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Explained | NASA’s missions to Venus

A photo of Venus comparing with Earth.   | Photo Credit: PTI

Venus is often referred to as Earth’s twin. Both the planets are almost alike in size, density and gravity. Despite similar physical makeup, like most siblings we know of, the two worlds turned out to be drastically different from each other. While Earth is a heaven for life, Venus is a blistering hellscape. Venus has a thick, toxic atmosphere filled with carbon dioxide and at 850 degrees Fahrenheit, it is the hottest planet in the solar system. It has a crushing air pressure and is perpetually shrouded in thick, yellowish clouds of sulphuric acid.

Though Venus was the first ever planet to be explored by a spacecraft (Russia’s Venera 1 in 1961), space agencies have largely ignored Venus in the last few decades and focussed on other planets, especially Mars.

But that’s set to change with NASA, the U.S. Space Agency, announcing two robotic missions to Venus as part of the Discovery Program. Recent studies, one suggesting that the planet's surface was habitable for several billion years, and another suggesting presence of microbes in Venusian skies, have reinvigorated an interest in Venus.

 

Set to be launched in 2028-2030 time period, the NASA missions will include an orbiter called VERITAS and an atmospheric probe known as DAVINCI+. The price tag of each mission is capped at around $500 million. Read on to know more about these missions...

What is DAVINCI+?

• Probe DAVINCI+, which stands for Deep Atmosphere Venus Investigation of Noble gases, Chemistry, and Imaging, will gather more detail on the composition of Venus' atmosphere to learn how it formed and evolved.

• The mission also seeks to determine whether the planet once had an ocean.

 

• A descent sphere will plunge through the dense atmosphere which is laced with sulphuric acid clouds. It will precisely measure the levels of noble gases and other elements to learn what gave rise to the runaway greenhouse effect we see today.

• DAVINCI+ will also beam back the first high resolution images of the planet's ‘tesserae,’ geological features roughly comparable with Earth's continents whose existence suggests Venus has plate tectonics.

• The results could reshape scientists' understanding of terrestrial planet formation.

What is the objective of VERITAS?

• The other mission is called VERITAS, an acronym for Venus Emissivity, Radio Science, InSAR, Topography, and Spectroscopy.

• This will aim to map the Venusian surface from orbit and delve into the planet's geologic history.

• Using a form of radar that is used to create three-dimensional constructions, it will chart surface elevations and confirm whether volcanoes and earthquakes are still happening on the planet.

• It will also use infrared scanning to determine rock type, which is largely unknown, and whether active volcanoes are releasing water vapour into the atmosphere.

• While the mission is NASA led, the German Aerospace Center will provide the infrared mapper. The Italian Space Agency and France's Centre National d'Etudes Spatiales will contribute to the radar and other parts of the mission.

WHAT do we know about Venus?
  • • Venus is the second closest planet to the Sun, orbiting at a distance of about 67 million miles. It falls under the habitable zone of the Sun.
  • • Venus rotates very slowly on its axis – one day on Venus lasts 243 Earth days. The planet orbits the Sun faster than Earth, however, so one year on Venus takes only about 225 Earth days, making a Venusian day longer than its year.
  • • Venus’ thick atmosphere traps heat creating a greenhouse effect. Its surface temperature is hot enough to melt lead.
  • • Venus rotates backward on its axis. This means the Sun rises in the west and sets in the east, opposite of what we see on Earth.
  • • The surface of Venus is dominated by volcanic features and has more volcanoes than any other planet in the Solar System

WHAT are some of the previous missions to Venus?

• Russia (former Soviet Union) launched a number of missions to Venus under its Venera program between 1961 and 1984. Its Venus program achieved some of the greatest successes of human space exploration—including the first landing of spacecraft on another planet and the first photos from another world’s surface.

• The first one to launch was Venera 1, which made a flyby in May 1961, however no data returned due to communication failure. Subsequently, ten probes successfully landed on the surface of the planet, including the two Vega program and Venera-Halley probes, while thirteen probes successfully entered the Venusian atmosphere.

• Venera 13 survived the intense heat and crushing pressure of Venus’ surface for more than two hours, while others survived only for a few minutes. Most atmospheric information and surface data from Venus were collected by the Soviet Union.

• NASA's Mariner 2 successfully flew by and scanned the cloud-covered world in 1962. NASA’s last Venus orbiter was Magellan, which arrived in 1990, and mapped the planet's surface with radar. Since then, numerous spacecraft from the U.S. (and other space agencies) have flew by Venus as part of their missions to other destinations. These include Galileo to Jupiter in 1990, Cassini-Huygens to Saturn in 1998/99 and NASA's MESSENGER mission to Mercury in 2006 and 2007.

• European Space Agency’s Venus Express Orbiter entered Venus orbit on April 2006 and the communication was lost in November 2014. Japan’s Akatsuki space probe tasked to study the atmosphere of Venus entered Venus orbit in 2015 and is still operational.

Why is there a renewed interest in Venus?

• Scientists think that Venus was once a balmy, temperate world with oceans, rivers and streams. Recent research suggests that Venus was habitable for life for several billion years, until greenhouse effect took hold around 700 million years ago.

• Another research suggests that Venus may be habitable today. Scientists theorise microbes might exist high in the clouds where it’s cooler and the pressure is similar to Earth’s surface. Detection of phosphine, a chemical released by microbes, suggested that life was possible in the clouds of Venus. The apparent phosphine find has not been confirmed by other teams, however, and remains a topic of considerable discussion and debate.

• So Venus has become an attractive target for extraterrestial study.

• Scientists studying exoplanets are trying to understand the Venus-Earth difference to know about how planets evolve in general, and how habitable conditions evolve.

 

HOW does future look like for Venus exploration?

• India is developing a potential Venus mission. Shukrayaan-1 is a proposed orbiter to Venus to be launched in 2024 or 2026. The project would include an orbiter and an atmospheric balloon probe and study the surface and atmosphere of the planet.

• Russia aims to go back to Venus with an ambitious mission called Venera-D that would feature an orbiter, a lander and atmospheric balloons. Venera-D will launch in 2029, if all goes according to plan.

• Rocket Lab, a private space agency, plans to launch a Venus mission in 2023 using its Electron rocket and Photon satellite bus.

• EnVision is an orbital mission to Venus being developed by the European Space Agency and proposed to be launched in 2023.


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Printable version | Jul 26, 2021 9:52:10 PM | https://www.thehindu.com/children/explained-nasas-missions-to-venus/article34863589.ece

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