Imperial College Space and Atmospheric Physics

André Balogh's Web Pages

The research group has been involved in scientific space missions since the early 1960s. It remains very active and has a programme which now stretches to beyond 2010. An overview of the group's involvement in missions over 50 years, from 1960 to 2010, is shown in the figure below. As I have been involved with the group's space programme since 1964, it is appropriate that I should give a brief historical overview.

The beginnings

The predecessor of the present Space and Atmospheric Physics Group, the Cosmic Ray and Space Physics Group, first participated in a space mission in 1962, when members of the group, led by Prof. Harry Elliot, built a cosmic ray detector for the first British scientific satellite, Ariel 1.

Following the establishment of the European Space Research Organisation (ESRO) in 1964, in which Prof. Elliot played a prominent role, the Cosmic Ray Group built three scientific instruments for ESRO's first satellite, ESRO II, launched in 1967. These instruments measured cosmic rays and other energetic particles in near-Earth space. On HEOS-1 (launched in December 1968), the first European spacecraft to venture outside the Earth's magnetosphere, the group again contributed three instruments: one to measure cosmic rays, one to measure energetic particles, and one to measure magnetic fields in space. The Imperial College team involved in that mission was led by Prof. Elliot, and consisted of Bob Hynds (now Head of Imperial College's Computer Centre), Andrew Engel, Peter Hedgecock and André Balogh. The magnetometer on that spacecraft started a long involvement by the group in the measurement of magnetic fields in space.

In 1972, HEOS-2 was launched, again with an Imperial College magnetometer on board, led by Peter Hedgecock. Measurements by the two magnetometers on HEOS-1 and -2 contributed significantly to the mapping of the Earth's magnetosphere, in particular at high latitudes. The results obtained remain of great interest, and the data gathered over 25 years ago have been re-analysed recently by Malcolm Dunlop and Peter Cargill, still yielding new insights into the little understood high latitude region of the magnetosphere.

The energetic particle telescope on the ISEE-3 mission

The next significant mission for us was ISEE-3. This was a NASA mission, launched in 1978 as one of the components of the three-spacecraft International Sun-Earth Explorer mission. Together with the Space Research Institute of Utrecht, the Netherlands, and the Space Science Department of the European Space Agency, we built an instrument to measure the fluxes of energetic particles in interplanetary space, as a function of energy and direction of propagation. The Principal Investigator of this instrument was Bob Hynds, of Imperial College, and the onboard Data Processing Unit was designed by André Balogh.

This spacecraft was the first to be launched to the L1 Lagrangian point in space, between the Earth and the Sun, where their gravitational pulls cancel. This type of orbit (since then succcessfully exploited by the SOHO solar observatory spacecraft) provides a good vantage point for observations in interplanetary space, in front of the Earth. ISEE-3 remained in that orbit for four years, through the maximum of solar activity cycle 21, and the observations of our energetic particle instruments led to studies (by André Balogh and Geza Erdos from Hungary) of the acceleration of 30 to 50 keV particles whith temporal and directional resolutions which remain unsurpassed.

Following this period at the Lagrange point, ISEE-3 was re-targeted to study the Earth's distant magnetospheric tail. Our particle instrument made the first observations of hot plasma bubbles ("plasmoids") being ejected down the magnetotail as a result of magnetospheric substorms. These studies were carried out by Stan Cowley and his students.

The third phase of the ISEE-3 mission was very spectacular. In 1983 the spacecraft was redirected, via a very close lunar flyby, to encounter the comet Giacobini-Zinner in September 1984. This was the first ever flyby of a comet by a spacecraft, but as there were no imaging instruments in the payload, no photos could be taken. However, the interaction of the comet with the solar wind was extensively studied, in particular by the ingenious use of our energetic particle telescope which was discovered to respond to cometary ions ! This work was also largely led by Stan Cowley.

Ulysses: exploration of the heliosphere in 3D

In 1977, even before ISEE-3 was launched, the group initiated its participation in the joint ESA-NASA Out-of-Ecliptic mission which first became ISPM (International Solar Polar Mission) and was finally renamed the Ulysses mission. The Ulysses spacecraft was eventually launched in October 1990, onboard the Space Shuttle Discovery. Ulysses was first targeted to fly by Jupiter, to use the giant planet's gravitational force to place the spacecraft into a nearly polar orbit around the Sun. This mission has become phenomenally successful. The observations that it made in its first complete orbit around the Sun, under conditions of solar minimum activity, have already revolutionised our understanding of the heliosphere. In the next years, it will revisit the polar regions of the Sun under conditions of solar maximum activity. We expect an equally revolutionary view of the heliosphere at solar maximum to emerge from the observations of Ulysses in 1999-2001.

Our group leads the Magnetic Field Investigation on the Ulysses mission (Principal Investigator: André Balogh since 1984, before that, it was Peter Hedgecock). We provided the Fluxgate Magnetometer and the Data Processing Unit for that instrument, while our colleagues at the Jet Propulsion Laboratory (Lead Investigator: Ed Smith) provided the excellent Vector Helium Magnetometer sensor to measure accurately the very small magnetic fields in space, at large distances from the Sun. At Imperial College, much of the instrument was built by Trevor Beek; since launch, Bob Forsyth has played a central role in the analysis of the Ulysses magnetometer observations. At present, Geraint Jones looks after the Ulysses magnetometer data at Imperial College.  More details on the results of the magnetic field investigation can be found on the group's Ulysses pages and in the extensive publication list.

We also provided an energetic particle detector, called the Anisotropy Telecope (Imperial College Lead Investigators: Bob Hynds and André Balogh) to the group of cosmic ray and energetic particle detectors (COSPIN, Principal Investigator: Bruce McKibben of the University of Chicago, since 1996, previous to that the Principal Investigator was John Simpson).  Data from this instrument has been used extensively to study the flows of energetic particles in the jovian magnetosphere during the epoch of the Ulysses Jupiter flyby in February 1992 by Stan Cowely and his students. Work in progress now concentrates on the study of energetic particle fluxes associated with the recent increases in solar activity (André Balogh and Silvia Dalla).

Overall, Ulysses has been our most successful space mission to date, when measured by the number of scientific papers published by members of the group (over 200 papers), or by the number of students who have obtained their PhDs working on the Ulysses data. Tim Horbury (PhD 1996) won the Royal Astronomical Society's Blackwell Prize for the best thesis in his year, on the study of turbulence in the heliospheric medium.

Cluster: magnetospheric processes and boundaries in 3D

The four-spacecraft Cluster mission of the European Space Agency has been called Europe's space fleet to the magnetosphere.  This mission concept arose from the need to determine the temporal and spatial aspects of small scale magnetospheric plasma processes and boundaries.  Simultaneous measurements at a minimum of four points are needed for this objective, a point recognised very early by Prof. Jim Dungey of Imperial College who proposed such a mission concept to ESRO in the mid 1960s (but he had called it  a "bunch").  The Space Physics Section (headed by Jim Dungey until 1983) of the old Cosmic Ray Group had a great deal of theoretical interest in magnetospheric phenomena; Jim Dungey's estwhile students, David Southwood (who became the Head of the new Space Physics Group in 1984) and Stan Cowley became very interested in the Cluster mission when ESA began seriosly considering it in the early 1980.  Their interests, allied with André Balogh's experimental interests in space magnetometry, naturally led to a proposal to undertake the Magnetic Field Investigation on Cluster.

A large international scientific team was gathered, including all the major research groups in Europe and in the USA with an interest in magnetic fields in space. The proposal was selected by ESA, with André Balogh as Principal Investigator. The Technical Manager was Ray Carvell; on his departure to Oxford, John Thomlinson became the Technical Manager, who then remained largely responsible for the FGM instrument (as the magnetic field investigation became known) until the launch disaster in 1996. The FGM technical team in Imperial College incuded, under John Thomlinson's leadership, Trevor Beek, Chris Carr, Ed Serpell and Bryan Wingfield. A considerable amount of scientific preparatory work, including the development of four-spacecraft data analysis tools and of in-flight calibration techniques, was undertaken mostly by Malcolm Dunlop.

After building breadboards, prototypes, Engineering Models, we built and delivered five sets of Flight Models of the FGM instrument for the four Cluster spacecraft in the period 1992-1994. This was a busy time for the Cluster team, building, testing and calibrating the FGM instruments, as well as taking part in the spacecraft integration ansd tests. Finally, in mid-1995, all four spacecraft were ready for launch and shipped to Kourou, French Guyana, to await the first test launch of Ariane-5.

The launch took place on 4 June 1996. We all remember that date only too well, as to our horror the launcher blew up some 40 seconds after lift-off. John Thomlinson and I watched, in the company of many other Cluster scientists and engineers, our work and plans blown out of the sky and scattered over the swamps of French Guyana, due to what turned out to be a stupid software error in the guidance control computer of Ariane-5. (See the Ariane 5 Failure Report.)

The explosion of the first Ariane-5 launch vehicle, and the destruction of the first Cluster mission: this is what happens when management shortcuts impose less than adequate testing of software !

Following the destruction of the four Cluster spacecraft in the explosion of Ariane-5, plans to rebuild the mission were immediately put forward to ESA. To cut a very long and nerve-racking story short, exactly 10 months after the distaster, ESA and the national agencies funding Cluster agreed to rebuild three spacecraft and refurbish a fourth one to make up the essential complement of four identical Cluster spacecraft. These, making up the Cluster-II mission, will be launched, according to current plans, in June-July 2000, onboard two Russian Soyouz launchers from Baykonur, Kazakhstan.

We are now rebuilding the FGM instruments. There is a new technical team at Imperial College, headed by Chris Carr as FGM Technical Manager, supported by Julian Harris, Patrick Brown and, of course, by Trevor Beek. We had to redesign and rebuild the FGM Data Processing Units, using new microprocessors and (almost) new flight software. In our rebuilding tasks, we have been well supported by our hardware collaborators from the Institut fuer Geophysik und Meteorologie of the Technische Universitaet, Braunschweig, the Institut fuer Weltraumforschung, Graz, and the Goddard Space Flight Center, Greenbelt, MD.

This page will be supplemented by additional sections on the Cassini, Equator-S and Rosetta missions.

Recent Publications:

Balogh, A., Mercury: the planet and its magnetosphere, Planet. Space Sci., 45, 1, 1997.

Balogh, A., Dunlop, M.W., Cowley, S.W.H., Southwood, D.J., Thomlinson, J.G., and the Cluster magnetometer team, The Cluster magnetic field investigation, Space Sci. Rev., 79, 65, 1997.

Andre Balogh 5 January 1999.