“Space dust” might sound like something out of a 1950s-era science fiction novel, but such particles actually may hold some of the greatest secrets of our universe. The problem is that the material is extremely difficult to examine, especially when larger meteorites are more available.
In a Feb. 3 study done by researchers at NASA’s Goddard Space Flight Center in Greenbelt, Md., it is now possible to analyze extremely small dust, comet particles and other extraterrestrial material for certain organic compounds such as amino acids: the building blocks of life.
Michael Callahan of NASA’s Goddard Space Flight Center and lead investigator of the study said examining small materials almost as thoroughly as meteorites could prove useful in examining these organic components.
“It started out kind of a technical challenge,” he said. “Looking at very small samples just is always difficult, even when it’s not even a meteorite sample … If we knew that we could be successful doing these techniques and methods, [we could] look at very specific organic molecules which are the classes of amino acids.”
The new analysis is made possible through a new technique aided by a previously used nanoflow liquid chromatography instrument, which separates mixtures into their components.
“If we could do this on meteorite samples, we could do this on other very small extraterrestrial materials like interplanetary dust particles and potentially cometary particles that were returned from NASA missions,” he said. “… These later types of samples are much less studied and really haven’t been studied for these biologically relevant molecules.”
Researchers were motivated because current methods of analyzing small particles of extraterrestrial material did not prove successful in identifying organic compounds, Callahan said.
“Existing methods are not well suited for these classes of organic compounds in extraterrestrial samples,” he clarified in a subsequent email.
So Callahan and his team of researchers decided to build on previous techniques of analyzing organic molecules, but with a more specific focus.
Callahan says the technique is based on the dissection of a meteorite.
“All starts with a meteorite,” he said. “Very, very, small particles that are extracted in liquid solvent — these things are kind of trapped in the meteorite.”
He described this extrapolation process with an analogy to making tea.
“[It is] kind of like extracting tea out of tea leaves,” he said. “You throw it in some hot water and extract everything out, and we did the same thing.”
Then, after a bit of processing, the liquid amounts extracted from the meteorite are brought to a nanoflow liquid chromatography instrument that separates the mixture into its components, or molecules, and ionizes them so they can be taken to a mass spectrometer. The mass spectrometer then weighs the mass of the molecules to help identify them.
“So it’s a way of basically producing very, very fine droplets to ionize the molecules and get them into this other instrument where you can weigh the mass to charge of a species, and you can deduce what the structure is and identify how much is there of the meteorite,” he said. “We do this specifically designed and optimized to look for amino acids.”
Callahan said that overall, the results showed that it is possible to analyze sample sizes at such small degrees for similar results as bigger sample sizes, and that such techniques have potential to go beyond amino acids.
“The biggest finding is that people usually look in much larger meteorite samples, and we can look at samples that are about a thousand times less and get the same results — that was kind of the punchline of the story,” he said. “And now that you can do this and you kind of have these methods for amino acids, you could probably apply this elsewhere.”
Callahan said that such techniques will also give researchers the ability to go beyond and analyze other extraterrestrial material that could potentially shed light to early earth.
“Now that we can do this, maybe we can do more exciting stuff and take it to the next level and look at other extraterrestrial material,” he said. “… If they’re … bringing in organic molecules then there are implications of maybe prebiotic chemistry on early earth.”
He added in a subsequent email that he and his team of researchers hope to further analyze different types of extraterrestrial material that reveal early earth’s biotic chemistry.
“We hope to expand our analyses to include interplanetary dust particles and cometary material to understand their organic composition, how ubiquitous amino acids (and other organics) are in these materials, and evaluate how these extraterrestrial materials may have influenced prebiotic chemistry on early Earth,” he said.
Cory Absi, president of the Boston University chapter of the American Institute of Aeronautics and Astronautics, said it has been previously known that such organic molecules came with meteorites. and Vice President of BU’s Students for the Exploration and Development of Space said it has been previously known that such organic molecules came with meteorites.
“They’ve known for quite some time that organic molecules could’ve been transported via meteorites stuff like that,” Absi, who is also Vice President of BU’s Students for the Exploration and Development of Space, said. “I think the difference between this finding is that they’re finding that the concentration of organic molecules is higher in smaller samples.”
Zoe Strassfield, secretary of SEDS, added that the results of this study also revealed some information on the structure of the early solar system.
“It was very different from how it is now,” Strassfield, a junior in the College of Arts and Sciences, said. “There was a lot of waste material that was largely either collided and combined to form planets or it was chucked entirely out of the solar system or caught in the asteroid belt and the cometary clouds … We’re looking … [at] the leftovers of the formation of our solar system and so we’re getting a look [at] what materials were available when they were formed.”
Absi adds now that with such techniques, scientists can apply them to current developments happening in space. He gave the example of the Rosetta spacecraft.
The European Space Agency launched the Rosetta spacecraft in 2004 to orbit and land on a comet by August 2014.
“The Rosetta space craft has been in space for the past couple of years and was in hibernation,” Absi said. “They just woke it up in January. By the end of this year, they’re going to ride it into a comet and try to land on a comet, so it’s kind of interesting that now instead of trying to get other scientific data from a comet they can also look for life that they have the specific scientific instruments for.”
Dean De Carli, an ENG sophomore and BU AIAA Secretary, said Callahan’s techniques should be applied to rovers in space.
“It needs to be put on rovers that are going to go to Mars and can do it a lot quicker,” he said. “… Most meteorites burn up in the atmosphere and then most of the molecules in the meteorites burn up with the meteorites.”
He said though he believes that this research is just small scale, it is an important step in the right direction.
“I think it’s just an incremental step, not a huge advancement, which is still a good thing,” he said.