Asteroid Ryugu, 200 million miles away, holds building blocks of life

Sci­en­tists have for the first time found the build­ing blocks for life on an aster­oid in space.
On the space rock Ryugu, which is more than 200 mil­lion miles from Earth, Japan­ese researchers have dis­cov­ered more than 20 amino acids.

Study­ing sam­ples retrieved from the near-Earth aster­oid by the Japan Aero­space Explo­ration Agen­cy’s (JAXA) Hayabusa2 space­craft, which land­ed on Ryugu in 2018, sci­en­tists made the first-of-its-kind detec­tion. In 2019, the space­craft col­lect­ed 0.2 ounce (5.4 grams) from the aster­oid’s sur­face and sub­sur­face, stowed it in an air­tight con­tain­er and launched it back to Earth on a fine-tuned trajectory.

Composition ingredients of an asteroid

An aster­oid is com­posed of min­er­als. And min­er­als are made from ele­ments. Amino acids, which are the build­ing blocks of life, are also chem­i­cal com­pounds con­tain­ing car­bon, oxy­gen and hydro­gen atoms. Sci­en­tists have detect­ed them on many dif­fer­ent aster­oids and comets since their exis­tence was first pre­dict­ed in the 1960s.

Comets have watery ice and gas­es such as car­bon monox­ide (CO), car­bon diox­ide (CO2) and methane (CH4).  Aster­oids have met­als like iron and nick­el, sil­i­cates such as olivine and phos­phates. But sci­en­tists have not found any life on any of them so far, except Earth-like microbes liv­ing below Earth­’s surface.

Asteroid Ryugu: Why is it specific?

Rather than being one large boul­der, many small rocks are the com­po­nents of Ryugu, and the aster­oid got its unusu­al spin­ning top shape from rapid rota­tion, sci­en­tists believe. As a car­bona­ceous, or C‑type, aster­oid, Ryugu con­tains a large amount of car­bon-rich organ­ic mat­ter, much of which like­ly orig­i­nat­ed from the same neb­u­la that gave birth to the sun and the plan­ets of the solar sys­tem rough­ly 4.6 bil­lion years ago. Pre­vi­ous sam­ple analy­sis has also sug­gest­ed that the aster­oid har­bors water.

Accord­ing to Hisayoshi Yuri­mo­to, a geo­science pro­fes­sor at Hokkai­do Uni­ver­si­ty and leader of the Hayabusa2 mis­sion’s ini­tial chem­i­cal analy­sis team, said while out­lin­ing the ini­tial find­ings at the Lunar and Plan­e­tary Sci­ence Con­fer­ence in March, the Ryugu mate­r­i­al is the most prim­i­tive mate­r­i­al in the solar sys­tem sci­en­tists have ever studied.

Molecules on Ryugu are different

Unlike the organ­ic mol­e­cules found on Earth, inter­ac­tions with Earth­’s envi­ron­ment have not changed the pitch-black aster­oid sam­ples, giv­ing them a chem­i­cal com­po­si­tion much clos­er to that of the ear­ly solar sys­tem. The sci­en­tists found the sam­ples only reflect 2% to 3% of the light that hits them,

“We detect­ed var­i­ous pre­bi­ot­ic organ­ic com­pounds in the sam­ples, includ­ing pro­teino­genic amino acids, poly­cyclic aro­mat­ic hydro­car­bons sim­i­lar to ter­res­tri­al petro­le­um, and var­i­ous nitro­gen com­pounds,” Hiroshi Narao­ka, a plan­e­tary sci­en­tist at Kyushu Uni­ver­si­ty and the leader of the team which looked for organ­ic mat­ter in the sam­ples, explained at the con­fer­ence. Narao­ka added, “These pre­bi­ot­ic organ­ic mol­e­cules can spread through­out the solar sys­tem, poten­tial­ly as inter­plan­e­tary dust from the Ruygu sur­face by impact or oth­er causes.”

Ini­tial­ly, sam­ple analy­sis detect­ed 10 amino acid types, but now the num­ber has bal­looned to more than 20, accord­ing to Japan’s edu­ca­tion min­istry. Amino acids are the fun­da­men­tal build­ing blocks of all pro­teins and are indis­pens­able pre­req­ui­sites for the exis­tence of life on our plan­et. A 2019 study in the jour­nal Geochim­i­ca et Cos­mochim­i­ca Acta found organ­ic mol­e­cules from space in a group of 3.3‑billion-year-old rocks dis­cov­ered in South Africa, rais­ing the pos­si­bil­i­ty that some — if not all — of these life-build­ing mol­e­cules first came to Earth on comets and aster­oids. The Ryugu find­ings make the evi­dence that aster­oids car­ry these mol­e­cules even stronger.

Relat­ed Readings:

Amino acids arrived on Earth from space?

Speak­ing Kyo­do News, Ken­sei Kobayashi, a pro­fes­sor emer­i­tus of astro­bi­ol­o­gy at Yoko­hama Nation­al Uni­ver­si­ty, said, “Prov­ing amino acids exist in the sub­sur­face of aster­oids increas­es the like­li­hood that the com­pounds arrived on Earth from space”. He fur­ther added “This means that amino acids could like­ly be found on oth­er plan­ets and nat­ur­al satel­lites — a clue that life could have been born in more places in the uni­verse than pre­vi­ous­ly thought”.

The researchers say they are con­tin­u­ing to ana­lyze Ryugu sam­ples, and more data on the aster­oid’s for­ma­tion and its com­po­si­tion will become avail­able soon.

Not Ryugu is the only space rock under inves­ti­ga­tion, instead, NASA’s OSIRIS-REx space­craft col­lect­ed a rock sam­ple from anoth­er dia­mond-shaped aster­oid, named Ben­nu, in 2021. The sam­ple returns to Earth in 2023. Then, signs of organ­ic mat­ter con­tained with­in it could pro­vide sci­en­tists with impor­tant clues into the evo­lu­tion of the solar sys­tem and its mate­ri­als, along­side how life emerged from them.

Thus, steroid Ryugu is an exam­ple of life in space. More and more evi­dences are of the same opin­ion. In future, sci­en­tists will find many oth­er bod­ies, includ­ing comets and plan­ets with water in their liq­uid state and/or min­er­als. We should not for­get that we do not know every­thing in the uni­verse. How­ev­er, if we find any life, then it will be a major con­tri­bu­tion to science.

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