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Space Sciences The two fundamental questions driving scientific research in Space Sciences are:
By studying our own Galaxy, scientists try to understand the living cycle of a star as well as how planetary systems are formed. Understanding our closest star, the Sun, is helping scientists to learn more about how stars evolve as well as helping scientists to better understand phenomena affecting the Earth's climate, such as solar eruptions. By comparative study of planets in the solar system, scientists are discovering mechanisms like volcanic or tectonic activity and the greenhouse effect, which have fashioned our planet and its climate. And to conclude this short introduction, astrophysics and particle physics are converging in their search for a single law common to the fundamental interactions governing the Universe, and for a fuller understanding of the role of gravity.
Research disciplines Planetary Atmospheres The behavior of the atmospheres of other planets is of interest in its own right and may also provide insights of value in the study of our own atmosphere and climate system. A small effort, focussed primarily on Mars, uses spacecraft data (including ongoing Mars missions) and computer simulation models to improve our understanding of the dynamics of planetary atmospheres. Comets and Asteroids Important clues to the origins of the solar system come from asteroids, comets and meteors, believed to be remnants from the early solar system. Until the early 1990s, the only information obtained on these bodies was through Earth-based observations, either by observing them in orbit or by examining the remnants that reach us here on Earth. In recent years, scientists have been able to investigate asteroids and comets in unprecedented detail by sending spacecraft to examine them from close range. But space missions allow for more than just observations of asteroids and comets. Our program will detail how the composition, orbits, and trajectories of asteroids, comets and meteorites help predict and record the life of the solar system. Planetary Geodesy This is a science which contributes to the metrology of Planet Earth. It refers to a variety of techniques mostly based on Satellite Laser Ranging (SLR), Doppler shifts on signals between satellites and ground networks (or other satellites), spacecraft in constellation (GPS, GLONAS,...) for precise positioning, altimetry of the oceans and polar caps, very long baseline interferometry (VLBI), Lunar Laser Ranging (LLR), and recently Interferometry by Synthetic Aperture Radar (INSAR). Space geodesy is at the cross-roads of many disciplines, especially solid Earth sciences, oceanography, glaciology, also planetology which benefits from similar approaches. Its primary objectives are to measure at a global scale the shape of the Earth, its gravity field and temporal variations, its rotation, tides, surface movements, the dynamics of oceans and polar caps. It has numerous applications for precise orbitography of artificial satellites, navigation and reference systems. Similar objectives are pursued in the exploration and study of solar system bodies : this is planetary geodesy. Astrophysics Astrophysics is defined merely as the study of the physical properties of planets and stars (a subset of astronomy). However, in more scientific circles, it is well known that this definition is expanded to include, for example, the study of the high energy physics of the early phases of the Universe, as evidenced experimentally by examples such as the European Space Agency's Planck mission. The very existence of such projects confirms something further that should really be obvious: that the definition of astrophysics is, in practice, still more comprehensively expanded to include the study of the relativistic properties of the space and time between the stars, which allows us to accurately define gravitation, thus the motions of these celestial bodies relative to one another, and from there, the dynamic physics of the creation and evolution of the observable universe. The interstellar medium is composed of material in various thermal and chemical phases, including: * cool atomic gas inside, or mixed with cold molecular clouds; Solar Physics The Sun is a source of light and heat for life on Earth. Our ancestors realized that their lives depended upon the Sun and they held the Sun in reverent awe. We still recognize the importance of the Sun and find the Sun to be awe inspiring. In addition we seek to understand how it works, why it changes, and how these changes influence us here on planet Earth. The Sun was much dimmer in its youth and yet the Earth was not frozen. The quantity and quality of light from the Sun varies on time scales from milli-seconds to billions of years. During recent sunspot cycles the total solar irradiance has changed by about 0.1% with the sun being brighter at sunspot maximum. Some of these variations most certainly affect our climate but in uncertain ways. The Sun is the source of the solar wind; a flow of gases from the Sun that streams past the Earth at speeds of more than 500 km per second (a million miles per hour). Disturbances in the solar wind shake the Earth's magnetic field and pump energy into the radiation belts. Regions on the surface of the Sun often flare and give off ultraviolet light and x-rays that heat up the Earth's upper atmosphere. This "Space Weather" can change the orbits of satellites and shorten mission lifetimes. The excessradiation can physically damage satellites and pose a threat to astronauts. Shaking the Earth's magnetic field can also cause current surges in power lines that destroy equipment and knock out power over large areas. As we become more dependent upon satellites in space we will increasingly feel the effects of space weather and need to predict it. Plasma Physics All stars, including the Sun, the interstellar and interplanetary medium, planetary upper atmosphere (ionosphere) - in a word, roughly 99% of matter in the Galaxy is in the plasma state. The processes of the transformation of some types of energy into other, which constitute the essence of active phenomena on the Sun and in the close vicinity (magnetospheres) of the planets, including the Earth, are of plasma nature.
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