PICARD (spacecraft)
Encyclopedia
PICARD is a satellite
dedicated to the simultaneous measurement of the absolute total and spectral
solar
irradiance, the diameter and solar shape, and to the Sun's interior probing by the helioseismology
method. These measurements obtained throughout the mission will allow study of their variations as a function of solar activity. It launched, along with the Prisma
spacecraft, on June 15, 2010 on a Dnepr-1 launcher from Dombarovskiy Cosmodrome, near Yasny
, Russia.
astronomer
of the 17th century Jean Picard
(1620–1682) who achieved the first accurate measurements of the solar diameter. These measurements are especially important as they were made during a period when the solar activity was minimum characterized by a sun nearly without sunspots between 1645 and 1710. This period was found by Gustav Spörer
using sunspots observations gathered in Europe and this period is now named Maunder minimum
. By comparing the diameter during the Maunder minimum and the diameter when the sun was active a variation has been found, leading to the still-unanswered question, "Are diameter and activity linked?" During this period in Europe, there was an unusually cold climate.
to use as much as possible common equipments. This platform was designed for a total mass of about 120 kg mass at launch. Its attitude in space is maintained by using a star sensor, solar sensors, a magnetometer, gyrometers, several magnetic rods and reaction wheels. If an orbit control and orbit manoeuvres are needed, a hydrazine system may be used. The on-board management is centralised, and uses a 10 MIPS microprocessor T805. A mass memory is available for the data storage. The telemetry and telecommand use CCSDS standard.
Satellite
In the context of spaceflight, a satellite is an object which has been placed into orbit by human endeavour. Such objects are sometimes called artificial satellites to distinguish them from natural satellites such as the Moon....
dedicated to the simultaneous measurement of the absolute total and spectral
Spectrum
A spectrum is a condition that is not limited to a specific set of values but can vary infinitely within a continuum. The word saw its first scientific use within the field of optics to describe the rainbow of colors in visible light when separated using a prism; it has since been applied by...
solar
Sun
The Sun is the star at the center of the Solar System. It is almost perfectly spherical and consists of hot plasma interwoven with magnetic fields...
irradiance, the diameter and solar shape, and to the Sun's interior probing by the helioseismology
Helioseismology
Helioseismology is the study of the propagation of wave oscillations, particularly acoustic pressure waves, in the Sun. Unlike seismic waves on Earth, solar waves have practically no shear component . Solar pressure waves are believed to be generated by the turbulence in the convection zone near...
method. These measurements obtained throughout the mission will allow study of their variations as a function of solar activity. It launched, along with the Prisma
Prisma
Prisma is a satellite project led by the Swedish Space Corporation which consist of two satellites that fly in formation.It was launched, along with the PICARD spacecraft, on 15 June 2010 on a Dnepr-1 launcher from Dombarovskiy Cosmodrome, near Yasny, Russia...
spacecraft, on June 15, 2010 on a Dnepr-1 launcher from Dombarovskiy Cosmodrome, near Yasny
Yasny
Yasny is a town in Orenburg Oblast, Russia, located southeast of Orenburg. Population: It was founded in 1961, granted urban-type settlement status in 1962, and town status in 1979....
, Russia.
Objectives
The objectives of the PICARD mission are to improve our knowledge of:- the functioning of our starStarA star is a massive, luminous sphere of plasma held together by gravity. At the end of its lifetime, a star can also contain a proportion of degenerate matter. The nearest star to Earth is the Sun, which is the source of most of the energy on Earth...
through new observations, - the influence of the solar activity on the climate of the EarthEarthEarth is the third planet from the Sun, and the densest and fifth-largest of the eight planets in the Solar System. It is also the largest of the Solar System's four terrestrial planets...
.
History
The PICARD mission was named after the FrenchFrench people
The French are a nation that share a common French culture and speak the French language as a mother tongue. Historically, the French population are descended from peoples of Celtic, Latin and Germanic origin, and are today a mixture of several ethnic groups...
astronomer
Astronomer
An astronomer is a scientist who studies celestial bodies such as planets, stars and galaxies.Historically, astronomy was more concerned with the classification and description of phenomena in the sky, while astrophysics attempted to explain these phenomena and the differences between them using...
of the 17th century Jean Picard
Jean Picard
Jean-Felix Picard was a French astronomer and priest born in La Flèche, where he studied at the Jesuit Collège Royal Henry-Le-Grand. He was the first person to measure the size of the Earth to a reasonable degree of accuracy in a survey conducted in 1669–70, for which he is honored with a...
(1620–1682) who achieved the first accurate measurements of the solar diameter. These measurements are especially important as they were made during a period when the solar activity was minimum characterized by a sun nearly without sunspots between 1645 and 1710. This period was found by Gustav Spörer
Gustav Spörer
Friederich Wilhelm Gustav Spörer was a German astronomer.He is noted for his studies of sunspots and sunspot cycles. In this regard he is often mentioned together with Edward Maunder. Spörer was the first to note a prolonged period of low sunspot activity from 1645 to 1715...
using sunspots observations gathered in Europe and this period is now named Maunder minimum
Maunder Minimum
The Maunder Minimum is the name used for the period roughly spanning 1645 to 1715 when sunspots became exceedingly rare, as noted by solar observers of the time....
. By comparing the diameter during the Maunder minimum and the diameter when the sun was active a variation has been found, leading to the still-unanswered question, "Are diameter and activity linked?" During this period in Europe, there was an unusually cold climate.
Platform
PICARD will use the MYRIADE microsatellite platform, developed by CNESCNES
The is the French government space agency . Established under President Charles de Gaulle in 1961, its headquarters are located in central Paris and it is under the supervision of the French Ministries of Defence and Research...
to use as much as possible common equipments. This platform was designed for a total mass of about 120 kg mass at launch. Its attitude in space is maintained by using a star sensor, solar sensors, a magnetometer, gyrometers, several magnetic rods and reaction wheels. If an orbit control and orbit manoeuvres are needed, a hydrazine system may be used. The on-board management is centralised, and uses a 10 MIPS microprocessor T805. A mass memory is available for the data storage. The telemetry and telecommand use CCSDS standard.
Payload
The PICARD payload is composed of the following instruments:- SOVAP (SOlar VAriability PICARD): composed of a differential radiometer and a bolometric sensor to measure the total solar irradiance (previously called solar constant),
- PREMOS (PREcision MOnitor Sensor): a set of 3 photometers to study the ozone formation and destruction, and to perform helioseismologic observations, and a differential radiometer to measure the total solar irradiance.
- SODISM (SOlar Diameter Imager and Surface Mapper): an imaging telescope accurately pointed and a CCD which allows to measure the solar diameter and shape with an accuracy of a few milliarc second, and to perform helioseismologic observations to probe the solar interior.