NASA's OSIRIS-REx Spacecraft Arrives at Asteroid Bennu

This image of Bennu was taken by the OSIRIS-REx spacecraft from a distance of around 50 miles (80 km).  Credits: NASA/Goddard/University of Arizona

Ken Kremer  --SpaceUpClose.com & RocketSTEM –10 December 2018

KENNEDY SPACE CENTER, FL –  After a two year and over two billion kilometer (1.2 billion mile) interplanetary journey NASA’s Origins, Spectral Interpretation, Resource Identification, Security-Regolith Explorer (OSIRIS-REx) spacecraft arrived at its destination, asteroid Bennu, on Monday, Dec. 3, 2018. 

The spacecraft executed a maneuver that transitioned it from flying toward Bennu to operating around the asteroid at an initial distance of about 11.8 miles (19 kilometers) from Bennu’s Sun-facing surface, NASA officials said.

The arrival event was broadcast live on NASA TV on a day that included a Soyuz crew launch to the ISS and prelaunch preparations for the SpaceX Falcon 9 Dragon CRS-16 resupply mission to he station. 

This series of images taken by the OSIRIS-REx spacecraft shows Bennu in one full rotation from a distance of around 50 miles (80 km). The spacecraft’s PolyCam camera obtained the thirty-six 2.2-millisecond frames over a period of four hours and 18 minutes.  Credits: NASA's Goddard Space Flight Center/University of Arizona

“The OSIRIS-REx team is proud to cross another major milestone off our list -- asteroid arrival,” said Dante Lauretta, OSIRIS-REx principal investigator at the University of Arizona, Tucson, in a statement. 

“Initial data from the approach phase show this object to have exceptional scientific value. We can’t wait to start our exploration of Bennu in earnest. We’ve been preparing for this moment for years, and we’re ready.”

This picture shows the OSIRIS-REx spacecraft’s view of Bennu during the final phase of its journey to the asteroid. From Aug. 17 through Nov. 27 the spacecraft’s PolyCam camera imaged Bennu almost daily as the spacecraft traveled 1.4 million miles (2.2 million km) toward the asteroid. The final images were obtained from a distance of around 40 miles (65 km). During this period, OSIRIS-REx completed four maneuvers slowing the spacecraft’s velocity from approximately 1,100 mph (491 m/sec) to 0.10 mph (0.04 m/sec) relative to Bennu, which resulted in the slower approach speed at the end of the video.  Credits: NASA's Goddard Space Flight Center/University of Arizona

The probe will now begin a preliminary survey of the asteroid using its suite of five science instruments - leading towards the ultimate goal of collecting soil and rock samples at a safe and scientifically interesting site for return to Earth September 2023.

“The spacecraft will commence flyovers of Bennu’s north pole, equatorial region, and south pole, getting as close as nearly 4 miles (7 kilometers) above Bennu during each flyover.”

“The primary science goals of this survey are to refine estimates of Bennu’s mass and spin rate, and to generate a more precise model of its shape. The data will help determine potential sites for later sample collection.”

“OSIRIS-REx’s mission will help scientists investigate how planets formed and how life began, as well as improve our understanding of asteroids that could impact Earth. Asteroids are remnants of the building blocks that formed the planets and enabled life. Those like Bennu contain natural resources, such as water, organics and metals. Future space exploration and economic development may rely on asteroids for these materials.”

OSIRIS-Rex spacecraft in KSC cleanroom prior to launch Sept 2016 from pad 41 on Cape Canaveral Air Force Station, FL. Credit: Ken Kremer/kenkremer.com/spaceupclose.com

Following the successfully arrival at Bennu, the spacecraft will spend the first month performing flybys of Bennu’s north pole, equator and south pole, at distances ranging between 11.8 and 4.4 miles (19 and 7 km) from the asteroid. These maneuvers will allow for the first direct measurement of Bennu’s mass as well as close-up observations of the surface. These trajectories will also provide the mission's navigation team with experience navigating near the asteroid.

“Bennu’s low gravity provides a unique challenge for the mission," said Rich Burns, OSIRIS-REx project manager at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. "At roughly 0.3 miles [500 meters] in diameter, Bennu will be the smallest object that any spacecraft has ever orbited.”

The spacecraft will extensively survey the asteroid before the mission team identifies two possible sample sites. Close examination of these sites will allow the team to pick one for sample collection, scheduled for early July 2020. After sample collection, the spacecraft will head back toward Earth before ejecting the Sample Return Capsule for landing in the Utah desert in Sept. 2023.   

Check back soon for my follow-up articles about the initial science results.

Watch for Ken’s continuing onsite coverage of NASA, SpaceX, ULA, Boeing, Lockheed Martin, Northrop Grumman and more space and mission reports direct from the Kennedy Space Center, Cape Canaveral Air Force Station, Florida and Wallops Flight Facility, Virginia.

Stay tuned here for Ken's continuing Earth and Planetary science and human spaceflight news: www.kenkremer.com –www.spaceupclose.com – twitter @ken_kremer – email: ken at kenkremer.com

Dr. Kremer is a research scientist, journalist and photographer based in the KSC area.

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