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Image Credit: NASA's Goddard Space Flight Center.

Farewell Bennu – OSIRIS-REx heads back home

NASA’s OSIRIS-REx spaceprobe yesterday evening, May 10, 2021, performed a seven minutes long burn of its engines, to depart the near Earth asteroid Bennu and to head back home. The spacecraft will arrive at planet Earth in about 2.5 years on September 24, 2023, where it will jettison its Sample Return Capsule loaded with rock samples from the asteroid. This capsule will then reenter our planet’s atmosphere and is expected to land at the Utah Test and Training Range in the West Desert in Utah, USA.

Scientists hope to learn more about the formation of the Solar System by studying the rocks Bennu is made off. Due to its old age (Bennu might have formed about 1 to 2 billion years ago during a collision of two asteroids), the celestial body serves as a time capsule, preserving rocks and minerals billions of years old. The object might also give clues to the origin of life on Earth. One theory states, that the molecules required for the formation of life once came to the planet though impacts of asteroids. NASA hopes to have collected more than 60 grams of material from Bennu during the Touch-and-Go (TAG) maneuver on October 20, 2020. These samples will have an enormous value to scientist all around the globe and can be used for decades to come.

Mission Timeline

OSIRIS-REx blasted off from Space Launch Complex 41 (SLC-41) at the Cape Canaveral Space Force Station in Florida, on September 08, 2016 atop an United Launch Alliance (ULA) Atlas V 401 rocket. After a more than two years and two billion kilometers voyage through deep space, the space probe arrived at its target, the asteroid Bennu, on December 03, 2018. Upon arrival, the craft did not immediately enter orbit around the asteroid, but performed several flyovers to refine the estimates about the space rock’s mass, spin rate and shape.

OSIRIS-REx launches atop an Atlas V rocket. Image Credit: NASA/Sandy Joseph and Tim Terry.
OSIRIS-REx launches atop an Atlas V rocket. Image Credit: NASA/Sandy Joseph and Tim Terry.
Mosaic image of asteroid Bennu taken by OSIRIS-REx. Image Credit: NASA/Goddard/University of Arizona.
Mosaic image of asteroid Bennu taken by OSIRIS-REx. Image Credit: NASA/Goddard/University of Arizona.

About a month later, on December 31, 2018, OSIRIS-REx finally entered orbit and began its close up investigation of Bennu using its onboard instruments.

The primary objective of the mission was to collect rock and dust samples from the asteroid’s surface, so the researchers soon began searching for potential sampling sites on Bennu. In December 2019, NASA announced the selection of the Nightingale crater as the primary sampling site. The Osprey site was chosen as the backup location, in case OSIRIS-REx was unable to touch down at Nightingale.

The final four potential landing sites. In the end Nightingale was chosen as the primary location and Osprey as the back up. Image Credit: NASA/Goddard/University of Arizona.
The final four potential landing sites. In the end Nightingale was chosen as the primary location and Osprey as the back up. Image Credit: NASA/Goddard/University of Arizona.

After multiple rehearsals, the probe finally descended to the surface of asteroid Bennu on October 20, 2020, touching down at Nightingale and pushing the sampler head into the asteroid’s surface. Just brief moments after contact, a burst of nitrogen gas was fired to stir up the material so it would land inside the sampler head. Just seconds later the spacecraft’s thrusters fired, to back away from the surface to a save distance.

Soon the spacecraft controllers realised that the sampler head was full of material, of which some already began falling out again. To avoid loosing the precious cargo, the sampler collecter head was stowed inside the Sample Return Capsule (SRC) a few days later on October 27, using the TAGSAM robotic arm.

Ahead of the departure from Bennu on May 10, 2021, OSIRIS-REx performed a final flyover over the Nightingale crater on April 09, 2021. Footage taken by the spacecraft showed rocks blown away by the craft’s thrusters during the back away maneuver.

Just a few hours ago, on Monday evening, May 10, 2021, OSIRIS-REx fired its engines for around seven minutes, to depart the asteroid and head back to Earth. The samples will arrive at our planet on September 24, 2023 and will land in the U.S. State of Utah, where the SRC will be recovered by recovery personal.

The OSIRIS-REx spacecraft

OSIRIS-REx, or Origins, Spectral Interpretation, Resource Identification, Security – Regolith Explorer, is a 880 kg (dry mass) heavy spacecraft, operated by NASA and built by Lockheed Martin Space Systems at their facility near Denver in the U.S. State of Colorado. The probe is 6.2 m in length with its two solar arrays fully deployed, 2.43 m in width and 3.15 m in height. The Touch-And-Go Sample Acquisiton Mechanism (TAGSAM) arm is 3.35 m in length and is comprised of a robotic arm and the sampler head.

OSIRIS-REx is beeing prepared for encapsulation ahead of its launch. Image Credit: NASA/Glenn Benson.
OSIRIS-REx is beeing prepared for encapsulation ahead of its launch. Image Credit: NASA/Glenn Benson.

Besides the TAGSAM payload, OSIRIS-REx carries five additional scientific instruments, which provided valuable knowledge about Bennu.

  • OSIRIS-REx Camera Suite (OCAMS): OCAMS is a system of three cameras used to map the asteroid and to find a potential sampling site.
  • Regolith X-ray Imaging Spectrometer (REXIS): A student built experiment that studied Bennu’s X-ray spectrum, to determine the composition of the rocks on the asteroid’s surface.
  • OSIRIS-REx Thermal Emission Spectrometer (OTES): OTES studied the asteroid’s thermal infrared spectrum, to gain mineral and temperature information.
  • OSIRIS-REx Laser Altimeter (OLA): An intrument to measure the distance between the asteroid and the spacecraft using laser beams. That enabled researchers to map Bennu’s surface.
  • OSIRIS-REx Visible and Infrared Spectrometer (OVIRS): OVIRS measured infrared and visible light originating from Bennu’s surface, to identify mineral and organic material on the asteroid’s surface.
Artist render of OSIRIS-REx at Bennu. Image Credit: NASA's Goddard Space Flight Center.
Artist render of OSIRIS-REx at Bennu. Image Credit: NASA’s Goddard Space Flight Center.

Click here to rewatch the launch of OSIRIS-REx.


Sources

https://www.nasa.gov/press-release/nasa-s-osiris-rex-spacecraft-heads-for-earth-with-asteroid-sample

https://www.nasa.gov/feature/why-bennu-10-reasons

https://www.nasa.gov/feature/goddard/2021/nasas-osiris-rex-leaves-its-mark-on-asteroid-bennu

https://blogs.nasa.gov/osiris-rex/

https://www.nasa.gov/feature/goddard/2018/osiris-rex-approach

https://www.asteroidmission.org/?latest-news=nasas-osiris-rex-spacecraft-arrives-asteroid-bennu

https://www.asteroidmission.org/?latest-news=x-marks-the-spot-nasa-selects-site-for-asteroid-sample-collection

https://www.nasa.gov/press-release/nasa-s-osiris-rex-spacecraft-successfully-touches-asteroid

https://www.asteroidmission.org/?latest-news=nasas-osiris-rex-successfully-stows-sample-of-asteroid-bennu

https://www.nasa.gov/sites/default/files/atoms/files/osiris_rex_factsheet5-9.pdf

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