PICARD is a

satellite A satellite or artificial satellite is an object intentionally placed into orbit in outer space. Except for passive satellites, most satellites have an electricity generation system for equipment on board, such as solar panels or radioisotope ...

dedicated to the simultaneous measurement of the absolute total and

spectral ''Spectral'' is a 2016 3D military science fiction, supernatural horror fantasy and action-adventure thriller war film directed by Nic Mathieu. Written by himself, Ian Fried, and George Nolfi from a story by Fried and Mathieu. The film stars ...

solar irradiance, the diameter and solar shape, and to the Sun's interior probing by the

helioseismology Helioseismology, a term coined by Douglas Gough, is the study of the structure and dynamics of the Sun through its oscillations. These are principally caused by sound waves that are continuously driven and damped by convection near the Sun's surfa ...

method. These measurements obtained throughout the mission allow study of their variations as a function of solar activity. It launched, along with the Prisma spacecraft, on 15 June 2010 on a

Dnepr Dnepr may refer to: *Dnieper, a river flowing through Russia, Belarus and Ukraine to the Black Sea * Dnepr (motorcycle), a Ukraininan motocycle brand * Dnepr (rocket), a 1999 space launch vehicle *Dnepr radar Dnepr may refer to: *Dnieper, a river ...

launcher from Dombarovskiy Cosmodrome, near Yasny, Russia. The mission, originally planned for two years, ended on 4 April 2014.

Objectives

The objectives of the PICARD mission are to improve our knowledge of: * the functioning of our

star A star is an astronomical object comprising a luminous spheroid of plasma (physics), plasma held together by its gravity. The List of nearest stars and brown dwarfs, nearest star to Earth is the Sun. Many other stars are visible to the naked ...

through new observations, * the influence of the

solar activity Solar phenomena are natural phenomena which occur within the atmosphere of the Sun. These phenomena take many forms, including solar wind, radio wave flux, solar flares, coronal mass ejections, coronal heating and sunspots. These phenomena are ...

on the climate of the

Earth Earth is the third planet from the Sun and the only astronomical object known to harbor life. While large volumes of water can be found throughout the Solar System, only Earth sustains liquid surface water. About 71% of Earth's surfa ...

History

The PICARD mission was named after the French

astronomer An astronomer is a scientist in the field of astronomy who focuses their studies on a specific question or field outside the scope of Earth. They observe astronomical objects such as stars, planets, natural satellite, moons, comets and galaxy, g ...

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 Friederich Wilhelm Gustav Spörer (23 October 1822 – 7 July 1895) 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 ...

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.

Platform

PICARD used the

Myriade Myriade is a European miniaturized satellite platform developed by EADS Astrium and CNES. EADS Astrium offers the Myriade bus under the commercial name Astrosat-100. CNES began developing Myriade in 1998, as a continuation of the Proteus program. ...

microsatellite platform, developed by

CNES The (CNES; French: ''Centre national d'études spatiales'') is the French government space agency (administratively, a "public administration with industrial and commercial purpose"). Its headquarters are located in central Paris and it is und ...

to use as much as possible common equipment. 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 A magnetometer is a device that measures magnetic field or magnetic dipole moment. Different types of magnetometers measure the direction, strength, or relative change of a magnetic field at a particular location. A compass is one such device, o ...

, gyrometers, several magnetic rods and reaction wheels. If an orbit control and orbit manoeuvres are needed, a

hydrazine Hydrazine is an inorganic compound with the chemical formula . It is a simple pnictogen hydride, and is a colourless flammable liquid with an ammonia-like odour. Hydrazine is highly toxic unless handled in solution as, for example, 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 used the

CCSDS The Consultative Committee for Space Data Systems (CCSDS) was founded in 1982 for governmental and quasi-governmental space agencies to discuss and develop standards for space data and information systems. Currently composed of "eleven member agenc ...

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 measuring the solar diameter and shape with an accuracy of a few milliarc second, and to perform helioseismologic observations to probe the solar interior.

References

External links

PICARD mission website

cnes.fr
{{DEFAULTSORT:Picard (Spacecraft) Missions to the Sun Solar telescopes Spacecraft launched in 2010 Solar space observatories Spacecraft launched by Dnepr rockets Satellites of France Derelict satellites orbiting Earth