TABLE OF CONTENTS
The Space Physics Group (SPG) studies the chain of energy transport from the surface of the sun to its eventual arrival in planetary stratospheres. It uses interplanetary measurements to investigate the structure of coronal mass ejections and their evolution in space. It uses Galileo observations to understand energy and mass transport in the jovian magnetosphere, and the secular variation of the jovian magnetic field. It studies the data received from the Cassini mission on its way to Saturn both to understand the physical process occurring at planetary bodies and to understand the structure and dynamics of the magnetized plasmas in interplanetary space. It uses Polar observations throughout the magnetosphere to understand how the solar wind couples to the Earth's magnetosphere and the magnetosphere couples to the ionosphere. It uses measurements from the FAST mission to determine the microprocess occurring in that coupling region. It is working with the University of Newcastle to investigate current systems and waves in the low altitude magnetosphere with the FedSat mission. It studies magnetic pulsations both to determine their origin and to use them as diagnoses of the state of the magnetosphere and it uses numerical simulations both as an extrapolation of localized data and as a tool to investigate magnetospheric behavior. The SPG is also preparing the data dissemination system for the IMPACT investigation on the STEREO mission to be launched in 2006 and installing an array of magnetometers across North America to support the THEMIS mission to be launched in 2006. The Dawn mission to Vesta and Ceres led by C. T. Russell and planned to be launched in 2006. The Space Physics Group plays a vital role in the community in disseminating the observations from current and past space missions, maintaining communications within the field, educating students of space physics through textbooks and software, interacting with visitors and training students. In the sections below we discuss the achievements of the SPG over the period July 2003 to June 2004 in the areas of instrumentation, research, dissemination of data, communication, education, visiting scientists and students.
In December 2002 the Australian government launched a microsatellite to celebrate their 100th anniversary and to demonstrate their scientific and technical prowess. The UCLA engineering team assembled, tested and delivered the magnetometer to Australia and helped install it on the spacecraft. The magnetometer continues to operate flawlessly.
The fifth project of the New Millennium Program is a three spacecraft mini-satellite mission in the Earth's magnetosphere. UCLA was selected to provide the magnetometers for this program. This is an important project to the group because it enables us to improve and modernize our design and it will eventually provide good data for studying processes in the magnetosphere. Finally, it keeps our magnetometer group competitive for future mission opportunities.
ST5 is one of the technology projects developed by NASA as part of its New Millenium Program. The magnetometers to be flown on ST5 take the classical fluxgate design as developed by the Space Physics Group, and apply new technology to the design to reduce the power, mass and size of the magnetometer. This effort includes building smaller (50 g) sensors, and moving much of the design out of the analog domain into the digital domain. This involves the use of "surface-mount" technologies, as well as flying new 20 bit analog/digital converters. As a result of the effort, UCLA will have built and flown the next generation flight-qualified fluxgate magnetometers that will in turn be the prime candidates for flight on missions such as the "Magnetospheric Constellation." Robert J. Strangeway is the Principal Investigator for this effort. Launch of ST-5 is currently scheduled for 2005. The first flight unit was delivered to NASA/GSFC in May 2004. Flight Units 2 and 3 are currently being fabricated.
The SPG has developed an inexpensive, high precision and accurately timed magnetometer for terrestrial ground-based studies. These magnetometers have been deployed in four different "arrays". The first array is the Sino Magnetic Array at Low Latitudes that consists of 14 magnetometers in a 2-D array across China. The second array is a chain of seven magnetometers that are being installed by M. Moldwin along the eastern seaboard of the U.S. in the MEASURE array. The third array is the IGPP/LANL array that is intended to ultimately cover the western U.S. At present there are six operating stations in San Gabriel, CA; Los Alamos, NM; the Air Force Academy; Colorado Springs, CO; Boulder, CO; Minneapolis, MN, and at Teoloyucan, Mexico. Finally there is a loose-knit global array with sites in Jicamarca, Peru; Ethiopia; and Tlamacas, Mexico. These magnetometers have now been used in innumerable studies including sounding the density of the plasmasphere, sudden impulse propagation and Pi2 timing of substorms. In addition, a new effort named Mid-continent Magnetoseismic Chain (McMAC) has started to build nine new stations in the United States and Mexico and connect the Fort Churchill Line of CANOPUS Array and a few existing IGPP magnetometer stations. This 4-year project led by Peter Chi is funded by NSF, and it will make use of the two methods of “magnetoseismology” on McMAC data to obtain the density distribution of the magnetosphere. Finally, UCLA has been asked to build 10 “EPO” magnetometers and 10 “Observatory” magnetometers for the THEMIS project. The EPO magnetometers will be installed in schools in the northern US and the observatory magnetometer in Canada.
The electronics laboratory has developed a protyping facility in the Geology Building basement. This facility allows ideas to be rapidly taken from concept to hardware.
Interplanetary Coronal Mass Ejections (ICMEs) are being studied using the solar cycle long data base obtained from Pioneer Venus and using multipoint datasets obtained from chance encounters of Pioneer Venus, ISEE, NEAR, Wind and ACE spacecraft. We continue to develop methods for diagnosing ICME properties including examining plasma properties such as cool ion temperatures and declining velocity profiles indicative of flux rope expansion.
The Space Physics Group is presently involved in two planetary magnetospheric missions: Galileo that was in orbit about Jupiter from December 1995 to September 2003 and Cassini on its way to Saturn for an arrival in July 2004. Prior to encounter the activities associated with the Cassini mission consist principally of software development and mission planning. We are also working with N. Omidi of UCSD and X. Blanco-Cano of UNAM, using hybrid simulations to model solar wind-magnetosphere interactions of different scale sizes. The hybrid code follows ion motion but assumes the electrons act as a massless fluid. The simulations reveal that the magnetospheres pass through phase transitions and the processes change as the magnetosphere gets stronger.
The Galileo activities resulted in major increases in our understanding of the jovian magnetosphere. In a series of papers we were able to show that the mass addition of Io leads to a radial outward flow of plasma that moves slowly outward at first but then accelerates as it moves outward. Signatures seen near Europa indicate that the flow is moving at close to 500 m/s there. At about 25 jovian radii this has increased to about 10 km/s and at 50 radii about 50 km/s. The plasma then flows down the magnetotail but does not take the magnetic flux with it because reconnection takes place episodically. These reconnection events create magnetic islands that transport no net magnetic flux but do transport ions. The ions on these islands are lost from the tail of the magnetosphere and the emptied magnetic flux tubes return to the inner magnetosphere. They appear to move inward because they are buoyant, being empty, and centrifugal force pulls the heavier full flux tubes outward. These empty flux tubes appear also to be small and to move inward relatively rapidly.
In 1999 the Galileo spacecraft finally returned to Io again and in a series of passes mapped out the region of ion cyclotron wave growth. This pattern indicated that cross field transit by neutrals must play an important role in the emplacement of the ions of the Io torus. A simulation of this process has been developed that enables us to test assumptions about the mass addition process and determine their consequences. These observations also revealed the presence of SO and S as well as the previously detected SO2 in the upper atmosphere of Io. These signals vary from pass to pass in a manner that suggests that the Io atmosphere itself is time varying.
The orbit of Galileo also provides data useful for the study of the secular variation of the jovian magnetic field. Pioneer 11 provided an excellent baseline for the later Galileo data. The ability of a spacecraft to probe the magnetic field depends very critically on its orbit. The initial orbits of Galileo were appropriate for studies of the dipole field but not until orbit C22 did Galileo begin to resolve the quadrupole terms sufficiently accurately to determine if there had been any change in the field since the Pioneer 11 measurements. Galileo's advantage over previous missions is that it makes multiple passes through the magnetosphere and can smooth out statistical fluctuations in noise sources. Thus Galileo provides a much improved measurement over missions such as Voyager and Ulysses. Thus far Galileo has provided a new estimate for the rotating period of Jupiter, shown that there is a change in the tilt of the dipole magnetic moment and that the secular change in the quadrupolar field is similar to that on Earth. Galileo ceased operations by impacting Jupiter on September 21, 2003.
The study of the terrestrial magnetosphere is centered principally around the POLAR and FAST missions with some retrospective studies of ISEE measurements. On POLAR we initially concentrated on understanding the formation of the polar cusp and how the polar cusp is controlled by the conditions in the solar wind, as the tilt of the Earth's dipole axis to the solar wind flow. We have shown that the pressure in the cusp plasma is directly controlled by the solar wind dynamic pressure incident along the normal to the surface of the cusp. When the solar wind pressure drops to low values the magnetosphere becomes dipolar and the fluctuations cease but the field-aligned currents remain constant.
Using Polar data, we have also examined effects of the equatorial ring current and the magnetopause current in the magnetic field observations in the magnetosphere. A preliminary map of the depression in the magnetosphere field at varying Dst levels and as a function of radius and latitude and local time has been created from databases of ISEE, CCE and POLAR data. In a separate study we have examined the effect of pressure changes in the solar wind on the magnetosphere. We have found that the magnetic field does not increase everywhere but that near noon principally off the equator and on the dayside the magnetic field decreases when the solar wind compresses the magnetosphere. ULF waves are also frequently amplified when these compressions occur.
Next we examined the strength of currents flowing into the auroral oval from the magnetosphere as a function of the interplanetary electric field and the solar illumination of the ionosphere. The currents do not depend on the interplanetary electric field if it is from dusk-to-dawn but they do vary proportional to the dawn-to-dusk field. Also currents are twice as strong into the dayside ionosphere as on the nightside.
Most recently we examined the distortions and variations of the magnetic field observed. When Polar was in the current sheet near local midnight when the apogee of Polar rotated into the equatorial plane.
In recent years one of the main focuses of our studies on magnetic pulsations is to use the observations of these waves to infer the plasma density distribution in the magnetosphere. We use this "magnetoseismic technique" to study the variation of magnetospheric density during the superstorm on October 29-31, 2003, and found that the density increased significantly in the afternoon sector at L-values less than 4 during this magnetic storm. This result is in sharp contrast to the depletion of the plasmasphere during the September 1998 magnetic storm that we studied earlier, and correlative ionospheric observations suggest that the density enhancement during the October 2003 resulted from the different response in the ionosphere.
Peter Chi also led the study to apply the Wigner-Ville distribution to the spectral analysis of ULF data, which often contains time-dependent characteristics due to the satellite motion crossing different regions or the new input of wave energy. The results show that this time-frequency representation can provide the finer spectral resolution that can be useful to the study of frequency drift in structured Pc 1 waves and Pc 3-4 wave packets.
Due to our long involvement in Space Physics research, we have built a tremendous data base of measurements of the solar terrestrial system. As part of NSF's Global Environmental Measurement program and later in cooperation with the Space Physics Data System, we set up systems for the dissemination of those data to the community. We originally set up an on-line data base of IMP-8 data. We then developed a web-based distribution system for this effort. Now we have added POLAR magnetometer data to this system, as well as Wind and ACE magnetometer and solar wind data, and now provide on-line access to the ground-based magnetometer data obtained during the IMS (1977+) to the ISEE1 and 2 magnetometer data and also all the 1-second ground based data. We have been asked by the IMPACT team on the STEREO mission to provide this capability for them in the future.
The Space Physics Group has taken the lead in fostering communication in the discipline as part of the NSF's Global Environment Modeling (GEM) program as well as for the American Geophysical Union's (AGU) Space Physics and Aeronomy section. The electronic newsletters for GEM and SPA are both run by Peter Chi. Robert J. Strangeway was elected to serve a two year term (2002-2004) as the Space Physics and Aeronomy - Magnetospheric Physics Section Secretary of the American Geophysical Union. In June 2003 Bob began a three year term as Chairman of the GEM Steering Committee.
There are four major developments in education from the Space Physics Group. First there is its development of the interactive Space Physics educational software, also known as Xspace. We continue to update and distribute this package. Some of the exercises have been converted to JAVA and can now be used over the internet. Second, we continue to participate in the International Space Physics Education Consortium that is fostering and coordinating computer-based instruction in Space Physics. Third, C. T. Russell is the Director of UCLA's branch of the California Space Grant activities. Fourth, the book Introduction to Space Physics, edited by M. G. Kivelson and C. T. Russell continues to sell well. In fact, it is now in its third printing.
Shin Ohtani (JHU/APL) visited for a week in April 2004 and presented his research at the Space Science Seminar. This year Martin Connors also dropped by for a brief visit.
During the period 2003/2004 there were eleven continuing graduate students: M. Cartwright, M. Cowee, G. Fowler, Yasong Ge, L. Jian, E. Jensen, J. Leisner, R. Troy, Y. L. Wang, Z. J. Yu, S. Meyerberger and undergraduate A. Shinde.
The SPG staff consists of students, engineering staff, programmers, computer operators and student assistants, clerical help and researchers. The student researchers have been listed above. The research staff are R. J. Strangeway, J. Raeder, and P. J. Chi. The other staff members are as follows:
C. T., Russell, Formation of planetary magnetospheres, presented at University of Newcastle, July 2003.
C. T., Russell, The Dawn mission to asteroids 1 Ceres and 4 Vesta, presented at University of Newcastle, July, 2003.
C. T., Russell, Dawn mission: Symbiosis with 1-AU based observations, presented at IAU XXVth General Assembly, Sydney, July, 2003.
C. T., Russell, Solar wind interaction with planetary magnetospheres, presented at NATO Meeting on Magnetospheric Response to Solar Activity Prague, Czech Republic, September, 2003.
C. T. Russell, Solar wind interaction with planetary magnetospheres, presented at Max Planck Institute for Aeronomy, Katenburg-Lindau, September, 2003.
C. T., Russell, P. J. Chi, G. Delory, M. Dougherty, J. G. Luhmann, R. Skoug, and C. W. Smith, Heliospheric response to the October-November solar events, Eos. Trans. AGU, 84(46), Fall Meeting Suppl., Abstract SM52G-04, 2003.
P. J. Chi, “Magnetospheric Sounding through Seismology,” presented at the Department of Earth and Planetary Sciences, Kyushu University, Fukuoka, Japan, July 24, 2003.
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