kg spacecraft payload) such as nuclear thermal propulsion (NTP) and laser sails. The ensuing mission duration for solid chemical propellant ranges from 45 years to 75 years, depending on the distance from the Sun for the Solar Oberth maneuver. NTP can achieve flight times of about 40 years with only a Jupiter Oberth maneuver whereas, in contrast, laser sails might engender timescales as little as 7 years. We conclude that Planet 9 is close to the transition point where chemical propulsion approaches its performance limits, and alternative advanced propulsion systems (e.g., NTP and laser sails) apparently become more attractive.

Planet 9... from outer space ?

It would be interesting to see if such a mission to the possible ninth planet would be possible, but we would need truly advanced technology to travel to it like the NTP rocket for example.
 
Main problem, there ain't even a budget for a classic Uranus orbiter probe. Throwing NEP into the lot would makes the cost explode. Last time NASA tried in 2005 Prometheus did not went too far (although it seems Griffin screwed it for Constellation's Ares big rockets, but that's another story).
 
Main problem, there ain't even a budget for a classic Uranus orbiter probe. Throwing NEP into the lot would makes the cost explode. Last time NASA tried in 2005 Prometheus did not went too far (although it seems Griffin screwed it for Constellation's Ares big rockets, but that's another story).

I can see your point about NASAs budget getting messed about (makes me angry :mad: just thinking about it), but if astronomers discover Planet 9 that would make the budget skyrocket.
 
Abstract
Planet 9 is an hypothetical object in the outer Solar system, which is as yet undiscovered. It has been speculated that it may be a terrestrial planet or gas/ice giant, or perhaps even a primordial black hole (or dark matter condensate). State-of-the-art models indicate that the semimajor axis of Planet 9 is ∼400 AU. If the location of Planet 9 were to be confirmed and pinpointed in the future, this object constitutes an interesting target for a future space mission to characterize it further. In this paper, we describe various mission architectures for reaching Planet 9 based on a combination of chemical propulsion and flyby maneuvers, as well as more advanced options (with a ∼100 kg spacecraft payload) such as nuclear thermal propulsion (NTP) and laser sails. The ensuing mission duration for solid chemical propellant ranges from 45 years to 75 years, depending on the distance from the Sun for the Solar Oberth maneuver. NTP can achieve flight times of about 40 years with only a Jupiter Oberth maneuver whereas, in contrast, laser sails might engender timescales as little as 7 years. We conclude that Planet 9 is close to the transition point where chemical propulsion approaches its performance limits, and alternative advanced propulsion systems (e.g., NTP and laser sails) apparently become more attractive.



When I see the bit about a primordial black hole I am always reminded of a story form one of the Niven and Pournelle books.

Pluto was a puzzler, however. An object six times Earth's mass was expected to show a disk when observed using large telescopes, but Pluto did not. Furthermore, the planet had a bizarre tilted orbit that partly overlapped that of Neptune.

As astronomers continued their observations of Pluto, they revised estimates of its size downward. By 1960, some astronomers thought that it was about the size of Earth; others thought it might be as small as Mercury. This only increased the mystery surrounding the planet, for if it was to account for the observed discrepancies in Neptune's orbit, then it had to be several times as massive as Earth. Some astronomers proposed the existence of another, larger planet beyond Pluto. One scientist proposed a much more novel explanation.

George Peterson Field was the pen name of Dr. Robert Forward. Safely hidden behind the protective cloak of his nom de plume, the newly minted Ph.D. physicist speculated in a "science fact" article in the December 1962 issue of Galaxy science fiction magazine that Pluto was a gift from a "Galactic Federation."

He began by calculating that a body about the size of Mercury but with six times the mass of Earth would be so dense that it would have to be made of the collapsed matter found only in certain dwarf stars. Such an object could not exist naturally; unrestrained by the massive gravity of a dwarf star, it should have exploded long ago. Therefore, Forward asserted, Pluto must be artificial.

He suggested that Pluto was in fact a "gravity catapult." He wrote that "it would have to be whirling in space like a gigantic, fat smoke ring, constantly turning from inside out." A spacecraft that approached the ring's center moving in the direction of its spin would be dragged through "under terrific acceleration" and ejected from the other side.

If the acceleration the ultradense smoke ring gave the spacecraft were about 1000 times the acceleration Earth's gravity imparts to falling objects, then the ring would boost the spacecraft to nearly the speed of light in about one minute. The passengers and crew would, however, feel nothing as their spacecraft accelerated, for the gravitational force from the roiling ring would act on every atom of it uniformly. The ring would slow by a small amount as it accelerated the spacecraft.

Forward wrote that a "network of these devices in orbit around interesting stars" would provide "an advanced race" with an "energetically economical" means of star travel. The rings in the network would "cartwheel slowly" so that over time they would point at many possible destination stars.

A spacecraft accelerated by a ring could, upon arriving at another star in the network, enter that star's ring moving against the ring's spin. This would decelerate the spacecraft very rapidly and increase the ring's spin by a tiny amount. In effect, the spacecraft would pay back the network for the acceleration it borrowed when it began its journey.

Forward ended his article by noting that such a device could be shot through space by a larger gravity catapult and braked "by pushing against a massive planet," such as Neptune. This, he added, might account for Pluto's odd orbit with respect to the eighth planet. He speculated that, at some time in the past, the Galactic Federation had noted the rise of humans and had launched Pluto toward Sol to serve as "a coming out present."

Forward's concept is so imaginative and appealing that it ought to be true. New data on Pluto soon ruled it out, however. In 1977, James Christy of the U.S. Naval Observatory Western Station, located just a few kilometers from Lowell Observatory in Flagstaff, Arizona, found Pluto's moon Charon. The discovery of a body orbiting Pluto enabled astronomers to calculate its mass accurately for the first time. Pluto, as it turned out, has only one-quarter of 1% of Earth's mass. Subsequently, it was found to have a diameter of only about 2350 kilometers, making it only two-thirds as large as Earth's moon. After the turn of the 21st century, Pluto was found to have four more moons, all smaller than Charon.

Though Pluto did not turn out to be a link in a galactic transportation network, it did turn out to be a link to something big. Pluto was the first member of the Kuiper Belt to be found. The Kuiper Belt, a part of the Solar System long theorized but only confirmed beginning in 1992, is the "third realm" of bodies orbiting the Sun after the Sun-hugging realm of the rocky planets and the realm of the giant planets. It is far bigger than the first two realms combined. As New Horizons closes in on Pluto, we know of over 1000 bodies in trans-Neptunian space. Astronomers estimate that more than 100 times that number might exist. Assuming that New Horizons continues to operate as planned, mission planners expect to direct it past several more Kuiper Belt Objects after the Pluto flyby.

If Pluto is so small that it cannot account for the discrepancies in Neptune's orbit, then what does? In August 1989, the Voyager 2 spacecraft flew past Neptune. By carefully tracking the robot spacecraft, celestial dynamicists refined their estimate of Neptune's mass. When they did, the observed discrepancies in its orbital motion vanished. There was thus never a need to find a Planet X. Error had led to coincidence, and the result was mysterious Pluto.
 
We’ve Finally Figured Out Why Saturn Is ‘Lord Of The Rings,’ Say Scientists

A new paper published in the journal Science this week claimed that Saturn’s rings are the result of a moon that was torn apart by the planet’s tidal forces about 160 million years ago. Since the planet is about the same age as the solar system—so about 4.5 billion years old—that's the blink of an eye.

The new theory also inextricably links the formation of Saturn’s rings to how the planet got its axial tilt.

“The tilt is too large to be a result of known formation processes in a protoplanetary disk or from later, large collisions,” said Jack Wisdom, a professor of planetary science at the Massachusetts Institute of Technology (MIT). “A variety of explanations have been offered, but none is totally convincing. The cool thing is that the previously unexplained young age of the rings is naturally explained in our scenario.”


How Saturn got its tilt and its rings

Abstract

The angle between a planet’s equator and its orbit plane is known as its axial tilt or obliquity. As gas giants form from the disk made of gas and dust that swirls around the host star, the gas accretion process is expected to conserve the angular momentum and force the planet to spin perpendicular to its orbital plane. However, within our own Solar System, all gas giants, except for Jupiter, have a substantial nonzero tilt. This implies that something else must have happened to these planets after they formed that caused them to tilt. On page 1285 of this issue, Wisdom et al. (1) describe a model that can explain the origin of Saturn’s obliquity. Its tilt may have been caused by a process involving Saturn’s wobbling tilt (i.e., spin-axis precession), Neptune’s wobbling orbit (i.e., nodal precession), the elimination of a hypothetical satellite, and the outward migration of Titan—the largest moon of Saturn.

 
Forgot to crosspost this over here earlier:
Regarding the Chang'e-5:

EDIT: Via the same Slashdot thread:
 
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The meteorite crashed into a driveway in the Gloucestershire town of Winchcombe last February and is believed to hold clues about where the water in the Earth's vast oceans came from.

Some 12% of the sample was made up of water, and offers a lot of insights since it was the least contaminated specimen to be collected, according to Ashley King, a researcher in the planetary materials group at the Natural History Museum.

"The composition of that water is very, very similar to the composition of water in the Earth's oceans," he told the British Science Festival.

"It's a really good piece of evidence that asteroids and bodies like Winchcombe made a very important contribution to the Earth's oceans."

Dr King continued: "We've had a hint that some asteroids match back nicely to the Earth.

"But now we have a meteorite which is really fresh that we know hasn't been modified, and it's confirming that same story."

Speaking at De Montfort University, which is hosting the festival, Dr King revealed that analysis suggests that the meteorite derived from an asteroid somewhere near Jupiter.

It is believed to have been formed around 4.6 billion years ago and has taken some 300,000 years to reach Earth.

 
SPECULOOS discovers a potentially habitable super-Earth

An international team of scientists, led by Laetitia Delrez, astrophysicist at the University of Liège, has just announced the discovery of two 'super-Earth' type planets orbiting LP 890-9. Also known as TOI-4306 or SPECULOOS-2, this small, cool star located about 100 light-years from our Earth is the second coolest star around which planets have been detected, after the famous TRAPPIST-1. This important discovery is published in the journal Astronomy & Astrophysics.

https://www.news.uliege.be/cms/c_16795199/en/speculoos-discovers-a-potentially-habitable-super-earth

Related paper:

https://www.aanda.org/component/article?access=doi&doi=10.1051/0004-6361/202244041
Some creative acronym-adaptive naming going on here:
Search for habitable Planets EClipsing ULtra-cOOl Stars =
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