Lagrange points - space "flypaper for flies"
“They are often called“ a place where gravity is absent. ” Huge outer space, millions of kilometers in length, where gravity does not work, areas exciting and not releasing any object there. Astronomers call them Lagrange points or, briefly, L4 and L5. ” Under the cut - a huge article about them, darling.
(Article by Stuart Clark, New Scientist ), quite large. Translation shortened)
Over the course of 4.5 billion years since the formation of the solar system, everything — from dust clouds to asteroids and hidden planets — could accumulate and accumulate in them. Some near-scientific publications even claim aliens hiding in L4 and L5 and watching the Earth from their plateau.
If for a moment you get distracted from green men, even the very presence at the points of the old cosmic fragments of rocks can make many scientists happy. “I think that in L4 and L5 one can really find a whole“ population ”of various objects,” says astrophysicist Richard Gott of Princeton University.
')
After a century of scientific speculation, we finally came to find out what is hiding in the points of Lagrange. This year, a little later, the two spacecrafts, which have so far been engaged in the study of the Sun, will reach the spaces L4 and L5.
Astronomers plan to use the instrumentation aboard NASA's STEREO A and B space probes to search for celestial bodies that are supposed to be hiding in areas of Lagrange points. Their findings could have a significant impact on our understanding of how the Solar System was formed, of the colossal interactions that formed the Moon and, perhaps, to warn us against future collisions.
Lagrange points were first discovered in 1772 by mathematician Jose Louis Lagrange. He calculated that the gravitational field of the Earth should neutralize the gravitational attraction of the Sun in five regions of space - in fact, the only regions where the object can indeed become weightless.
Of the five points L4 and L5 are the most intriguing. They are the only stable areas if the satellite gets into L1 or L2, after a few months it will “let go” and it will fly further, but any object caught in the “sight” of L4 or L5 will remain there for a very long time, if not forever. They are located at a distance of 150 million km from the Earth, on the plane of the earth's orbit, with L4 orbiting the Sun 60 degrees in front of the Earth, and L5 is at exactly that angle behind the planet.
Evidence of similar areas is observed around other planets. In 1906, Max Wolf discovered an asteroid located behind the main belt between Mars and Jupiter, and realized that he was in L4 of Jupiter. Wolf called him Achilles, and thus founded the tradition of naming such asteroids by the names of participants in the Trojan War. Understanding that Achilles could fall into such a trap raised a wave of searching for additional examples. About 1000 asteroids caught by the Jupiter Lagrange points are now known.
Searches for "Trojan" asteriods near other planets are not yet very successful. They could not be found near Saturn, they found exactly one near Neptune. And, of course, interested in the Earth.
The only problem is that L4 and L5 points are difficult to access from Earth. They are located close to the Sun, so that at night the L5 area is above the horizon and quickly descends, while L4 is eclipsed by the dawn rays.
This did not prevent Paul Weigert from the University of Eastern Ontario, Canada, from conducting a series of searches in the 1990s, using the French-Hawaiian telescope on Mauna Kea, Hawaii. This was a rather difficult task, since L4 and L5 occupy visible areas in the sky more than the moon in the full moon. Unfortunately, the Weigert team failed to discover any interesting things.
Closer to our time, an automatic search, such as a project to study asteroids near the Earth (Lincoln Near Earth Asteroid Research project) also began to pay attention to the areas of Lagrange, but so far there has not been able to detect anything. “This line of research has withered because everyone is sitting and waiting for someone else to make a discovery,” says Weigert.
STEREO spacecraft can change things — even though the probes were not specifically designed to search for asteroids. They were launched in 2006, one in front of the Earth, the other behind, so now they can explore the space between the Earth and the Sun, mainly studying solar storms that can destroy orbital satellites or equipment on Earth. L4 and L5 are very good “observation points” for solar activity “We even talked about stopping the probes when they reached these areas, because it takes several days for accurate recordings,” says Michael Keizer from the Space Center. flights to Goddard in Greenbelt, Maryland, is also a participant in the STEREO project.
In fact, the STEREO project team believes that stopping their probes in zones L4 and L5 requires too much fuel. Therefore, the probes will set up a very slow “span”, though not so slow as to fall into a gravity trap.
In connection with this, Richard Harrison from the laboratory of Rutford Appleton in Oxfordshire had the idea that the probes could be loaded with another task. He explored all the possibilities and realized that the tools intended for obtaining heliospheric images can be reconfigured to search for asteroids. Even in this case, it will be very difficult to find a Trojan asteroid, since it will be a point moving against a background of thousands of stars. Fortunately, a team of volunteers has already formed who will study the pictures in detail.
If an asteroid is found, it will be possible to determine its rotation and predict the location of other asteroids at Lagrange points by changing the sunlight reflected by its surface. And then, perhaps, there will be an answer to the question: why does the Earth have such a massive satellite? Now most scientists believe that the moon was formed from space debris, or rather, debris left after an object the size of Mars crashed into the Earth about 4 billion years ago. The problem is to explain where he could come from. Because, as computer models of the situation show, all objects of this size entering the solar system would have to destroy the Earth in a collision, instead of disintegrating into pieces and forming satellites. So such an object should have appeared “near” in order not to have enough time to accelerate before the collision. Another confirmation of the proximity of such a body is the discovery in the lunar matter of the same amount of oxygen isotopes, which is typical for the Earth. Mars, for example, is characterized by a different ratio. But it remains unclear how such a large celestial body could have formed close to the Earth and not collide with it. Unless formation took place at Lagrange points. And as soon as the object reached a certain size, the attraction of other planets, for example, Venus, tore it out of this area and forced it to crash into the Earth. “The same amount of oxygen isotopes with the Earth could be explained by the fact that its formation occurred close to the Earth,” says Gott. In addition, being in the same orbit, both planets could not differ too much in speed when a collision occurred. And, if at the Lagrange points near the Earth, it will be possible to detect the remains of the formation of such a planet and prove that the oxygen isotopes content they have in common with the earth, in fact, the theory will almost be proved.
If asteroids are found, they are unlikely to be more than a kilometer in diameter, says Weigert. With that, the average size of the asteroids of the main belt is 100 kilometers.
Finally, you can add a little yellowness to the expectations of discovery: some astronomers suggest that a whole planet may be hiding at Lagrange points. “No way,” says Paul Weigrt. - There is no necessary amount of substance for the formation of such a large body ",
But 4.5 billion years ago, the situation was different: the planets were formed from a mixture of dust and gas, and L4 and L5 were just the right “batteries” for large celestial bodies to appear there. Nothing is planetary in size, but Richard Gott thinks that asteroids of ominous sizes could still be hiding there “If we could find something large enough, it would be like a bomb”, because the gravitational influence of other planets, especially Venus, can pull ”such an asteroid just enough distance to take him out of the Lagrange point. And send it to Earth.
“If we see a large enough asteroid there, we’ll just blow it up and take the wreckage for ourselves,” says Gott.
(Article by Stuart Clark, New Scientist ), quite large. Translation shortened)
Over the course of 4.5 billion years since the formation of the solar system, everything — from dust clouds to asteroids and hidden planets — could accumulate and accumulate in them. Some near-scientific publications even claim aliens hiding in L4 and L5 and watching the Earth from their plateau.
If for a moment you get distracted from green men, even the very presence at the points of the old cosmic fragments of rocks can make many scientists happy. “I think that in L4 and L5 one can really find a whole“ population ”of various objects,” says astrophysicist Richard Gott of Princeton University.
')
After a century of scientific speculation, we finally came to find out what is hiding in the points of Lagrange. This year, a little later, the two spacecrafts, which have so far been engaged in the study of the Sun, will reach the spaces L4 and L5.
Astronomers plan to use the instrumentation aboard NASA's STEREO A and B space probes to search for celestial bodies that are supposed to be hiding in areas of Lagrange points. Their findings could have a significant impact on our understanding of how the Solar System was formed, of the colossal interactions that formed the Moon and, perhaps, to warn us against future collisions.
Lagrange points were first discovered in 1772 by mathematician Jose Louis Lagrange. He calculated that the gravitational field of the Earth should neutralize the gravitational attraction of the Sun in five regions of space - in fact, the only regions where the object can indeed become weightless.
Of the five points L4 and L5 are the most intriguing. They are the only stable areas if the satellite gets into L1 or L2, after a few months it will “let go” and it will fly further, but any object caught in the “sight” of L4 or L5 will remain there for a very long time, if not forever. They are located at a distance of 150 million km from the Earth, on the plane of the earth's orbit, with L4 orbiting the Sun 60 degrees in front of the Earth, and L5 is at exactly that angle behind the planet.
Evidence of similar areas is observed around other planets. In 1906, Max Wolf discovered an asteroid located behind the main belt between Mars and Jupiter, and realized that he was in L4 of Jupiter. Wolf called him Achilles, and thus founded the tradition of naming such asteroids by the names of participants in the Trojan War. Understanding that Achilles could fall into such a trap raised a wave of searching for additional examples. About 1000 asteroids caught by the Jupiter Lagrange points are now known.
Searches for "Trojan" asteriods near other planets are not yet very successful. They could not be found near Saturn, they found exactly one near Neptune. And, of course, interested in the Earth.
The only problem is that L4 and L5 points are difficult to access from Earth. They are located close to the Sun, so that at night the L5 area is above the horizon and quickly descends, while L4 is eclipsed by the dawn rays.
This did not prevent Paul Weigert from the University of Eastern Ontario, Canada, from conducting a series of searches in the 1990s, using the French-Hawaiian telescope on Mauna Kea, Hawaii. This was a rather difficult task, since L4 and L5 occupy visible areas in the sky more than the moon in the full moon. Unfortunately, the Weigert team failed to discover any interesting things.
Closer to our time, an automatic search, such as a project to study asteroids near the Earth (Lincoln Near Earth Asteroid Research project) also began to pay attention to the areas of Lagrange, but so far there has not been able to detect anything. “This line of research has withered because everyone is sitting and waiting for someone else to make a discovery,” says Weigert.
STEREO spacecraft can change things — even though the probes were not specifically designed to search for asteroids. They were launched in 2006, one in front of the Earth, the other behind, so now they can explore the space between the Earth and the Sun, mainly studying solar storms that can destroy orbital satellites or equipment on Earth. L4 and L5 are very good “observation points” for solar activity “We even talked about stopping the probes when they reached these areas, because it takes several days for accurate recordings,” says Michael Keizer from the Space Center. flights to Goddard in Greenbelt, Maryland, is also a participant in the STEREO project.
In fact, the STEREO project team believes that stopping their probes in zones L4 and L5 requires too much fuel. Therefore, the probes will set up a very slow “span”, though not so slow as to fall into a gravity trap.
In connection with this, Richard Harrison from the laboratory of Rutford Appleton in Oxfordshire had the idea that the probes could be loaded with another task. He explored all the possibilities and realized that the tools intended for obtaining heliospheric images can be reconfigured to search for asteroids. Even in this case, it will be very difficult to find a Trojan asteroid, since it will be a point moving against a background of thousands of stars. Fortunately, a team of volunteers has already formed who will study the pictures in detail.
If an asteroid is found, it will be possible to determine its rotation and predict the location of other asteroids at Lagrange points by changing the sunlight reflected by its surface. And then, perhaps, there will be an answer to the question: why does the Earth have such a massive satellite? Now most scientists believe that the moon was formed from space debris, or rather, debris left after an object the size of Mars crashed into the Earth about 4 billion years ago. The problem is to explain where he could come from. Because, as computer models of the situation show, all objects of this size entering the solar system would have to destroy the Earth in a collision, instead of disintegrating into pieces and forming satellites. So such an object should have appeared “near” in order not to have enough time to accelerate before the collision. Another confirmation of the proximity of such a body is the discovery in the lunar matter of the same amount of oxygen isotopes, which is typical for the Earth. Mars, for example, is characterized by a different ratio. But it remains unclear how such a large celestial body could have formed close to the Earth and not collide with it. Unless formation took place at Lagrange points. And as soon as the object reached a certain size, the attraction of other planets, for example, Venus, tore it out of this area and forced it to crash into the Earth. “The same amount of oxygen isotopes with the Earth could be explained by the fact that its formation occurred close to the Earth,” says Gott. In addition, being in the same orbit, both planets could not differ too much in speed when a collision occurred. And, if at the Lagrange points near the Earth, it will be possible to detect the remains of the formation of such a planet and prove that the oxygen isotopes content they have in common with the earth, in fact, the theory will almost be proved.
If asteroids are found, they are unlikely to be more than a kilometer in diameter, says Weigert. With that, the average size of the asteroids of the main belt is 100 kilometers.
Finally, you can add a little yellowness to the expectations of discovery: some astronomers suggest that a whole planet may be hiding at Lagrange points. “No way,” says Paul Weigrt. - There is no necessary amount of substance for the formation of such a large body ",
But 4.5 billion years ago, the situation was different: the planets were formed from a mixture of dust and gas, and L4 and L5 were just the right “batteries” for large celestial bodies to appear there. Nothing is planetary in size, but Richard Gott thinks that asteroids of ominous sizes could still be hiding there “If we could find something large enough, it would be like a bomb”, because the gravitational influence of other planets, especially Venus, can pull ”such an asteroid just enough distance to take him out of the Lagrange point. And send it to Earth.
“If we see a large enough asteroid there, we’ll just blow it up and take the wreckage for ourselves,” says Gott.
Source: https://habr.com/ru/post/52861/
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