Space Dust Is Filled with Amino acids, the Building Blocks for Life

Life's building blocks were found in a much smaller sample of the so-called "Murchison meteorite" than before, as this diagram shows. 

Credit: Michael Callahan

A study of teeny-tiny meteorite fragments revealed that two essential components of life on Earth as we know it, could have migrated to our planet on space dust.

Researchers at Goddard's Astrobiology Analytical Lab discovered DNA and amino acids components in a smidgen of a space rock that fell over Murchison, Victoria, in Australia in September 1969.

Previous studies of the meteorite revealed organic material, but the samples examined then were much larger.

This study would lend more credence to the idea that life arose from outside of our planet, researchers said in a statement.

Michael Callahan

"Despite their small size, these interplanetary dust particles may have provided higher quantities and a steadier supply of extraterrestrial organic material to early Earth," said Michael Callahan, a research physical scientist at NASA's Goddard Space Flight Center in Greenbelt, Md.

Amino acids are the basis of proteins, which are structures that make up hair, skin and other bits of living creatures.

DNA is a molecule that contains information on building and running an organism.

This equipment is used by Goddard's Astrobiology Analytical Lab to analyze very small samples. 

On the right is the nanoelectrospray emitter, which gives sample molecules an electric charge and transfers them to the inlet of the mass spectrometer (left), which identifies the molecules by their mass. 

Image Credit: Michael Callahan

Size matters
Meteorites such as Murchison are rare types of space rocks: the carbonaceous chondrites make up less than 5 percent of meteorites found on Earth, NASA said.

Further, the molecules discovered in these space rocks are usually in miniscule concentrations of parts-per-million or parts-per-billion.

These factors have researchers questioning how significant the carbon-rich rocks themselves were in bringing life to Earth.

Space dust, however, is more plentiful as it is constantly available from comets and asteroids shedding debris in their travels through the solar system.

The Murchison study (a proof of concept for further work, the researchers say) found life's building blocks in a sample that weighed about the same as a few eyebrow hairs.

The 360-microgram sample was about 1,000 times smaller than a typical sample analyzed by researchers.

Samples from space
This micro-sample required a more sensitive technique than usual to extract the information scientists needed.

A nanoflow liquid chromatography instrument organized the molecules, which were then ionized with a nanoelectrospray for analysis in a mass spectrometer.

NASA and other agencies have dealt with small sample sizes before, such as on the Stardust mission that collected particles from Comet Wild-2 and returned them to Earth in 2006.

Researchers anticipate the techniques they are using today could be used for other missions in the solar system, especially for sample-return missions.

"This technology will also be extremely useful to search for amino acids and other potential chemical biosignatures in samples returned from Mars and eventually plume materials from the outer planet icy moons Enceladus and Europa," said Goddard astrobiologist Daniel Glavin, who was co-author on the research.

The study, led by Callahan, was recently published in the Journal of Chromatography A.

More Information: 'Amino acid analysis in micrograms of meteorite sample by nanoliquid chromatography–high-resolution mass spectrometry': Michael P. Callahana, Corresponding author contact information, E-mail the corresponding author, Mildred G. Martinb, Aaron S. Burtonc, 1, Daniel P. Glavina, Jason P. Dworkina: dx.doi.org/10.1016/j.chroma.2014.01.032

Space dust carries water and organic compounds

The surfaces of tiny interplanetary dust particles are space-weathered by the solar wind, causing amorphous rims to form on their surfaces. 

Hydrogen ions in the solar wind react with oxygen in the rims to form tiny water-filled vesicles (blue). 

This mechanism of water formation almost certainly occurs in other planetary systems with potential implications for the origin of life throughout the galaxy. 

Credit: John Bradley, UH SOEST/ LLNL.

Researchers from the University of Hawaii-Manoa (UHM) School of Ocean and Earth Science and Technology (SOEST), Lawrence Livermore National Laboratory, Lawrence Berkeley National Laboratory, and University of California – Berkeley discovered that interplanetary dust particles (IDPs) could deliver water and organics to the Earth and other terrestrial planets.

Interplanetary dust, dust that has come from comets, asteroids, and leftover debris from the birth of the solar system, continually rains down on the Earth and other Solar System bodies.

These particles are bombarded by solar wind, predominately hydrogen ions.

This ion bombardment knocks the atoms out of order in the silicate mineral crystal and leaves behind oxygen that is more available to react with hydrogen, for example, to create water molecules.

Hope Ishii

"It is a thrilling possibility that this influx of dust has acted as a continuous rainfall of little reaction vessels containing both the water and organics needed for the eventual origin of life on Earth and possibly Mars," said Hope Ishii, new Associate Researcher in the Hawaii Institute of Geophysics and Planetology (HIGP) at UHM SOEST and co-author of the study.

This mechanism of delivering both water and organics simultaneously would also work for exoplanets, worlds that orbit other stars.

These raw ingredients of dust and hydrogen ions from their parent star would allow the process to happen in almost any planetary system.

Implications of this work are potentially huge: Airless bodies in space such as asteroids and the Moon, with ubiquitous silicate minerals, are constantly being exposed to solar wind irradiation that can generate water.

In fact, this mechanism of water formation would help explain remotely sensed data of the Moon, which discovered OH and preliminary water, and possibly explains the source of water ice in permanently shadowed regions of the Moon.

"Perhaps more exciting," said Ishii, "interplanetary dust, especially dust from primitive asteroids and comets, has long been known to carry organic carbon species that survive entering the Earth's atmosphere, and we have now demonstrated that it also carries solar-wind-generated water. So we have shown for the first time that water and organics can be delivered together."

More information: Detection of solar wind-produced water in irradiated rims on silicate minerals, John Bradley, Hope Ishii, Jeffrey Gillis-Davis, James Ciston, Michael Nielsen, Hans Bechtel, Michael Martin. Proceedings of the National Academy of Sciences, DOI: 10.1073/pnas.1320115111