Modern journeys into space|
Before the space age the atmosphere obstructed many types of observations. Only visible radiation and some types of radio radiation reach the ground relatively undisturbed. Ground based observations are at the mercy of weather conditions and cannot go on when the sun is below the horizon.
|The first observations|
|For this reason a revolution in the research on the Sun took place when the space age began to allow new types of studies. There has been a close connection between technological development and the progress of the researchers.
Here we shall give a short description of the projects. The most important among these, such as SOHO, will be discussed somewhat more thoroughly.
|Into the satellite age|
|Rocket observations last a very limited period of time because rockets fall down again. Observations from the satellites may on the other hand be made over a longer period of time because the satellites have more a less stable orbits that keep them up for days, weeks and even for several years.|
|Modern space studies of the Sun|
|Many advanced instruments have been flown into space after Skylab. The
Soviet Union had solar instruments on several satellites, an early example was OST-1, which was flown on Salyut 4 in 1975. This telescope was used in order to study the Sun at distant ultraviolet wavelengths with the result that many new properties with several types of solar activities, among others flares, were discovered.
|Cluster-satellites supervise the solar wind|
|The four Cluster satellites were launched at the second attempt in the summer 2000. This project, in which Norway has played an active role, supervises and studies the conditions in the near space.|
|Norwegian research on Cluster|
|The Physical Institute of the University of Oslo participates in an international research teamwork intended to measure electrical fields and waves in the magnetosphere by means of the four Cluster satellites. This teamwork is led from Sweden and has participants from several countries in Europe and from the USA.|
|Cluster spacecraft reach greatest separation at fifth anniversary|
|The four spacecraft of ESA’s Cluster fleet have reached (July 2005) their greatest distance from each other in the course of their mission to study Earth’s magnetosphere in three dimensions.|
|From "macro" to "micro" – turbulence seen by Cluster|
|Thanks to measurements by ESA’s Cluster mission, a team of European scientists have identified ‘micro’-vortices in Earth’s magnetosphere.|
|Ulysses investigates the Sun‘s polar areas|
|Ulysses was launched by the space shuttle Discovery in October 1990. It has now completed its main task, to observe both solar poles. The space probe gives us a better understanding of the Sun’s magnetic fields and of the solar wind.|
|Genesis collects tests of the solar wind|
|In August 2001 a very special space probe was launched in Florida. It is going to collect samples of the solar wind. Since the particles in the solar wind come right from the Sun’s outer layers, this will be as if they were taking samples of the Sun itself. |