Today, more than 1,000 satellites are orbiting in low Earth orbit. Not only is the limited outer space becoming more and more crowded, the satellite radio signals are becoming more and more “crowded”, and some satellite signals may overlap and interfere with each other.
In order to avoid this problem, satellite signals must be transmitted in a narrow frequency band. To achieve the most accurate calibration, it is inseparable from the world’s most advanced anechoic chamber built by the Danish University of Science and Technology, also known as the radio wave darkroom.
The anechoic chamber is surrounded by a steel Faraday cage that blocks any external electromagnetic interference, such as Wi-Fi wireless network signals, cell phone signals, and so on. The interior walls are filled with foam cones. This is a silencing material that absorbs any sound and signal interference in the room and prevents satellite radio waves from randomly reflecting and changing, thus ensuring that the instrument only receives and measures signals directly from the satellite.
Only in this way can scientists calibrate thousands of satellite signals, sometimes even re-planning. Otherwise, once the satellite signal interferes, it is equivalent to failure, and the loss of satellite early retirement is huge.
If someone asks you how the earth today is forming the four oceans of the seven continents, you will probably answer without thinking: plate movement. Indeed, for billions of years, plate tectonics have been shaping the earth’s surface, and the plates continue to move slowly, giving the earth a mountain bee, a canyon, and volcanoes and earthquakes. Recently, scientists have discovered that in the future, plate tectonic movement will stop.
The researchers established a mantle movement model that studied the changes in the mantle over the past 3 billion years and found that the mantle is continuously cooling, and the plate tectonics is the mechanism by which the earth releases internal heat. In other words, the plate structure requires heat to be pushed, and the researchers calculate After the introduction, after 1.45 billion years, the mantle will be cooled to no flow, and the plate tectonic movement will stop.
This means that volcanoes and earthquakes will not happen again, and you may be excited about it, but by then, the mountains are likely to disappear. For example, because the plates are no longer squeezed each other, the Himalayas are no longer lifted, and the rest are only wind and other erosions, and the Himalayas are likely to become hills and even plains. Without the mountain peaks, the warm and humid air currents cannot rise and form precipitation. The global drought is aggravated, and the earth may enter the era of “great desert”.
The African savannah is a dangerous place, especially for petite animals such as foxes. The fox is a small squat animal with a slender torso and limbs. They are usually 25 to 35 centimeters in length. The survival of petite foxes in the prairie can only rely on the power of the group. They need a sentinel companion, but the post is not simple.
In the fox community, becoming a sentinel trusted by a peer requires one of two conditions: experience and blood. The researchers used 544 tests of recordings of foxes of different ages and status. If other foxes trust the whistle, they would quickly hide. Otherwise, they would look up and look around to see if there were any hunters. The test results show that gender, age, and status are not the criteria for investigating posts. Experienced foxes are trusted by everyone. The blood-related foxes will be more convinced of their blood relatives, whether or not they have experience.
It seems that to become a qualified sentinel, the fox needs to practice more and become an experienced sentinel.
On June 18, 1815, a famous battle in history – the Battle of Waterloo started in Waterloo, Belgium, on the one hand, the seventh anti-French alliance, and the other on the French army led by Napoleon. In this battle, Napoleon was defeated, the First Empire of France was destroyed, and then Napoleon was exiled to St. Helena on the Atlantic.
Recently, some scientists have discovered that an important part of Napoleon’s defeat of Waterloo is likely to be the eruption of the Tambora volcano on Sumbawa Island, Indonesia. Just two months before the war started, the largest volcanic eruption in human history occurred in the Tambora volcano, killing at least 71,000 people.
At the same time, volcanic eruptions release large amounts of volcanic ash In the process, many small volcanic ash enters the ionosphere, which promotes the formation of more rain clouds and causes a lot of rainfall. It was the volcanic eruption that led to the heavy rain in the history books. The heavy rain made the land on the marching road muddy. Historians believed that the muddy land seriously delayed the marching speed of the Napoleonic army. It was Napoleon slippery. One of the reasons for the failure of the Battle of Thiel. Although there was no heavy rain, the Napoleonic army was likely to fail, but in the course of his failure, the volcanic eruption slammed him and accelerated the process.
Can you imagine what life is like to be isolated? Recently, researchers have approached a truly isolated tribe for the first time. They called this tribe “the most lonely tribe in the world.” However, it is not a scientific researcher who visited the tribe, but a drone.
Like the Bermuda Triangle, the Amazon Rainforest is one of the most mysterious regions on the planet, hiding many unknown secrets. This lonely tribe is hidden in the Amazonian jungle of Brazil. The tribal name or the ethnicity of the tribal ethnic group is unknown because they have never been in contact with the outside world. Researchers manipulate drones and fly into this mysterious tribe to observe their lives. The drone photographed the residents of the tribe holding bows and arrows, hunting, logging, wearing the simplest clothes, and living the original life.
With the development of the rainforest, the life of the tribe will be threatened. Researchers hope that the outside world will not disturb their lives, keep the land and keep them isolated, until one day, the tribe residents may take the initiative to contact the outside world. .
In the famous sayings of ancient and modern China and foreign countries, they have always been persuading people to work diligently. They have never seen any laziness. However, a new study shows that in the animal world, there seems to be a new rule of survival: lazy survival.
Researchers have studied many mollusc species since 5 million years, in which gastropods such as sea snails and bivalves such as oysters are almost never extinct. They compared 299 extinct species with endangered species such as gastropods and bivalves, and found that species that are not extinct have a commonality—too lazy and low metabolic rate. Those extinct species have a generally higher metabolic rate, while non-extinct species tend to have less energy requirements for survival.
However, they also found that there is no necessary connection between the metabolic rate and extinction of a wide range of species. Therefore, the distribution range is also the key to species extinction. If a species has a small distribution range and a high metabolic rate, the probability of extinction of this species is relatively large.
The study is aimed at mollusks, and researchers have yet to prove whether this connection exists in other species, such as humans.