Solar and Heliospheric Observatory

The Solar and Heliospheric Observatory ( Solar and Heliospheric Observatory ), short SOHO is a spacecraft or a space observatory of ESA and NASA.

Mission

The tasks of the SOHO include numerous experiments that serve the study of the Sun. The SOHO here combines European and U.S. probe plans of the 1980s. ESA is responsible for the direction of the mission and provides nine experiments. NASA provides three experiments and was responsible for the launch vehicle. Communication with the SOHO and its control is also ensured by NASA.

Construction

SOHO is a dreiachsstabilisierter, modular satellite, which is permanently aligned to the sun. The probe is approximately 4.3 × 2.7 × 3.7 feet tall ( 9.5 meters with the deployed solar cells) and about 610 kg ( 1850 kg at the start ) difficult. About the high-gain antenna main can be sent to Earth images and data at a rate of 200 kbit / s. As receiving stations serve the facilities of the Deep Space Network NASA. SOHO was built by a European team led by Astrium.

Course

SOHO was built in Europe and launched on 2 December 1995 by the Cape Canaveral Air Force Station with an Atlas II -AS rocket.

SOHO is in a halo orbit of 600,000 km radius of the L1 Lagrange point, at a distance of approximately 1.5 million kilometers from the Earth. In this orbit, it has because of gravity the same orbital period around the Sun as the Earth, and can be kept there without expenditure of energy. From Earth, it is always seen near the sun, but always has a sufficient distance so that the radio traffic to the earth is not disturbed by parallel solar radiation.

In 2003, one of the orientation engines of the main antenna failed. By recording the data in the probe to provide improved data compression and use larger receiving antennas on the ground, the data could have been without significant degradation, but also be transmitted via the low-gain antenna replacement.

The most critical situation but there were already in the initial phase of the mission. On 25 June 1998 was lost during normal orbital maneuvers of contact with the probe. A resumption of the wireless connection did not succeed at first, so that SOHO seemed almost lost. Only with the aid of radio telescopes in Arecibo (305 m diameter) and Goldstone (70 m) succeeded a month later, to locate and recover SOHO on 3 August 1998 using the Deep Space Network contact. There followed a long and difficult reactivation procedure. Finally, SOHO was on 5 November 1998 and 133 days after the interruption of communication again fully operational.

SOHO is still a flagship solar research probes. The mission was extended until December 2014. An extension until 2016 is planned.

Scientific experiments

Below is a list of facilities and experiments of SOHO:

• CDS ( Coronal Diagnostic Spectrometer)
• CELIAS (Charge, Element, and Isotope Analysis System, University of Bern )
• COSTEP (Comprehensive Supra Thermal and Energetic Particle Analyzer, University of Kiel)
• EIT ( Extreme ultraviolet Imaging Telescope, NASA / Goddard Space Flight Center )
• Erne ( Energetic and Relativistic Nuclei and Electron experiment, University of Turku in Finland)
• LASCO (Large Angle and Spectrometric Coronagraph, Naval Research Laboratory, USA and Max - Planck Institute for Solar System Research )
• MDI / SOI ( Michelson Doppler Imager / Solar Oscillations Investigation, Stanford University)
• SUMER (Solar Ultraviolet Measurements of Emitted Radiation, Max Planck Institute for Solar System Research and the Goddard Space Flight Center, USA )
• SWAN (Solar Wind Anisotropies; FMI, Finland and Service d' Aeronomy, France)
• UVCS ( Ultraviolet Coronagraph Spectrometer; Harvard - Smithsonian Center for Astrophysics, USA )
• VIRGO ( Variability of Solar Irradiance and Gravity Oscillations; PMOD / WRC, Switzerland and Institut d' Astrophysique Spatiale, France)

Accidental discoveries

Although the probe was originally not explicitly intended, could be detected with SOHO well over a thousand previously unknown comet. The Comets fell to when they moved through the field of view of the imaging LASCO detector. In order to be detected by LASCO, these comets the sun must come closer than 800,000 kilometers, therefore referred to this group as Sungrazer ( sungrazer ).