Although asteroids may pose a threat to life on Earth, they are also a valuable resource for making fuel or water and to help explore deep space, and being far from geological processes and erosion factors, they provide us with insight into the evolution of the solar system, but to learn more, scientists must know their composition. Internal.
Reasons for internal study
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4 spacecraft were able to land on asteroids before, the last of which was in October 2020, but what is inside these asteroids has not been studied, although studying the internal structure of these cosmic rocks is very important to answer important questions about the emergence of our planet, for example .
Dr Fabio Ferrari, who studies asteroid dynamics at the University of Bern, Switzerland, said: “Asteroids are the only celestial bodies in our solar system that have not changed almost since the beginning of the formation of the solar system. Planets, everything in our solar system, and what might happen in the future. “
There are also more practical reasons for scientists to know what is inside the asteroid, such as searching for materials that can help human exploration of other celestial bodies, as well as to defend against rocks floating in the Earth’s field from the risk of colliding with them.
NASA’s upcoming mission, the Double Asteroid Redirection Test (DART), is a mission to test whether a spacecraft collision with an asteroid could push it away from a collision course with Earth, which is expected to be launched later this year.
The mission is expected to collide with the asteroid Dimorphos, which has a diameter of 160 meters, in 2022, with the aim of changing its course, and the experiment will show for the first time whether humans can change the path of an asteroid that may be considered a potential danger.
But scientists have only speculation about what will happen as a result of this collision, because they know very little about the moon asteroid Dimorphus and the parent asteroid that Didymus orbits.
Types of asteroids
There are many types of asteroids, some of which are solid blocks of hard rocks, and others are agglomerations of gravel, rocks and sand, which are the products of many orbital collisions, which hold together only by the force of gravity, and there are rare metallic asteroids that are heavy and dense.
“In order to divert the trajectory of hard and denser asteroids, we will need a larger spacecraft, and a higher collision speed,” said Dr. Hannah Csarni, a research fellow in planetary sciences at the University of Bristol in the United Kingdom.
“As for asteroids that are just clumping of material and are called a pile of rubble, they can explode into thousands of pieces. These pieces can become dangerous in and of themselves.”
Dr Sesrni is researching the surface characteristics of asteroids, which could reveal their internal structures as part of a project called EROS, which is an EU-funded project to develop a fast and cost-effective way to learn the internal structure of asteroids.
This information may also be useful to space mining companies, a recent industry that some companies are preparing to start in, and in which they will want to know as much as possible about an asteroid, before investing in an expensive exploration mission, in addition to knowing the potential risks.
“There are thousands of asteroids close to Earth, those whose paths could one day intersect with the path of the Earth,” she said, adding, “We have visited only a handful of them, and we do not know anything about the vast majority.”
Topography of asteroids
Dr Seserni tries to create detailed topographic models of the topography of two of the most well-studied asteroids, Itokawa, which was explored by the Japanese Hayabsa 1 mission in 2005, and Eros, which was explored in detail by the NEAR Shoemaker space probe in the late 1990s.
“The topography of the surface can tell us a lot,” says Dr. Sesrni. “If we have an asteroid” pile of rubble “, such as Itokawa, we do not expect to see steep slopes on its surface, while solid asteroids, such as Eros, tend to have clearer topographic features and deeper craters. Much more steeper. “
Sesrni took high-resolution models from spacecraft data and extracted semantics that could then be used with less accurate models from ground-based radar observations.
Asteroid scattering test
Dr. Ferrari is working with the team preparing for the “asteroid scattering test”, and as part of a project called GRAINS that aims to study the formation of asteroids by means of remote monitoring, where Dr. Ferrari developed a machine that enables the modeling of the internal composition of the planet Dimorphus (collision target) in addition to asteroids. Another “heap of rubble.”
Dr. Ferrari said, “We expect that Dimorphus is an asteroid” a pile of rubble “because we believe that it formed from material expelled by the asteroid Didymus, when it was rotating very quickly; this ejected material coalesced and formed the moon, but we do not have actual observations of what is inside.”
Dr. Ferrari has borrowed a technique to solve asteroid runes, called particle dynamics.
“This technology can be used on the ground to study problems such as supporting the foundations of installations with sand compaction piles or various industrial processes involving small particles. It is a digital machine that allows us to model the interaction between the different components of rocks and gravel within the asteroid,” adds Dr. Ferrari.
Researchers model different shapes and sizes, different rock and gravel compositions, and the interactions of gravity and friction between them. They can run thousands of these simulations and then compare them with surface data about known asteroids to understand the behavior and composition of “pile of rubble” asteroids.
Asteroid “pile of rubble”
“We can look at the external shape, study different properties on the surface, and compare them with our simulations. For example, some asteroids have a clear equatorial bulge,” said Dr. Ferrari, referring to the distortion around the equator that can appear as a result of the asteroid rotation.
Dr. Ferrari adds that for the first time, a machine can work with non-spherical objects, which greatly improves the accuracy of the data. “Spherical bodies behave completely differently from non-spherical objects,” he said.
The model indicates that in the case of Dimorphos, the collision of the “asteroid scattering test” would create a crater and throw a lot of material from the surface of the asteroid, but there are still many questions, especially the size of the crater.
“The crater may be as small as 10 meters, but it may also reach 100 meters, occupying half the size of the asteroid. We do not really know. Asteroids, a” stack of rubble “are difficult, because they are inconsistent, and may only absorb collisions,” said Dr.
Regardless of what happens in Daimorphus, the experiment will provide a valuable treasure trove of data to improve future simulations and models. We will be able to see whether the asteroid behaves as we expected and learn to predict more accurately the future missions life on Earth may depend on.