For the first time, science will explore a metallic world up close. This is the goal of the Psyche mission, which NASA will launch on Friday at 4:19 p.m. (Spanish peninsula time) from the Kennedy Space Center in Florida (USA), using a SpaceX Falcon Heavy rocket to propel the probe becomes the earth. This begins a long journey of almost six years through the solar system until it reaches a strange asteroid very rich in metal; and that makes it one of the closest bodies that can help us understand how the Earth came to be.
When the new NASA probe reaches the asteroid 16 Psyche in August 2029, it will begin orbiting it at different altitudes with the aim of determining both its composition and its formation process, which are as unknown as its specific shape and that appearance of its surface. Then Psyche’s cameras and instruments will begin to unveil the asteroid’s mysteries.
With the data we have so far, it can be assumed that the asteroid is the heart of a failed planet that never formed at all. No one has ever been able to directly observe the metallic core of a planet, and the ability to do so was what drove this space mission, but it is not the only possibility, and we could find something completely different.
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The first hypothesis is that 16 Psyche is the remnant of a planetesimal (the progenitor of a planet), which was larger and already differentiated: it had an inner iron core that was separated from its rocky mantle, but was then subjected to violent impacts that destroyed it abandoned core exposed. But there could also be another explanation for its metal-rich surface: the material could have escaped from the core through volcanic iron eruptions through a relatively thin mantle of about 25 kilometers; and this ferrovolcanism would also explain the asteroid’s low density. The third and most alternative hypothesis describes 16 Psyche as a collection of metallic material that accumulated near the Sun. However, if this were the case, it would remain to be explained how this astronomical object was able to reach its current location at a distance three times greater than that from the Earth to the Sun.
This low-cost mission – by NASA standards, as its budget is just under $1 billion – will carry a probe the size of a pickup truck nearly 4 billion kilometers to the main asteroid belt (between Mars and Jupiter), where it orbits 16 Psyche. The spacecraft’s scientific instruments will make it possible to map and study the properties of this 226-kilometer-diameter asteroid. For example, by observing the shape of its craters, we can learn about the impact processes, the nature of the material or its age, and this data also tells us whether it was formed under conditions similar to those in the Earth’s core.
The Earth’s core is not a place full of dinosaurs where a bizarre adventure can take place, as Jules Verne imagined in his Journey to the Center of the Earth. Nor is it hollow, as Edmund Halley erroneously deduced from the value of the relative density of the Moon given by Isaac Newton. The Earth’s core is simply made of metal; and that alone makes it fascinating.
representation of the layers of the earth; the coat in green, the outer core in cream and the inner core in burgundy with the new deeper ball in the middle. The lines represent the path of the earthquakes.Drew Whitehouse
Although we can only drill about 12 kilometers with current technology and the core is 3,000 kilometers deep, this does not prevent us from drawing conclusions about its composition. Just like we don’t have to cut a girl’s leg open to know if she broke her tibia. The physics of the process are the same whether you want to deduce what’s inside a leg or in the earth. However, in the latter case, measurements of the waves carried by earthquakes at different points on the planet are used, rather than analyzing the transmission of X-ray waves as in an X-ray.
We also know that the Earth’s core is very hot due to the slow decay of radioactive elements left over from the planet’s formation, and that it is also subject to pressures several million times greater than that of the atmosphere. But knowing all this without being able to see it or reach it does not put an end to scientific curiosity, especially when there is the slightest opportunity to observe something even remotely resembling it. And this is where objects like 16 Psyche appear.
This asteroid, which economists have set a price for, is not cheap. They estimate it is worth 70,000 times the entire current global economy. It is a metal world composed primarily of iron and nickel and may be similar to the Earth’s core. And therein lies its scientific interest, since these types of metallic asteroids are the parts from which planets are made. To understand how this process occurs, let’s try to collect all the information to which we have access in one way or another. And to do this, the Psyche probe will orbit the asteroid and study its composition, topography and also the possible presence of a paleomagnetic field that has been fossilized in the asteroid since its formation.
The Archeology of Space Rocks
An asteroid is a rock that orbits the Sun like planets in space, but is neither large enough to be classified as a planet nor small enough to be considered a meteoroid. And despite what it may seem, asteroids, as rocks, are an extremely diverse group. To distinguish and classify the more than 100,000 known asteroids, we look at the sunlight reflected from them. Depending on the chemical composition of their surface, which allows the reflected light to be detected, they can be divided into different types, which are assigned a letter.
For example, C stands for carbonaceous substances that are dark: for this reason, only a few of this type are known in the most distant parts of the solar system. S stands for silicates, which are shiny and therefore highly visible; If we ever have one on a collision course with Earth, it had better be this type. And then there are the M made of metal; like 16 Psyche, a fairly large M-class asteroid.
Psyche was one of the first asteroids to be discovered, as evidenced by the number 16 in its name. The Italian astronomer who discovered it in 1852 decided to name it in honor of the Greek personification of the soul, which takes the form of a woman with butterfly wings. With the mission that bears this name launched today, we will learn new details about the history of the solar system. The findings of this new space expedition will take us into the past and perhaps into the interior of our planet.
Cosmic emptiness It is a section in which our knowledge of the universe is presented qualitatively and quantitatively. The aim is to explain the importance of understanding the cosmos not only from a scientific perspective, but also from a philosophical, social and economic perspective. The name “cosmic vacuum” refers to the fact that the universe is mostly empty and there is less than one atom per cubic meter, although paradoxically in our environment there are trillions of atoms per meter cubic, which invites us to wonder about our existence and to reflect on the presence of life in the universe. The section is composed Pablo G. Pérez GonzálezResearchers at the Astrobiology Center, and Eva VillaverDirector of the Space and Society Office of the Spanish Space Agency and Research Professor at the Institute of Astrophysics of the Canary Islands.
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