NASA's OSIRIS-REx spacecraft mission, launched on Sept. 8, 2016, is the first U.S. mission designed to retrieve a pristine sample of an asteroid and return it to Earth for further study. The mission's target is Bennu, a carbon-rich near-Earth asteroid that is potentially hazardous, representing an approximately 1 in 2,700 chance of impacting the Earth late in the 22nd century.
Scientists believe Bennu may contain the molecular precursors to the origin of life and the Earth's oceans, so one of the mission's main objectives is to determine Bennu's physical and chemical properties.
"The spacecraft has been observing the asteroid for nearly two years now," said Joshua Emery, associate professor in NAU's Department of Astronomy and Planetary Science and a member of the OSIRIS-REx science team. "Bennu has turned out to be a fascinating small asteroid and has given us many surprises."
The mission's first attempt to pick up the sample is scheduled for Oct. 20, 2020, and the spacecraft is scheduled to return the sample back to Earth on Sept. 24, 2023. In advance of the sample collection, the science team published a set of six papers in Science and Science Advances , four of which Emery co-authored, to share its scientific findings to date while building interest in the upcoming event.
"We've been working for over a decade toward the upcoming sampling attempt," he said. "It's such an exciting time. The spacecraft will send back data pretty quickly to let us know if the maneuver itself was successful, and it'll be exciting to see images from the sampling event, which should be sent back within a day."
The papers describe the detailed characterization of the surface using images, spectroscopy (composition) and thermal measurements. Emery summarizes each of the four papers he co-authored:
"It's been such thrill and honor to be part of the OSIRIS-REx team," Emery said. "As lead of the thermal analysis working group, it has been very exciting for me to be very involved in planning the observations the spacecraft has made in preparation for sampling and then figuring out from the data what the surfaces is like. The rocks on Bennu look strange, and we found from the thermal data that they are so weak that we could easily crush them in our hands. Still, they have existed on this asteroid for over a billion years! These rocks also contain complex organic molecules that form naturally in space, and asteroids like Bennu could have brought these organic molecules to Earth billions of years ago to seed the beginnings of life. When the sample is returned to Earth, scientists will be able to study these molecules in exquisite detail."
Emery, who joined NAU in 2019, applies the techniques of astronomical reflection and emission spectroscopy and spectrophotometry of primitive and icy bodies in the near- (0.8 to 5.0 microns) and mid-infrared (5 to 50 microns) to investigate the formation and evolution of the Solar System and the distribution of organic material.
The Jupiter Trojan asteroids have been a strong focus of his research, and he also regularly observes Kuiper Belt objects, icy satellites and other asteroid groups to understand the state of their surfaces as related to these topics. In addition to contributing to Solar System exploration as a science team member on the OSIRIS-REx asteroid sample return mission, he also collaborated on the upcoming Lucy Trojan asteroid flyby mission and the NEO Surveyor Mission infrared telescope mission.
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Links to the four papers:
https://science.sciencemag.org/cgi/doi/10.1126/science.abc3522
https://science.sciencemag.org/cgi/doi/10.1126/science.abc3557
https://advances.sciencemag.org/lookup/doi/10.1126/sciadv.abc3699
https://advances.sciencemag.org/lookup/doi/10.1126/sciadv.abc3350
Science