On Saturday evening (5.12.2020), a container
containing a sample of the asteroid that had been dropped by the Hayabusa 2
space probe landed in the Australian desert. The chemical
"fingerprint" of the water from the asteroid Ryugu could prove that
the water on Earth actually originated from asteroid impacts in the early
history of the Earth. Up to now, asteroids could only be examined after fragments
impacted onto the Earth and therefore contamination by the Earth's water could
not be ruled out. In the coming year, the material sample will be examined by
scientists all over the world, including a scientific team from Goethe
University.
FRANKFURT. When
it was formed, the young proto-Earth was hot and probably circled around the
sun in a very dry zone where water evaporated and was blown into space by the
solar wind. According to one theory, our blue planet came to its great oceans
through watery celestial bodies that hit the earth. As spectral analyses of
comet tails have shown, it was most likely not comets.
This is because in their ice, the ratio of
hydrogen with two protons in its nucleus, deuterium (D), to hydrogen with one
proton in its nucleus (H) is usually different from that on Earth. On the other
hand, the water trapped in certain meteorites - i.e. in fragments of asteroids
that have hit the Earth - is almost exactly the same as terrestrial water. Such
C-class asteroids are highly carbonaceous and come from the outer part of the
asteroid belt that orbits the sun between Mars and Jupiter. Ryugu is one of
them.
Prof. Frank Brenker, geoscientist at
Goethe University, will examine the Ryugu sample together with his colleague
Dr. Beverly Tkalcec. He explains: "There are very good scientific
arguments that the D/H ratio we find in meteorites is indeed similar to that of
asteroids in space. Nevertheless, we cannot rule out water vapour contamination
on Earth: after all, 90 percent of an asteroid evaporates when it passes
through the atmosphere, and even if it hits a dry desert, the meteorite can
absorb water until it is found, for example from early morning fog. With the
Ryugu sample we will finally get certainty on this issue".
To this end, from the middle of next year,
the Frankfurt researchers will examine and screen Ryugu samples for their
chemical composition at the particle accelerators ESRF in Grenoble and DESY in
Hamburg. Later in the year, Ryugu samples will be cut with the help of a
focused ion beam and will be examined with a transmission electron microscope
at Goethe University. Tkalcec and Brenker want to determine the exact
geological history of the asteroid. In order to be able to assess the measured
values for the water, but also the organic compounds that occur, it is
immensely important to understand all the processes that led to their formation
in the first place. The temperature achieved by the asteroid is just as
important here as the circumstances of the formation of water-containing
minerals, and the influence of impacts on the surface of the asteroid.
The building blocks for life on Earth may
also come from carbon-rich asteroids such as Ryugu, since sugars and components
of proteins (amino acids) and the hereditary molecule DNA (nucleobases), which could
have been formed from inorganic substances under suitable conditions, have
already been found in meteorites. For this reason as well, numerous scientific
teams from all over the world will be working on the analysis of the Ryugu
samples.
Images for download:
- Prof. Dr. Frank Brenker, Institute für Geosciences, Goethe University Frankfurt. Credit:
Jürgen Lecher for Goethe University. http://www.uni-frankfurt.de/95132289
- Prof. Dr. Frank Brenker, Institute für
Geosciences, Goethe University Frankfurt. Credit: personal photo. http://www.uni-frankfurt.de/95132407
- Dr. Beverley Tkalcec, Institute für Geosciences, Goethe University
Frankfurt. Credit: personal photo. http://www.uni-frankfurt.de/95132444
- Landing of space probe Hayabusa 2 on the asteroid Ryugu for the collection of samples. Illustration: Akihiro
Ikeshita für JAXA. https://www.hayabusa2.jaxa.jp/en/galleries/cg/pages/touchdown1.html
- The asteroid Ryugu from a distance of 20 kilometres, photographed
by the probe Hayabusa 2. Credit: JAXA, University of Tokyo, Kochi University,
Rikkyo University, Nagoya University, Chiba Institute of Technology, Meiji
University, University of Aizu and AIST.
https://www.hayabusa2.jaxa.jp/en/galleries/ryugu/pages/fig11_fmhome_front.html
- Hayabusa 2 passes by Earth: On
its return, the probe flew past Earth on its way to another mission and sent a
capsule containing the Ryugu sample to Earth. The capsule landed in the
Australian desert on Saturday, 5 December 2020. Illustration: Akihiro Ikeshita for JAXA.
https://www.hayabusa2.jaxa.jp/en/galleries/cg/pages/swingby.html
Further
information
Prof. Dr. Frank Brenker
Institute for Geosciences – Nanoscience
Phone: +49 151 68109472
f.brenker@em.uni-frankfurt
