ESA's spacecraft set to observe mysterious dark matter

London: European Space Agency's Euclid spacecraft to study the properties and effects of the mysterious dark matter and dark energy is set to launch in 2020.

NASA has delivered three detector for the spacecraft's near-infrared instrument.

"The delivery of these detector systems is a milestone for what we hope will be an extremely exciting mission, the first space mission dedicated to going after the mysterious dark energy," said Michael Seiffert, from the NASA's Jet Propulsion Laboratory in the US.

The Euclid will carry two instruments: a visible-light imager (VIS) and a near-infrared spectrometer and photometer (NISP).

A special light-splitting plate on the Euclid telescope enables incoming light to be shared by both instruments, so they can carry out observations simultaneously.

The spacecraft will observe billions of faint galaxies and investigate why the universe is expanding at an accelerating pace.

Astrophysicists think dark energy is responsible for this effect, and Euclid will explore this hypothesis and help constrain dark energy models.

This census of distant galaxies will also reveal how galaxies are distributed in our universe, which will help astrophysicists understand how the delicate interplay of the gravity of dark matter, luminous matter and dark energy forms large-scale structures in the universe.

Additionally, the location of galaxies in relation to each other tells scientists how they are clustered.

Dark matter, an invisible substance accounting for over 80 per cent of matter in our universe, can cause subtle distortions in the apparent shapes of galaxies.

That is because its gravity bends light that travels from a distant galaxy toward an observer, which changes the appearance of the galaxy when it is viewed from a telescope.

Euclid's combination of visible and infrared instruments will examine this distortion effect and allow astronomers to probe dark matter and the effects of dark energy.

Detecting infrared light, which is invisible to the human eye, is especially important for studying the universe's distant galaxies.

Each detector system consists of a detector, a cable and a "readout electronics chip" that converts infrared light to data signals read by an onboard computer and transmitted to Earth for analysis. Sixteen detectors will fly on Euclid, each composed of 2040x2040 pixels.

They will cover a field of view slightly larger than twice the area covered by a full moon. The detectors are made of a mercury-cadmium-telluride mixture and are designed to operate at extremely cold temperatures.