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Our understanding of the Universe is profound. Only a century ago, astronomers held a Great Debate to argue over whether our galaxy was an island universe, or whether nebulae such as Andromeda were galaxies in a much larger cosmos. Now we know that the Universe is billions of years old, ever expanding to billions of light-years across, and filled with not just stars and galaxies but with dark energy and cold dark matter. Astronomers summarize this understanding as the LCDM model, which is the standard model of cosmology. While the observational data we have strongly supports this model, it is not without its challenges.

The most striking challenge is known as the Hubble tension. When we measure the rate of cosmic expansion in various ways, we can calculate what is known as the Hubble constant or Hubble parameter, which defines the rate of cosmic expansion. This rate also tells us things such as the age of the Universe and the average density of dark energy and matter. While the various observations generally cluster around 68-69 km/s/Mpc, several of the methods give results outside that range. There is some evidence to support the idea that the current rate of cosmic expansion is greater than that during the early Universe, which is known as cosmic shear tension. All of this means either some of our methods are in error somehow or there is a fundamental aspect of cosmic expansion we don’t yet understand.

Related to this are the mysteries surrounding dark energy. Within the standard model, dark energy is a property of space and time and is universal throughout the cosmos. But there is an alternative view that holds dark energy is an independent scalar field within spacetime, sometimes referred to as quintessence. Observations such as the clustering scale of galaxies generally support the former model, but there are a few studies here and there that suggest the latter. We don’t yet have enough data to rule out either completely.

Observations of the Hubble parameter. Credit: N. Palanque-Delabrouille

Then, of course, there is the great bugbear of dark matter. Observations strongly support its existence, and that dark matter makes up most of the matter in the Universe. But within the standard model of particle physics, there is nothing that could comprise dark matter, and countless experiments trying to detect dark matter directly have so far yielded nothing. Alternative models such as modified gravity can account for some of our observations, but models must be tweaked just so to fit data, and no alternative approach agrees with all our observations. Dark matter remains central to the standard cosmological model, but its true nature remains in shadow.

In short, we are tantalizingly close to a complete and unifying model of the Universe, but there are deep and subtle mysteries we have yet to solve. We need more theoretical ideas, and we desperately need more observational data. Fortunately, there are exciting projects in the pipeline that could solve these mysteries in the near future.

One of these is the Dark Energy Spectroscopic Instrument (DESI) survey, which is currently underway. Over the course of the five-year project, DESI will observe the spectra of more than 35 million distant galaxies, giving us a detailed 3D map of the Universe. In comparison, the Sloan Digital Sky Survey (SDSS) gathered data on 4 million galaxies and gave us the most detailed view of galactic clustering at the time. With DESI, we will be able to see the interaction between dark matter and dark energy across billions of years and hopefully determine whether dark energy is constant or changes over time.

Comparison of SDSS (left) with DESI (right). Credit: David J. Schlegel

Another useful tool will be the Vera Rubin observatory, which should come online in a few months. By giving us a high-resolution map of the sky every few days, Rubin will allow us to study transient phenomena such as supernovae used to measure cosmic expansion. It will also give us a rich view of matter within our galaxy and could reveal aspects of how that matter interacts with dark matter.

Further into the future, there are planned projects such as the Wide-field Spectroscopic Telescope (WST), which will expand on the abilities of Rubin observatory, and the Spec-S5, which will complement the DESI surveys. Both of these are still in the planning stage, but could become the DESI surveys. Both of these are still in the planning stage but could become operational within a decade or so.

In the 1920s, the Great Debate of Astronomy was solved thanks to a wealth of data. The rise of photographic astronomy allowed us to see the Universe in transformative new ways and made modern cosmology possible. We are now entering an era of large data astronomy, where wide-field telescopes and large surveys will provide more data in an evening than could be gathered in a year just decades ago. Brace yourselves for another revolutionary era of astronomy.

Reference: Palanque-Delabrouille, N. “Future directions in cosmology.” arXiv preprint arXiv:2411.03597 (2024).

The post Cosmology is at a Crossroads, But New Instruments are Coming to Help appeared first on Universe Today.

One of the great things about CubeSat designs is that they constrain the engineers who design them. Constraints are a great way to develop novel solutions to problems that might otherwise be ignored without them. As CubeSats become increasingly popular, more and more researchers are looking at how to get them to do more with less. A paper from 2020 contributes to that by designing a 3U CubeSat mission that weighs less than 4 kilograms to perform a fly-by of a Near Earth Asteroid (NEA) using entirely off-the-shelf parts.

The research, carried out by a team based at the Delft University of Technology, had several mission requirements they were trying to meet. Some were standard like it had to have a propulsion system and a way to get data back to Earth. However, some were more challenging – it had to weigh less than 4 kg, it had to fit into a 3U CubeSat body (which measures (100mm x 100mm x 340.5mm), it had to perform its mission in less than 650 days, and, perhaps the most technically challenging goal – it has to “exploit a fully-autonomous navigation strategy.”

First, let’s look at the mission design. Since there are around 35,000 known NEAs, mission designers would be spoiled for choice. However, getting to one with a relatively limited propulsion budget (since propellant increases the weight – one of the design constraint limits) and finding the right one would require extensive searching of the JPL Small-Body Database. 

Fraser discusses how we find NEAs

Once an NEA has been selected, the mission designers could plan the optimal trajectory. However, to meet the requirement of an autonomous navigation strategy, the CubeSat itself will have to find its way to the asteroid and enact any course corrections along the way. This could be extremely difficult, given the low brightness of many of the target asteroids and how that brightness might change based on what side of it is facing the Sun and what angle the CubeSat is approaching it from. The scientific payload, including a visible light and IR camera, would have to work in tandem with a micro star tracker to ensure the trajectory is optimal for scientific data collection.

That data collection might only last a few minutes, as the limited propellant for the mission would require it to be a fly-by rather than an orbit. The resulting image might be as small as a 6 x 6 pixel image for a 300m diameter asteroid. This would provide orders of magnitude with more resolution than ground-based observations for most. Still, it would not be enough to get into the details of mass and composition that planetary protectors and asteroid mining enthusiasts alike would most desire.

Any new information is better than no information, though, and the simplicity of the design for this mission’s hardware makes it relatively inexpensive and, therefore, mass-producible. It consists of six major sub-systems – the “payload,” which is essentially a visible light and infrared camera; the propulsion system, which is a microjet ion propulsion engine; the attitude determination and control system (ADCS), which helps navigate; a communication system that uses an X-band antenna to communicate back to the Deep Space Network infrastructure, and a power system that would involve deployable solar panels. 

Some of the engineering that goes into CubeSats is pretty impressive, as this JPL video shows.
Credit – NASA Jet Propulsion Laboratory YouTube Channel

Overall, the mission met the goal of fitting entirely into a 3U package and came in at 3.8kg using off-the-shelf components. However, thermal management systems and radiation shielding were not considered in the design. Other challenges, like getting time on the already overstretched Deep Space Network ground antennas, are left for another paper.

But if nothing else, this paper proves that it is possible, on paper at least, to design an inexpensive mission to collect data on an asteroid and that that mission can be replicated hundreds or even thousands of times at relatively low cost. As CubeSats gain more and more capabilities and more and more traction, and as launch costs get lower and lower, it’s becoming increasingly plausible that someday, a system like this might very well make its way past an asteroid and send data back that we otherwise wouldn’t have gotten.

Learn More:
Casini et al – Novel 3U Stand-Alone CubeSat Architecture for Autonomous Near Earth Asteroid Fly-By
UT – A Pair of CubeSats Using Ground Penetrating Radar Could Map The Interior of Near Earth Asteroids
UT – A Mission To Find 10 Million Near Earth Asteroids Every Year
UT – Swarms of Orbiting Sensors Could Map An Asteroid’s Surface

Lead Image:
ESA’s Hera Mission is joined by two triple-unit CubeSats to observe the impact of the NASA-led Demonstration of Autonomous Rendezvous Technology (DART) probe with the secondary Didymos asteroid, planned for late 2022.
Credit: ESA

The post A 3U CubeSat Could Collect Data During an Asteroid Flyby appeared first on Universe Today.

Bees visited flowers on plants inoculated with diverse fungi more than plants without this treatment – but not every combination of fungus had the same effect

As I reported on November 22, I was shocked to find that, on a list of 18 U.S. Senators who voted to move forward with Bernie Sanders’s bill to block a $20 billion sale of weapons to Israel, was one of my own Senators, Democrat Dick Durbin. Here’s the whole list:

The measure failed miserably on the Senate floor, with none of its three provisions garnering more than 19 votes. But of course I wrote to Senator Durbin, expressing my dissatisfaction as a constituent, and chastising him for giving succor to Israel’s enemies and impeding the self-defense of Jewish state in its attempt to root out Hamas.

Yesterday I got this weaselly response from Durbin:

December 4, 2024
MY ADDRESS REDACTED

Dear Dr. Coyne:

Thank you for contacting me about measures to block weapons shipments to Israel.  I appreciate hearing from you.

On September 25, 2024, Senator Bernie Sanders of Vermont introduced six measures that would block a proposed $20 billion in arms sales to Israel.  These sales include joint direct attack munitions and launchers, mortar and tank cartridges, F-15s, and other defense articles.  Under the Foreign Assistance Act of 1961 (P.L. 87-195) and the Arms Export Control Act of 1976 (P.L. 94-329), the president must notify Congress of a pending arms sale.  These statutes also give Congress the authority to suspend such a sale by passing a joint resolution of disapproval through both the House of Representatives and the Senate.  All six of these measures were referred to the Senate Committee on Foreign Relations.

On November 20, 2024, the Senate considered whether to discharge three of Senator Sanders’ joint resolutions of disapproval, S.J. Res. 111, S.J. Res. 113, and S.J. Res. 115, from the Senate Committee on Foreign Relations.  While I voted in favor of discharging these three measures from the Senate Foreign Relations Committee, all three of these measures were rejected by the Senate.  S.J. Res. 111 was rejected by a vote of 18-79, S.J. Res. 113 was rejected by a vote of 19-78, and S.J. Res. 115 was rejected by a vote of 17-80.

My reason for supporting these measures is straightforward.  More than 43,000 Palestinians have died in the conflict in Gaza since October 7, 2023, and 60 percent of them have been women, children, and elderly.  The denial of humanitarian aid to Gaza threatens the lives of so many more.

I believe that Israel has not only the right to exist, but the right to defend itself in the face of threats such as from Hamas, Hezbollah, and Iran.  I consistently have voted for security assistance to Israel throughout my career to protect it from these threats.  But this war must end.  I will stand by Israel, but I will not support the devastation of Gaza and the deaths of thousands of innocent Palestinians.

For too long, this protracted conflict has inflicted untold suffering on innocent Israelis and Palestinians alike.  I hope out of the ashes and pain of this current crisis that there can be a renewed focus on a two-state solution.

Thank you again for contacting me.  Please feel free to keep in touch.

Sincerely,
Richard J. Durbin
United States Senator

I sent this response to Malgorzata, and when I woke up this morning she had written a response, one that I reproduce here with permission. Durbin is apparently as dumb and uninformed about the Gaza conflict as many Americans.

Malgorzata’s response is indented.

Durbin’s figures are taken directly from Hamas, figures that have been debunked many times.

Hamas doesn’t count combatants and civilians separately. In this fictitious number of dead are the non-existent 500 people allegedly killed in a strike on the hospital Al-Ahli. As was discovered and confirmed by independent authorities (and admitted by the real perpetrator: Palestinian Islamic Jihad), it was a misfired PIJ rocket that fell short, creating the strike. Instead of killing Israeli civilians, the rocket fell on the hospital’s parking lot (NOT THE HOSPITAL). It killed several people, but far less than 100—not to mention 500.

How many other Palestinian civilians killed by rockets from PIJ and Hamas rockets have been counted by Hamas’s Ministry of Health as having been killed by Israel? After previous wars between Gaza and Israel, when there was really time to count the dead and ascertain their identities, it always turned out that Hamas had counted everybody (including combatants killed in war as well as people who died in Gaza of natural causes) in their earlier communicates about people “killed by Israel”.

The percentages of women, children, and elderly given by Durbin (and Hamas) are also false. According to the IDF, up to 19,000 Hamas combatants were killed. Moreover, both Hamas and PIJ use teenagers as fighters. Everybody killed when he/she is under 18 is counted as a child. A 17-year-old fighter killed when shooting a rocket at Israelis is counted as a child. Even if you accept the false numbers given by Hamas, the ratio of civilian to combatant deaths is the lowest ever achieved in urban warfare by any army.

Further, not one person in Gaza would have been killed by the IDF if Hamas and PIJ didn’t invade Israel on October 7, 2023, didn’t kill, rape, torture, and burn 1200 Israeli women, men, children and the elderly, and didn’t take 252 hostages, including women, children and the elderly. There are still 101 hostages somewhere in the dungeons of Hamas, among them baby Kfir (9 months old at the moment of kidnapping) and his older brother Ariel (4 years at the moment of kidnapping).

From Jerry. I would add this.  Besides credulously adopting Hamas’s misleading figures that count dead combatants as “innocent Palestinians”, Durbin implicitly calls for a cease-fire and explicitly for a “two-state solution,” something that, if implemented now, would be a disaster for Israel.

We already know that the ratio of civilians killed to combatants killed is far lower than seen in other conflicts in which the U.S. has engaged, including World War II and the more recent battles in the Middle East. Durbin of course ignores that, just as he ignores what happened on October 7 of last year.  In his attempt to look evenhanded, Durbin has proven himself a useful asset for Hamas. And I will communicate this to the misguided Senator.

Prescribed medicines are somewhat resistant to fads. Marketing can certainly drive demand and use, but long-term use tends to be driven by effectiveness. Some medicines used routinely today are decades old (e.g., penicillin for strep throat), because nothing better has been identified. Other drugs may be used for decades, only to largely disappear as newer, more effective treatments are introduced (I’m thinking […]

The post Pycnogenol – Does maritime pine bark extract live up to the hype? first appeared on Science-Based Medicine.

What is Power-to-X (PtX)? It’s just a fancy marketing term for green hydrogen – using green energy, like wind, solar, nuclear, or hydroelectric, to make hydrogen from water. This process does not release any CO2, just oxygen, and when the hydrogen is burned back with that oxygen it creates only water as a byproduct. Essentially hydrogen is being used as an energy storage medium. This whole process does not create energy, it uses energy. The wind and solar etc. are what create the energy. The “X” refers to all the potential applications of hydrogen, from fuel to fertilizer. Part of the idea is that intermittent energy production can be tied to hydrogen production, so when there is excess energy available it can be used to make hydrogen.

A recent paper explores the question of why, despite all the hype surrounding PtX, there is little industry investment. Right now only 0.1% of the world’s hydrogen production is green. Most of the rest comes from fossil fuel (gray and brown hydrogen) and in many cases is actually worse than just burning the fossil fuel. Before I get into the paper, let’s review what hydrogen is currently used for. Hydrogen is essentially a high energy molecule and it can be used to drive a lot of reactions. It is mostly used in industry – making fertilizer, reducing the sulfur content of gas, producing industrial chemicals, and making biofuel. It can also be used for hydrogen fuel cells cars, which I think is a wasted application as BEVs are a better technology and any green hydrogen we do make has better uses. There are also emerging applications, like using hydrogen to refine iron ore, displacing the use of fossil fuels.

A cheap abundant source of green hydrogen would be a massive boost to multiple industries and would also be a key component to achieving net zero carbon emissions. So where is all the investment? This is the question the paper explores.

The short answer has to do with investment risk. Investors, especially when we are talking about billions of dollars, like predictability. Uncertainty increases their risk and is a huge disincentive to invest large sums of money. The paper concludes that there are two main sources of uncertainty that make PtX investments seem like they are high risk – regulatory uncertainty and lack of infrastructure.

Regulations in many countries are still in flux. This, fortunately, is an entirely solvable problem. Governments can put resources and priority into hammering out comprehensive regulations for the hydrogen and related industries, lock in those regulations for years, and provide the stability that investors want. Essentially the lack of proper regulations is a hurdle for green hydrogen investment, and governments simply need to do their job.

The second issue is lack of infrastructure, with further uncertainty about the completion of planned hydrogen projects –

“For instance, in October, the Danish government announced that a planned hydrogen pipeline to Germany would not be established until 2031 at the earliest, whereas the previous target was scheduled for 2028.”

The fossil fuel industry has the advantage of a mature infrastructure. Imagine if we had to develop all the oil rigs, oil wells, pipelines, trucking infrastructure, and gas stations from scratch. That would be a massive investment on an uncertain timeline. Hydrogen is facing the same issue. Again, this is a solvable issue – invest in hydrogen infrastructure. Make sure projects are sufficiently funded to keep on the originally promised timeline. Governments are supposed to craft regulation and invest in common infrastructure in order to facilitate private industry investing in new technologies. This may be all that is necessary to accelerate the green transition. At least we shouldn’t be holding it back because governments are doing their job.

The authors of the paper also explore another aspect of this issue – incentives for industry to specifically invest in green technology. This is essentially what the IRA did in the US. Here incentives fall into two broad categories, carrots and sticks. One type of carrot is to reduce risk for private investment. Beyond what I already mentioned, government can, for example, guarantee loans to reduce financial risk. They can also provide direct subsidies, such as tax breaks for investments in green technology. For context, the fossil fuel industry received $1.4 trillion in 2022 in direct subsidies worldwide. It is also estimated that the fossil fuel industry was allowed to externalize $5.6 trillion in health and environmental costs (whether or not you consider this a “subsidy”). This is for a mature industry with massive profits sitting on top of a massive infrastructure partly paid for with public dollars. The bottom line is that some targeted subsidies for green energy technology is perfectly reasonable, and in fact is a good investment.

But the authors argue that this might not be enough. They also recommend we add some sticks to the equation. This usually takes the form of some type of carbon tax, which would make fossil fuels less profitable. This seems perfectly reasonable. They also recommend mandated phase out of fossil fuel investments. This is trickier, and I think this type of approach should be a last resort if anything. You won’t have to mandate a phase out if you make green technologies more attractive through subsidies and infrastructure, and fossil fuels less attractive by eliminating subsidies and perhaps taxing carbon.

At the very least governments should be not slowing down the green transition because they are neglecting to do their basic job.

The post Power-To-X and Climate Change Policy first appeared on NeuroLogica Blog.

A US ban on exporting high-end chips used for AI development to China doesn't seem to have affected Tencent, as US researchers suggest they may have found signs of the tech giant still using the chips

A US ban on exporting high-end chips used for AI development to China doesn't seem to have affected Tencent, as researchers have found signs of the tech giant using the chips well after the ban was put in place

A robotic wheeled rat that was trained with AI learned how to play and fight with real rodents – and could one day offer companionship to lab rats

Women are more susceptible to autoimmune conditions than men, but also more protected against infections - and we are starting to understand why

China’s growing presence in space has been undeniable since the turn of the century. Between sending the first “taikonaut” to space in 2003 (Yang Liwei), launching the first Chinese robotic mission to the Moon (Chang’e-1) in 2007, and the deployment of their Tiangong space station between 2021-2022, China has emerged as a major power in space. Accordingly, they have bold plans for the future, like the proposed expansion of their Tiangong space station and the creation of the International Lunar Research Station (ILRS) by 2035.

In their desire to become a space power that can rival NASA, China also has its sights on Mars. In addition to crewed missions that will culminate in a “permanent base,” they intend to conduct a sample-return mission in the near future. This will be performed by the Tianwen-3 mission, which is currently scheduled to launch in 2028 and return samples to Earth by 2031. In a recent article, the Tianwen-3 science team outlined their exploration strategy, including the methods used to retrieve the samples, the target locations, and how they’ll be analyzed for biosignatures that could indicate the presence of past life.

Zengqian Hou was the article’s lead author, a geologist with the Deep Space Exploration Laboratory (DSEL) and the Chinese Academy of Geological Sciences (CAGS), and the mission team supervisor. His fellow team members included the mission’s chief designer, Liu Jizhong, and colleagues from the DSEL, the Lunar Exploration and Space Engineering Center, the Chinese Academy of Sciences (CAS), and the University of Science and Technology of China (USTC). The article was recently published in the November edition of National Science Review.

This image was taken by a small camera jettisoned from China’s Tianwen-1 spacecraft to photograph the spacecraft in orbit above the Martian north pole. Credit: CNSA/PEC

This mission is the third in China’s Tianwen (Chinese for “questions to heaven”) exploration program. The previous mission (Tianwen-1) included an orbiter, a lander, and the Zhurong rover, which reached Mars in February 2021. The successful deployment of this mission made China the third nation (after the Soviet Union and the U.S.) to land on Mars. Highlights of the mission include the mapping of the entire Martian surface by the orbiter and the discovery of hydrated minerals by Zhurong, further confirming that Mars once had liquid water on its surface.

News of this latest mission was first shared by Jizhong at the 2nd International Deep Space Exploration Conference, which took place from September 4th to 7th in Huangshan City, China. However, few details were shared at the time, though a concurrently published paper suggested that the mission could include a helicopter similar to NASA’s Ingenuity. According to the latest from Jizhong, the Tianwen-3 will consist of two launches sometime in 2028 using the Long March 5 (CZ-5) rocket. While one CZ-5 will send the orbiter/return vehicle, the second will send the lander/ascent vehicle. As Liu told the state-owned news agency Xinhua:

“China has retrieved the first-ever samples from the far side of the moon with the Chang’e-6 mission this year. Since Mars is much farther away than the moon, it will take two launches to carry out the Mars sample-return mission due to the limited carrying capacities of our current rockets. Two Long March-5 carrier rockets will be used for the mission.”

Other details include the 86 potential landing sites proposed by the team, which are primarily concentrated in the ancient Chryse Planitia and Utopia Planitia regions. These areas are considered good places to search for potential biosignatures that could be preserved remains of ancient life. This includes features that indicate the presence of past water, including delta fans, lake beds, and the coastline, suggesting the presence of a past ocean in the Northern Lowlands. The team also stated that Tianwen-3 will carry payloads developed with international partners.

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

They also stressed the necessity for new instruments specifically designed to detect biosignatures. To this end, they have developed a 13-phase mission plan that leverages in-situ and remote-sensing detection technologies. Liu also disclosed that the mission will rely on multi-point surface sampling, fixed-point in-depth drilling, and in-flight vehicle sampling to obtain diverse samples. They also state that China will conduct joint research with scientists worldwide on Mars samples and detection data.

What is clear from this latest news is that China intends to preempt NASA and the ESA’s proposed Mars Sample Return (MSR) mission. Due to budget cuts announced earlier this year, this mission is currently stuck in the design phase. Similarly, China has indicated that the Tianwen-4 mission will explore the Jupiter system to learn more about its moons and their evolutionary history. This mission is scheduled to launch in September 2029 and will follow on the heels of NASA’s Europa Clipper and the ESA’s JUpiter Icy Moons Explorer (JUICE).

This is in keeping with China’s pattern of following in NASA’s footsteps, catching up with them and surpassing them as the leader in space exploration. If they manage to return Martian samples to Earth before either NASA or the ESA, they will have accomplished a task no other space agency has. However, given the scientific value of these samples and the international cooperation that will go into their analysis will be to the benefit of all.

Further Reading: CGTN, Xinhua

The post China Plans to Retrieve Mars Samples by 2031 appeared first on Universe Today.

An innovative algorithm called Spectral Expansion Tree Search helps autonomous robotic systems make optimal choices on the move.

An innovative algorithm called Spectral Expansion Tree Search helps autonomous robotic systems make optimal choices on the move.

With the help of an AI tool, computed tomography (CT) scans taken originally to look for tumors or bleeding or infections, also revealed calcium buildup in arteries, a sign of worsening cardiovascular disease.

Researchers characterize the chemical makeup of 81 common household items. Researchers also evaluated the potential risk to users.

Since the 1960s, scientists who study X-rays, lightning and similar phenomena have observed something curious: In lab experiments replicating these occurrences, electrons accelerated between two electrodes can be of a higher energy than the voltage applied. According to researchers, this defies an assumption in physics that the energy of the electrons should correspond with the voltage applied. Despite the decades-long awareness of this apparent contradiction, researchers couldn't figure out why this was happening. Recently, a team of researchers used mathematical modeling to explain the underlying mechanism at play.

Since the 1960s, scientists who study X-rays, lightning and similar phenomena have observed something curious: In lab experiments replicating these occurrences, electrons accelerated between two electrodes can be of a higher energy than the voltage applied. According to researchers, this defies an assumption in physics that the energy of the electrons should correspond with the voltage applied. Despite the decades-long awareness of this apparent contradiction, researchers couldn't figure out why this was happening. Recently, a team of researchers used mathematical modeling to explain the underlying mechanism at play.

In a unique demonstration of brain implants that incorporate living cells, the devices were able to connect with the brains of live mice

When Oumuamua traversed our Solar System in 2017 it was the first confirmed Interstellar Object (ISO) to do so. Then in 2019, Comet 2l/Borisov did the same thing. These are the only two confirmed ISOs to visit our Solar System. Many more ISOs must have visited in our Solar System’s long history, and many more will visit in the future. There are obviously more of these objects out there, and the upcoming Vera Rubin Observatory is expected to discover many more.

It’s possible that the Sun could capture an ISO or a rogue planet in the same way that some of the planets have captured moons.

It all comes down to phase space.

What would happen to our mature, sedate Solar System if it suddenly gained another member? That would depend on the object’s mass and the eventual orbit that it found itself in. It’s an interesting thought experiment; while Borisov and Oumuamua were smaller objects, a more massive rogue planet joining our Solar System could generate orbital chaos. It could potentially alter the course of life on Earth, though that is highly improbable.

How likely is this scenario? A new research note in Celestial Mechanics and Dynamical Astronomy outlines how our Solar System could capture an ISO. It’s titled “Permanent capture into the solar system,” and the authors are Edward Belbruno from the Department of Mathematical Sciences at Yeshiva University, and James Green, formerly of NASA and now from Space Science Endeavours.

Phase space is a mathematical representation that describes the state of a dynamical system like our Solar System. Phase space uses coordinates that represent both position and momentum. It’s like a multidimensional space that contains all of the possible orbital configurations around the Sun. Phase space captures the state of a dynamical system by tracking both position and momentum characteristics. Our Solar System’s phase space has capture points where an ISO can find itself gravitationally bound to the Sun.

Phase space is complex and is based on Hamiltonian mechanics. Things like orbital eccentricity, semi-major axis, and orbital inclination all feed into it. Phase space is best understood as a multidimensional landscape.

Our Solar System’s phase space includes two types of capture points: weak and permanent.

Weak capture points are regions in space where an object can be temporarily drawn into a semi-stable orbit. These points are often where the outer edges of objects’ gravitational boundaries meet. They’re more like gravitational nudges than an orbital adoption.

Permanent capture points are regions in space where an object can be permanently captured into a stable orbit. An object’s angular momentum and energy are an exact configuration that allows it to maintain an orbit. In planetary systems, these permanent capture points are stable orbital configurations that persist for extremely long periods of time.

Our Solar System’s phase space is extremely complex and involves many moving bodies and their changing coordinates. Subtle changes in phase space coordinates can allow objects to transition between permanent capture states and weak capture states. By the same token, subtle differences in ISOs or rogue planets can lead them into these points.

In their research note, the authors describe the permanent capture of an ISO this way: “The permanent capture of a small body, P, about the Sun, S, from interstellar space occurs when P can never escape back into interstellar space and remains captured within the Solar System for all future time, moving without collision with the Sun.” Purists will note that nothing can be the same for all future time, but the point stands.

Other researchers have delved into this scenario, but this work goes a step further. “In addition to being permanently captured, P is also weakly captured,” they write. It revolves around the notoriously difficult to solve three-body problem. Also unlike previous research, which uses Jupiter as the third body, this work uses the galaxy’s tidal force as the third body, along with the P and S. “This tidal force has an appreciable effect on the structure of the phase space for the velocity range and distance from the Sun we are considering,” they explain in their paper.

The paper focuses on the theoretical nature of phase space and ISO capture. It studies “the dynamical and topological properties of a special type of permanent capture, called permanent weak capture which occurs for infinite time.” An object in permanent weak capture will never escape, but will never reach a consistent stable orbit. It asymptotically approaches the capture set without colliding with the star.

There’s not much debate that rogue planets exist likely in large numbers. Stars form in groups that eventually disperse over a wider area. Since stars host planets, some of these planets will be dispersed through gravitational interactions prior to co-natal stars gaining some separation from one another.

“The final architecture of any solar system will be shaped by planet-planet scattering in addition to the stellar flybys of the adjacent forming star systems since close encounters can pull planets and small bodies out of the system creating what are called rogue planets,” the authors explain.

“When taken together, planet ejection from early planet-planet scattering and stellar encounters and in the subsequent evolution of a multi-planet solar system should be common and supports the evidence for a very large number of rogue planets that are free floating in interstellar space that perhaps exceed the number of stars,” the authors write, noting that that assertion is controversial.

So what does this all add up to?

The researchers developed a capture cross-section for the Solar System’s phase space then calculated how many rogue planets are in our Solar System’s vicinity. In our solar neighbourhood, which extends to a radius of six parsecs around the Sun, there are 131 stars and brown dwarfs. Astronomers know that at least several of them host planets, and all of them may very well host planets we haven’t detected yet.

Every million years, about two of our stellar neighbours come within a few light years of Earth. “However, six stars are expected to closely pass by in the next 50,000 years,” the authors write. The Oort Cloud’s outer boundary is about 1.5 light years away, so some of these stellar encounters could easily dislodge objects from the cloud and send them toward the inner Solar System. This has already happened many times, as the cloud is likely the source of long-period comets.

The familiar Solar System with its 8 planets occupies a tiny space inside a large spherical shell containing trillions of comets – the Oort Cloud. Gravitational perturbations dislodge comets from the cloud, sending some of them into the inner Solar System. Image Credit: Wikimedia Commons

The researchers identified openings in the Solar System’s phase space that could allow some of these objects, or ISOs or rogue planets, to reach permanent weak capture. They’re openings in the Sun’s Hill sphere, a region where the Sun’s gravity is the dominant gravitational force for capturing satellites. These openings are 3.81 light years away from the Sun in the direction of the galactic center or opposite to it.

“Permanent weak capture of interstellar objects into the Solar System is possible through these openings,” the authors state. “They would move chaotically within the Hill’s sphere to permanent capture about the Sun taking an arbitrarily long time by infinitely many cycles.” These objects would never collide with the Sun and could be captured permanently. “A rogue planet could perturb the orbits of the planets that may be possible to detect,” they conclude.

We’re still in the early days of understanding ISOs and rogue planets. We know they’re out there, but we don’t know how many or where they are. The Vera Rubin Observatory might open our eyes to this population of objects. It may even show how they cluster in some regions and avoid others.

According to this work, if they’re close to any of the openings in the Sun’s Hill sphere, we could have a visitor that decides to stay.

The post Here’s How Interstellar Objects and Rogue Planets Can be Trapped in the Solar System appeared first on Universe Today.

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