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Gloeckler, G.

Publications and source records attributed to Gloeckler, G..

At least 19 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS2012

Heliospheric Neutral Atom Spectra Between 0.01 and 6 keV fom IBEX

Since 2008 December, the Interstellar Boundary Explorer (IBEX) has been making detailed observations of neutrals from the boundaries of the heliosphere using two neutral atom cameras with overlapping energy ranges. The unexpected, yet defining feature discovered by IBEX is a Ribbon that extends over the energy range from about 0.2 to 6 keV. This Ribbon is superposed on a more uniform, globally distributed heliospheric neutral population. With some important exceptions, the focus of early IBEX studies has been on neutral atoms with energies greater than approx. 0.5 keV. With nearly three years of science observations, enough low-energy neutral atom measurements have been accumulated to extend IBEX observations to energies less than approx. 0.5 keV. Using the energy overlap of the sensors to identify and remove backgrounds, energy spectra over the entire IBEX energy range are produced. However, contributions by interstellar neutrals to the energy spectrum below 0.2 keV may not be completely removed. Compared with spectra at higher energies, neutral atom spectra at lower energies do not vary much from location to location in the sky, including in the direction of the IBEX Ribbon. Neutral fluxes are used to show that low energy ions contribute approximately the same thermal pressure as higher energy ions in the heliosheath. However, contributions to the dynamic pressure are very high unless there is, for example, turbulence in the heliosheath with fluctuations of the order of 50-100 km/s.

Fuselier, S. A.↗
NASA NTRS2008

Messenger Observations of Mercury's Bow Shock and Magnetopause

The MESSENGER spacecraft made the first of three flybys of Mercury on January 14.2008 (1). New observations of solar wind interaction with Mercury were made with MESSENGER'S Magnetometer (MAG) (2.3) and Energetic Particle and Plasma Spectrometer (EPPS) - composed of the Energetic Particle Spectrometer (EPS) and Fast Imaging Plasma Spectrometer (FIPS) (3,4). These MESSENGER observations show that Mercury's magnetosphere has a large-scale structure that is distinctly Earth-like, but it is immersed in a comet-like cloud of planetary ions [5]. Fig. 1 provides a schematic view of the coupled solar wind - magnetosphere - neutral atmosphere - solid planet system at Mercury.

Slavin J. A.↗
NASA NTRS2008

MESSENGER Observations of Mercury's Bow Shock and Magnetopause

MESSENGER'S 14 January 2008 encounter with Mercury will provide the first new observations of the solar wind interaction with this planet since the Mariner 10 flybys that took place over 30 years ago. The closest approach distance for this first MESSENGER flyby is targeted for an altitude of 200 km as compared with the 707 km and 327 km attained by Mariner 10 on 29 March 1974 and 16 March 1975, respectively. The locations of the bow shock and magnetopause boundaries observed by MESSENGER will be examined and compared against those found in the earlier Mariner 10 measurements and the predictions of theoretical models and numerical simulations. The structure of the magnetopause will be investigated for the presence of flux transfer events or other evidence of magnetic reconnection as will the more general implications of these new MESSENGER bow shock and magnetopause observations for the global solar wind interaction with Mercury.

Slavin, James A.↗
NASA NTRS2008

MESSENGER and Venus Express Observations of the Near-tail of Venus: Magnetic Flux Transport, Current Sheet Structure, and Flux Rope Formation

At 23:08 UT on 5 June 2007 the MESSENGER spacecraft reached its closest approach altitude (338 km) during its second flyby of Venus en route to its 2011 orbit insertion at Mercury. Whereas no measurements were collected during MESSENGER'S first Venus flyby in October 2006, the Magnetometer (MAG) and the Energetic Particle and Plasma Spectrometer (EPPS) operated successfully throughout this second encounter. Venus provides the solar system's best example to date of a solar wind - ionosphere planetary interaction. We present MESSENGER observations of the near-tail of Venus with emphasis on determining the time scales for magnetic flux transport, the structure of the cross-tail current sheet at very low altitudes (approx. 300 to 1000 km), and the nature and origin of a magnetic flux rope observed in the current sheet. The availability of the simultaneous Venus Express upstream measurements provides a unique opportunity to examine the influence of solar wind plasma and interplanetary magnetic field conditions on this planet's solar wind interaction at solar minimum.

Slavin, James A.↗
NASA NTRS2008

MESSENGER Observation of Mercury's Magnetopause: Structure and Dynamics

MESSENGER'S 14 January 2008 encounter with Mercury has provided new observations of the magnetopause of this small magnetosphere, particularly concerning the effect of the direction of the interplanetary magnetic field (IMF) on the structure and dynamics of this boundary. The IMF was northward immediately prior to and following the passage of the MESSENGER spacecraft through Mercury's magnetosphere. However, several-minute episodes of southward IMF were observed in the magnetosheath during the inbound portion of the encounter. Evidence for reconnection at the dayside magnetopause in the form of well-developed flux transfer events (FTEs) was observed in the magnetosheath following some of these southward-B, intervals. The inbound magnetopause crossing seen in the magnetic field measurements is consistent with a transition from the magnetosheath into the plasma sheet. Immediately following MESSENGER'S entry into the magnetosphere, rotational perturbations in the magnetic field similar to those seen at the Earth in association with large-scale plasma sheet vortices driven by Kelvin-Helmholtz waves along the magnetotail boundary at the Earth were observed. The outbound magnetopause occurred during northward IMF B(sub z) and had the characteristics of a tangential discontinuity. These new observations by MESSENGER may be combined and compared with the magnetopause measurements collected by Mariner 10 to derive new understanding of the response of Mercury's magnetopause to IMF direction and its effect on the rate of solar wind energy and mass input to this small magnetosphere.

Slavin, J. A.↗
NASA NTRS2007

MESSENGER and Venus Express Observations of the Solar Wind Interaction with Venus: A Dual Spacecraft Study

At 23:08 UT on 5 June 2007 the MESSENGER spacecraft reached its closest approach altitude (338 krn) during its second flyby of Venus en route to its 201 1 orbit insertion at Mercury. Whereas no measurements were collected during MESSENGER'S first Venus flyby in October 2006, the Magnetometer (MAG) and the Energetic Particle and Plasma Spectrometer (EPPS) operated successfully throughout this second encounter. Venus provides the solar system's best example to date of a solar wind - ionosphere planetary interaction. Pioneer Venus Orbiter measurements have shown that this interaction affects the upper atmosphere and ionosphere down to altitudes of - 150 km. Here we present an initial overview of the MESSENGER observations during the - 4 hrs that the spacecraft spent within 10 planet radii of Venus and, together with Venus Express measurements, examine the influence of solar wind plasma and interplanetary magnetic field conditions on the solar wind interaction at solar minimum.

Slavin, James A.↗
NASA NTRS2007

Encounter of the Ulysses Spacecraft with the Ion Tail of Comet McNaught

Comet McNaught was the brightest comet observed from Earth in the last 40 years. For a period of five days in early 2007 February, four instruments on the Ulysses spacecraft directly measured cometary ions and key properties of the interaction of the comet's ion tail with the high-speed solar wind from the polar regions of the Sun. Because of the record-breaking duration of the encounter, the data are unusually comprehensive. O3(+) ions were detected for the first time in a comet tail, coexisting with singly charged molecular ions with masses in the range 28-35 amu. The presence of magnetic turbulence and of ions with energies up to approximately 200 keV indicate that at a distance of approximately 1.6 AU from the comet nucleus, the ion tail McNaught had not yet reached equilibrium with the surrounding solar wind.

plasmas↗
NASA NTRS2003

The sun and heliosphere at solar maximum

Recent Ulysses observations from the Sun's equator to the poles reveal fundamental properties of the three-dimensional heliosphere at the maximum in solar activity. The heliospheric magnetic field originates from a magnetic dipole oriented nearly perpendicular to, instead of nearly parallel to, the Sun'rotation axis. Magnetic fields, solar wind, and energetic charged particles from low-latitude sources reach all latitudes, including the polar caps. The very fast high-latitude wind and polar coronal holes disappear and reappear together. Solar wind speed continues to be inversely correlated with coronal temperature. The cosmic ray flux is reduced symmetrically at all latitudes.

magnetic field solar winds galactic cosmic rays↗
NASA NTRS2002

Low-Latitude Solar Wind During the Fall 1998 SOHO-Ulysses Quadrature

Solar and Heliospheric Observatory (SOH0)-Ulysses quadratures occur when the SOHO-Sun-Ulysses-included angle is 90 deg. These offer the opportunity to directly compare properties of plasma parcels, observed by SOHO [Dorningo et al.] in the low corona, with properties of the same parcels measured, in due time, in situ, by Ulysses [ Wenzel et al]. We refer the reader to Suess et al. for an extended discussion of SOHO-Ulysses quadrature geometry. Here it suffices to recall that there are two quadratures per year, as SOHO makes its one-year revolution around the Sun. This, because SOHO is at the L1 Lagrangian point, in essentially the same place as the Earth, while Ulysses is in a near-polar -5-year solar orbit with a perihelion of 1.34 AU and aphelion of 5.4 AU.

Poletto, G.↗
NASA NTRS2002

Support of Data Access for the IMP-8 UMD Experiment

This grant report provides information on data from the Interplanetary Monitoring Platform-8 (IMP-8). Topics covered include: (1) the science involved in the project; (2) the collection of data; (3) the processing of data; (4) the submission of data to other facilities; (5) the availability of data on the world wide web (WWW). Graphs are also included of data on the interstellar medium.

Ipavich, F. M.↗
NASA NTRS2001

Iron Charge Distribution as an Identifier of Interplanetary Coronal Mass Ejections

We present solar wind Fe charge state data measured on the Advanced Composition Explorer (ACE) from early 1998 to the middle of 2000. Average Fe charge states in the solar wind are typically around 9 to 11. However, deviations from these average charge states occur, including intervals with a large fraction of Fe(sup greater or = 16+) which are consistently associated with interplanetary coronal mass ejections (ICMEs). By studying the Fe charge state distribution we are able to extract coronal electron temperatures often exceeding 2 x 10(exp 6) kelvins. We also discuss the temporal trends of these events, indicating the more frequent appearance of periods with high Fe charge states as solar activity increases.

Lepri, S. T.↗
NASA NTRS2001

Low-Latitude Solar Wind During the Fall 1998 SOHO-Ulysses Quadrature

The Fall 1998 SOlar-Heliospheric Observatory (SOHO) - Ulysses quadrature occurred when Ulysses was at 5.2 AU, 17.4 deg South of the equator, and off the West line of the Sun. SOHO coronal observations, at heliocentric distances of a few solar radii, showed that the line through the solar center and Ulysses crossed, over the first days of observations, a dark, weakly emitting area and through the northern edge of a streamer complex during the second half of the quadrature campaign. Ulysses in situ observations showed this transition to correspond to a decrease from higher speed wind typical of coronal hole flow to low speed wind. Physical parameters (density, temperature, flow speed) of the low latitude coronal plasma sampled over the campaign are determined using constraints from what is the same plasma measured later in situ and simulating the intensities of the Hydrogen Lyman-alpha and OVI 1032 and 1037 Angstrom lines, measured by the Ultra Violet Coronagraph Spectrometer (UVCS) on SOHO. The densities, temperatures and outflow speed are compared with the same characteristic flow parameters for high-latitude fast wind streams and typical slow solar wind.

Poletto, G.↗
NASA NTRS2000

Reconnection Remnants in the Magnetic Cloud of October 18-19, 1995: A Shock, Monochromatic Wave, Heat Flux Dropout and Energetic Ion Beam

Evidence is presented that the WIND spacecraft observed particle and field signatures on October 18-19, 1995 due to reconnection near the footpoints of a magnetic cloud (i.e., between 1 and 5 solar radii). These signatures include: (1) an internal shock traveling approximately along the axis of the magnetic cloud, (2) a simple compression of the magnetic field consistent with the footpoint magnetic fields being thrust outwards at speeds much greater than the solar wind speed, (3) an electron heat flux dropout occurring within minutes of the shock indicating a topological change resulting from disconnection from the solar surface, (4) a very cold 5 keV proton beam and (5) an associated monochromatic wave. We expect that, given observations of enough magnetic clouds, Wind and other spacecraft will see signatures similar to the ones reported here indicating reconnection. However, these observations require the spacecraft to be fortuitously positioned to observe the passing shock and other signatures and will therefore be associated with only a small fraction of magnetic clouds. Consistent with this, a few magnetic clouds observed by Wind have been found to possess internal shock waves.

Collier, Michael R.↗
NASA NTRS1998

Here Comes Solar Prove!

Flying a trajectory perpendicular to the Earth-Sun line during its perihelion passage, Solar Probe will use in-situ and imaging instruments to provide the first three dimentional viewing of the corona, direct observations of solar polar regions, and local sampling of the solar environment. These primary observations are complemented by context-setting cruise measurements and Earth-based observations.

solar corona solar wind solar probe heliosphere ph↗