NASA today revealed its first sample collected from an asteroid. The OSIRIS-REx mission traveled 1.2 billion miles to visit asteroid Bennu and scoop up a sample, and last month that sample was dropped through Earth’s atmosphere before landing in the Utah desert.
The sample was carefully sealed in a capsule to protect it on its journey, and that capsule was taken to NASA’s Johnson Space Center in Houston, where it was carefully opened for the first time. While the capsule was being opened, however, a small group of scientists were already racing to get early results on the asteroid material.
One of these scientists, Pierre Haenecour of the University of Arizona, told us about what it took to do a super fast analysis of NASA’s first asteroid sample. “It’s very exciting to have the chance to be among the first to look at the sample and get data,” he said.
Tip of the iceberg
The “quick-look team” was a group of experts who were tasked with doing a first analysis of dust that had collected on the outside of the canister — and doing it within just a few days. Their big headline finding is that the sample contains evidence of both water and carbon-rich material, supporting the theory that the building blocks of life were originally brought to Earth by asteroids like Bennu.
The team went to Houston to study the sample in NASA’s new facility there, and they worked on material that was on the outside of the sample collector, called the TAGSAM or Touch-and-Go Sample Acquisition Mechanism. There was just a small amount of black dust on the outer part of the canister, but it was enough to do a preliminary analysis.
Getting a millimeter-sized particle — we could work for years on it.
“The curator at the Johnson Space Center basically wiped a little bit of that material, put it in a vial, and put it aside for us. And that’s what we analyzed,” Haenecour said.
That means that the particles examined by the quick-look team might be different from those from within the sample. “There is a very good chance there will be differences” between the two, Haenecour said. “We have to remember that we are looking at very, very small particles — we’re looking at millimeter- to hundreds-of-micron-sized particles. So we don’t necessarily have a representative sample of what’s inside.”
What lies inside
The sample inside the canister is likely to contain a greater diversity of particles, with all sorts of different size particles with different compositions included. That would be ideal from a scientific standpoint, as it would reflect the diversity of materials seen on the surface of Bennu — including exciting findings like large carbonate rocks.
“The more material you have, and the more diversity, the more context you can get,” Haenecour said. It would be great to find larger pieces like centimeter-sized chunks of carbonates, as the asteroid is thought to host a wide variety of organic compounds and water-bearing minerals like clays. One of the exciting questions for the first peek into the sample is, “Can we see those micro-scale variations that we see on the surface of Bennu?”
The reason that scientists are so excited to get their hands on a piece of Bennu is that it can help answer questions as big as how life evolved on Earth. The building blocks of life, called organic molecules, are thought to have been originally brought to Earth by asteroids like Bennu. Finding evidence of these organics in the asteroid sample helps researchers piece together this journey, which occurred billions of years ago.
Waste not, want not
The long-term analysis of the sample will keep researchers busy for years, but in the meantime, Haenecour and his colleagues had just days to perform a first analysis of the sample, using techniques like electron microscopy and mass spectrometry. They began by taking detailed images of the particles before moving on to investigating its chemistry. The idea was “getting a general lay of the land of what the sample looks like and what it’s composed of,” Haenecour explained.
To do that, the group ran the tiny, precious sample through a battery of tests, starting with the least destructive techniques like taking photographs, and progressing to more destructive techniques that could tell them more about the composition but that would degrade or destroy the sample they had.
It’s possible to gain a huge amount of understanding from a very small amount of material thanks to the sophisticated analysis methods that are available now. “For us, getting a millimeter-sized particle — we could work for years on it,” Haenecour said. “A lot of the measurements we do are at the nanoscale level.”
It’s providing us with insight into how life might have started on Earth.
There’s laser ablation, for example, which involves blasting off a few microns of material with a laser — it removes only a few nanograms of sample, but it’s still slightly destructive, so it isn’t performed first. Other destructive techniques include step heating, where the sample is heated more and more to release noble gases, or techniques to look for soluble organics using mass spectrometry, which involve crushing and dissolving the sample.
“The idea is always to use as little mass as possible,” Haenecour said.
With information from this asteroid sample, scientists hope to be able to trace back the origin of organics not only to asteroids in the early solar system, but perhaps even further, to where those compounds originated from.
“If we know that life started from asteroids or comets, where did those organics come from? Did they form in the solar system? Did they form in the interstellar medium, even before the solar system?” Haenecour said. These compounds could even have formed among stardust grains, originating within a stellar environment while the material that would eventually form planets swirled around as a circumstellar disk.
“It’s providing us with insight into how life might have started on Earth,” Haenecour said.
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