Greek scientist enlivens NASA missions with groundbreaking space research
Vassilis Angelopoulos has every reason to feel good. The 45-year-old Thessaloniki-born physicist, who works at the University of California in Berkeley, has seen the fruition of one of his projects. A suggestion he made to NASA a decade ago for a new approach to satellite missions that study unknown phenomena has become a reality. The new approach involves studying dynamic systems instead of random measurements that were carried out until today. The satellites will be launched to explore the interplanetary area with the aim of radically changing the course of space research. The five satellites in the THEMIS project (Time History of Events and Macroscale Interactions during Substorms), recently launched from Cape Canaveral in Florida, are going on different orbits and will measure the behavior of the magnetic sphere and the creation of storms and substorms. Solar storms, which have fascinated scientists since the beginning of space research, are created by the powerful bursts of light on the surface of the sun, releasing huge amounts of energy in the form of plasma and ionized gases (particles at very high energy). The plasma travels in the solar system and bombards planets with enormous quantities of energy. Any planet that has a magnetic field around it, such as the Earth, Mercury, Saturn and Jupiter, is protected from these catastrophic explosions. Without this magnetic field there would be no life on Earth. However, sometimes these powerful storms pass through the Earth’s magnetic shield and accumulate energy in plasma reservoirs within the magnetic field. This energy is converted from kinetic particles to electromagnetic energy. When another solar storm breaks out, this energy is converted back again into particles and substorms are produced inside the magnetic sphere. They wreak havoc on satellite circuits, create problems in energy transport networks in the Northern Hemisphere and produce the beautiful northern lights (aurora borealis). We still know very little about the way the Earth’s magnetic field operates and about solar storms and substorms. It took Angelopoulos three years to persuade NASA to fund the mission and six to prepare it. «We first made the suggestion in 1998. Then we had a cluster of four much simpler satellites and that’s why it was rejected. We kept bringing it up each time with further improvements until 2001, when they accepted it. From the initial four satellites we now have five highly advanced ones. And from $12 million the project now costs $200 million,» he said. These figures might seem huge but in fact they are small for the purposes of space research, in particular for such a revolutionary project as THEMIS. Five years ago another NASA cluster mission cost $2 billion. Angelopoulos and his colleagues have managed to produce a low-cost but fascinating mission. «We managed to make the satellites quite small and integrate the circuits. We made a low-cost proposal without cutting back on the scientific research needed. We were not sparing with the detectors or the data analysis later. We focused correctly on one item only,» he said. The success of THEMIS has led to the approval of three other missions by NASA. In the «Magnetospheric Constellation» project, there are plans to launch 50 satellites in order to study the magnetic sphere. «These electromagnetic storms affect our satellites and are crucial to us as the satellite clusters become ever smaller and more complex. The problem we had 10 years earlier is today a hundred times greater,» Angelopoulos said. Each of the five THEMIS satellites has three detectors. Two detectors measure the electric and magnetic field and the third measures the particles (electrons and protons). By scattering the five satellites at different points in the magnetic diodes, Angelopoulos and his colleagues hope to find where the plasma is accumulated in the Earth’s magnetic field and how electromagnetic energy is converted to kinetic energy and vice versa. Studies will help to boost energy production Vassilis Angelopoulos was born and raised in Thessaloniki. He got his first degree from Aristotle University in Thessaloniki and a master’s degree from UCLA, where he first worked as a researcher. He was recruited by Johns Hopkins University in 1993 and in 1995 he went to UC-Berkeley, where he still works. He often returns to Greece, which he says he loves. He has two children. Why is it important to understand what is happening in the magnetic sphere? Because it is a basic natural phenomenon which does not only occur on Earth but also on Mercury, Saturn, Jupiter and other planets. It also occurs in other systems, such as black holes, which release enormous amounts of energy that we can measure even here on Earth. The mechanism that creates these activities in the black holes may well be linked to the mechanism that creates substorms. The physics we learn there we will then apply in the lab, for example in experiments on fusion and energy production. You claim there are pockets of accumulated solar energy, ionized gas, which is activated every time there is a solar storm. How does this occur? These pockets do not have kinetic but electromagnetic energy. The energy is converted as the solar wind strikes the Earth, from kinetic to electromagnetic energy, which is accumulated in the Earth’s magnetic field as it is compressed by the solar wind. With solar storms, this energy is emitted and converted back into kinetic energy. If we can understand what mechanism creates substorms then it is quite likely that we will understand how the large solar storms are produced and we will be able to protect satellites and astronauts more effectively as well as the distribution of energy in the Northern Hemisphere. What changes will constellation missions bring about in space research? Space is very complex. We cannot just make random observations. Just as atmospheric physicists and meteorologists use many stations to understand the weather and how air masses move from one stratum to another, in the same way we want to understand space weather. I am pleased because we will be able to see how the different parts of the system we measure are related. Are any Greek organizations cooperating with the consortium? The Athens Observatory’s Institute of Space Applications and Telescopy is a member of our research team. Its director, Yiannis Daglis, is an experts in Van Allen zones, two particle energy zones around the Earth that increase in energy and intensity when magnetic storms are released.
