Why in News:

• NASA announced plans to launch a pair of missions to Venus between 2028 and 2030.

About the mission

• To study the atmosphere and geologic features of Venus and better understand why Earth and Venus emerged so differently.
• NASA is  awarding about $500 million each to develop the two missions, dubbed DAVINCI+ (short for Deep Atmosphere Venus Investigation of Noble Gases, Chemistry and Imaging) and VERITAS (an acronym for Venus Emissivity, Radio Science, InSAR, Topography and Spectroscopy).
• DAVINCI+ will measure the composition of the dense, hothouse atmosphere of Venus to further understand how it evolved, while VERITAS will map the planet’s surface from orbit to help determine its geologic history.
• DAVINCI+, consisting of a fly-by spacecraft and an atmospheric descent probe, is also expected to return the first high-resolution images of unique geological characteristics on Venus called “tesserae.” Scientists believe those features may be comparable to Earth’s continents and suggest that Venus has plate tectonics.
• After two fly-by passes to capture time-lapse imagery of Venus’ clouds, DAVINCI+ will release its spherical probe for an hour-long descent to a vast mountainous region.
• Slowed first by a parachute, then by aerial friction, the probe will sample atmospheric chemistry, pressure and temperature all the way down, and take high-resolution images as it nears the surface.

About Venus

• Earth’s closest planetary cousin and the second planet from the sun, Venus is similar in structure but slightly smaller than Earth and much hotter. Above its forbidding landscape lies a thick, toxic atmosphere consisting primarily of carbon dioxide, with clouds of sulfuric acid droplets.
• The consequence is a runaway greenhouse effect that scorches the surface of Venus at temperatures as high as 471℃. The “air” on Venus is so dense and pressurized that it behaves more like a fluid than a gas near the surface.
• Scientists believe Venus may once have harbored seas of water potentially suitable for life, before unknown forces triggered its extreme greenhouse effect, vaporising its oceans.
• Venus is a ‘Rosetta stone’ for reading the record books of climate change, the evolution of habitability and what happens when a planet loses a long period of surface oceans.
• NASA’s last dedicated mission to Venus, the Magellan spacecraft, reached the planet in 1990. After four years in orbit making the first global map of the Venusian surface and charting its gravity field, Magellan was sent plunging to the surface to gather atmospheric data before ceasing operations.
• In 2020, a team of International Astronomers discovered the presence of phosphine gas in the atmosphere of Venus. Phosphine acts as a biosignature because it is known to be produced mainly through biological processes, and not through any naturally occurring chemical process.
• Earlier in 2011, the European Space Agency’s mission, Venus Express, found signs of ozone, a biomarker, in the upper atmosphere of Venus.

India’s Venus Mission

• The Shukrayaan orbiter will be the first mission to Venus by the India Space Research Organization (ISRO)
• The purpose of the mission is investigation of the surface processes and shallow subsurface stratigraphy; and solar wind interaction with Venusian Ionosphere, and studying the structure, composition and dynamics of the atmosphere.
• The satellite is planned to be launched onboard GSLV Mk II rocket.

Reference:

1. https://www.thehindu.com/sci-tech/science/nasa-plans-two-new-missions-to-venus-its-first-in-decades/article34713518.ece