C.T. Russell on the Magnetism of Planetary Exploration

Special Topic of Planetary Exploration Interview, June 2011

C.T. Russell In our Special Topics analysis on Planetary Exploration, the work of Dr. C.T. Russell ranks at #6 by number of papers and #18 by total cites, based on 124 papers cited 1,554 times. His current record in Essential Science IndicatorsSM from Thomson Reuters includes 208 papers cited a total of 2,767 times between January 1, 2001 and February 28, 2011.

Russell is Professor of Geophysics and Space Physics at both the Institute of Geophysics and Planetary Physics (IGPP) and the Department of Earth and Space Sciences at the University of California, Los Angeles. He is also the Head of the IGPP Space Physics Center for UCLA, Director of the UCLA Branch of the California Space Grant Consortium, and the acting System-wide Director of the IGPP.

He is a part of many planetary exploration missions, including but not limited to the Cassini mission to Saturn, the Venus Express mission, and the Dawn mission to the asteroids Vesta and Ceres.

Below, ScienceWatch.com talks with russell about his highly cited research.

SW: Please tell us about your educational background and research experiences.

I received my B.Sc. in Physics and Math from University of Toronto in 1964 and my Ph.D. in Planetary and Space Science in 1968 from UCLA.

I have done research on solar radio waves with the Alouette 1 and 2 spacecraft; on the Earth's magnetosphere and its interaction with solar wind using the six Orbiting Geophysical Observatory spacecraft; on the lunar magnetic field with the Apollo 15 and 16 subsatellites; on the Earth's magnetosphere and its interaction with the solar wind using the International Earth-Sun Explorers; on Venus with the Pioneer Venus Orbiter; on Jupiter and its satellites using the Galileo mission; on the Earth's magnetosphere with the Polar mission; on Saturn and its moons using the Cassini measurements; on the solar wind and the Sun with the STEREO mission; on Venus with the Venus Express mission; and on the asteroids Eros, Vesta, and Ceres with the NEAR mission and now the Dawn mission.

I am actively pursuing the studies with the Cassini, STEREO, Venus Express, and Dawn missions which are still gathering data.

SW: What first drew you to planetary research? Is there a specific area within this field on which you focus, or do you maintain a wide variety of interests?

I evolved from terrestrial to lunar studies when the Apollo mission was active and then moved on to Venus when the Pioneer Venus mission was being planned. I then moved on to Jupiter and Saturn when opportunities arose. I have also written papers on Mercury, Mars, Uranus, Neptune, Pluto, and comets. I principally focus on problems concerned with planetary magnetism but am involved in a wide range of studies.

SW: Your most-cited original article in our analysis is the March 2006 Science paper you coauthored, "Identification of a dynamic atmosphere at Enceladus with the Cassini magnetometer." Would you tell us a bit about this paper—your expectations going in, your findings, where this work has gone since this publication?

We had known before Cassini flew by Enceladus that this moon was important, as it appeared to be associated with the formation of Saturn's E-ring, but we did not know how dynamic Saturn's magnetosphere was. The Pioneer and Voyager flybys had not provided us with sufficient data to determine the variability of Saturn's magnetosphere.

"Technologically mankind can conquer space but it is expensive and spatial scales are large and time scales long for interplanetary travel."

The distortion of the magnetic field at Enceladus showed that Enceladus was a major source of gas, dust, and plasma to the Saturnian magnetosphere. This observation was followed by imagery and many close flybys, confirming our initial conclusions and deepening our appreciation of the role of Enceladus as being the engine that drives a dynamic magnetosphere. Enceladus is to Saturn as Io is to Jupiter.

SW: You also have several papers dealing with the Venus Express mission. What would you say are the key findings from Venus Express, and what sort of implications do they have?

There was far too long an interval between the Pioneer Venus Orbiter launched in 1978 and the Venus Express mission launched in 2005. Instrumentation is now much improved and we understand much better what we need to measure. Fortunately I was able to participate in both missions. Two questions that were left unanswered by the Pioneer Venus orbiter were the degree of active volcanism renewing the surface and the amount and strength of lightning occurring in the Venus atmosphere. Unfortunately in the absence of definitive information people often establish positions on issues that they are unwilling to change later when information does arise.

The advance on Venus Express that allowed us to determine that Venus is volcanically active is the realization that windows in the IR spectrum allow a spacecraft to image the surface through the thick atmosphere. This has allowed Venus Express to show that there have been changes in the surface between the time of Pioneer Venus, Venera 15, Magellan, and the present.

Pioneer Venus and the Venera 9, 10, 11, 12, 13, and 14 missions should have made an open-and-shut case for the existence of Venus lightning, but a few investigators took public opinions early against lightning and refused to admit the observations were overwhelmingly in favor of it, so Venus Express was cast in the role of the deciding vote.

The observations of lightning-generated electromagnetic waves by Pioneer Venus, below the ionosphere before it finally entered the Venus atmosphere for the last time, were used to predict the strength of the signals produced by lightning. This information was then used to design a magnetic sensor for Venus Express that would complement the electric sensor on Pioneer Venus. The Venus Express sensor has worked perfectly, finding the magnetic counterpart to the Pioneer Venus electric signals.

Thus the existence of lightning on Venus is no longer an issue and work continues on lightning's distribution and occurrence rate on the planet as well as the mechanisms responsible for creating it.

SW: You're the principal investigator on the Dawn mission. What are the goals of this project, and what is its current status?

"We had known before Cassini flew by Enceladus that this moon was important, as it appeared to be associated with the formation of Saturn's E-ring, but we did not know how dynamic Saturn's magnetosphere was."

The Dawn mission is an ion-propelled spacecraft that is heading to Vesta and Ceres, the two most massive bodies in the main asteroid belt. Dawn will orbit both and map their surfaces, determining their shapes, densities, and mineral and elemental composition. This is an attempt to travel back in time to determine what conditions were like in the earliest epoch of the solar system and to determine what were the properties of those smaller bodies that served as the building blocks for the creation of Mercury, Venus, Earth, and Mars. Dawn arrives at Vesta in July 2011.

SW: Obviously, these missions are the result of great team effort. Can you give us some insight into how these mission teams work?

Each project consists of teams that are engaged in specific activities such as power, propulsion, science planning, etc. These teams work in parallel with deliveries and budgets that need to be met. Since everything is needed for a specific launch date or arrival date, the teams have to be effectively managed. Much time is spent on managing and reviewing the efforts. Good communication is very important.

SW: How has the field as a whole changed over the years?

In the early days the number of scientists and engineers involved in each project was much smaller and the time between projects was shorter and the number of launches much greater. The tendency of the largest most expensive project to be pursued is now the order of the day. In fact, a space program of more but smaller projects would be more robust, more scientifically productive, and easier to manage.

SW: Where do you hope to see this research go in the next decade?

We need to learn much more about the Sun. Venus is under-explored. In the rush to return a sample from Mars we must be sure that we have the right samples before we bring those samples back. Galileo was successful but was unable to return as much information as it should have. Hence a new and more comprehensive mission is needed there. Further out in the solar system Uranus and Neptune present us with entirely different giant planets than Jupiter and Saturn. We need to undertake a detailed orbital investigation on at least one of them.

SW: Stephen Hawking recently stated that he believes the long-term future of the human race is in space. Do you agree with him – why or why not?

Technologically mankind can conquer space but it is expensive and spatial scales are large and time scales long for interplanetary travel. It is not obvious whether the cooperation and planning that would be necessary will ever occur. If it does not occur on the proper timetable, global change may divert attention from space exploration as the human race attempts to cope with a changed planet.End

C.T. Russell, Ph.D.
Department of Earth and Space Sciences
Institute of Geophysics and Planetary Physics
University of California, Los Angeles
Los Angeles, CA, USA


Angelopoulos V, et al., "Tail reconnection triggering substorm onset," Science 321(5891): 931-5, 15 August 2008 with 71 cites. Source: Essential Science Indicators from Clarivate Analytics .



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