PDF Basket
The asteroids, comets and meteors that orbit our sun are chunks of ice, metal and rock left over from the formation of the solar system. These objects – which can range from a few to several hundred kilometres in diameter – represent a fossil record of our cosmic past.
“We wanted to better understand the nature of these small bodies in our solar system,” explains SOLARYS project coordinator, Pierre Beck, from the Université Grenoble Alpes in France. “A key challenge though is that these objects are often extremely dark and can be challenging to analyse.”
Scientists therefore cannot always be sure what these objects are made of, or of the exact origin of the extraterrestrial material that falls on Earth every day in the form of meteorites and dust.
Advanced techniques
To address these challenges, the SOLARYS project, supported by the European Research Council, pioneered the use of an advanced infrared spectroscopy technique. Analysing how a piece of meteorite absorbs or reflects infrared light yields clues about the minerals present in the sample, and the meteorite’s history, without damaging the material. The analysis can help reveal the age of an asteroid, and where it was likely formed.
From this, Beck and his team were able to characterise the make-up of meteorite samples and extraterrestrial dust particles at an extremely small scale.
“The instrument we used has a spatial resolution 10 times finer than the previous generation of instruments,” says Beck. “This gave us a much sharper look at how our samples absorb infrared light, and what they are made of.”
This approach allowed for the identification of mineral components, and organic ones, such as hydrocarbons. In their samples, the team discovered tiny spheres – measured in nanometres – of organic compounds made at the dawn of the solar system.
“We also found that the darkness of these objects is likely the result of the presence of very fine opaque grains made of sulfides or iron,” adds Beck.
“Some samples also contained very unusual material on their surface, in the form of ammonium salts. Such salts are unstable at the surface of the Earth but can occur on these very cold and atmosphere-free bodies. These salts are important for understanding the origin of nitrogen on Earth, a key element for life as we know it.”
Understanding the role of asteroids and meteors
Beck and his team believe that the findings gleaned from the new analytical techniques could shed new light not only on the make-up of these samples, but also on the extraterrestrial source of Earth-bound meteorites and dust.
Next steps include analysing existing observations of asteroids, meteors and comets, and looking for molecular signatures corresponding to those found in the samples. If the search for parent bodies is successful, this could remove the need for expensive exploratory space missions to gather such samples.
This is a big challenge though – in our solar system alone, there are currently around 1.3 million known asteroids, and more than 3 800 known comets.
Ultimately, the hope is that the new analytical techniques pioneered through the SOLARYS project will contribute to a better understanding of the origin and evolution of our solar system.
“The techniques we developed have worked beyond my expectations,” remarks Beck. “I am currently working on detecting organics in Martian samples – the infrared spectroscopy technique could be very relevant here. I am also investigating the potential of using this technique to look at soil samples.”
This could lead to breakthroughs in understanding the formation processes of meteors and asteroids, and their possible role in the development of terrestrial planets like ours.