September 11, 2019
Published by Kalpit Veerwal
According to new research, all comets might come from the same place. Astronomer Christian Eistrup from Leiden University used chemical models on fourteen widely known comets only to find a clear pattern.
Comets move through the solar system and they are made of dust, ice, and small rocks. Their nuclei can span as wide as several kilometers. Some of them have strange orbits around the Sun and have also hit Earth in the past. Eistrup said that the composition of comets is very well known and are usually considered as icy balls. So he wanted to find out if they actually belong to one group or are divided by several subsets.
Eistrup’s research team also included Ewine van Dishoeck, Kavli Prize winner who created models for predicting the chemical composition of protoplanetary discs, which are flat discs made of dust and gas encompassing younger stars. These discs help in knowing about the formation of stars and planets. These were now applied to comets. Ewine along with Eistrup used statistics to understand if there was a particular place in the solar system where the models meet the comets’ data. It turned out that all the fourteen comets showed the same result. Each comet could be described by only one model indicating that their common origin. The work can be found here.
The origin is near to our Sun at a time when a protoplanetary disc encircled it while the formation of the planets took place. The model suggests a zone that is farther from the Sun’s nucleus and where the temperature varies in the range of 21 to 28 Kelvin, a very low temperature where CO (carbon monoxide) turns into ice. There are several reactions that are taking place in the ice phase in the time frame of a hundred thousand to million years. This explains different comets with different types of compositions.
The orbits of the comets vary since some of the comets might have been disturbed by planets like Jupiter, which explains the varied nature of the orbits.
Eistrup wants to test the hypothesis on many more comets as the current sample size is pretty small, only fourteen. He hopes that astronomers studying the solar system and its origins can use his results which can provide them with new insights, hence he is interested to discuss this model with other comet researchers.
We still do not how life started on our planet. However, the chemistry of the comets could be responsible for some of life’s building blocks. Life could start with the right comet hitting the right planet accompanied by a suitable environment. Understanding comets could lead to understanding the origin of life on our planet.
June 28, 2019 (updated June 28, 2019)
Published by Kalpit Veerwal
Both carbon monoxide and cyanide are highly poisonous to human beings. However, a group of researchers from Boise State University and NASA have discovered compounds in meteorites containing iron, cyanide and carbon monoxide, which may have been helpful in the beginning of life on Earth. The compounds which are found in meteorites are quite similar to the active site of hydrogenases, the enzymes which provide energy to bacteria by decomposition of hydrogen gas. The results present the conclusion that these compounds were also there on early stages of Earth before the initiation of life. In this time period, several meteorites crashed onto Earth and there was a greater percentage of hydrogen in the atmosphere.
Dr. Karen Smith, a senior researcher at the Boise State University explained that most people think of cyanide as a compound which instantly kills a person if consumed but on the other hand, it was an important compound for the formation of life on Earth. Cyanide consists of a carbon atom bound to nitrogen and it is an important participant in the non-biological synthesis of compounds such as amino acids and nucleobases. These are the building blocks of proteins, nucleic acids that are used by all life forms. The study is published in Nature Communications.
Smith along with Mike Callahan, a co-author of the paper created analytical methods for extracting and calculating the traces of cyanide present in the meteorites. They saw that the cyanide belonged to a group of carbon-rich meteorites known as CM chondrites. In other types of meteorites, no cyanide was found. Jason Dworkin of Goddard Space Flight Centre of NASA said that according to the data collected by OSIRIS-REx spacecraft of Bennu asteroid, the cyanides are from CM chondrites. A sample of this asteroid will be delivered to Earth in 2023 by the spacecraft. Researchers will then search for the compounds for drawing a relation of Bennu with the known meteorites and also understand how compounds such as cyanide got delivered to Earth.
Although cyanide was found before in meteorites, scientists were surprised to find a bonding of cyanide and carbon monoxide with iron for the formation of stable compounds in meteorites. Two different kinds of iron cyano-carbonyl complexes were found in the meteorites with the help of liquid chromatography-mass spectrometry.
Hydrogenases are present in almost all types of modern bacteria. They are huge proteins but the active site is a very small metal organic compound present in the protein. The similarities between the active site of hydrogenases and cyanide compounds could be a possible explanation of the origin of life from non-biological chemical processes.