Engineering topics

Gladstone, Randy

Publications and source records attributed to Gladstone, Randy.

4 records

NASA NTRS2014

Preliminary Results from a Coordinated Hisaki/Chandra/XMM-Newton Study of the Jovian Aurora and Io Plasma Torus

We present preliminary results from a coordinated Hisaki/Chandra/XMM-Newton observational campaign of the Jovian aurora and Io plasma torus. The data were taken over a three week period in April, 2014. Jupiter was observed continuously with Hisaki, six times with the Chandra/HRC instrument for roughly 12 hours per observation, and twice by XMM-Newton. The goal of this observational campaign was to understand how energy and matter are exchanged between the Jovian aurora, the IPT, and the Solar wind. X-ray observations provide key diagnostics on highly stripped ions and keV electrons in the Jovian magnetosphere. We use the temporal, spatial, and spectral capabilities of the three instruments to search for correlated variability between the Solar wind, the EUV-emitting plasma of the IPT and UV aurora, and the ions responsible for the X-ray aurora. Preliminary analysis suggests a strong 45 min periodicity in the EUV emission from the electron aurora. There is some evidence for complex variability of the X-ray auroras on scales of tens of minutes. There is also clear morphological changes in the X-ray aurora that do not appear to be correlated with either variations in the IPT or Solar wind.

Kraft, Ralph↗

NASA NTRS2008

The New Horizons Mission to Pluto and Flyby of Jupiter

New Horizons (NH) is NASA's mission to provide the first in situ reconnaissance of Pluto and its moons Charon, Nix, and Hydra. The NH spacecraft will reach Pluto in July 2015 and will then, if approved for an extended mission phase, continue on to a flyby encounter with one or more Kuiper belt objects (KBOs). NH was launched on 19 January 2006 and received a gravity assist during a flyby encounter with Jupiter (with closest approach at -32 RJ on 28 February 2007) that reduced its flight time to Pluto by 3 years. During the Jupiter flyby, NH collected a trove of multi-wavelength imaging and fields-and-particles measurements. Among the many science results at Jupiter were a detection of planet-wide mesoscale waves, eruptions of atmospheric ammonia clouds, unprecedented views of Io's volcanic plumes and Jupiter's tenuous ring system, a first close-up of the Little Red Spot (LRS), first sightings of polar lightning, and a trip down the tail of the magnetosphere. In 2015, NH will conduct a seven-month investigation of the Pluto system culminating in a closest approach some 12,500 km from Pluto's surface. Planning is presently underway for the Pluto encounter with special emphasis on longidentified science goals of studying the terrain, geology, and composition of the surfaces of Pluto and Charon, examining the composition and structure of Pluto's atmosphere, searching for an atmosphere on Charon, and characterizing Pluto's ionosphere and solar wind interaction. Detailed inspections will also be performed of the newly discovered satellites Nix and Hydra. Additionally, NH will characterize energetic particles in Pluto's environment, refine the bulk properties of Pluto and Charon, and search for additional satellites and rings.

Stern, Alan↗

NASA NTRS2005

A Comparative View of X-rays from the Solar System

With the advent of sophisticated X-ray observatories, viz., Chandra and XMM-Newton, the field of planetary X-ray astronomy is advancing at a faster pace. Several new solar system objects are now know to shine in X-rays at energies generally below 2 keV. Jupiter, Saturn, and Earth, all three magnetized planets, have been observed by Chandra and XMM-Newton. At Jupiter, both auroral and non-auroral disk X-ray emissions have been observed. The first soft X-ray observation of Earth's aurora by Chandra shows that it is highly variable. X-rays have been detected from Saturn's disk, but no convincing evidence of X-ray aurora has been seen. Several comets have been observed in X-rays by Chandra and XMM-Newton. Cometary X-rays are produced due to change exchange of solar wind ions with cold cometary neutrals. Soft X-rays have also been observed from Venus, Mars, Moon, Io, Europa, Io plasma torus, and heliosphere. The non-auroral X-ray emissions from Jupiter, Saturn, and Earth, and those from sunlit disk of Mars, Venus, and Moon are produced due to scattering of solar X-rays. The spectral characteristics of X-ray emission from comets, heliosphere, darkside of Moon, and Martian halo are quite similar, but they appear to be quite different from those of Jovian auroral X-rays. The X- ray aurora on Earth is generated by electron bremsstrahlung and on Jupiter by precipitation of highly-ionized energetic heavy ions. In this paper we will present a comparative overview of X-ray emission from different solar system objects and make an attempt to synthesize a coherent picture.

Bhardwaj, Anil↗

NASA NTRS2004

Aurora and Non-Auroral X-ray Emissions from Jupiter: A Comparative View

Jovian X-rays can be broadly classified into two categories: (1) auroral emission, which is confined to high-latitudes (approximately greater than 60 deg.) at both polar regions, and (2) dayglow emission, which originates from the sunlit low-latitude (approximately less than 50 deg.) regions of the disk (hereafter called disk emissions). Recent X-ray observations of Jupiter by chandra and XMM-Newton have shown that these two types of X-ray emission from Jupiter have different morphological, temporal, and spectral characteristics. In particular: 1) contrary to the auroral X-rays, which are concentrated in a spot in the north and in a band that runs half-way across the planet in the south, the low-latitude X-ray disk is almost uniform; 2) unlike the approximately 40 plus or minus 20-min periodic oscillations seen in the auroral X-ray emissions, the disk emissions do not show any periodic oscillations; 3) the disk emission is harder and extends to higher energies than the auroral spectrum; and 4) the disk X-ray emission show time variability similar to that seen in solar X-rays. These differences and features imply that the processes producing X-rays are different at these two latitude regions on Jupiter. We will present the details of these and other features that suggest the differences between these two classes of X-ray emissions from Jupiter, and discuss the current scenario of the production mechanism of them.

Bhardwal, Anil↗