Context: 

The National Aeronautics and Space Administration (NASA) is set to launch its Polarimetry to Unify the Corona and Heliosphere (PUNCH) Mission from Vandenberg Space Force Base in California, USA.

About PUNCH Mission:

• Under the mission, a constellation of four small satellites in low Earth orbit will make 3D observations of the entire inner heliosphere to study how the Sun's corona becomes the solar wind.
• PUNCH is a first-of-its-kind solar mission that will study the solar corona (the outermost layer of the Sun’s atmosphere) and focus on the inner Heliosphere.
• The PUNCH mission is led by the Southwest Research Institute’s office in Boulder, Colorado, USA.
• It will be the first to image the Sun’s corona, or outer atmosphere, and solar wind together to better understand the Sun, solar wind, and Earth as a single connected system.  
• The mission will study how potentially disruptive solar events form and evolve.
• The PUNCH mission is the first mission specifically designed to make use of the polarization of light to measure the corona and solar wind in 3D. 

• The PUNCH satellites include one Narrow Field Imager and three Wide Field Imagers. 

• The Narrow Field Imager (NFI) is a coronagraph, which blocks out the bright light from the Sun to better see details in the Sun’s corona. 
• The Wide Field Imagers (WFI) are Heliospheric imagers that view the very faint, outermost portion of the solar corona and the solar wind itself — giving a wide view of the solar wind as it spreads out into the solar system.   

Why is there an increase in Solar missions?

• Every 11 years, the Sun's magnetic field flips, meaning its north and south poles switch places. This is called the solar cycle.
• The solar cycle affects the Sun's activity. The Sun is most active during the magnetic field flip, known as the solar maximum.
• During the solar maximum, the Sun sends out more intense bursts of radiation and particles into space.
• After the flip, the Sun calms down and reaches the solar minimum; then, a new cycle begins.
• The solar maximum is the best time for scientists to observe and study the Sun.
• There has been an increase in missions to observe the Sun because missing this window means waiting until around 2035-2036 for the next active period.

Similar mission to study the Sun’s corona

• Aditya-L1 Mission of ISRO: It was the first space-based observatory class Indian solar mission to study the Sun and its corona. 

• The mission is expected to study the problems of coronal heating, Coronal Mass Ejection, pre-flare and flare activities, their characteristics, dynamics of space weather, etc.

• Proba-3 mission (European Space Agency's (ESA)): It aims to study the Corona, which is hotter than the Sun's surface, and explore the solar wind, which is a stream of charged particles emanating from the Sun

• NASA's Parker Solar Probe: It became the first spacecraft to fly through the corona – the Sun’s upper atmosphere – in 2021.