NASA’s OSIRIS-REx (Origins, Spectral Interpretation, Resource Identification, Security-Regolith Explorer) is on its way home with an otherworldly gift for Earth’s scientists – a sample from asteroid Bennu. With anticipation growing ahead of its Sept. 24 arrival, Dr. Jason Dworkin, project scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, visited Kennedy Space Center in Florida, where the mission launched seven years ago.

In a launch managed by NASA’s Launch Services Program, based at Kennedy, OSIRIS-REx lifted off Sept. 8, 2016, on an Atlas V 411 from Cape Canaveral Space Force Station (formerly Cape Canaveral Air Force Station) in Florida, as the third mission in the agency’s New Frontiers Program and the first U.S. mission to travel to an asteroid, retrieve samples, and return them to Earth.

“The OSIRIS-REx Bennu samples are really a treasure trove of information about the history of our solar system that will not only solve the scientific questions that we’re asking today, but those that people will be asking for many generations into the future,” said Rex Englehart, Launch Services Program mission manager, who managed the launch in 2016.

With a target of collecting 2.1 ounces (60 grams) of asteroid material – the largest asteroid sample ever received on Earth – scientists hoped studying material from the ancient solar system would shed light on some of science’s biggest mysteries.

“Can we look at samples of leftover material from the remnants of our solar system – from asteroids – to understand this environment and everything that happened after it?” Dworkin asked the audience inside the Mission Briefing Room of the Neil A. Armstrong Operations and Checkout Building at Kennedy. “That’s the goal of OSIRIS-REx – to understand that input of extraterrestrial material to the early Earth (or early Mars, Europa, Enceladus, etc.) and try to understand how this connects to the origin and early evolution of life.”

Choosing from around 500,000 known asteroids in 2010 and aiming to retrieve the sample within the lifespan of the science and engineering team, project scientists selected asteroid Bennu from around 7,000 near-Earth asteroids – 192 with optimal orbits for sample return, 26 big enough not to be a fast-rotator, and five carbon-rich asteroids. Bennu was selected of these five since it was the best understood at the time.

The spacecraft spent two years cruising to Bennu, arriving in August 2018, then entering into a .6-mile (1 km) orbit around the .3-mile (500 m) asteroid, later setting the record for closest orbit around the smallest object (500 m). Its specialized instruments mapped the asteroid’s surface, identified minerals and chemicals, and provided the information required for the mission team to select the site where the spacecraft’s Touch-And-Go Sample Acquisition Mechanism (TAGSAM) would collect the sample on Oct. 20, 2020, with Bennu 200 million miles (321 million km) from Earth at the time.

“The surface of Bennu is so soft, like a children’s ball pit or freshly fallen snow,” Dworkin said. “This spacecraft descending at 10 cm per second didn’t even slow down. It kept going until the back-away thrusters fired automatically, and then we pulled it away and that left a crater and threw meter-sized rocks dozens of meters away.”

OSIRIS-REx collected much more material than the mission target of 2.1 ounces (60 grams) – approximately 8.8 ounces (250 grams) – necessitating some adjustments from the mission team to quickly stow the sample for the return trip.

“Sample collection is just the pinnacle of the mission so far,” Dworkin said. “Sixty grams is a lot of sample – 250 grams is a massive amount of sample.”

When OSIRIS-REx returns to Earth this fall, the spacecraft will eject the sample return capsule from 155 miles (250 kilometers) above Earth. Mission teams will be ready to retrieve the capsule after it lands with the help of parachutes at the Department of Defense’s Utah Test and Training Range/Dugway Proving Ground, southwest of Salt Lake City, transporting quickly to a cleanroom at NASA’s Johnson Space Center in Houston where it will be curated.

During the next two years, 25% of the sample material from asteroid Bennu will go to 200 scientists around the world for research, including Dworkin’s team at Goddard, using instruments too large and fussy to put on spacecraft. Most of the sample is reserved for future generations of scientists.

“This is the legacy that OSIRIS-REx will bring,” Dworkin said. “Seventy-five percent of the sample is archived for scientists around the world to write proposals to, and material will be archived for decades as technology advances come up with new ideas and new techniques.”

Its mission complete, the OSIRIS-REx spacecraft will fly on to a new target and mission with a new name: OSIRIS-APEX (OSIRIS-APophis EXplorer). The spacecraft will head to the asteroid Apophis – a potentially hazardous asteroid roughly 1,200 feet (roughly 370 meters) in diameter that will come within 20,000 miles (32,000 kilometers) of Earth in 2029 – to study the changes in the asteroid by its close flyby of Earth.

While a new generation of scientists will lead OSIRIS-APEX, Dworkin will continue following the asteroid Bennu sample and plans to return to Kennedy to share the science made possible through the OSIRIS-REx mission.

“I love coming to Kennedy Space Center,” Dworkin said. “The launch pads are cathedrals to science. It is a region of contrast – it’s history and the future. It’s fire and water. It’s nature and technology.”

By Jason Costa
NASA’s John F. Kennedy Space Center

Related Link: https://www.nasa.gov/feature/nasa-scientist-visits-kennedy-ahead-of-osiris-rex-return