The image/poetry education and public outreach program

Education and public outreach are viewed by NASA as significant undertakings for all of its space missions. The IMAGE satellite is one of the first missions to explicitly include `E&PO in its original proposal to NASA in 1996. We will discuss what IMAGE has accomplished in this area to date, and what new activities it will conduct following a successful launch.     

Radio plasma imager simulations and measurements

The Radio Plasma Imager (RPI) will be the first-of-its kind instrument designed to use radio wave sounding techniques to perform repetitive remote sensing measurements of electron number density (N _e) structures and the dynamics of the magnetosphere and plasmasphere. RPI will fly on the Imager for Magnetopause-to-Aurora Global Exploration (IMAGE) mission to be launched early in the year 2000. The design of the RPI is based on recent advances in radio transmitter and receiver design and modern digital processing techniques perfected for ground-based ionospheric sounding over the last two decades. Free-space electromagnetic waves transmitted by the RPI located in the low-density magnetospheric cavity will be reflected at distant plasma cutoffs. The location and characteristics of the plasma at those remote reflection points can then be derived from measurements of the echo amplitude, phase, delay time, frequency, polarization, Doppler shift, and echo direction. The 500 m tip-to-tip X and Y (spin plane) antennas and 20 m Z axis antenna on RPI will be used to measures echoes coming from distances of several R _E. RPI will operate at frequencies between 3 kHz to 3 MHz and will provide quantitative N _e values from 10^–1 to 10⁵ cm^–3. Ray tracing calculations, combined with specific radio imager instrument characteristics, enables simulations of RPI measurements. These simulations have been performed throughout an IMAGE orbit and under different model magnetospheric conditions. They dramatically show that radio sounding can be used quite successfully to measure a wealth of magnetospheric phenomena such as magnetopause boundary motions and plasmapause dynamics. The radio imaging technique will provide a truly exciting opportunity to study global magnetospheric dynamics in a way that was never before possible.     

The Radio Plasma Imager investigation on the IMAGE spacecraft

Radio plasma imaging uses total reflection of electromagnetic waves from plasmas whose plasma frequencies equal the radio sounding frequency and whose electron density gradients are parallel to the wave normals. The Radio Plasma Imager (RPI) has two orthogonal 500-m long dipole antennas in the spin plane for near omni-directional transmission. The third antenna is a 20-m dipole along the spin axis. Echoes from the magnetopause, plasmasphere and cusp will be received with the three orthogonal antennas, allowing the determination of their angle-of-arrival. Thus it will be possible to create image fragments of the reflecting density structures. The instrument can execute a large variety of programmable measuring options at frequencies between 3 kHz and 3 MHz. Tuning of the transmit antennas provides optimum power transfer from the 10 W transmitter to the antennas. The instrument can operate in three active sounding modes: (1) remote sounding to probe magnetospheric boundaries, (2) local (relaxation) sounding to probe the local plasma frequency and scalar magnetic field, and (3) whistler stimulation sounding. In addition, there is a passive mode to record natural emissions, and to determine the local electron density, the scalar magnetic field, and temperature by using a thermal noise spectroscopy technique.     

Field-aligned currents and ion convection at high altitudes

Hot plasma observations from Dynamics Explorer 1 have been used to investigate solar-wind ion injection, Birkeland currents, and plasma convection at altitudes above 2 R_E in the morning sector. The results of the study, along with the antiparallel merging hypothesis, have been used to construct a B_Y-dependent global convection model. A significant element of the model is the coexistence of three types of convection cells (“merging cells,” “viscous cells,” and “lobe cells”). As the IMF direction varies, the model accounts for the changing roles of viscous and merging processes and makes testable predictions about several magnetospheric phenomena, including the newly-observed theta aurora in the polar cap.     

Overview of the image science objectives and mission phases

The Imager for Magnetopause-to-Aurora Global Exploration (IMAGE) mission uses a suite of imaging instruments to investigate the global response of the magnetosphere to changing solar wind conditions. Detailed science questions that fall under this broad objective include plasma processes that occur on the dayside, flanks, and nightside of the magnetosphere. The IMAGE orbit has been carefully designed to optimize the investigation of these plasma processes as the orbit precesses through the magnetospheric regions. We discuss here the phasing of the IMAGE orbit during the two-year prime mission and the relationship between the orbit characteristics and the critical science objectives of the mission.     

Observations of magnetospheric convection from low altitudes

Some of the observations and interpretive models that have provided a substantial increase in our knowledge of magnetospheric and ionospheric convection are discussed. While a two-cell convection pattern may be generally consistent with many ionospheric measurements, it is now clear that some significant departures from such a pattern must be considered. We can now specify more accurately the number of convection cells and their shape as well as the electrostatic potential distribution within the cells. All these factors can be shown to be sensitive functions of the interplanetary magnetic field (IMF). Interpretation of these findings in terms of the interaction of the earth's magnetosphere with the interplanetary medium has led to detailed consideration of the location of magnetic merging regions and the magnetic field topology of the outer magnetosphere. In addition, the relative importance of merging, viscous interaction and ionospheric processes in providing the driving force for convection has been considered. In general, the bulk of the driving force is magnetic reconnection; however, viscous processes play a significant role in times of northward interplanetary magnetic fields, and thermospheric drag may contribute to the maintainence of a convection pattern for several hours after such a northward turning.     

Learning in an immersive digital theater

The Houston Museum of Natural Science, in collaboration with Rice University has an outreach program taking portable digital theaters to schools and community sites for over five years and has conducted research on student learning in this immersive environment. By using an external independent evaluator, the effectiveness of NASA-funded Education and Public Outreach (EPO) projects can be assessed. This paper documents interactive techniques and learning strategies in full-dome digital theaters. The presentation is divided into Evaluation Strategies and Results and Interactivity Strategies and Results. All learners from grades 3–12 showed statistically significant short-term increase in knowledge of basic Earth science concepts after a single 22-min show. Improvements were more significant on items that were taught using more than one modality of instruction: hearing, seeing, discussion, and immersion. Thus immersive theater can be an effective as well as engaging teaching method for Earth and Space science concepts, particularly those that are intrinsically three-dimensional and thus most effectively taught in an immersive environment. The portable system allows taking the educational experience to rural and tribal sites where the underserved students could not afford the time or expense to travel to museums.