Cluster II, regenerated ash phenich

2000/10/01 Irazabalbeitia, Inaki - kimikaria eta zientzia-dibulgatzaileaElhuyar Fundazioa Iturria: Elhuyar aldizkaria

• Astronomia

4 July 1996. From the Kourou launch base, pitcher Ariane 5 started a path to space between smoke and fire. The session was corrupt. An explosive explosion destroyed the four satellites of the Cluster mission that carried the launcher and the end.

This fact did not discourage the leaders and scientists of the ESA and during the months of July and August of this year have departed from the launch base of Baiconur, carried by the launcher Soiuz, the four satellites of his twin mission Cluster II. History, however, began in 1986. ESA, within its scientific program Horizons 2000, proposed two interrelated missions as a first milestone. One, called the Cluster, would study the rapidly occurring changes in the magnetic layer of the Earth (the magnetosphere) and the other, the SOlar and Heliospheric Obvatory (SOlar), would study the solar energy particles that expel the Sun to Earth.

What happened next is known: The success of SOHO, which has gathered a lot of data about our star and made many discoveries, and the devastating accident of the Clusters.

Non-empty space

Although interplanetary space is almost empty, it is not completely empty. It is dominated by charged particles, mainly electrons and protons, which the Sun emits at supersonic speed. This current of particles is called solar wind. Fortunately, the Earth's magnetic field is quite powerful in protecting itself from this solar energy, as it does not allow these particles to reach the Earth's surface. In the space near the Earth, where the solar wind and the Earth's magnetic field are found, several layers and special regions appear. These are what the Cluster II Mission will analyze.

The first indicator of interaction between the solar wind and the earth's magnetic field is the shock wave that appears in the Sun-oriented part (see figure). This shock wave is similar to the one that occurs when the plane exceeded the sound barrier. When the solar wind approaches the planet's magnetosphere, the charged particles slow down sharply, resulting in a region called the shock surface.

The region protected by the Earth's magnetic field is called the magnetosphere and is like an island located in the water currents, capable of diverting the particles that reach it on both sides. The sliding of energy particles around the planet makes the magnetosphere look decorative: it has a big head looking at the Sun and a long tail that stretches in millions of kilometers towards the same wind.

On the other hand, the magnetosphere has a considerable edge or limit, called magnetopause. When the activity of the Sun is very violent, the solar wind exerts a great pressure on the magnetosphere and the galanta dragging only up to 35,000 km of the surface. However, the Earth's defense lines are not quite robust, with two weak points at the magnetic poles north and south. Solar wind particles filter through the magnetosphere following magnetic field lines and reach the high atmosphere. When they collide with their atoms the auroras are created, those impressive light shows that appear in the skies of the high latitudes.

Precisely, the main objective of the Cluster II mission is the study of the plasma microstructures of the aforementioned regions: solar and shock surface, magnetopause, polar depression, magnetoisage and auro region.

Mission

The Cluster II mission consists of four synchronized working satellites. The names of dance styles are: Rumba, Tango, Samba and Salsa. As satellites will receive simultaneously measurements and data on the same phenomenon, it is possible, for the first time, to conduct a three-dimensional study of the changes and processes that occur in space near the Earth. When the four satellites are very close to each other, only a few hundred kilometers away, they can make very precise measurements on a small scale. They will also be able to distance each other up to 20,000 km in order to obtain a wider view of what is happening.

Likewise, the orbits of the satellite will be polar and very eccentric: apogee 19,6 terrestrial radio and perigee 4 terrestrial radio. The orbit parameters of each satellite have been specially adjusted so that each of them is located at the apex of a tetrahedron every time an interesting region of the magnetosphere is crossed. Spacecraft distances will be adjusted during the mission based on the size of the structures being studied.

Rumba, Tango, Samba and Salsa are already in space, in the orbit of the Earth. Soon they will begin to work collecting and sending a large number of data about the magnetic field around us, and after a few years, scientists will have a more accurate picture of the magnetosfe and the processes that occur there. The four are already in working positions. During the month of September the work team will wake up. The ignition sequence of the tooling will be sequential. One instrument will first be lit on one spacecraft, then on another, until all four are lit. Then, during the fall all appliances will be tried and adjusted and, finally, in early December the 44 tools will be prepared for the work Rumba, Tango, Samba and Salsa.

Cluster II will be another step in understanding the activity of the shield that protects us, but it is not.