Context: After the success of the Mars Orbiter Mission (Mangalyaan) and Chandrayaan lunar missions, India now aims to explore Venus with its proposed Venus Orbiter Mission (Shukrayaan).
Venus Orbiter Mission:
- The Union Cabinet has approved India’s first mission to Venus which ISRO aims to launch in March 2028. This is the country’s second interplanetary mission after the Mars Orbiter Mission launched in 2013.
- The mission is being developed by the Indian Space Research Organisation (ISRO).
- Objective: To study the planet’s atmosphere, surface, and geological features using sophisticated scientific instruments.
- Study the structure, composition, and dynamics of Venus's atmosphere.
- Investigate surface processes and subsurface stratigraphy.
- Explore solar wind interactions with the Venusian ionosphere.
- The mission will place a spacecraft in orbit around Venus. Once the satellite exits the Earth orbit, it will take around 140 days to reach Venus.
- The mission will carry scientific payloads weighing around 100 kg. The orbiter is expected to carry instruments like synthetic aperture radar, infrared and ultraviolet cameras, and sensors that will study Venus’s ionosphere.
- The mission will also see India perform aero-braking for the first time.
- Aero-braking is a technique used to reduce a satellite's orbit by using atmospheric drag instead of relying solely on fuel-powered engines.
- It is particularly useful for missions to planets with significant atmospheres, like Venus, where it helps conserve fuel while gradually lowering the satellite's altitude.
Significance of the mission:
- Clues about Earth's Evolution: Venus is often termed "Earth's twin" due to its similar size, mass, and density. By studying Venus, scientists can gather valuable information about how planetary bodies evolve over time. Understanding why Venus evolved into a hot, dry planet while Earth remains habitable may offer critical insights into planetary development, particularly for Earth-like planets.
- Insights into Venus's Atmosphere: The mission will provide key insights into the thick clouds that shroud Venus, composed primarily of carbon dioxide and sulfuric acid, and explore whether there are any signs of active volcanoes.
- Clues about Climate Change and Atmospheric Dynamics: Scientists believe that more than four billion years ago, Venus had enough water to cover its surface with an ocean 3 km deep. But now the planet has become dry and dusty. By comparing Venus’s climate with Earth’s, scientists hope to better understand how climate change affects planetary atmospheres.
Facts about Venus:
- Venus has a solid surface by virtue of being one of the 3 inner planets besides Mercury and Earth. It is nearly the same size as the Earth.
- 96.5% of the atmosphere of Venus is made up of carbon dioxide and there are sulphuric acid clouds on the planet. Thus, the palnet has a high greenhouse effect.
- It has an extremely high surface temperature of around 462 degree Celsius, even hotter than Mercury (the planet that is closest to the Sun).
- This may be possible due to a runaway greenhouse effect. The water present on the Venusian surface has evaporated because of the proximity of the planet to the Sun.
- As water vapour is a greenhouse gas, it led to the planet trapping more heat and further evaporating water from its surface.
- The atmospheric pressure on Venus is much higher than on Earth. It is almost similar to the pressure felt underneath the oceans on Earth.
- Surface pressure on Venus is about 90 times that on Earth while surface pressure on Mars is 1/100th of that on Earth.
- Venus rotates very slowly on its axis as compared to Earth. One rotation of Venus lasts around 243 Earth days.
- Its rotation period is longer than its orbital period. (Rotation on its own axis – 243 days, Orbital period around the sun - 224.7 days).
- The planet has retrograde rotation, meaning it spins in the direction opposite to the direction in which it orbits the Sun.
- Due to the slow rotation of Venus it has no global magnetic field. (Earth’s magnetic field is due to rotation of iron core).
- NASA’s image data from the Magellan spacecraft's visit to Venus has revealed evidence of volcanic activity on it. About 80% of the surface of Venus is composed of flat plains of volcanic origin.
Upcoming Venus missions:
- The US has planned at least two more missions to Venus in the future — DaVinci in 2029 and Veritas in 2031.
- NASA's DAVINCI (Deep Atmosphere Venus Investigations of Noble gases, Chemistry, and Imaging) mission will study Venus from above its clouds down to its surface, investigating how the planet and its dense atmosphere formed and evolved over the past 4.5 billion years. Tentatively scheduled to be launched in June 2029 and would enter the Venusian atmosphere in June 2031.
- VERITAS: NASA's VERITAS (Venus Emissivity, Radio Science, InSAR, and Spectroscopy) mission is expected to be launched in 2031. VERITAS will use a suite of seven instruments to study the surface and atmosphere of Venus.
- The European Space Agency (ESA) has planned the EnVision mission for 2030. EnVision will study the atmosphere, surface, and interior of Venus.