N. Mastrodemos - Academia.edu (original) (raw)
Papers by N. Mastrodemos
Advances in the Astronautical Sciences
The Dawn spacecraft spent over a year in orbit around Vesta from July 2011 through August 2012. I... more The Dawn spacecraft spent over a year in orbit around Vesta from July 2011 through August 2012. In order to maintain the designated science reference orbits and enable the transfers between those orbits, precise and timely orbit determination was required. Challenges included low-thrust ion propulsion modeling, estimation of relatively unknown Vesta gravity and rotation models, tracking data limitations, incorporation of real-time telemetry into dynamics model updates, and rapid maneuver design cycles during transfers. This paper discusses the dynamics models, filter configuration, and data processing implemented to deliver a rapid orbit determination capability to the Dawn project.
The Astrophysical Journal, 1996
One of the most plausible scenarios for the formation of asymmetric molecular envelopes from AGB ... more One of the most plausible scenarios for the formation of asymmetric molecular envelopes from AGB stars and bipolar preplanetary nebulae, involves a mass losing red giant in the presence of a binary companion in a detached or common envelope configuration. The likelihood of the detached binary system scenario in the formation of asymmetric and bipolar flows is assessed by constructing 3-Dimensional Smooth Particle Hydrodynamic wind models. We investigate the effects of the binary companion, on an otherwise spherically symmetric dust-driven wind, as a function of the binary mass ratio and separation and we examine the importance of various heating and cooling mechanisms. We also produce models of outflows emanating from a tidally spun-up primary. In particular we examine whether appropriate conditions can arise that will allow the formation of an accretion disk around the secondary and of an exterior disk beyond the outer Lagrangian point of the system as proposed by Morris (1987,PASP...
The Astrophysical Journal, 1998
We have observed the field of the gamma-ray burst GRB 970508 at infrared wavelengths (2.2 mm) and... more We have observed the field of the gamma-ray burst GRB 970508 at infrared wavelengths (2.2 mm) and have found a variable source coincident with the visible transient thought to be associated with the burst. The source was decaying in brightness with K s magnitudes of , , and mag on May 13.25, 18.2 ע 0.1 18.8 ע 0.1 19.0 ע 0.3 16.25, and 20.21 UT, respectively. A 1 j upper limit of mag was obtained for the brightness of the K ϭ 21.3 source on June 14.27 UT. The infrared light curve during this period is consistent with a ∼t Ϫ1.2 power law, similar to the visible light curve. We do not find evidence for extended structure around the burst, as has been claimed for GRB 970228, and we obtain an upper limit of 0.04L * for the luminosity of an underlying galaxy at the position of the infrared transient.
The Astrophysical Journal, 1998
Mass-losing giant stars and objects in transition to planetary nebulae often display a bipolar sy... more Mass-losing giant stars and objects in transition to planetary nebulae often display a bipolar symmetry in their outÑowing circumstellar envelopes. Here we initiate a detailed study of the hypothesis that the observational characteristics of asymmetric and bipolar preplanetary nebulae result from the e †ects of a detached binary companion upon the otherwise spherical wind of a single mass-losing star. We follow the gas Ñows in this system using three-dimensional smoothed particle hydrodynamics models. In this Ðrst work we describe the dusty wind models and the numerical procedure employed, and we address the issue of wind accretion and the formation of accretion disks about the binary companion to the mass-losing giant as a function of wind velocity and binary separation. In all of our models, we Ðnd that permanent, stable accretion disks of various sizes form around the binary companion. The disks are geometrically thin, and their equilibrium structure has elliptical streamlines with a range of eccentricities. Our results also indicate that such disks may be susceptible to tilt or warping instabilities. We also Ðnd that wind accretion in such binaries is stable, displaying no evidence for any type of Ñip-Ñop instability.
On January 2, 2004, the STARDUST spacecraft flew by the short period comet P/Wild 2 at a distance... more On January 2, 2004, the STARDUST spacecraft flew by the short period comet P/Wild 2 at a distance of 237 km. The primary goal of the flyby was to collect samples of the coma and return them to Earth on January, 2006. An additional goal was to shutter images of the nucleus during the flyby. In order to meet these
Lunar topography is being created at several hundred meter resolution by applying stereophotoclin... more Lunar topography is being created at several hundred meter resolution by applying stereophotoclinometry to Clementine and Lunar Orbiter images. This will provide a framework for the rapid inclusion of data from current and upcoming missions.
Topography of the lunar poles, constructed using stereophotoclinometry (SPC) and Clementine image... more Topography of the lunar poles, constructed using stereophotoclinometry (SPC) and Clementine images, is compared with results from LOLA and LRO wide-angle camera analyses.
Proceedings of the International Astronomical Union, 2012
ABSTRACT We report the global photometric properties of Vesta in the visible and near-infrared wa... more ABSTRACT We report the global photometric properties of Vesta in the visible and near-infrared wavelengths derived from Dawn data.
Detailed global and local digital topographies of eight of Saturn's satellites are being cons... more Detailed global and local digital topographies of eight of Saturn's satellites are being constructed from ensembles of overlapping maplets which completely cover the visible surfaces. Each maplet is a digital representation of a piece of the surface topography and albedo constructed from imaging data with stereophotoclinometry. Multiple images projected onto the maplet provide brightness values at each pixel which are used in a least-squares estimation for slope and relative albedo. The slopes are then integrated to produce the topography solution. The central pixel of each maplet represents a control point, and the ensemble of these points is used in an estimation for their body-fixed locations, the rotational state of the body, and the position and attitude of the spacecraft. Applications of these data products include studies of cratering of icy bodies and the subsequent relaxation of the surface, while detailed shapes for the small, irregular satellites can be used to predic...
ABSTRACT This year two spacecraft, MESSENGER and Dawn, were placed into orbit around Mercury and ... more ABSTRACT This year two spacecraft, MESSENGER and Dawn, were placed into orbit around Mercury and the asteroid Vesta, respectively. We have been using stereophotoclinometry (SPC) to analyze MESSENGER and Dawn images both for navigation and to determine the precise shapes and topography of these bodies. Because SPC requires images at different local Sun elevations and azimuths to distinguish between albedo and topographic variations, Mercury presents the challenges of a slow spin rate and a long solar day. Vesta, on the other hand, rotates more than four times per Earth day, allowing a given area of surface to be viewed under rapidly changing illumination and topographic information to be built up rapidly. The essence of SPC is that small pieces of surface called maplets and modeled with digital elevation and albedo are illuminated and correlated with images. Hundreds of these maplets are found in each image, providing a valuable data type for spacecraft navigation. Hundreds of images go into the construction of each maplet, and the resulting multi-image stereo over a wide range of viewing conditions provides a precise determination of the maplet's body-fixed position. The construction of topography with SPC uses each pixel, allowing resolutions comparable to the images themselves. Mercury's topography varies by about 5 km above and below that of a sphere of radius 2440 km. We compare the SPC-derived shape and topography with data from MESSENGER's Mercury Laser Altimeter (MLA). Vesta, although a tenth of Mercury's size, exhibits variations in elevation between 17 km below and 12 km above the equipotential that best matches its surface. The lowest areas lie on the floor of the south polar impact crater, and the highest points lie on the crater's rim.
Space Science Reviews, 2011
Page 1. Space Sci Rev DOI 10.1007/s11214-011-9863-z The Dawn Topography Investigation CA Raymond ... more Page 1. Space Sci Rev DOI 10.1007/s11214-011-9863-z The Dawn Topography Investigation CA Raymond · R. Jaumann · A. Nathues · H. Sierks · T. Roatsch · F. Preusker · F. Scholten · RW Gaskell · L. Jorda · H.-U. Keller · MT Zuber · DE Smith · N. Mastrodemos · S. Mottola ...
Review of Scientific Instruments, 2008
Advances in the Astronautical Sciences
The Dawn spacecraft spent over a year in orbit around Vesta from July 2011 through August 2012. I... more The Dawn spacecraft spent over a year in orbit around Vesta from July 2011 through August 2012. In order to maintain the designated science reference orbits and enable the transfers between those orbits, precise and timely orbit determination was required. Challenges included low-thrust ion propulsion modeling, estimation of relatively unknown Vesta gravity and rotation models, tracking data limitations, incorporation of real-time telemetry into dynamics model updates, and rapid maneuver design cycles during transfers. This paper discusses the dynamics models, filter configuration, and data processing implemented to deliver a rapid orbit determination capability to the Dawn project.
The Astrophysical Journal, 1996
One of the most plausible scenarios for the formation of asymmetric molecular envelopes from AGB ... more One of the most plausible scenarios for the formation of asymmetric molecular envelopes from AGB stars and bipolar preplanetary nebulae, involves a mass losing red giant in the presence of a binary companion in a detached or common envelope configuration. The likelihood of the detached binary system scenario in the formation of asymmetric and bipolar flows is assessed by constructing 3-Dimensional Smooth Particle Hydrodynamic wind models. We investigate the effects of the binary companion, on an otherwise spherically symmetric dust-driven wind, as a function of the binary mass ratio and separation and we examine the importance of various heating and cooling mechanisms. We also produce models of outflows emanating from a tidally spun-up primary. In particular we examine whether appropriate conditions can arise that will allow the formation of an accretion disk around the secondary and of an exterior disk beyond the outer Lagrangian point of the system as proposed by Morris (1987,PASP...
The Astrophysical Journal, 1998
We have observed the field of the gamma-ray burst GRB 970508 at infrared wavelengths (2.2 mm) and... more We have observed the field of the gamma-ray burst GRB 970508 at infrared wavelengths (2.2 mm) and have found a variable source coincident with the visible transient thought to be associated with the burst. The source was decaying in brightness with K s magnitudes of , , and mag on May 13.25, 18.2 ע 0.1 18.8 ע 0.1 19.0 ע 0.3 16.25, and 20.21 UT, respectively. A 1 j upper limit of mag was obtained for the brightness of the K ϭ 21.3 source on June 14.27 UT. The infrared light curve during this period is consistent with a ∼t Ϫ1.2 power law, similar to the visible light curve. We do not find evidence for extended structure around the burst, as has been claimed for GRB 970228, and we obtain an upper limit of 0.04L * for the luminosity of an underlying galaxy at the position of the infrared transient.
The Astrophysical Journal, 1998
Mass-losing giant stars and objects in transition to planetary nebulae often display a bipolar sy... more Mass-losing giant stars and objects in transition to planetary nebulae often display a bipolar symmetry in their outÑowing circumstellar envelopes. Here we initiate a detailed study of the hypothesis that the observational characteristics of asymmetric and bipolar preplanetary nebulae result from the e †ects of a detached binary companion upon the otherwise spherical wind of a single mass-losing star. We follow the gas Ñows in this system using three-dimensional smoothed particle hydrodynamics models. In this Ðrst work we describe the dusty wind models and the numerical procedure employed, and we address the issue of wind accretion and the formation of accretion disks about the binary companion to the mass-losing giant as a function of wind velocity and binary separation. In all of our models, we Ðnd that permanent, stable accretion disks of various sizes form around the binary companion. The disks are geometrically thin, and their equilibrium structure has elliptical streamlines with a range of eccentricities. Our results also indicate that such disks may be susceptible to tilt or warping instabilities. We also Ðnd that wind accretion in such binaries is stable, displaying no evidence for any type of Ñip-Ñop instability.
On January 2, 2004, the STARDUST spacecraft flew by the short period comet P/Wild 2 at a distance... more On January 2, 2004, the STARDUST spacecraft flew by the short period comet P/Wild 2 at a distance of 237 km. The primary goal of the flyby was to collect samples of the coma and return them to Earth on January, 2006. An additional goal was to shutter images of the nucleus during the flyby. In order to meet these
Lunar topography is being created at several hundred meter resolution by applying stereophotoclin... more Lunar topography is being created at several hundred meter resolution by applying stereophotoclinometry to Clementine and Lunar Orbiter images. This will provide a framework for the rapid inclusion of data from current and upcoming missions.
Topography of the lunar poles, constructed using stereophotoclinometry (SPC) and Clementine image... more Topography of the lunar poles, constructed using stereophotoclinometry (SPC) and Clementine images, is compared with results from LOLA and LRO wide-angle camera analyses.
Proceedings of the International Astronomical Union, 2012
ABSTRACT We report the global photometric properties of Vesta in the visible and near-infrared wa... more ABSTRACT We report the global photometric properties of Vesta in the visible and near-infrared wavelengths derived from Dawn data.
Detailed global and local digital topographies of eight of Saturn's satellites are being cons... more Detailed global and local digital topographies of eight of Saturn's satellites are being constructed from ensembles of overlapping maplets which completely cover the visible surfaces. Each maplet is a digital representation of a piece of the surface topography and albedo constructed from imaging data with stereophotoclinometry. Multiple images projected onto the maplet provide brightness values at each pixel which are used in a least-squares estimation for slope and relative albedo. The slopes are then integrated to produce the topography solution. The central pixel of each maplet represents a control point, and the ensemble of these points is used in an estimation for their body-fixed locations, the rotational state of the body, and the position and attitude of the spacecraft. Applications of these data products include studies of cratering of icy bodies and the subsequent relaxation of the surface, while detailed shapes for the small, irregular satellites can be used to predic...
ABSTRACT This year two spacecraft, MESSENGER and Dawn, were placed into orbit around Mercury and ... more ABSTRACT This year two spacecraft, MESSENGER and Dawn, were placed into orbit around Mercury and the asteroid Vesta, respectively. We have been using stereophotoclinometry (SPC) to analyze MESSENGER and Dawn images both for navigation and to determine the precise shapes and topography of these bodies. Because SPC requires images at different local Sun elevations and azimuths to distinguish between albedo and topographic variations, Mercury presents the challenges of a slow spin rate and a long solar day. Vesta, on the other hand, rotates more than four times per Earth day, allowing a given area of surface to be viewed under rapidly changing illumination and topographic information to be built up rapidly. The essence of SPC is that small pieces of surface called maplets and modeled with digital elevation and albedo are illuminated and correlated with images. Hundreds of these maplets are found in each image, providing a valuable data type for spacecraft navigation. Hundreds of images go into the construction of each maplet, and the resulting multi-image stereo over a wide range of viewing conditions provides a precise determination of the maplet's body-fixed position. The construction of topography with SPC uses each pixel, allowing resolutions comparable to the images themselves. Mercury's topography varies by about 5 km above and below that of a sphere of radius 2440 km. We compare the SPC-derived shape and topography with data from MESSENGER's Mercury Laser Altimeter (MLA). Vesta, although a tenth of Mercury's size, exhibits variations in elevation between 17 km below and 12 km above the equipotential that best matches its surface. The lowest areas lie on the floor of the south polar impact crater, and the highest points lie on the crater's rim.
Space Science Reviews, 2011
Page 1. Space Sci Rev DOI 10.1007/s11214-011-9863-z The Dawn Topography Investigation CA Raymond ... more Page 1. Space Sci Rev DOI 10.1007/s11214-011-9863-z The Dawn Topography Investigation CA Raymond · R. Jaumann · A. Nathues · H. Sierks · T. Roatsch · F. Preusker · F. Scholten · RW Gaskell · L. Jorda · H.-U. Keller · MT Zuber · DE Smith · N. Mastrodemos · S. Mottola ...
Review of Scientific Instruments, 2008