Space
Publication of the latest map of the distribution of dark matter in the universe
Publication of the latest map of the distribution of dark matter in the universe . A ground-breaking new map depicts how the mysterious dark matter is distributed, and cosmologists say they have created this detailed map of dark matter to understand the expansion of the universe. The new map uses light from the cosmic background radiation (CMB) as a background light to show all the matter between us and the Big Bang.
Publication of the latest map of the distribution of dark matter in the universe
In this article we’re going to read about the publication of the latest map of the distribution of dark matter in the universe. The cosmic world is full of mysteries that scientists have been trying to discover for centuries. Dark matter is one such puzzling mystery, and understanding it can help us learn more about the evolution and structure of the universe.
Now, using the Atacama Cosmological Telescope (ACT), researchers have created a detailed map of invisible dark matter. This groundbreaking new image depicts mysterious dark matter distributed across a quarter of the entire sky.
The creation of this map confirms Albert Einstein’s theory about how massive cosmic structures and light curves grow over the 14 billion-year span of the universe.
Blake Sherwin, professor of cosmology at the University of Cambridge and head of the ACT group, said in a statement: “We have mapped the invisible dark matter in the sky to the greatest distances, and we clearly see the characteristics of this invisible universe, which is hundreds of millions of light-years across and looks exactly like this.” which our theories predict.
More than 160 researchers reviewed ACT data under the auspices of the US National Science Foundation. However, capturing the properties of dark matter, which makes up 85 percent of the universe, has been difficult.
Because dark matter does not interact with light or other types of electromagnetic radiation, it is difficult to probe, and gravity is the only thing that can reveal information about dark matter.
Dark matter is a type of matter that has been hypothesized in astronomy and cosmology to explain phenomena that appear to be caused by the presence of a certain amount of mass that exceeds the mass observed in the universe.
Dark matter cannot be seen directly with a telescope. Dark matter is called “dark” because it apparently has no interaction with the electromagnetic field; This means that it does not emit electromagnetic radiation (such as light), does not reflect it, and does not absorb it; Therefore it is not visible. In other words, dark matter is a substance that does not react to light; Instead, the existence and properties of dark matter can be inferred indirectly through the effects of gravity on visible matter, radiation, and the large-scale structure of the universe.
According to data from the Planck mission team in 2013 and based on the Standard Model of Cosmology, the total mass energy in the known universe consists of 4.9% ordinary matter, 26.8% dark matter, and 68.3% dark energy. This means that dark matter constitutes 26.8% of the total matter in the universe, and dark energy and dark matter together constitute 95.1% of the total contents of the universe.
Astrophysicists proposed the dark matter hypothesis to explain the difference between the mass calculated for giant celestial bodies by either using their gravitational effects or using the luminous material inside them (stars, gas, dust).
This hypothesis was first proposed by Jan Evert in 1932 to explain the orbital velocities of stars in the Milky Way and by Fritz Zwicki in 1933 to explain evidence of “missing mass” in the orbital velocities of galaxies in galaxy clusters. After that, many other observations were made which indicated the existence of dark matter in the universe. Among these observations, we can mention the observation of the rotational speeds of galaxies by Vera Rubin in the 1960s-1970s, the gravitational convergence of background objects by galaxy clusters such as the Bullet cluster, and temperature anisotropy patterns in the cosmic background radiation.
Cosmologists agree that dark matter is composed mostly of some unknown subatomic particle. Searching for this particle using various means is one of the main efforts of elementary particle physics.
Although the existence of dark matter is generally accepted by the scientific community, alternative theories of gravity have also been proposed. For example, we can refer to modified Newtonian dynamics (MOND) or tensor-vector-fence gravity (TeVeS), which try to explain these unusual observations without the need to introduce additional mass. For this purpose, the researchers observed the distortion of light left over from the Big Bang, when the universe was only 380,000 years old. This type of scattered light travels freely throughout the universe and is known as cosmic background radiation (CMB).
In cosmology, cosmic background radiation is electromagnetic radiation that covers the entire universe. This radiation has the spectrum of a black body with a temperature of 2.726 Kelvin. Therefore, the maximum of this radiation is in the microwave range with a frequency of 160 GHz and a wavelength of 1.9 mm. Cosmologists consider cosmic background radiation to be the best evidence for the Big Bang theory.
The gravitational pull of large, heavy structures, including dark matter, bends cosmic background radiation on its 14-billion-year journey toward us, much like a magnifying glass bends light as it passes through its lens, the researchers’ statement explained.
Read More: Astronomers have identified the most distant galaxy
In addition, this research adds to the ongoing debate about the “crisis in cosmology”, which focuses on the discrepancy in the measurement of the age of the universe and the need to know how much it is expanding. This crisis stems from different measurements of the cosmic background light rather than the CMB. These deviations show that the dark matter in the standard model of cosmology is not considered enough and this model is incorrect.
“This map remarkably provides measurements that show that both the bulge of the universe and its growth rate after 14 billion years of evolution are exactly what you expect from the model,” says Mathew Madhavacheril, an assistant professor in the Department of Physics and Astronomy at the University of Pennsylvania. You would expect standard cosmology based on Einstein’s theory of gravity.
This research will be presented at a scientific conference that is being held from April 10 to 14 at Kyoto University.
Maybe the Earth is not doomed by the death of the sun
Will the sun one day destroy the earth? This may or may not happen. Astronomers have spotted a rocky planet the size of Earth orbiting a white dwarf, hinting at a future in which our planet outlives its star.
In 6 billion years, the sun will grow and become a red giant star. At this point, Mercury and perhaps Venus will be swallowed up, and for a long time, we thought that planet Earth would also be incinerated. But maybe the blue planet is not doomed, even though it may become an uninhabitable world in the next 6 billion years.
According to the New York Times, scientists have discovered a rocky planet orbiting a star that has passed its red giant phase. The planet now orbits a white dwarf, a smaller stellar body left over after a star burns out.
Importantly, the planet appears to have once been in the same position as the Earth now orbits our Sun. Before being swallowed up by its dying star, the rocky planet was pushed into a distant orbit, twice the distance between Earth and the Sun. In this way, the discovered world is considered the first rocky planet that has been seen rotating around a white dwarf.
A rocky Earth-like planet has survived the destruction of its star
“We don’t know if Earth can survive,” said astrophysicist Kaming Zhang of the University of California, San Diego, who led the study published in the journal Nature Astronomy. “If it survives, it will become such a system.”
The rocky planet is about 4,000 light-years away and in 2020, the South Korean Radio Astronomy Observatory discovered it using a process called gravitational microconvergence. The Korean team observed the star of the rocky planet while passing in front of a distant star, and that star magnified the amount of light reaching the telescope by a thousand times. This effect, known as convergence or gravitational lensing, makes it possible to identify very distant and faint objects.
That particular event was a one-off event, and the chances of further detailed observations are limited until powerful new telescopes can get a better look at the rocky planet in the future. But Dr. Zhang and his team were able to do more last year at the Keck Observatory in Hawaii and found out that the planet’s star is actually a white dwarf.
The researchers calculated that at least two objects are orbiting the white dwarf. One of them was a brown dwarf; That is, the failed star that had never ignited by nuclear fusion and was located at a great distance from the central star. But the other object is a planet with a mass of about 1.9 times that of Earth, which orbits closer to the star’s period and is therefore likely to be a rocky world.
By modeling the evolution of the star system, Zhang’s team calculated that the planet may have once been in a habitable orbit like Earth. The star was probably the same size as ours. “We expect the star to have been roughly the same mass as the Sun,” Dr. Zhang said.
Gravitational convergence shows the white dwarf shown by the vertical white lines. The researchers captured images of the star years before the event (a), shortly after the background star peaked in 2020 (b), and after it disappeared in 2023 (c).
But as the star ran out of fuel, it lost some of its mass, causing the rocky planet’s orbit to lengthen. The rocky planet escaped from the expanding red giant phase of the star and survived to the white dwarf stage.
A handful of gas planets have been found orbiting white dwarfs, but they were either in more distant orbits or had migrated inward and closer after the red giant phase. “If Dr. Zhang’s diagnosis is correct, this would be the first rocky planet orbiting such a star,” said Susan Mulally, an astronomer at the Space Telescope Science Institute in Maryland. “It’s definitely the smallest and clearest rocky planet we’ve ever found around a white dwarf.”
A handful of gas planets have been discovered orbiting white dwarfs
Stephen Kane, an astronomer at the University of California Riverside, noted that he was excited when he first read the paper. He has previously investigated whether planets can survive when their stars pass through the red giant phase, so he is intrigued by the new discovery. However, the presence of the brown dwarf complicates everything. If the brown dwarf was once closer to the star but moved outward, it could change the dynamics of the entire system, he explained. That means, maybe there are other planets that have been thrown out and the planets that are currently observed are among the survivors.
NASA is scheduled to launch the Nancy Grace Roman Space Telescope before 2027 and is expected to find more planets through gravitational microconvergence. Perhaps some of them are orbiting white dwarfs.
Alien life may be hiding under the Martian ice cover
A new study suggests that the conditions necessary for photosynthesis on Mars may exist beneath the dusty ice cover in the Red Planet’s mid-latitudes.
Photosynthesis is a process by which living organisms such as plants, algae, and cyanobacteria can produce chemical energy. This process requires water and light to progress and produces much of the oxygen in the Earth’s atmosphere. According to the new findings, Martian ice layers of sufficient thickness can filter out intense solar radiation while still allowing sunlight to penetrate beneath them for photosynthesis, creating so-called “radiatively habitable” zones.
Since the process of photosynthesis is suitable for light, the new results should be considered in sufficient light conditions. While the findings don’t prove that life exists on Mars, or even existed in the distant past, they can give scientists ideas to search for. Aditya Kholler, a postdoctoral researcher and research supervisor at NASA’s Jet Propulsion Laboratory, says the Martian dusty ice in the mid-latitudes is exposed to sunlight and could be an accessible environment to search for life on Mars today.
Images of the Red Planet from NASA’s Mars Exploration Orbiter (MRO).
Earth vs. Mars
Both Earth and Mars are located in a range known as the Sun’s life belt; A region around a star where the temperature is favorable for the flow of surface liquid water. Although 71% of Earth’s surface is covered by liquid water oceans, Mars has a mostly dry landscape.
Discoveries of Mars rovers such as Curiosity and Perseverance have shown that conditions on Mars are different. Surface features such as dry lake beds and river forks discovered by these robots indicate the presence of surface liquid water billions of years ago. Additionally, Mars missions such as the Mars Reconnaissance Orbiter (MRO) have often discovered water ice in unexpected areas.
According to scientists, Mars lost its liquid water billions of years ago; Just as the planet’s magnetic field weakened (Earth’s magnetism is still very strong) and much of its atmosphere was lost. Thus, there were few barriers to surface water evaporation. The absence of a thick atmosphere also means that today’s Mars is under the bombardment of harmful ultraviolet radiation from the sun, which is fatal for living organisms and can destroy the complex molecules needed for life.
NASA’s Discovery Orbiter image of craters in the Cyrene region of Mars.
Unlike Earth, Mars does not have an ozone protective shield; As a result, the level of surface ultraviolet radiation is 30% higher than that of the earth; Therefore, photosynthesis on Mars probably occurs in places that are inside the dusty ice; Because the dusty ice cover can block harmful UV rays on the surface of Mars, and liquid water is highly unstable due to the planet’s dry atmosphere.
Using computer simulations, the researchers found that Martian dusty ice may melt from the inside and that the overlying ice cover prevents shallow subsurface liquid water from evaporating in the dry Martian air. According to Kholer:
Thus, two key elements for photosynthesis could be present in mid-latitude Martian dust ices. Photosynthesis requires sufficient amounts of sunlight as well as liquid water. Two previous independent simulations of dense Martian snow show that if small amounts of dust (less than one percent) are present in the snow, subsurface melting could occur in the mid-latitudes of present-day Mars.
“With the discovery of dusty ice that was exposed a few years ago within snow masses in Martian glaciers, there is a mechanism for subsurface melting that could underlie the formation of shallow subsurface liquid water,” Kholer added. According to Kholer, the dusty ice on the ice cap can block UV radiation from the surface of Mars and also allow sunlight to penetrate below the surface for photosynthesis.
An image from NASA’s Discovery Orbiter of a puddle in the Dao Wallis region of Mars.
The depth required for the formation of radiative habitable zones depends on the amount of dust in the ice. Very dusty ice can block a lot of sunlight, the researchers’ simulations show. However, ice with 0.01 to 0.1 percent dust allows for the formation of a radiative zone between 5 and 38 cm deep. Less contaminated ice allows for a deeper and wider radiation zone at a depth between 2.2 and 3.1 meters.
According to researchers, the polar regions that have the most ice on Mars are too cold for habitable radiation zones; Because they do not have the subsurface melting mechanism. Such a mechanism probably occurs in the middle latitudes of the Red Planet.
Scientists have taken scientific support for their theory from evidence on planet Earth. Kholer says:
I was surprised to learn that similar areas for life exist within dusty and sedimentary polar ice. These areas are called cryoconite cavities and are formed when dust and sediment on the ice melts into it because it is darker than the ice.
Evidence from Earth: Cryoconite-formed cavities on the Matanuska Glacier, Alaska, 2012
Every summer, due to heating by sunlight, liquid water gathers around the dark dust inside the ice. This happens because the ice is semi-transparent, allowing sunlight to penetrate below its surface. According to Khüler, the researchers discovered that the tiny organisms that live in these shallow subsurface habitats on Earth usually go dormant in the winter, when there isn’t enough light to form liquid water in the dusty ice.
Of course, none of the above findings mean that photosynthetic life exists on Mars or probably ever existed; But it could inspire further research into the possibility of radiation habitats on the Red Planet. Kholer adds:
I am working with a group of scientists on improved simulations of where and when the ice melts on present-day Mars. Additionally, we are recreating these dusty ice scenarios in the lab to investigate them in more detail.
The results of the research were published on October 17 in the journal Communications Earth & Environment.
Why is it still difficult to land on the moon?
This year, the private company Spacel and the Indian Space Organization both met tragic ends when they tried to land their spacecraft on the surface of the moon. Despite the astonishing leaps made in recent decades in computing, artificial intelligence and other technologies, it seems that landing on the moon should be easier now; But recent setbacks show that we still have a long way to go with safe and trouble-free landings on the surface of Earth’s only moon.
50 years after sending the first man to the surface of the moon, the question arises as to why safely landing a spacecraft on Earth’s nearest cosmic neighbor is still a difficult task for space agencies and private space companies. Stay with Zoomit to check the answer to this question.
Why is the lunar landing associated with 15 minutes of fear?
Despite the complexities of any space mission, sending an object from Earth into orbit around the moon today is easy. Christopher Riley, the director of the documentary film In the Shadow of the Moon produced in 2007 and the author of the book Where We Stood (2019), both of which are about the history of the Apollo 11 mission, explained the reasons for the difficulty of landing on the moon in an interview with Digital Trends. is According to him: “Today, the paths between the Earth and the Moon are well known, and it is easy to predict them and fly inside them.”
Chandrayaan 2 mission launch
However, the real challenge is getting the spacecraft out of orbit and landing it on the lunar surface; Because there is a delay in the communication between the Earth and the Moon, and the people in the control room who are present on the Earth cannot manually control the spacecraft in order to land it safely on the Moon. As a result, the spacecraft must descend automatically, and to do so, it will fire its descent engines to slow its speed from thousands of kilometers per hour to about one meter per second, in order to make a safe landing on the lunar surface.
For this reason, the director of the Indian Space Research Organization (ISRO), who was trying to land the Vikram lander last month, described the final descent of the spacecraft as “frightening 15 minutes”; Because as soon as the spacecraft enters the landing stage, the control of its status is out of the hands of the mission control members. They can only watch the spacecraft land and hope that everything goes according to plan, that hundreds of commands are executed correctly, and that the automatic landing systems gently bring the spacecraft closer to the surface of the moon.
The Great Unknown: The Landing Surface
One of the biggest challenges in the final descent phase is identifying the type of landing site. Despite the availability of instruments such as the Lunar Reconnaissance Orbiter (LRO) that can capture amazing views of the lunar surface, it is still difficult to know what kind of surface the spacecraft will encounter when it lands on the moon.
Left: Breshit crash site. Right: The ratio of the before and after images highlights the occurrence of minor changes in surface brightness.
Leonard David, author of Moon Fever: The New Space Race (2019) and veteran space reporter, says:
The Lunar Reconnaissance Orbiter is a very valuable asset that has performed really well over the years; But when you get a few meters above the surface of the moon, complications appear that cannot be seen even with the very powerful LRO camera.
Even today, despite the imaging data available, “some landing sites still have unknown remains,” Riley says. He notes that the Apollo 11 mission included an advantage that today’s unmanned landers lack, which is the presence of an astronaut’s observer’s eyes that can closely observe the surface of the spacecraft’s landing site. As you probably know, in the mission that led to the landing of the first man on the surface of the moon, the Eagle computer was guiding the spacecraft to a place full of boulders; But to avoid hitting the rocky surface of the moon, Armstrong took control of the spacecraft himself and landed it on a flat surface.
The uneven surface of the landing site had caused many problems in previous lunar missions such as Apollo 15. In this mission, the astronauts were told that as soon as the spacecraft touched the surface of the moon, they should turn off the engines to prevent dust from being sucked in and the risk of a return explosion. But the Apollo 15 spacecraft landed in a crater, and because of this, one of its legs came into contact with the surface earlier than the others. When the crew shut down the engines, the spacecraft, moving at a speed of 1.2 meters per second, experienced a hard landing. The lander landed at an oblique angle, and although it eventually landed safely, it nearly overturned, causing a fatal disaster.
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The difficult landing of Apollo 15 introduced another complicating factor in lunar landings: lunar dust. The Earth’s moon is covered with dust that is thrown into the air by any movement and sticks to everything it comes in contact with. As the spacecraft approaches the surface of the moon, huge plumes of dust are kicked up that limit the field of view and endanger the spacecraft’s electronics and other systems. We still do not have a solution to deal with the dust problem.
An achievement that has been achieved before
Another reason why the moon landing remains a challenge is that gaining public support for lunar projects seems difficult. Referring to Neil Armstrong and Buzz Aldrin, the two astronauts who walked on the moon during the Apollo 11 mission, David says, “We convinced ourselves that we had sent Neil and Buzz [to the surface of the moon]; “As a result, when it comes to lunar missions, people may say we’ve been there before and we’ve had this success.”
But in reality, our understanding of the moon is still very little, especially in relation to long-term missions. Now, with a 50-year gap between the Apollo missions and NASA’s upcoming Artemis project, the knowledge gained has been lost as engineers and specialists retire. David says:
We need to recover our ability to travel into deep space. We haven’t gone beyond near-Earth orbit since Apollo 17 and since 1972. NASA is no longer the same organization that put men on the moon, and there is a whole new generation of mission operators.
The importance of redundancy
As the first private spacecraft entered into orbit around the moon, the Space project was of considerable importance; But its failure to land smoothly on the surface of the moon made the achievement of landing on the surface of the moon still remain in the hands of governments. However, we can expect more private companies, such as Jeff Bezos ‘ Blue Origin, which is developing its lunar lander, to target the moon in the future. According to Elon Musk, even the giant SpaceX Starship spacecraft, which is being built with the ultimate goal of sending a human mission to Mars , can also land on the moon.
According to David, private companies’ participation in lunar landings has advantages such as increased innovation. However, companies are under pressure to save money, and this can lead to a lack of redundancy and support systems that are essential in the event of errors and malfunctions. Lunar rovers typically include two or even three layers of support systems. David is concerned that private companies will be encouraged to eliminate these redundancies in order to cut costs and save money.
Crew Dragon SpaceX passenger capsule
“We saw Elon Musk’s Dragon capsule catch fire after a failed test on the stand,” says David, referring to the explosion of the SpaceX spacecraft in April, which had no crew on board. “This accident was kind of a wake-up call about how unpredictable the performance of spacecraft can be.” David compared the Crew Dragon incident to the Apollo 1 disaster, which killed three NASA astronauts during a test launch in 1967.
Another problem related to the lack of redundancy systems is the lack of information needed when an error occurs. As for the recent landings, it seems that the SpaceX crash was caused by human error; however, it is not clear what caused the failure of Chandrayaan 2 in the calm landing, and it is possible that without the necessary systems to record and send information to the lander, we will never find out the main reason for the failure of this mission. Without the required data, it becomes much more difficult to prevent problems from reoccurring in the future.
The future of lunar landings
Currently, many projects are underway to facilitate future moon landings. Ultimately, we need to be able to build the necessary infrastructure for a long-term stay on the moon.
Conceptual design of Moonrise technology on the moon. On the left side is the Alina lunar module, and on the right side, the lunar rover equipped with Moonrise technology melts the lunar soil with the help of a laser.
If we can make long-term stays on the moon possible, or even build a permanent base there, landing spacecraft on the lunar surface will be much easier. By constructing the landing sites, a flat, safe, and free surface of unknown debris can be created for the landing of surface occupants. For example, researchers are currently conducting research at NASA’s Kennedy Space Center to investigate the feasibility of using microwaves to melt the lunar soil (regolith) and turn it into a hard foundation so that it can be used as a landing and launch site. The European Space Agency is also investigating how to use 3D printing to create landing sites and other infrastructure on the moon.
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Other ideas include the use of lidar remote sensing systems, which are similar to radar systems; But instead of radio waves, it uses lasers to land the spacecraft. Lidar technology provides more accurate readings and uses a network of GPS satellites to help guide the spacecraft during landing.
The problem of public support
As important as technology is, public interest and support are essential to the success of the lunar landing program. “Apollo had enormous resources that are perhaps only comparable today to China’s space program,” says Riley. “Remember that Apollo carried the best computer imaginable, the human brain.” It goes without saying that there is an element of luck involved in every landing.
US Vice President Mike Pence speaking at the 50th anniversary of the Apollo 11 mission
Finally, there is the question of what kind of failure is acceptable for people. David says:
I think we have to be serious about the fact that we’re probably going to lose people. There is a serious possibility that the manned lunar lander will crash and kill the astronauts inside. The American people continued to support NASA despite the failures and bad luck of the Apollo program, But at that time there was a lot of pressure to compete with the Soviet Union. Without the bipolar atmosphere of the Cold War and the space race, would people still support missions with human lives in between?
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