Rock of Ages … how asteroid dust can reveal the secrets of life on earth


myselfAfter a few days, the capsule containing soil samples from a distant asteroid will be released from the robotic spacecraft and fall into Earth’s upper atmosphere. Hopefully, the containers will parachute safely into the Woomera Test Series in South Australia on December 6, completing a mission that involves traveling three billion miles through our solar system.

The information sent could help solve some of the major astronomical mysteries, scientists say, including how water first appeared on our planet.

“Asteroids are the building blocks of our solar system 4.6 billion years ago, which makes them very important to science,” said Martin Lee, professor of planetary science at the University of Glasgow. “If you want to know where the planet comes from, you have to study the asteroids.”

The Japanese probe Hayabusa 2 was launched six years ago and sent to the asteroid Ryugu, which orbits the sun every 16 months at a distance of between 90 million and 131 million miles. For 18 months they interrogated this ancient 1,100-meter-wide rock near the surface to collect a few spoons of soil. Then sin released its ion blades and began returning to earth for a year.

Hayabusa 2 before launch in 2014. Photo: Newscom / Alamy

Lee and his colleagues will be one of the first groups of scientists to study Ryugu’s soil samples once they are sent, even though the team doesn’t have much work to do. “We expect to obtain only a few grains of material, each a few millimeters in diameter,” said geologist Luke Daly, a team member from the University of Glasgow. “However, we won’t really know how much we’ll get before the Hayabusa capsules hit the bridge – soft, we hope.”

Analyzing the composition of the asteroid’s surface from multiple points on the ground seems ambitious. The Glasgow team remains confident. They plan to use a device called an atomic probe that will allow researchers to identify individual atoms in a sample. Given the large number of atoms that make up even the smallest sample size, it is important to count and analyze the atoms of tens of millions of individuals.

“Basically, we’re going to take a piece of dirt and scrape the outer surface with a laser,” Lee said. ‘In other words, we’re going to blow up the atoms one by one. And then each of these atoms will be measured to determine the identity of the element and its specific isotope.

‘We will also be able to reconstruct exactly where the atoms are in the sample in order to obtain a three-dimensional image of the atomic structure of our sample.’

The engineers of the Japanese space agency Jaxa are still not sure how much material Hayabusa 2 managed to collect. its target, the asteroid Itokawa.

Hayabusa 2 will have to return for more, even though the monsters must first survive on Earth. It will begin when the probe releases the Earth capsule from Ryugu. If you enter the atmosphere at a speed of 27,000 km / h, it will descend to Earth until it places the parachute six kilometers above Australia and glides to the ground.

The sample will then be distributed to scientists around the world. “In addition to telling us what the first solar system was, they will also tell us what happens to rocks when they are bombarded billions of years by the solar wind – and this is very important. of water in the solar system and, above all, on earth, ”added Lee.

The solar wind is a stream of protons and other subatomic particles emitted by the sun. The Earth’s atmosphere protects us, but in outer space the particles occupy the surfaces that have such protection without mercy. “This bombardment could lead to the creation of water on the asteroid,” Daly added. “Protons are actually hydrogen ions and can react with oxygen in rocks to create water molecules.”

Scientists are divided on the fundamental question of how water first appeared on our planet. Did it come with all the rest of the material that made up our planet 4.6 billion years ago, or was it brought here much later by an icy comet that crashed into our planet?

Recent spacecraft – such as the Rosetta mission which visited Comet 67P / Churyumov – Gerasimenko between 2014 and 2016 – have found water in these bodies. However, it is not like water on earth. These extraterrestrial samples contain higher levels of deuterium, an isotope of hydrogen, than those found in Earth’s water, and this has led many scientists to conclude that our stock here should be from the beginning.

“However, it is possible that this ancient comet was not the only source of water from other parts of the solar system and the reservoir was recently created by solar winds that hit the rocks of an asteroid,” Lee said.

The water created there may have lower levels of deuterium and this would explain how our oceans contain water with different isotopic signatures. And, of course, this could give us the answer to studying the atoms of the asteroid Ryugu, which has been plagued by solar winds for billions of years. “

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