The OSIRIS-REx Radio Science Experiment at Bennu

McMahon, Jay W.; Scheeres, Daniel J.; Hesar, Siamak G.; Farnocchia, Davide; Chesley, Steven R.; Лауретта, Д. С.

doi:10.1007/s11214-018-0480-y

Cited by 45 publications

(20 citation statements)

References 40 publications

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“…After more than 2 years, the detection will be extremely firm (McMahon et al, 2018). At a resolution of 35 cm, detecting an offset of features by 0.08°of rotation should be possible after about 180 days of spacecraft observation.…”

Section: Discussionmentioning

confidence: 98%

Detection of Rotational Acceleration of Bennu Using HST Light Curve Observations

Nolan

Howell

Scheeres

et al. 2019

Geophysical Research Letters

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We observed the near‐Earth asteroid (101955) Bennu from the ground in 1999 and 2005, and with the Hubble Space Telescope (HST) in 2012, to constrain its rotation rate. The data reveal an acceleration of 2.64 ± 1.05 × 10−6 deg/day2, which could be due to a change in the moment of inertia of Bennu or to spin up from the Yarkovsky‐O'Keefe‐Radzievskii‐Paddack effect or other source of angular momentum. The best solution is within 1 σ of the period determined by Nolan et al. (2013, https://doi.org/10.1016/j.icarus.2013.05.028). The Origins, Spectral Interpretation, Resource Identification, and Security–Regolith Explorer (OSIRIS‐REx) mission will determine the rotation state independently in 2019. Those measurements should show whether the change in rotation rate is a steady increase (due, e.g., to the Yarkovsky‐O'Keefe‐Radzievskii‐Paddack effect) or some other phenomenon. The precise shape and surface properties measured by the OSIRIS‐REx science team will allow for a better understanding of variations in rotation rate of small asteroids.

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Section: Discussionmentioning

confidence: 98%

Detection of Rotational Acceleration of Bennu Using HST Light Curve Observations

Nolan

Howell

Scheeres

et al. 2019

Geophysical Research Letters

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“…Given the altitude of the spacecraft, more than 2.5 Bennu radii in altitude, the gravity field measurements were limited in their signal. Prearrival analysis of the OSIRIS-REx mission plan indicated reliable detection of the gravity field to degree and order 3, and that the degree and order 4 gravity field coefficients would be able to be sensed but not strongly determined (25). The fixed geometry of the spacecraft orbit when in close proximity to the asteroid also limited the ability to fully explore the dynamical implications of the mass distribution.…”

Section: Gravity Field Measurement From Spacecraft-based Trackingmentioning

confidence: 99%

“…The initial values for the gravity field spherical harmonic coefficients were based on the constant-density model. Uncertainties in these coefficients were based on the modified Kaula rule derived for Bennu (25). Degree 1 terms, reflective of offsets between the center of mass and center of volume, were zeroed and not estimated, implying that the estimated gravity field was based at the Bennu center of mass.…”

Section: Particle Gravity Field Solutionmentioning

confidence: 99%

Heterogeneous mass distribution of the rubble-pile asteroid (101955) Bennu

et al. 2020

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The gravity field of a small body provides insight into its internal mass distribution. We used two approaches to measure the gravity field of the rubble-pile asteroid (101955) Bennu: (i) tracking and modeling the spacecraft in orbit about the asteroid and (ii) tracking and modeling pebble-sized particles naturally ejected from Bennu’s surface into sustained orbits. These approaches yield statistically consistent results up to degree and order 3, with the particle-based field being statistically significant up to degree and order 9. Comparisons with a constant-density shape model show that Bennu has a heterogeneous mass distribution. These deviations can be modeled with lower densities at Bennu’s equatorial bulge and center. The lower-density equator is consistent with recent migration and redistribution of material. The lower-density center is consistent with a past period of rapid rotation, either from a previous Yarkovsky-O’Keefe-Radzievskii-Paddack cycle or arising during Bennu’s accretion following the disruption of its parent body.

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“…A student-designed X-ray imaging spectrometer (REXIS) 8 determines the presence and abundance of elements on the surface of Bennu. In addition, the spacecraft has telecommunications equipment that enables radio science 9 .…”

Section: A Rendezvous With Asteroid Bennumentioning

confidence: 99%