For scientists who, like us, try to understand what the cosmos was like in the early stages of its life, there could be nothing more exciting than capturing the light from a galaxy as old as the universe or capturing the first image of a supermassive black hole. . However, no matter how many photos we take of these objects, we will always arrive home with nothing tangible to give away: not a piece of a black hole, not a piece of a primeval galaxy, not even a fridge magnet … nothing.
Although it is exciting that the development of technology is bringing us closer, more and more, to observing the first steps of our universe, it is even more fascinating to visit other worlds and be able to bring an extraterrestrial souvenir and in this the Japanese, always so detailed, have an advantage over us to the rest of the world. Bypassing the Moon and missions like Apollo, the material from the farthest outer space that we have brought to Earth has been imported by the Japanese. The first mission of the Peregrine falcon, Hayabusa, visited a small asteroid, an elongated potato-shaped object about 300 meters in size. And more recently Hayabusa 2 visited another somewhat larger asteroid, a kilometer in diameter, to collect samples of material and bring them home for Christmas.
Why is it so interesting to visit these little wandering stars and why bring samples to Earth? Regarding the first question, asteroids are considered as the rubble of the great work that should have been to build the Solar System, so the materials that we find there will inform us of the materials existing at that time, about 4,500 million ago. of years.
Today it is thought that our solar system was formed from a cloud of gas and small specks of dust one tenth of a millimeter, not so different from the size of the dust we have at home. The dust specks formed larger agglomerations, first as a result of electromagnetic forces, then by gravitational action when they reach sizes of hundreds of meters. The process gave rise to the so-called planetesimals, which coalesced to form moons-sized protoplanets like ours, and these coalesced to form rocky planets like Mercury, Venus, Earth, and Mars. The giant planets they may have a nucleus similar to a rocky planet, but most of their mass is gas accumulated by gravity.
Debris of planetary formation
When the planets of a system reach enough mass, and that happens relatively quickly, in a few hundred thousand years, the interactions between them can cause much of the material that is still free orbit around the star, to be expelled from the vicinity of the star or confined to relatively stable orbits, preventing them from falling further and fattening any planet. The small rocky objects expelled or confined that, therefore, we can consider remains or debris of the planetary formation, are called asteroids. Their study can provide very interesting information about those first moments of the Solar System.
It is true that since their formation so much time has passed that many asteroids have had time to collide with other asteroids and shatter (back to their origins!), Others have finally fallen to some planet forming meteoroids and meteorites. There are different types of asteroids according to their origin and history, which is noticeable in their composition, for example. Asteroids that survive intact have suffered the action of solar radiation for billions of years, but their interior has been protected, so digging into an asteroid and studying the material in its internal area gives us the most reliable information about what the Solar System was like in its infancy. Bringing to Earth that material that we call pristine, locked in the asteroid’s time capsule, is the objective of missions such as Hayabusa 2, heir to the Hayabusa 1.
Hayabusa 1 visited the asteroid 25143 Itokawa, discovered in 1998 and that every 18 months goes around the Sun, sometimes approaching the Earth at a distance equal to about 5 times the distance to the Moon. The Japanese, not without difficulties due to the asteroid’s low gravity, managed to land a probe that tore dust particles from its surface and returned them to Earth in 2010. Since then, detailed studies of imported material have been carried out with increasingly powerful instrumentation. , something that is only possible because we have the samples on our planet. The study of the material collected by Hayabusa 1 determined that he had been exposed to solar radiation for about 8 million years, so it was concluded that this asteroid came from a larger one, which had broken relatively recently compared to the 4.5 billion years that the Solar System has. This year a team of researchers detected organic material on a speck of dust from the Itokawa.
With this shocking news, expectations of what the Hayabusa 2 they are soaring. He Peregrine Falcon 2 visited 162173 Ryugu, a so-called C-type asteroid, the most abundant, composed mainly of clays formed by silicates and carbonates and a lot of water (at least a fifth of its mass). The mission took samples of the asteroid until November last year, at which time it launched its ion thrusters as if it were a Darth Vader TIE fighter, and now travels with them to Earth, where it will arrive on December 6, 2020. This second mission, learning from the first, carried more sophisticated systems, including a trigger that intended, and succeeded, to penetrate with a bullet inside the asteroid to tear off pristine material, which was collected. Hayabusa 2 bring between 10 and 100 milligrams of material to study, we will not know until it arrives in a capsule A special one of just under 1 meter in size that will fall to the Earth enduring temperatures of thousands of degrees Celsius and slowing from speeds around 12 km / s to land as gently as possible on the ground at an Australian military base.
Scientists will be able to analyze the samples to study the origins of the Solar System, the possible origin of life beyond our planet, or how Earth’s oceans were formed. All through small particles, some as small as a red blood cell, that the Japanese bring with them from their space travels, they just need to have written “Memory of Ryugu”.
Pablo G. Pérez González He is a researcher at the Astrobiology Center, dependent on the Higher Council for Scientific Research and the National Institute for Aerospace Technology (CAB / CSIC-INTA).
Patricia Sánchez Blázquez She is a tenured professor at the Complutense University of Madrid (UCM).
Cosmic Void It is a section in which our knowledge about the universe is presented in a qualitative and quantitative way. It is intended to explain the importance of understanding the cosmos not only from a scientific point of view but also from a philosophical, social and economic point of view. The name “cosmic vacuum” refers to the fact that the universe is and is, for the most part, empty, with less than 1 atom per cubic meter, despite the fact that in our environment, paradoxically, there are quintillion atoms per meter cubic, which invites us to reflect on our existence and the presence of life in the universe.