Robert J. Strangeway - Research Interests

Earth

FAST

The FAST Spacecraft was launched on August 21st, 1996 into a polar orbit. The spacecraft is designed to investigate the Earths auroral zones with high temporal and spatial resolution. The primary task of the UCLA effort is to analyze the DC (flux gate) and AC (search coil) magnetometer data. In addition to information provided concerning the orientation of the spacecraft with respect to the terrestrial magnetic field, the flux gate data also allow us to study field-aligned currents and ULF waves. The search coils measure waves in the VLF range (primarily whistler- mode) and LF range (Auroral Kilometric Radiation).

More information on FAST, as well as examples of magnetic fields data can be found on the IGPP/UCLA FAST web page.

ISEE-1 and -2

We have investigated the signatures of field-aligned currents within the inner magnetosphere. This work was a follow on from some work begun by former graduate student Francis Chun (now at the United States Air Force Academy) and continued by Prof. W. X Jiao, a visiting scholar from Peking University, China. This work was continued by Thomas C. Meseroll, forming the basis of his master thesis.

SPDS

I was also a member of the magnetospheres panel for the Space Physics Data System (SPDS). SPDS is a largely grass roots effort to preserve and facilitate the distribution of important space physics data sets. Geoff Reeves from Los Alamos National Laboratory has put together an on-line data directory: SPDS-MOLD.

As part of the SPDS efforts, we have also developed an interactive data server for the ISEE-1 and -2 magnetometer data.

Venus

Pioneer Venus Orbiter

Most of my research has centered on the analysis and interpretation of the plasma wave data acquired by the Pioneer Venus Orbiter Electric Field Detector (PV OEFD). This research can be divided into three basic topics: 1) The generation of plasma waves in a planetary foreshock; 2) The interaction of the solar wind with an unmagnetized planet; and 3) The plasma wave evidence for lightning on Venus. Much of this work was carried out in collaboration with Prof. Christopher T. Russell and former graduate students Greg Crawford (now at SRI International) and Christian Ho (now at JPL).

GIF The analysis of plasma waves in the Venus foreshock allows us to investigate the possible generation mechanisms for the waves. Through statistical studies of the distribution of the waves we find that Fast-Fermi acceleration, where solar wind electrons bounce off the bow-shock, which appears as a moving mirror in the solar wind frame, explains much of the features of the waves. We also find that shock curvature may play a role in limiting the amount of energy the electrons gain as they reflect of the shock. As such, then, the studies of waves in the Venus foreshock provide a laboratory for the investigation of shock acceleration and wave generation.

GIF The second topic, the investigation of the interaction of the solar wind with an unmagnetized planet, was originally motivated by the observation of plasma waves near the ionopause of Venus. It was argued that these waves could supply heat to the ionosphere as they propagate to lower altitudes. However, some of our more recent work suggests that the waves are probably not a significant heat source for the ionosphere. Instead they appear to be involved in the coupling process between plasma of planetary origin and the solar wind. Whether the waves provide momentum coupling, or local heating, has yet to be determined. In our efforts to understand the wave morphology, we have found that the waves are observed in or near regions of field-aligned current. These field-aligned currents deflect the magnetosheath field from the ambient magnetosheath orientation to an orientation dictated by the hanging up of field lines as they penetrate the ionosphere and are mass-loaded.

Some of this research was presented in a poster paper at the Venus II Conference.

GIF The last research topic in the area of Venus related work is the controversial one of whether or not the plasma waves observed on the nightside of Venus are due to planetary lightning. Our work over the last few years has provided a large body of evidence that the waves are indeed due to lightning. No individual piece of evidence is conclusive, but the evidence, when viewed as a whole, clearly supports the lightning interpretation.

However it has recently been pointed out that the heating due to collisional Joule dissipation at low altitudes could be very large within the Venus ionosphere. It has been argued that this alone precludes a lightning source for the waves. We are currently developing models to investigate this point further. Our initial conclusion is that some heating might occur, but it is not significant.

Some of this work was presented in poster papers at the 1994 Fall AGU Meeting and the 1995 Spring AGU Meeting.

UCLA/IGPP Space Physics Center home page     Bob Strangeway's home page

email: strange@igpp.ucla.edu

Last updated: February 8th, 2000