PASIPHAE: International collaborative sky surveying project

SCIENCE & TECH/ INTERNATIONAL

Topic:

• GS-3: Science and Technology- developments and their applications and effects in everyday life 

PASIPHAE: International collaborative sky surveying project

About

• Polar-Areas Stellar-Imaging in Polarisation High-Accuracy Experiment (PASIPHAE) is an international collaborative sky surveying project. 
• The project has been funded by the world’s leading institutions from USA, Norway, South Africa and Private foundations.
• Scientists aim to study the polarisation in the light coming from millions of stars.
• The survey will use two high-tech optical polarimeters to observe the northern and southern skies, simultaneously.
• It will focus on capturing starlight polarisation of very faint stars that are so far away that polarisation signals from there have not been systematically studied. 
• The distances to these stars will be obtained from measurements of the GAIA satellite (of European Space Agency)
• By combining these data, astronomers can create a 3-Dimensional model of the distribution of the dust and magnetic field structure of the galaxy using a novel polarimeter instrument known as WALOP (Wide Area Linear Optical Polarimeter).

What is WALOP?

• Wide Area Linear Optical Polarimeter (WALOP) is an instrument, when mounted on two small optical telescopes, that will be used to detect polarised light signals emerging from the stars along high galactic latitudes.
• A WALOP each will be mounted on the 1.3-metre Skinakas Observatory, Crete (Greek islands), and on the 1-metre telescope of the South African Astronomical Observatory located in Sutherland.
• Once built, they will be unique instruments offering the widest ever field of view of the sky in polarimetry. In simple terms, the images will simultaneously have the finest of details of a star along with its panoramic background.
• 200 kg weighing WALOP will be capable of observing hundreds of stars concurrently present both in the northern and the southern skies 

Why is PASIPHAE important?

• Since its birth about 14 billion years ago, the universe has been constantly expanding, as evidenced by the presence of Cosmic Microwave Background (CMB) radiation which fills the universe.
• Immediately after its birth, the universe went through a short inflationary phase during which it expanded at a very high rate, before it slowed down and reached the current rate. 
• However, so far, there have only been theories and indirect evidence of inflation associated with the early universe.
• A definitive consequence of the inflationary phase is that a tiny fraction of the CMB radiation should have its imprints in the form of a specific kind of polarisation (known scientifically as B-mode signal).
• All previous attempts to detect this signal met with failure mainly due to the difficulty posed by our galaxy, the Milky Way, which emits copious amounts of polarised radiation.
• Besides, it contains a lot of dust clouds that are present in the form of clusters. When starlight passes through these dust clouds, they get scattered and polarised.
• It is like trying to see faint stars in the sky during daytime. The galactic emission is so bright that the polarisation signal of CMB radiation is lost.
• The mysteries surrounding the origin of the universe can be unravelled with the help of insights provided by PASIPHAE

Connecting the dots:

• IN-Space of India
• UN Outer Space Treaty