Cluster (spacecraft)
Cluster is a satellite project of ESA and NASA to study the terrestrial magnetosphere, the geomagnetic field. The program of a group of four identical satellites suffered in 1996 with the launch failure of the first Ariane 5 rocket a setback, however, since the summer of 2000 with spare satellites in operation.
Mission overview - 4 satellites
The operated in conjunction satellite investigate the Earth's magnetic field, which shields the planet from the solar wind. Cluster 5-8 measure three-dimensional data from collisions of the solar wind with the Earth's magnetic field, the time course and the consequent interactions in space. The latter often lead to auroras, but can also cause strong interference and even electrical failures.
German institutions are responsible for two of each of eleven instruments of each satellite, with two other German scientists were involved. A special challenge of the mission - in addition to sophisticated measuring technology - models to improve the prediction of the so-called space weather, so the interference by solar wind.
The satellites have approximately cylindrical shape (290 x 130 cm) and spin stabilization in inertial space (15 rotations per minute). Your solar cells provide for the operation and radio communications, an electric power of 224 watts. The satellites were the SCID ( Spacecraft ID) from 90h to 93h for the active satellites, 94h for the backup unit and assigned to 95h to 96h for the simulators by the World Data Center for Satellite Information.
False start in 1996 and naming of specimens 2000
In the first flight of the Ariane 5 on June 4, 1996, the four satellites (provisional name FM1 to FM4 ) should be started, but due to an error in the form adopted by Ariane 4 flight software came from the rocket after the start of the course, began to break apart and finally blew himself up after 36.7 seconds itself
By early 2000, four additional copies FM5 were built to FM8. In this case, a replacement satellite and several replacement instruments of the original mission were used to keep the costs down. Were the occasion of the successful launch on 16 July 2000 Darmstadt on European Space Operations Centre (ESOC ) announced the winners of the competition name the Cluster satellites known. From over 5,000 entries, it was decided for the proposal of an Englishman who is an avid dancer: The four satellites are called future Rumba, Salsa, Samba and Tango.
Starts in July and August 2000,
On July 16, 2000, two of the four new spacecraft were launched by a Soyuz -Fregat rocket from Russia's Baikonur cosmodrome and arrived 90 minutes later, a preliminary orbit. Originally an almost simultaneous start with the German mini-satellites CHAMP (from Plesetsk off) was planned, but this was delayed by one day. 90 minutes after the start of the engines of the Fregat stage were again fired to lift the satellite into a parking orbit of 240 × 18,000 km. A little later reported the ESA ground station in Kiruna, Sweden 's successful orbital maneuvers and the decoupling. Salsa and Samba reached during the next few weeks with their own drive its final orbit at an altitude 19000-119000 km at 57 hours turnaround time.
The second cluster pair was started about three weeks later, on August 9. This time, however, not everything worked right off the bat: the third stage of the Soyuz - Fregat yielded too little power and put the Fregat upper stage with the Cluster satellites in a lower orbit than planned. But the Fregat saved the mission - as it was filled with excess fuel, they could reach the planned orbit and suspend the satellite successfully.
The four Cluster satellites can - depending on the magnetic field structure to be examined - work in different constellations. The fuel for orbital maneuvers makes more than half of the starting weight of the probes ( ever 650 of 1200 kg).
The expected end of the mission is scheduled for December 2014.
Constellation the end of 2003
In December 2003, the four Cluster formed a pyramidal structure at 200 kilometers mutual distance, which you can increase to several thousands of kilometers. The polar orbits of four satellites are highly elliptical (high 19000-119000 km). Thus, the instruments can detect a wide variety of magnetic effects from many regions of the Earth's magnetic field on board each satellite:
- Measurements of charged particles
- Measuring electrical and magnetic fields
- Interactions between the solar clouds of high-energy particles, the Earth's atmosphere and magnetic field.
To date, Rumba, Salsa, Samba and Tango have the expectations placed in them fully satisfied.
Chinese " Double Star " 2003
Two Chinese Double Star scientific satellites will in future - but from lower orbits out - cooperate with the cluster system: On 27 December 2003 starting at 20:23 clock (CET ), the first of two satellites, and in close cooperation between ESA China emerged. The two identical satellites TC -1 and TC -2 have a mass of 330 kg, and are the first Chinese magnetospheric satellites. They were constructed in China, built, and were equipped with eight measuring instruments of Chinese origin. The launch took place with launchers Long March 2C, the measurements of the Double Stars should take 12 to 18 months.
The European contribution to this mission are eight other instruments, of which seven are counterparts of cluster (reserve instruments or inexpensive duplicates). In addition to the economic advantages are similar instruments on several satellites and technically and scientifically interesting: they allow conclusions on the function and give a multi-dimensional picture of the surrounding our planet magnetic field.
In contrast to the relatively high-flying Cluster satellites the Double Star duo of the China National Space Administration ( CNSA ) will come close to their elliptical orbits of the earth up to 550 and 700 kilometers. While TC - 1 on a relatively equatorial orbit - which will be compared to the equator but still inclined by 28.5 degrees - to swim lengths, TC -2 is circling in a polar orbit around the Earth.