VELOCITY DISTRIBUTIONS OF THE INTERPLANETARY PLASMA DETECTED BY EXPLORER 10
The plasma data recorded by the explorer x with regard to the velocity and angular distribution of the plasma ions
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The plasma data recorded by the explorer x with regard to the velocity and angular distribution of the plasma ions
Analysis of plasma data recorded by explorer x with regard to velocity and angular distribution of plasma ions
This research explores sonification as a useful tool for space science data exploration. Our interest lies in basic scientific analysis of plasmas of the ionosphere, of interplanetary space and of the interstellar medium. These plasmas all contain irregularities. Propagation of electromagnetic waves, like optical or radio waves, through a medium with random fluctuations in refractive index results in amplitude and phase fluctuations (Scheuer 1968). These variations may be displayed via sonification, using changes in sounds to represent the data variations. This is particularly useful extending science to the visually-impaired. The xSonify Java-based tool was developed to explore sonification techniques and its value for general science analysis and also assistive technology.
Polar Cap Boundary Layer waves are ELF/VLF electric and magnetic waves detected on field lines adjacent to the polar cap, thus their name.
The following represents trajectory sensor development work for the space-station-based Cosmic Dust Collection Facility (CDCF). This facility-class payload was to expose some 7 sq m of NASA-provided general-user instruments in addition to three instruments provided by formally selected principal investigators. The preferred trajectory sensor for this general-user instrument envisioned the detection of impact-triggered plasma for both velocity measurement and location instruments. Space station developments in late 1992/early 1993 lead to cancellation of this potential flight project, for both technical and fiscal reasons. This precipitated termination of all plasma detection work at JSC on behalf of CDCF's general-user instrument. The following comprises three informal reports that summarize the CDCF efforts regarding plasma sensing for trajectory determinations. The reports were initially written for internal CDCF use and were not widely distributed. Because no formal publications are envisioned at present, the three reports are included in full in this document. They not only demonstrate that substantial progress was accomplished in the development of plasma trajectory sensors during 1990-1992, but the results are hopefully of interest and use to others who may continue these developments. The chronological sequence of these three reports is reversed, with the first containing the latest information.
We show direct evidence for the same very hot plasma being detected remotely from SOHO in the corona and subsequently, at Ulysses in the solar wind. This is, to our knowledge, the first time that such an unambiguous identification has been made in the case of hot plasma. This detection complements studies correlating other plasma and field properties observed to the properties measured at the source in the corona. This observation takes advantage of a SOHO-Sun-Ulysses quadrature, during which the Sun-Ulysses included angle is $90^\circ$ and it is possible to observe with Ulysses instruments the same plasma that has previously been remotely observed with SOHO instruments in the corona on the limb of the Sun. The identification builds on an existing base of separate SOHO and interplanetary detections of hot plasma. SOHO/UVCS has found evidence for very hot coronal plasma in current sheets in the aftermath of CMEs in the [Fe XVIII] $\lambda$ \AA\ line, implying a temperature on the order of $6\times 10(exp 6)$ K. This temperature is unusually high even for active regions, but is compatible with the high temperature predicted in current sheets. In the solar wind, ACE data from early 1998 to middle 2000 revealed high frozen-in Fe charge state in many cases to be present in interplanetary plasma.
The ISEE-3 plasma wave instrument detects associated bursts of electron plasma oscillations and whistler mode waves at an average rate of event one every two days. The plasma wave measurements give the electron number density, and simultaneously measured E and B amplitudes are used to deduce an index of refraction consistent with whistler mode propagation for the measured number density and magnetic field. Burst durations are a few minutes, with some trains of bursts lasting up to an hour. Individual spectral scans (two per second) reveal that the whistler and plasma wave amplitude-time profiles differ within a burst. Peak plasma wave amplitudes are near one mV/m, and the peak whistler mode energy density exceeds that of the plasma oscillations by about a factor 100. The frequency of the whistler mode wave observed in one well diagnosed event agrees with the predictions of the heat flux whistler instability theory. The associated plasma wave instability probably requires a bump-on-tail feature in the heat flux electron component, possibly due to impulsive heating elsewhere on the field-line connecting to ISEE-3.
It has recently been suggested that Io is an important source of ions for the plasma detected by Pioneer 10 in the inner magnetosphere of Jupiter. Assuming this to be true, we show that near the orbit of Io the central collector of the Pioneer-10 plasma instrument could detect only inwardly diffusing ions created at a radial distance greater than that of the spacecraft. The rapid decrease in ion density observed beyond Io's orbit is attributed, at least partially, to this effect and thus may not represent a real plasma boundary such as a 'plasmapause'. Instead, the drop in observed ion density could correspond to a decrease in the density of Io-associated neutral particles orbiting Jupiter.
Voyager 1 measurements of wave-particle interactions of Jupiter's bow shock are reported. Some of the wave phenomena detected during the spacecraft's third inbound passage are discussed. The results indicate that the Jovian magnetosheath was characterized by a virtual absence of detectable plasma wave turbulence after passage through the bow shock and that there were impulsive wave structures within the shock with durations as small as 1, 2, or 3 sec.
Possible relationships of cometary brightness outbursts with the solar wind and interplanetary magnetic field are examined. Two types of outburst are distinguished: those which involve a significant brightening of both the head and the tail in a comet with a conspicuous plasma tail (Class I), and those involving the brightening of the central condensation of a previously faint comet with no detectable plasma tail (Class II). Class I bursts, as exemplified by Comet Morehouse 1908c, are attributed to the generation in the head of enhanced amounts of ions and their injection into the tail shortly before it disconnects, with ionization provided by sector boundary crossings. Class II events, as exhibited by Comet P/Tuttle-Giacobini-Kresak 1973b, are interpreted as the result of the bombardment of the nucleus by disturbed solar wind near corotated high-speed streams and sector boundaries, leading to highly exothermic chemical reactions.
The results are presented of the survey of known shell stars detected by the Infrared Astronomy Satellite (IRAS) at sufficient bandpasses to permit evaluation of the nature of the infrared excess, and having archival International Ultraviolet Explorer (IUE) high dispersion spectra suitable for identifying stars with infalling circumstellar plasma. Detection of infall in shell stars with infrared signatures of circumstellar dust is described. One star which shows infalling plasma, but apparently no circumstellar dust is described. The implications for the understanding of Beta Pictoris and similar systems are discussed.
The evidence from the Pioneer 10 plasma analyzer that plasma derived from Europa was present in the Jovian magnetosphere in December 1973 is summarized. Plasma detected between 1900 UT and 2100 UT on December 3, 1973, reveals a number of significant phenomena near the expected position of Europa's L shell. Mass addition to the magnetospheric plasma is indicated by a local increase in density apparently superimposed on the density gradient of Iogenic plasma. This increase in plasma density is unlike any phenomenon observed when the spacecraft is near a lunar L shell. The density shows fluctuations that make possible an estimate of the net outflow speed of magnetospheric ions per Jovian rotation. A radial flow speed in 1973 of 0.37 km/s from the Pioneer data is made, together with an estimate of 1 km/s in 1979 from Voyager 2 data, thus indicating a significant change.
The voyager 2 spacecraft begins its initial observations of Uranus November 4, 1985, and makes its final observation February 25, 1996. The data from the infrared interfermometer spectrometer, photopolarimeters, plasma wave, plasma detecter, and ultraviolet spectrometer will be processed to add a large block of infermation to the small amount already known. The trajectory of Voyager 2 is also discussed.
A summary is presented of the results of experiments on the Spacelab 2 mission, which was flown on the Shuttle Orbiter between July 29 and August 6, 1985. The background and flight of the mission and the payload configuration are examined. The experiments include the Ejectable Plasma Diagnostics Package, Vehicle Charging and Potential Experiment, and plasma detection experiments. Life science experiments include studies of the effects of spaceflight on the growth of plant tissues and perturbations of bone and calcium homeostasis in flight crew members. Solar studies include the Solar UV Spectral Irradiance Monitor, the Coronal Helium Abundance Spacelab Experiment, the High Resolution Telescope and Spectrograph, the Solar Magnetic and Velocity Field Measurement System, and the Solar Optical Universal Polarimeter. Additional experiments include observations with a small He-cooler IR telescope, Hard X-ray imaging of galaxy clusters and extended X-ray sources, the composition and energy spectra of cosmic ray nuclei, and the properties of superfluid He in zero gravity.
Industry and university participants have joined together to form the IMPA:Ct consortium (In-situ Monitors of the Particulate Ambient: Circumterrestrial) which offers a broad range of flight qualified instruments for monitoring the small particle (0.1 micron to 10 cm) environment in space. Instruments are available in 12 months or less at costs ranging from 0.5 to 1.5 million dollars (US) for the total program. Detector technologies represented by these groups are: impact-induced capacitor-discharge (MOS, metal-oxide-silicon), cratering or penetration of electroactive thin film (polyvinylidene fluoride (PVDF)), impact-plasma detection, acoustic detection, CCD tracking of optical scatter of sunlight, and photodiode detection of optical scatter of laser light. The operational characteristics, general spacecraft interface and resource requirements (mass/power/telemetry), cost and delivery schedules, and points of contact for seven different instruments are presented.
Several related topics are briefly discussed. Reviewed here is work on an investigation of plasma wave phenomena associated with the question of lightning on Venus. The work supported the contention that lightning is at least a candidate explanation for many of the 100 Hz-only Pioneer Venus orbital electric field detector (OEFD) signals. A review of the work on the investigation of mechanisms other than lightning to explain certain wideband plasma wave bursts detected in the Venusian nightside ionosphere is given. A summary is given of our analysis of data from 23 OEFD observing periods as well as a discussion of the properties of specifically multifrequency events. Our opportunity to work on this topic was not sufficient to draw any firm conclusions about the origins of the multifrequency bursts, but we call attention to what we consider to be several candidate sources. Also discussed are case studies to test for evidence of whistler mode propagation from subionospheric sources, results of a search for dispersive effects in the OEFD data, the results for a search for simultaneous 100 Hz and 730 Hz observations at altitudes below 150 km, changes with altitude in dispersive broadening effects in the time signatures of 100 Hz bursts, and a survey of activity at altitudes above 1000 km.
On January 19, 1972, in situ measurements by Explorer 45, orbiting in the magnetosphere near the equatorial plane, and ISIS 2, in a circular polar orbit at 1400 km, simultaneously detected patches of enhanced ionization outside the main body of the plasmasphere. The magnetospheric plasma region extended between (geomagnetic latitude) L values 3.4-4.8 and the ionospheric electron density enhancement extended between L values 3.6-4.4. The two plasma features were detected near 22 hours magnetic local time (MLT). Based on a number of observations, it is inferred that the plasma density enhancement persisted for more than 5 hours and extended over at least 2 hours in MLT near L = 5. These results provide experimental evidence that some detached magnetospheric plasma regions are signatures of a flux tube containing enhanced ionization throughout a volume extending from the topside ionosphere out to the equator.
Theoretical feasibility of detecting laser radiation scattered from plasma