Euclid (spacecraft)
Encyclopedia
Euclid is a planned space telescope, an M-class mission of the ESA Cosmic Vision 2020-2025
Cosmic Vision
The Cosmic Vision is the paraphrasing name given to the roadmap for scientific space based missions of the European Space Agency in the time frame between 2015 and 2025....

, planned to be launched in 2019. Its goal to map the large scale distribution of the dark matter
Dark matter
In astronomy and cosmology, dark matter is matter that neither emits nor scatters light or other electromagnetic radiation, and so cannot be directly detected via optical or radio astronomy...

 and characterize properties of dark energy
Dark energy
In physical cosmology, astronomy and celestial mechanics, dark energy is a hypothetical form of energy that permeates all of space and tends to accelerate the expansion of the universe. Dark energy is the most accepted theory to explain recent observations that the universe appears to be expanding...

.

Originally two, similar proposals were submitted for the call, the Dark Universe Explorer (DUNE, intended to measure effects of weak gravitational lensing) and Spectroscopic All Sky Cosmic Explorer (SPACE, to measure the baryon acoustic oscillations
Baryon acoustic oscillations
In cosmology, baryon acoustic oscillations refers to an overdensity or clustering of baryonic matter at certain length scales due to acoustic waves which propagated in the early universe. In the same way that supernova experiments provide a "standard candle" for astronomical observations, BAO...

). Both proposals were selected and considered as equally important, and a combined mission was planned enabling cross-checking the results of both missions.

The survey covers 15,000 square degree
Square degree
A square degree is a non-SI unit measure of solid angle. It is denoted in various ways, including deg2, sq.deg. and ². Just as degrees are used to measure parts of a circle, square degrees are used to measure parts of a sphere. Analogous to one degree being equal to π /180 radians, a...

s (and also has a 40 square degree deep survey), approximately half of the whole sky (not covered by the Milky Way
Milky Way
The Milky Way is the galaxy that contains the Solar System. This name derives from its appearance as a dim un-resolved "milky" glowing band arching across the night sky...

).

The spacecraft uses a 1.2 meter Korsch telescope
Korsch telescope
A Korsch telescope is a three-mirror telescope with a wide field of view, whose design ensures that there is little stray light in the focal plane...

 with three sensors.
  • A visible light CCD
    Charge-coupled device
    A charge-coupled device is a device for the movement of electrical charge, usually from within the device to an area where the charge can be manipulated, for example conversion into a digital value. This is achieved by "shifting" the signals between stages within the device one at a time...

     images the whole field of view down to magnitude
    Magnitude (astronomy)
    Magnitude is the logarithmic measure of the brightness of an object, in astronomy, measured in a specific wavelength or passband, usually in optical or near-infrared wavelengths.-Background:...

     24.5 for measuring gravitational lensing.
  • A near infrared
    Infrared
    Infrared light is electromagnetic radiation with a wavelength longer than that of visible light, measured from the nominal edge of visible red light at 0.74 micrometres , and extending conventionally to 300 µm...

     photometer
    Photometer
    In its widest sense, a photometer is an instrument for measuring light intensity or optical properties of solutions or surfaces. Photometers are used to measure:*Illuminance*Irradiance*Light absorption*Scattering of light*Reflection of light*Fluorescence...

     measures brightnesses of galaxies
    Galaxy
    A galaxy is a massive, gravitationally bound system that consists of stars and stellar remnants, an interstellar medium of gas and dust, and an important but poorly understood component tentatively dubbed dark matter. The word galaxy is derived from the Greek galaxias , literally "milky", a...

     in three (Y, J, H) bands
  • A spectrometer
    Spectrometer
    A spectrometer is an instrument used to measure properties of light over a specific portion of the electromagnetic spectrum, typically used in spectroscopic analysis to identify materials. The variable measured is most often the light's intensity but could also, for instance, be the polarization...

     gathers (infrared) spectra of 108 brighter galaxies than magnitude 22 of each field of view.

History

On October 5, 2011 it was announced that Euclid is one of the two programs ESA has selected to be built.

External links

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