Asteroid Ryugu is rich in organic molecules that can be building blocks of life

dark rocks in a white container
A sample of material collected from the asteroid Ryugu. (Image credit: JAXA)

The asteroid Ryugu is rich in organic molecules that could serve as the building blocks of life. The discovery was made when scientists took a first look at a sample collected by the Hayabusa2 spacecraft from the asteroid. 

The Ryugu sample contains several so-called "prebiotic organics" including several types of amino acids that are used by living things to build proteins essential for regulating chemical reactions and forming structures like hair and muscles. These molecules can also be created by various non-living processes, such as chemical reactions that can take place in asteroids.

The findings add more credibility to the theory that the basic ingredients needed to kickstart the development of life on Earth could have been delivered to the planet in its infancy from space.

Related: Asteroid Ryugu: The twirling space rock visited by Hayabusa2

"The presence of prebiotic molecules on the asteroid surface despite its harsh environment caused by solar heating and ultraviolet irradiation, as well as cosmic-ray irradiation under high-vacuum conditions, suggests that the uppermost surface grains of Ryugu have the potential to protect organic molecules," research lead author and Kyushu University researcher Hiroshi Naraoka, said in a statement (opens in new tab). "These molecules can be transported throughout the solar system, potentially dispersing as interplanetary dust particles after being ejected from the uppermost layer of the asteroid by impacts or other causes."

The term "organic molecules" describes a wide range of compounds containing the element carbon coupled with hydrogen, oxygen, nitrogen, sulfur and other atoms and are the building blocks of all forms of life here on Earth.

These compounds can be created by chemical reactions that don't involve living things, meaning that chemical processes within asteroids can create the ingredients for life. The search for these chemical processes that could have led to the emergence of life on Earth is known as "prebiotic chemistry." 

Also found in the Ryugu sample were organic prebiotic molecules that form in presence of liquid water, another vital ingredient for life, like aliphatic amines, carboxylic acids, polycyclic aromatic hydrocarbons, and nitrogen-containing heterocyclic compounds.

"So far, the amino acid results from Ryugu are mostly consistent with what has been seen in certain types of carbon-rich (carbonaceous) meteorites that have been exposed to the most water in space," research co-author and NASA Goddard Space Flight Center scientist, Jason Dworkin, said.

Solvent extractions of the Ryugu samples on a clean bench (ISO6, Class 100) inside a clean room (ISO5, Class 1000) performed by Hiroshi Naraoka at Kyushu University in Japan. (Image credit: JAXA)

Missing thus far from the Ryugu sample are sugars and components of DNA and RNA that have been discovered in other carbon-rich asteroids. The team suspects it is possible these compounds are present in Ryugu but they are below the limits of detection given the small sample mass examined for this research.

The Japan Aerospace Exploration Agency (JAXA) spacecraft Hayabusa2 collected samples from Ryugu, located around 215 million miles (347 million kilometers) from Earth, in February 2019. The samples were then returned to Earth in December 2020, and they were extracted in Japan in 2021.

A tiny amount, 30 milligrams or about 0.001 ounces, of that sample, was then analyzed at by the international soluble organic analysis team at NASA Goddard in the Fall of that year.

This new research represents the first organic analysis of the Ryugu sample that will be studied for many years to come. These future investigations will include comparing the Ryugu sample with samples from the asteroid Bennu collected in 2020.

"We will do a direct comparison of the samples from Ryugu and the sample from asteroid Bennu when NASA's OSIRIS-REx mission returns it to Earth in 2023," said Dworkin. "OSIRIS-REx is expected to return much more sample mass from Bennu and will provide another important opportunity to look for trace organic building blocks of life in a carbon-rich asteroid."

The team's research is published in the Feb. 24 edition of the journal Science. (opens in new tab)

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Robert Lea
Contributing Writer

Robert Lea is a science journalist in the U.K. whose articles have been published in Physics World, New Scientist, Astronomy Magazine, All About Space, Newsweek and ZME Science. He also writes about science communication for Elsevier and the European Journal of Physics. Rob holds a bachelor of science degree in physics and astronomy from the U.K.’s Open University. Follow him on Twitter @sciencef1rst.

  • Unclear Engineer
    This article says

    "Also found in the Ryugu sample were organic prebiotic molecules that form in presence of liquid water,".

    My Question: How could there ever be "liquid water" on a "rubble pile" type asteroid, so that these chemicals could have formed where they were found?

    Is there some theory that these rubble pile asteroids once were parts of a larger planetoid that had some sort of differentiated composition that allowed for water to exist, maybe below a surface covered with ice, like some of the giant planet's moons?
  • Ryan F. Mercer
    "Water molecules form in interstellar space by chemical reactions between hydrogen molecules and oxygen-bearing molecules such as carbon monoxide.

    The Solar System inherited its water from ice-coated interstellar grains in the dust cloud from which the Sun and planets formed 4.6 billion years ago.

    In the Solar System this water became locked in two principal forms.

    Far from the Sun, where temperatures are low, water formed icy objects such as comets, while closer to the Sun water reacted with rocky materials to form hydrated minerals.

    It's thought that the mostly likely way that planet Earth inherited its water was from asteroids and comets crashing into it." -- Where did Earth get its water from?
  • Unclear Engineer
    Ryan, I am understanding what you posted.

    What I am questioning is the article's statement that "liquid water" was needed to produce some of the chemicals found.

    "Liquid" water is not the same as "ice", nor "steam" not "hydrated minerals", and requires a subset of possible combinations of temperture and pressure to exist. I do not understand how any of that subset of required conditions for liquid water would ever exist on a "rubble pile" asteroid. Therfore, I don't understand how liquid water would ever be present on a rubble pile asteroid to form the chemicals found there.

    So, my question is basically: How did liquid water ever exist on a rubble pile asteroid, or, is the article using misleading language, or did these chemicals get produced in some other environment before they became part of the rubble in the asteroid?

    It is the third option that I find most integing, but I am suspecting that the article has just used improper language.
  • rod
    Ryugu has a variety of reports out on the asteroid with a variety of data to make interesting interpretations about the asteroid.

    First look at Ryugu asteroid sample reveals it is organic-rich,
    “Asteroid Ryugu has a rich complement of organic molecules, according to a NASA and international team's initial analysis of a sample from the asteroid's surface delivered to Earth by Japan's Hayabusa2 spacecraft. The discovery adds support to the idea that organic material from space contributed to the inventory of chemical components necessary for life…"The presence of prebiotic molecules on the asteroid surface despite its harsh environment caused by solar heating and ultraviolet irradiation, as well as cosmic-ray irradiation under high-vacuum conditions, suggests that the uppermost surface grains of Ryugu have the potential to protect organic molecules," said Hiroshi Naraoka of Kyushu University, Fukuoka, Japan."

    Ref - Soluble organic molecules in samples of the carbonaceous asteroid (162173) Ryugu,, 24-Feb-2023.

    My observation. Converting “prebiotic molecules” found on the asteroid’s surface into life on Earth – appears to be a difficult task for abiogenesis. There are numerous undefined steps needed for nature to accomplish starting with prebiotic molecules on an asteroid surface to abiogenesis creating life on Earth. This includes a variety of impacts and giant impacts too.

    Here are some other reports on this asteroid and how it is dated.

    How was the solar system formed? The Ryugu asteroid is helping us learn,
    ref - Early fluid activity on Ryugu inferred by isotopic analyses of carbonates and magnetite,, 12-Jan-2023.

    My observation. Ryugu has some parts dated now 1.8 Myr so reconciliation scenarios are used to show how the asteroid could be as old as the solar system, some 4.5 Gyr. Comments about the asteroid starting out only about 20 km in diameter and today about 1 km diameter illustrate this. “The researchers' analysis determined that Ryugu's carbonates formed several million years earlier than previously thought, and they indicate that Ryugu—or a progenitor asteroid from which it may have broken off—accreted as a relatively small object, probably less than 20 kilometers (12.5 miles) in diameter. This result is surprising, McKeegan said, because most models of asteroid accretion would predict assembly over longer periods, resulting in the formation of bodies at least 50 kilometers (more than 30 miles) in diameter that could better survive collisional evolution over the long history of the solar system.” A simple answer is that Ryugu has not orbited the Sun for billions of years and undergone much mass and size reduction.

    Ancient asteroid grains provide insight into the evolution of our solar system,
    The ref paper: A dehydrated space-weathered skin cloaking the hydrated interior of Ryugu,, 19-Dec-2022.

    My observation. I note these references to young exposure ages. "These independent results suggest that it may take >3 × 10^3 years to form a detectable smooth layer on phyllosilicates. The exposure age of the smooth layer-covered surface of Ryugu grain A0067 is estimated to be 3 × 10^4 years, calculated by its crater population assuming they formed by interplanetary meteoroid impacts..."

    My notes. "These crater statistics, based on images collected by Hayabusa2, even show that the age of the overall asteroid surface itself is likely no more than around 17 million years, much younger than the time when the main-belt parent asteroids of Ryugu are thought to have broken apart, which happened hundreds of millions to over a billion years ago.", see the attached copy from report, May 2020. Touching the asteroid Ryugu revealed secrets of its surface and changing orbit, This new report some parts of Ryugu exposure ages are less than 10^5 years, some 3 x 10^4 years or 30,000 years old. Very young ages reported on this asteroid considered to be a piece of a larger parent body that existed at least 4.5 billion years ago.

    Near-Earth asteroid Ryugu was born in the outer solar system 4 billion years ago,
  • rod
    FYI, just how many different ages do we have for Ryugu? IMO, this is a larger issue than ices, water, liquid water or how prebiotic molecules said to be on the asteroid, evolved into life on Earth. Just how many different age dates are found?
  • Unclear Engineer
    So, it seems that the term "liquid" is thought to be actual liquid water in the iterior of some larger body that was hit by another body, with the resulting rubble eventually coalscing into the rubble pile asteroid. I am guessing that the necessary pressure somehow came from an ice overburden that was resistent enough to gas leakage that pressure could build to the point that liquid water could be retained.

    Or, could these minerals have been formed in the instant of impacts? I am getting the impression from the grain sizes that isn't possible.
  • C5quaredequlsR47
    I'd like to see slides of these grains, and what you mean by that. but i am not totally certain how rubble piles have been formed. what we are talking about here are proto solar planets. rocks can only be formed on planetoids, even moons were once planetoids. the earth hit another planetoid very early and out came the moon, is this theory or fact?
    my point is that other remnants of earth might have ejected as asteroids, this also happened to other theoretical planets, which may have had water gravity and solar protection, enough to ferment amino acids.

    this still does a little something to answer my questions about dna. it brings us closer to the idea that DNA may be more universal than we popularly assume. Meaning it's out there, possibly millions of instances in EVERY galaxy.

    Is DNA a natural formation according to universal laws? This is the real question. These amino acids are probably not earthly, because the moon split before water, right?