Engineering topics
Ostro, S. J.
Publications and source records attributed to Ostro, S. J..
Multi-Wavelength Observations of 2100 Ra-Shalom: Radar and Lightcurves
We conducted a multi-wavelength campaign to study the near-Earth asteroid (NEA) 2100 Ra-Shalom during its August 2003 encounter. Rotationally resolved observations were acquired at Arecibo (12.6 cm radar), the IRTF (0.8-2.5 micron and 3 micron), McDonald Observatory (0.48-0.92 micron), Palomar Observatory (8-15 micron), and Ondrejov Observatory (optical lightcurves). Our objectives were to determine Ra-Shalom's size and shape, and the composition and physical state of its near-surface material. Preliminary results from radar and lightcurve measurements will be presented here.
Direct detection of the Yarkovsky effect by radar ranging to ateroid 6489 Golevka
Radar ranging from Arecibo, Puerto Rico, to the 0.5-kilometer near-Earth asteroid 6489 Golevka unambiguously reveals a small nongravitational acceleration caused by the anisotropic thermal emission of absorbed sunlight. The magnitude of this perturbation, known as the Yarkovsky effect, is a function of the asteroid's mass and surface thermal characteristics. Direct detection of the Yarkovsky effect on asteroids will help constrain their physical properties, such as bulk density, and refine their orbital paths.
Measuring the Yarkovsky effect via radar ranging to Golevka: place your bets
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Geophysical constraints on asteroids from groundbased radar
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Exploring Asteroid Interiors: The Deep Interior Mission Concept
Deep Interior is a mission to determine the geophysical properties of near-Earth objects, including the first volumetric image of the interior of an asteroid. Radio reflection tomography will image the 3D distribution of complex dielectric properties within the ~1 km rendezvous target and hence map structural, density or compositional variations. Laser altimetry and visible imaging will provide high-resolution surface topography. Smart surface pods culminating in blast experiments, imaged by the high frame rate camera and scanned by lidar, will characterize active mechanical behavior and structure of surface materials, expose unweathered surface for NIR analysis, and may enable some characterization of bulk seismic response. Multiple flybys en route to this target will characterize a diversity of asteroids, probing their interiors with non-tomographic radar reflectance experiments. Deep Interior is a natural follow-up to the NEARShoemaker mission and will provide essential guidance for future in situ asteroid and comet exploration. While our goal is to learn the interior geology of small bodies and how their surfaces behave, the resulting science will enable pragmatic technologies required of hazard mitigation and resource utilization.
Radar reconnaissance of potentially hazardous asteroids and comets
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Imaging the interiors of near-earth objects with radio reflection tomography
Scenarios for mitigation of asteroid comet collisions include the use of explosives to deflect or destroythe projectile. However, as demonstrated by Asphaug et al.( 1998), the outcome of explosive energy transfer to an asteroid or comet (via a bomb or a hypervelocity impact) is extremely sensitive to the pre-existing configuration of fractures and voids.
Asteroid 1950 DA's encounter with Earth in A.D. 2880
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Radar reconnaissance of potentially hazardous asteroids and comets
Groundbased radar is uniquely able to reduce uncertainty in trajectories and physical properties of near-earth objects. Radar can prevent the loss of a newly discovered object caused by the normal decay of orbit knowledge prior to the next optical observing opportunity, can add decades or centuries to the interval over which close Earth approaches can accurately be predicted, can significantly refine collision probability estimates that are based on optical astrometry alone.
Asteroid 1950 DA's encounter with Earth in 2880: physical limits of collision probability prediction
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Asteroid Radar Astronomy at the Dawn of the New Millennium
This talk will use images, movies, and radar-derived three-dimensional models to present recent highlights of asteroid radar research, concentrating on low-V mission candidates. Additional information is contained in the original extended abstract.
Radar Discovery and Characterization of Binary Near-Earth Asteroids
The radar instruments at Arecibo and Goldstone recently provided the first confirmed discoveries of binary asteroids in the near-Earth population. The physical and orbital properties of four near-Earth binary systems are described in detail. Additional information is contained in the original extended abstract.
The Surface of Titan: Arecibo Radar Observations
The Arecibo 12.6 cm radar system was used to observe Titan in 1999, 2000 and 2001. The mean value of the radar albedo is 0.16 and the polarization ratio is 0.35. For some longitudes the echo has a specular component although most of the echo power is contained in a diffuse component. Additional information is contained in the original extended abstract.
Groundbased Radar Investigations of Asteroids and Planetary Satellites
Radar is a powerful source of information about the physical and dynamical properties of solar system bodies. Radar-detected targets include the Moon, Mercury, Mars, Venus, Phobos, Io, Europa, Ganymede, Callisto, Titan, Iapetus, Saturn's rings, eight comets, and 179 asteroids (75 main-belt and 104 near-Earth). This talk offers a perspective on the disc-integrated radar properties of solar system bodies and then turns to what radar remote sensing can tell us about asteroids using spatially-resolved measurements.
Radar observations of asteroid 25143 (1998 SF36)
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