Although the origins of life remains elusive, researchers are beginning to stumble across evidence to suggest that organic material, created in space, may have been transported to Earth through the impact of comets and meteors. With the need to examine these meteorites in finer detail, scientists at NASA now believe they have developed technology capable of analyzing the individual components of the most infinitesimal of sample sizes, from collected space dust.
On previous occasion, researchers have identified constituents of genetic material, alongside individual amino acids, hidden away inside carbonaceous chondrites (a.k.a. carbon-rich meteorites). Amino acids are the subunits required to make larger protein macromolecules – including those used to make hair and nails – and cellular structures that can regulate and catalyze chemical reactions. Meanwhile, DNA is required for carrying instructions on the development and function of living organisms. Aside from amino acids and constituents of DNA, other biologically critical “building blocks” have been discovered inside meteorite samples, including sugar-related compounds and nitrogen heterocycles.
Carbonaceous chondrites are, nonetheless, relatively infrequent and only make up a twentieth of all retrieved meteorites. The afore-mentioned building blocks are also found at extremely low concentrations – in the parts-per-million or -billion range. However, with Earth receiving a consistent supply of dust particulate from comets and asteroids, the planet is subject to a steady supply of extraterrestrial organic material. This is something that Michael Callahan, based at NASA’s Goddard Space Flight Center, reflected upon in a recent press release. Callahan explains that, regardless of their tiny size, interplanetary space dust can actually deliver relatively high quantities of organic material, but, thus far, few studies have been performed into their organic composition; Callahan indicates that researchers have been unable to effectively analyze collected specimens of space particulate for “biologically relevant molecules,” due to an absence of technology capable of analyzing the miniscule samples.
In light of this, Callahan and his research group at Goddard’s Astrobiology Analytical Laboratory have devised an advanced technique to inspect a sample, weighing just 360 micrograms, from the Murchison meteorite. The Murchison meteorite was witnessed falling from the skies as a bright fireball, close to the town of Murchison in Victoria, Australia. The carbonaceous chondrite split up into several fragments, which were scattered over the region; all in all, a total sample size of 100 kilograms was acquired. When the meteorite was initially inspected, researchers established that it housed around 15 amino acids, including a mixture of left- and right-handed subunits (i.e. a racemic mixture), leading scientists to believe that the amino acids were not terrestrial in nature.
Callahan recently explained that their advanced analytical techniques were able to explore sample sizes that were 1,000 times smaller than conventionally required. To put the sample size the group used into perspective, 360 micrograms equates to the weight of a few eyebrow hairs. Incredibly, using a technique called nanoflow liquid chromatography, the team were able to use small sample sizes to reproduce the same results that other research groups had obtained in the past, when using much larger samples.
Nanoflow liquid chromatography was used to separate the sample molecules, which were then given an electric charge through nanoelectrospray ionization. The charged molecules were then transported to a high-resolution mass spectrometer, which identified the molecules based upon their mass.
Explaining the potential applications for the highly sensitive instrument, Callahan indicates that it could prove critical to analyzing micrometeorites, cometary particles and interplanetary dust particulate. Coauthor of the latest research paper Daniel Glavin also discussed the implications of their advanced analytical tool:
“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.”
Ultimately, the team believe that their space dust analysis techniques could be applied to future sample-return missions, based on the limited sample sizes that are collected. Callahan considers that their work could pave the way for routinely “… targeting biologically relevant samples,” where traditional methods usually looked at inorganic or elemental composition.
By James Fenner
Top Image Credit: Michael Callahan