By Mikayla Mace Kelley, University Communications - August 22, 2023
The University of Arizona-led OSIRIS-REx mission – NASA's first mission to collect an asteroid sample and deliver it to Earth – was dreamed up in 2004 by the late Michael Drake, who at the time was head of the UArizona Lunar and Planetary Laboratory.
His most burning questions were about the origins of life, and a sample from an asteroid was key to answering those questions. Drake, who would become the principal investigator of OSIRIS-REx, spent years designing the asteroid-sampling mission with his team. But shortly after NASA made OSIRIS-REx an official mission in 2011, Drake died.
His legacy has lived on through his mentee, Dante Lauretta, a UArizona planetary scientist who worked with Drake from the mission's inception. Now, two decades later, Lauretta will see OSIRIS-REx through its final stage on behalf of them both.
"The origin of life investigation is where my mind is a lot these days," Lauretta said. "It's a really challenging scientific puzzle, and I'm excited to really dig into it after more than 20 years of mission planning and execution."
On Sept. 24, the OSIRIS-REx spacecraft, which launched in 2016, will deliver a capsule containing rocks and dust it picked up from asteroid Bennu in 2020. The spacecraft will release the capsule over the Department of Defense's Utah Test and Training Range, 80 miles southwest of Salt Lake City.
The next day, on Sept. 25, the Bennu sample – an estimated 8 ounces, give or take 4 ounces – will be delivered to NASA's Johnson Space Center in Houston, where it will be cared for and stored. This will mark the end of the OSIRIS-REx mission in space. But the occasion also will mark the beginning of research that will keep scientists busy for generations and supply intellectual fodder for conversations about the origins of life, the nature of asteroids, planetary defense and much more.
Lauretta's biggest question
Lauretta and other scientists have been waiting for years to study pieces of Bennu in their labs to help tease out the details of how life emerged on Earth. To do this, they need samples collected in space; these are the best records of the solar system's chemical history because they are so well preserved compared to anything found on Earth, where activity such as erosion and shifting continents have erased most evidence of the planet's ancient history.
When it comes to unraveling the origins of life, many scientists are keen to trace organic molecules – chains of atoms associated with living things – back in time to find out how they evolved into living creatures.
Lauretta and his colleagues will study organic compounds called amino acids, which are components of proteins that are critical to the structure, function and regulation of all living things on Earth.
Scientists know amino acids can be formed in space, because they have detected them in meteorites, which are space rocks that fall to Earth's surface. But scientists wonder if the first amino acids used by life were delivered by meteorites or if they were a product of "primordial soup," the chemical mixture on Earth during its earliest days, from which life first took hold.
To try to find out, Lauretta's team members at NASA's Goddard Space Flight Center in Greenbelt, Maryland, will steep a powdered sample of Bennu in cool water to extract the amino acids in a process similar to making cold-brew coffee. Then, they will use chemical methods to separate, identify and quantify the amino acids present.
"Some of the amino acids used in biology are relatively fragile – too fragile to survive the harsh methods, such as boiling water, typically used to extract them from rocks," said Jason Dworkin, an OSIRIS-REx project scientist at NASA's Goddard Space Flight Center. "So, Dante challenged the Goddard team to develop a method that is tough enough to liberate amino acids from a stone, yet sufficiently gentle to preserve the delicate molecules that emerge, and that's what we've done."
The OSIRIS-REx research team will provide their amino acids data to Sawsan Wehbi, a UArizona graduate student studying astrobiology and genetics. She will compare Bennu's amino acid inventory with that of the theoretical microbe known as the Last Universal Common Ancestor, from which all Earth life is thought to have emerged about 4 billion years ago.
A strong correlation could mean that some early lifeforms used the organic material delivered from outer space, Wehbi hypothesizes.
"Right now, we just don't know," Wehbi said. "It might be that life was surrounded by meteorites containing precious amino acids but couldn't access them. Or, maybe early life only relied on terrestrial amino acids or was dependent on what was delivered by meteorites. If we find that early life was dependent on meteorite amino acids, that would change the whole story."
Launching the next generation
Between 1988 and 1993, Lauretta studied math, physics and Japanese at UArizona. He returned as a faculty member in 2001. Drake quickly took Lauretta under his wing, appointing him deputy principal investigator of OSIRIS-REx. They worked for seven years to develop the mission. Drake died four months after OSIRIS-REx was selected by NASA, and Lauretta stepped into the lead role.
"His death was terrible and unexpected, and it put me in the leadership role really quickly," Lauretta said. "But Mike taught me a lot in those years we worked together, so I was ready."
As principal investigator, Lauretta, too, has taken on many mentees. One of them is Dani DellaGiustina, who began working with Lauretta and Drake as a student in 2004. She was appointed OSIRIS-REx imaging team lead in 2015, then deputy principal investigator in 2021.
Next, DellaGiustina will lead a new mission, OSIRIS-APEX, to study asteroid Apophis. The new mission will use the existing OSIRIS-REx spacecraft after it drops the Bennu sample to Earth in September.
"I'm looking forward to handing the flight system off to a new generation and getting back into the laboratory," Lauretta said.