On May 10, NASA’s Origins, Spectral
Interpretation, Resource Identification, Security, Regolith Explorer
(OSIRIS-REx) spacecraft will say farewell to asteroid Bennu and begin its
journey back to Earth. During its Oct. 20, 2020, sample collection event, the
spacecraft collected a substantial amount of material from Bennu’s surface,
likely exceeding the mission’s requirement of 2 ounces (60 grams). The
spacecraft is scheduled to deliver the sample to Earth on Sep. 24, 2023.
“Leaving Bennu’s vicinity in May puts us in the ‘sweet
spot,’ when the departure maneuver will consume the least amount of the
spacecraft’s onboard fuel,” said Michael Moreau, OSIRIS-REx deputy project
manager at NASA’s Goddard Space Flight Center in Greenbelt, Maryland.
“Nevertheless, with over 593 miles per hour (265 meters per second) of velocity
change, this will be the largest propulsive maneuver conducted by OSIRIS-REx
since the approach to Bennu in October 2018.”
The May departure also provides the OSIRIS-REx team
with the opportunity to plan a final spacecraft flyby of Bennu. This activity
was not part of the original mission schedule, but the team is studying the
feasibility of a final observation run of the asteroid to potentially learn how
the spacecraft’s contact with Bennu’s surface altered the sample site.
If feasible, the flyby will take place in early April
and will observe the sample site, named Nightingale, from a distance of
approximately 2 miles (3.2 kilometers). Bennu’s surface was considerably
disturbed after the Touch-and-Go (TAG) sample collection event, with the
collector head sinking 1.6 feet (48.8 centimeters) into the asteroid’s surface.
The spacecraft’s thrusters also disturbed a substantial amount of surface
material during the back-away burn.
The mission is planning a single flyby, mimicking one
of the observation sequences conducted during the mission’s Detailed Survey
phase in 2019. OSIRIS-REx would image Bennu for a full rotation to obtain
high-resolution images of the asteroid’s northern and southern hemispheres and
equatorial region. The team would then compare these new images with the
previous high-resolution imagery of Bennu obtained during 2019.
"OSIRIS-REx has already provided incredible
science,” said Lori Glaze, NASA's director of planetary science at the agency's
headquarters in Washington. "We're really excited the mission is planning
one more observation flyby of asteroid Bennu to provide new information about
how the asteroid responded to TAG and to render a proper farewell.”
These post-TAG observations would also give the team a
chance to assess the current functionality of science instruments onboard the
spacecraft – specifically the OSIRIS-REx Camera Suite (OCAMS), OSIRIS-REx
Thermal Emission Spectrometer (OTES), OSIRIS-REx Visible and Infrared
Spectrometer (OVIRS), and OSIRIS-REx Laser Altimeter (OLA). It is possible dust
coated the instruments during the sample collection event and the mission wants
to evaluate the status of each. Understanding the health of the instruments is
also part of the team’s assessment of possible extended mission opportunities
after the sample is delivered to Earth.
The spacecraft will remain in asteroid Bennu’s
vicinity until May 10, when the mission will enter its Earth Return Cruise
phase. As it approaches Earth, OSIRIS-REx will jettison the Sample Return
Capsule (SRC). The SRC will then travel through the Earth’s atmosphere and land
under parachutes at the Utah Test and Training Range.
Once recovered, NASA will transport the capsule to the
curation facility at the agency’s Johnson Space Center in Houston and
distribute the sample to laboratories worldwide, enabling scientists to study
the formation of our solar system and Earth as a habitable planet.
Goddard provides overall mission management, systems
engineering, and the safety and mission assurance for OSIRIS-REx. Dante
Lauretta of the University of Arizona in Tucson is the principal
investigator, and the University of Arizona also leads the science team and the
mission’s science observation planning and data processing. Lockheed Martin
Space in Littleton, Colorado, built the spacecraft and provides flight operations.
Goddard and KinetX Aerospace are responsible for navigating the OSIRIS-REx
spacecraft. OSIRIS-REx is the third mission in NASA’s New Frontiers Program,
which NASA’s Marshall Space Flight Center in Huntsville, Alabama, manages for
the agency’s Science Mission Directorate in Washington.
For more information on OSIRIS-REx, visit: https://www.nasa.gov/osiris-rex and https://www.asteroidmission.org
Source: https://www.nasa.gov/press-release/nasa-s-osiris-rex-mission-plans-for-may-asteroid-departure
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