Aditya L1: All You Need To Know About VELC Payload Developed By Indian Institute of Astrophysics

ISRO on Monday announced that India's first solar mission Aditya-L1 to study the Sun will be launched on September 2 at 11.50 AM from Sriharikota spaceport.

Aditya-L1 spacecraft is designed to provide remote observations of the solar corona and in-situ observations of the solar wind at L1 (Sun-Earth Lagrange point), which is about 1.5 million kilometres from the Earth.

The Aditya-L1 mission would carry seven payloads to observe the photosphere, chromosphere and the corona -- the outermost layers of the Sun -- in different wavebands.

The Indian Institute of Astrophysics (IIA) on Tuesday said it has designed, assembled, and tested the Visible Emission Line Coronagraph (VELC), one of the seven payloads of Aditya-L1.

The IIA said the VELC was developed in close collaboration with the ISRO.

"IIA had to build India's first large-sized 'Class to Clean Rooms' at (sic) its CREST campus in Hosakote to assemble VELC," IIA said in a statement.

The Aditya L1 satellite carries six other payloads:

• Solar Ultraviolet Imaging Telescope (SUIT)

• Aditya Solar Wind Particle Experiment (ASPEX)

• Plasma Analyser Package for Aditya (PAPA)

• SoLEXS-Solar Low Energy X-ray Spectrometer (SoLEXS)

• High Energy L1 Orbiting X-ray Spectrometer HEL1OS and

• Magnetometer with enhanced science scope and objectives possible by extensive remote and in-situ observation of the Sun.

"Earlier, this mission was conceived as Aditya-1 with a 400 kg class satellite carrying one payload, the Visible Emission Line Coronagraph (VELC), and was planned to be launched in an 800 km low earth orbit," the IIA said.

A satellite placed in the halo orbit around the first Lagrangian point (L1) of the Sun-Earth system has the major advantage of continuously viewing the Sun without any occultation/eclipses, the IIA said.

Therefore, the Aditya-1 mission has now been revised to 'Aditya-L1 mission' and will be inserted in a halo orbit around the L1, which is 1.5 million km from the earth towards the Sun, it explained.

"The VELC payload on-board Aditya-L1 is an internally occulted solar coronagraph with simultaneous imaging, spectroscopy and spectro-polarimetry channels close to the solar limb. VELC is designed to image solar corona," IIA said.

Both imaging and spectroscopic observations obtained by VELC payload are key to study the diagnostic parameters of solar corona and dynamics as well as origin of the coronal mass ejections and magnetic field measurements of the solar corona.

Stokes vector measurements in the plane-of-sky and imaging in white-light are the unique features of this payload, it added.

The scientific studies by the satellite will enhance the current understanding of the solar corona and also provide vital data for space weather studies, the IIA said.

(With PTI inputs)