The OSIRIS-REx Laser Altimeter (OLA) Investigation and Instrument

Daly, M. G.; Barnouin, Olivier S.; Dickinson, C.; Seabrook, J. A.; Johnson, C. L.; Cunningham, G. F.; Haltigin, T.; Gaudreau, D.; Brunet, Claude; Aslam, Imran; Taylor, Aster G.; Bierhaus, E. B.; Boynton, W. V.; Nolan, M. C.; Лауретта, Д. С.

doi:10.1007/s11214-017-0375-3

Cited by 108 publications

(73 citation statements)

References 19 publications

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“…Dust and natural satellite searches were conducted during the spacecraft's approach to Bennu during early proximity operations in September through November 2018, which yielded null results (10). Signs of asteroid activity may have been detected by the OSIRIS-REx Laser Altimeter [OLA (11) Bennu's center. These signals prompted a search for corresponding objects in imaging data, without success.…”

Section: Particle Detectionsmentioning

confidence: 99%

Episodes of particle ejection from the surface of the active asteroid (101955) Bennu

Лауретта

Hergenrother

Chesley

et al. 2019

Science

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Active asteroids are those that show evidence of ongoing mass loss. We report repeated instances of particle ejection from the surface of (101955) Bennu, demonstrating that it is an active asteroid. The ejection events were imaged by the OSIRIS-REx (Origins, Spectral Interpretation, Resource Identification, and Security–Regolith Explorer) spacecraft. For the three largest observed events, we estimated the ejected particle velocities and sizes, event times, source regions, and energies. We also determined the trajectories and photometric properties of several gravitationally bound particles that orbited temporarily in the Bennu environment. We consider multiple hypotheses for the mechanisms that lead to particle ejection for the largest events, including rotational disruption, electrostatic lofting, ice sublimation, phyllosilicate dehydration, meteoroid impacts, thermal stress fracturing, and secondary impacts.

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Section: Particle Detectionsmentioning

confidence: 99%

Episodes of particle ejection from the surface of the active asteroid (101955) Bennu

Лауретта

Hergenrother

Chesley

et al. 2019

Science

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151

187

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“…A number of off‐body returns from the OSIRIS‐REx Laser Altimeter instrument (Daly et al, 2017) during Preliminary Survey may constitute the first evidence of particle ejection activity, although this remains to be confirmed (Lauretta, Hergenrother, et al, 2019). After the discovery of particle ejection in January 2019, a small number of particles were later identified in Preliminary Survey NavCam 1 images.…”

Section: Observationsmentioning

confidence: 99%

Photometry of Particles Ejected From Active Asteroid (101955) Bennu

Hergenrother

Maleszewski

et al. 2020

JGR Planets

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Near‐Earth asteroid (101955) Bennu is an active asteroid experiencing mass loss in the form of ejection events emitting up to hundreds of millimeter‐ to centimeter‐scale particles. The close proximity of the Origins, Spectral Interpretations, Resource Identification, and Security–Regolith Explorer spacecraft enabled monitoring of particles for a 10‐month period encompassing Bennu's perihelion and aphelion. We found 18 multiparticle ejection events, with masses ranging from near zero to hundreds of grams (or thousands with uncertainties) and translational kinetic energies ranging from near zero to tens of millijoules (or hundreds with uncertainties). We estimate that Bennu ejects ~104 g per orbit. The largest event took place on 6 January 2019 and consisted of ~200 particles. The observed mass and translational kinetic energy of the event were between 459 and 528 g and 62 and 77 mJ, respectively. Hundreds of particles not associated with the multiparticle ejections were also observed. Photometry of the best‐observed particles, measured at phase angles between ~70° and 120°, was used to derive a linear phase coefficient of 0.013 ± 0.005 magnitudes per degree of phase angle. Ground‐based data back to 1999 show no evidence of past activity for Bennu; however, the currently observed activity is orders of magnitude lower than observed at other active asteroids and too low be observed remotely. There appears to be a gentle decrease in activity with distance from the Sun, suggestive of ejection processes such as meteoroid impacts and thermal fracturing, although observational bias may be a factor.

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“…The auxiliary role of remote sensing in support of the primary objective of sample return makes OSIRIS-REx somewhat unique among planetary missions. By combining coordinated observations from the OSIRIS-REx Camera Suite (OCAMS; Rizk et al, 2018), the OSIRIS-REx Laser Altimeter (OLA; Daly et al, 2017), the OSIRIS-REx Visible and InfraRed Spectrometer (OVIRS; Reuter et al, 2018), the OSIRIS-REx Thermal Emission Spectrometer (OTES; Christensen et al, 2018), the REgolith X-Ray Imaging Spectrometer (REXIS; Masterson et al, 2018), and the OSIRIS-REx radio communication system (McMahon et al, 2018), the mission produces four maps of decision-making properties: deliverability, safety, sampleability, and scientific value (Lauretta et al, 2017). Each of these maps play a key role in selecting the OSIRIS-REx sample-site.…”

Section: Introductionmentioning

confidence: 99%

Overcoming the Challenges Associated with Image‐Based Mapping of Small Bodies in Preparation for the OSIRIS‐REx Mission to (101955) Bennu

DellaGiustina

Bennett

Becker

et al. 2018

Earth and Space Science

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The OSIRIS‐REx Asteroid Sample Return Mission is the third mission in National Aeronautics and Space Administration (NASA)'s New Frontiers Program and is the first U.S. mission to return samples from an asteroid to Earth. The most important decision ahead of the OSIRIS‐REx team is the selection of a prime sample‐site on the surface of asteroid (101955) Bennu. Mission success hinges on identifying a site that is safe and has regolith that can readily be ingested by the spacecraft's sampling mechanism. To inform this mission‐critical decision, the surface of Bennu is mapped using the OSIRIS‐REx Camera Suite and the images are used to develop several foundational data products. Acquiring the necessary inputs to these data products requires observational strategies that are defined specifically to overcome the challenges associated with mapping a small irregular body. We present these strategies in the context of assessing candidate sample sites at Bennu according to a framework of decisions regarding the relative safety, sampleability, and scientific value across the asteroid's surface. To create data products that aid these assessments, we describe the best practices developed by the OSIRIS‐REx team for image‐based mapping of irregular small bodies. We emphasize the importance of using 3‐D shape models and the ability to work in body‐fixed rectangular coordinates when dealing with planetary surfaces that cannot be uniquely addressed by body‐fixed latitude and longitude.

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The OSIRIS-REx Laser Altimeter (OLA) Investigation and Instrument

Cited by 108 publications

References 19 publications

Episodes of particle ejection from the surface of the active asteroid (101955) Bennu

Episodes of particle ejection from the surface of the active asteroid (101955) Bennu

Photometry of Particles Ejected From Active Asteroid (101955) Bennu

Overcoming the Challenges Associated with Image‐Based Mapping of Small Bodies in Preparation for the OSIRIS‐REx Mission to (101955) Bennu

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