Diadème is the name of a pair of French artificial satellites of the D-1 series developed by
CNES
CNES () is the French national space agency. Headquartered in central Paris, the agency is overseen by the ministries of the Armed Forces, Economy and Finance and Higher Education, Research and Innovation.
It operates from the Toulouse Spac ...
and built by
Matra
Matra (an acronym for Mécanique Aviation Traction) was a major French industrial Conglomerate (company), conglomerate. Its business activities covered a wide range of industries, notably aerospace manufacturer, aerospace, defence industry, def ...
, launched in February 1967 using
Diamant
The Diamant rocket (French for "diamond") was the first exclusively French expendable launch system and at the same time the first satellite launcher not built by either the United States or USSR. As such, it has been referred to as being a key ...
rockets.
Like the first satellite of the Diapason series (D-1A), the purpose of Diadème 1 and 2 was to carry out geodetic surveys using
Doppler
The Doppler effect (also Doppler shift) is the change in the frequency of a wave in relation to an observer who is moving relative to the source of the wave. The ''Doppler effect'' is named after the physicist Christian Doppler, who described ...
and laser telemetry techniques. They were also used to test a
satellite navigation
A satellite navigation or satnav system is a system that uses satellites to provide autonomous geopositioning. A satellite navigation system with global coverage is termed global navigation satellite system (GNSS). , four global systems are ope ...
system.
Characteristics
Both satellites had a mass of about 23 kg. In addition to the Doppler oscillator and
laser reflectors,
the satellites also carried a
radio beacon
In navigation, a radio beacon or radiobeacon is a kind of beacon, a device that marks a fixed location and allows direction finding, direction-finding equipment to find relative Bearing (navigation), bearing. But instead of employing visible lig ...
operating at 136
MHz
The hertz (symbol: Hz) is the unit of frequency in the International System of Units (SI), often described as being equivalent to one event (or cycle) per second. The hertz is an SI derived unit whose formal expression in terms of SI base u ...
for the transmission of telemetry data. It was also equipped with a "
solar cell
A solar cell, also known as a photovoltaic cell (PV cell), is an electronic device that converts the energy of light directly into electricity by means of the photovoltaic effect. " experiment, where the battery was recharged by a solar generator.
The satellites were stabilized relative to the
Earth's magnetic field
Earth's magnetic field, also known as the geomagnetic field, is the magnetic field that extends from structure of Earth, Earth's interior out into space, where it interacts with the solar wind, a stream of charged particles emanating from ...
, with the satellite's axis tangent to the lines of force. Initially only three French tracking stations, all around the Mediterranean, tracked the satellites. Later a worldwide tracking programme was established, involving two American tracking stations.
Satellites
Both satellites were launched by a Diamant-A from
CIEES in
Hammaguir
Hammaguir (also written Hamaguir and Hammaguira) () is a village in Abadla District, Béchar Province, Algeria, south-west of Béchar. It lies on the N50 national highway between Béchar and Tindouf. The location is notable for its role in Fre ...
, Algeria:
* Diadème 1, launched on 8 February 1967, failed on 2 January 1970, although it could be tracked by laser until June 1971;
* Diadème 2, launched on 15 February 1967, ceased operations on 5 April of that year, although it was followed by laser until July 1971.
References
{{Reflist
Satellites of France
CNES
Satellites orbiting Earth