April 13, 2024

Meteorites: Why study them? What can they teach us about finding life beyond Earth?

Universe today explored the importance of studying impact craters, planetary surfaces, exoplanets, astrobiology, solar physics, comets, planetary atmospheres, planetary geophysics and cosmochemistry, and how this myriad of intrinsically linked scientific disciplines can help us better understand our place in the cosmos and in search of life beyond Earth. Here, we will discuss the incredible research field of meteorites and how they help researchers better understand the history of our solar system and cosmos, including the benefits and challenges, the discovery of life beyond Earth, and potential routes for future students. who wish to continue. studying meteorites. So why is it so important to study meteorites?

Alex Ruzicka, professor in the Department of Geology at Portland State University, says Universe today, “They provide our best information about how the solar system formed and evolved. This includes the formation of planets. We also obtain information about astrophysics (stellar processes) through studies of pre-solar grains.”

There is often confusion regarding the differences between an asteroid, a meteor, and a meteorite, so it is important to explain their respective differences to help better understand why scientists study meteorites and how they study them. An asteroid is an orbiting physical planetary body that is composed primarily of rock but can sometimes be composed of additional water ice, with most asteroids orbiting in the Main Asteroid Belt between Mars and Jupiter and the remainder orbiting as Trojan Asteroids in the orbit of Jupiter or in the Kuiper Belt with Pluto. A meteor is the visual phenomenon that an asteroid produces as it burns up in a planet’s atmosphere, often seen as varying colors of the minerals within the asteroid when heated. The pieces of the asteroid that survive the incoming fire and hit the ground are called meteorites, which scientists study to try to learn about the larger asteroid body it came from and where that asteroid could have come from as well. But what are some of the benefits and challenges of studying meteorites?

Dr. Ruzicka tells Universe today, “Benefits: scientific knowledge, information on potential resources (e.g. metals, water) for human use, information on how to connect meteorites and asteroids, which can provide information on space collision risks for Earth. Challenges: compared to Earth’s rocks, we do not have field evidence of their source bodies and parent bodies (how they relate to other rocks), we have to take into account the element of time which is longer for space rocks than for Earth’s rocks, and sometimes we are dealing with formation environments that are completely unlikely to those we have on Earth. So, the challenges are big and many.”

According to NASA, more than 50,000 meteorites have been recovered around the world, from the deserts of Africa to the snowy plains of Antarctica. In terms of their origins, it is estimated that 99.8 percent of these meteorites came from asteroids, with 0.1 percent coming from the Moon and 0.1 percent coming from Mars. The reason we find meteorites from the Moon and Mars is due to pieces of these planetary bodies being catapulted off their surfaces (or subsurfaces) after suffering large impacts of their own, and these pieces then travel through the Solar System for thousands, if not millions, of years before they were caught by Earth’s gravity and the rest is history. So, with meteorites originating from various locations in the Solar System, what can meteorites teach us about finding life beyond Earth?

Morgan Nunn Martinez, who was a doctoral student at UC San Diego, and Dr. Alex Meshik were seen photographing and measuring a meteorite specimen in Antarctica’s Miller Range during the 2013 Antarctic Meteorite Survey (ANSMET) program field season -2014. (Credit: NASA/JSC/ANSMET)

“That the ingredients to create life formed in space and were delivered to Earth,” says Dr. Ruzicka Universe today. “We know that organic molecules formed in gas clouds were incorporated into our solar system and processed in asteroidal and cometary bodies at higher temperatures in the presence of water. These were then delivered to Earth, which would not have been very hospitable in the early days due to the sterilizing impacts. We also know that there must have been a lot of planetary rock exchange early on, when impact rates were high. Life itself may have been transplanted from Mars to Earth.”

It turns out that one of the most fascinating meteorites ever recovered came from Mars, which was identified as ALH84001, as it was found in Allan Hills, Antarctica, on December 27, 1984, during the 1984-85 field season, where researchers of all from all over the world gather in Antarctica to search for meteorites using snowmobiles. Despite being collected in 1984, it wasn’t until 1996 that a team of scientists discovered what initially appeared to be evidence of microscopic fossils of bacteria inside the 1.93-kilogram (4.25-pound) meteorite.

ALH84001, which is one of the most famous meteorites ever recovered, helped catapult the field of astrobiology to new heights when scientists discovered what initially appeared to be microscopic fossils of bacteria within this meteorite, although these discoveries remain inconclusive to this day. (Credit: NASA)

This immediately made headlines around the world, resulting in numerous unscientific claims that these microfossils were clear evidence of life on Mars. However, both the initial study researchers and the scientific community were quick to point out the unlikelihood of these features resulting from life based on other observations made about ALH84001. For example, although ALH84001 is estimated to be 4.5 billion years old, which is when Mars is assumed to have had liquid water on its surface, radiometric dating techniques have revealed that ALH84001 was catapulted from Mars approximately 17 million years ago and landed on Earth approximately 13,000 years ago. years ago.

Microscopic image of ALH84001, which initially made headlines for potentially possessing microscopic fossils of bacteria, although these discoveries remain inconclusive to this day. (Credit: NASA)

To date, there has been no clear evidence that ALH84001 contains traces of life. Despite this, ALH84001 helped launch the field of astrobiology to new heights, with current scientists claiming that this meteorite was the reason they pursued their careers in finding life beyond Earth. But what were the most interesting aspects about meteorites that Dr. Ruzicka studied throughout his career?

Dr. Ruzicka tells Universe today, “A lot of things are interesting, what is most exciting? That’s hard to say. I find satisfaction in picking up clues left by rocks to discover or narrow down the processes that formed them. I am involved in a meteoritic version of CSI, we can call it MSI (for meteoritic scene investigation).

Like many scientific fields, this “meteoritic version of CSI” requires individuals from a multitude of backgrounds and disciplines, including geology, physics, geochemistry, cosmochemistry, mineralogy, and artificial intelligence, just to name a few, with the aforementioned radiometric dating often used. estimate the age of meteorites by measuring the radioactive isotopes in the sample. It is through this constant collaboration and innovation that scientists continue to unlock the secrets of meteorites with the aim of understanding their origins and compositions, as well as how our Solar System and life on Earth (and possibly elsewhere) came to be. So what advice can Dr. Ruzicka offer prospective students who want to study meteorites?

Dr. Ruzicka tells Universe today, “Work hard and chase your dreams. Find a rigorous study program because it will be helpful.”

Although meteorites are space rocks that fall to Earth after traveling through the skies for millions, and possibly billions, of years, these incredible geological specimens are slowly helping scientists unravel the origins of the Solar System and beyond, and even even how life may have arisen on our little blue world and possibly elsewhere. With a multitude of tools and instruments at their disposal, scientists around the world will continue to study meteorites in hopes of answering the universe’s most difficult questions.

Dr. Ruzicka concludes by telling Universe today, “Space rocks are the best types of rocks to study. Much colder than most rocks on Earth because they are, in some ways, more intriguing.”

How will meteorites help us better understand our place in the cosmos in the years and decades to come? Only time will tell, and that’s why we do science!

As always, keep doing science and looking up!

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