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India's first mission to Venus — Earth's twin that went wrong. A planet 96% CO₂, surface temperatures of 465°C, atmospheric pressure 90 times Earth's, and sulfuric acid clouds. Why did Earth and Venus evolve so differently? Shukrayaan will find out.
Watch: Shukrayaan — Venus MissionShukrayaan-1 — Shukra being the Sanskrit name for Venus — is India's first Venus mission, formally approved by the Union Cabinet in 2024 with a dedicated budget. This moved Shukrayaan from a proposal to a fully sanctioned, actively funded project. It is expected to launch around 2028. The mission will place an orbiter around Venus for a minimum of four years, studying its dense atmosphere, mysterious surface (hidden under permanent cloud cover), volcanic activity, and the space environment around the planet.
Venus is the most Earth-like planet in terms of size and mass — yet its surface is a hellscape of crushing pressure, extreme heat, and sulfuric acid rain. Understanding why Venus became what it is, while Earth became habitable, is one of the most important questions in planetary science — directly relevant to understanding climate change, planetary habitability, and the search for life elsewhere.
ISRO received over 100 experiment proposals from the global scientific community when it opened Shukrayaan for instrument selection — a testament to how scientifically valuable the mission is considered internationally.
Venus and Earth formed at the same time from the same solar nebula. They are nearly identical in size (Venus is 95% of Earth's diameter) and mass (81% of Earth's). Yet today, Earth is a water-covered, life-bearing world with a 21% oxygen atmosphere — and Venus is a runaway greenhouse planet with surface temperatures hot enough to melt lead.
What happened to Venus? Current leading theories suggest it had liquid water oceans until about 700 million years ago, when a massive resurfacing event released enormous amounts of CO₂, triggering a runaway greenhouse effect. Understanding this transition — and whether it was triggered by geological, orbital, or chemical processes — is critical for understanding Earth's own climate future.
Additionally, in 2020, astronomer Jane Greaves and her team announced the detection of phosphine (PH₃) in Venus's atmosphere — a gas that on Earth is only produced by biological processes. The finding remains scientifically contested, but if confirmed, it would be the first evidence of life beyond Earth. Shukrayaan will have the instruments to investigate.
Shukrayaan faces unique engineering challenges. Venus's proximity to the Sun means the spacecraft receives twice the solar radiation of Earth-orbiting satellites — thermal management is critical. The elliptical orbit is designed to bring the spacecraft close to Venus for high-resolution observations, then swing far out to study the magnetosphere and solar wind interaction.
The spacecraft bus is derived from ISRO's heritage interplanetary platform — the same class used for Mangalyaan — adapted for the thermal environment near Venus. SAC (Space Applications Centre) in Ahmedabad is leading the development of several key instruments including a synthetic aperture radar to image Venus's surface through its impenetrable clouds.
Launch windows to Venus occur approximately every 19 months. A significant mission design consideration is aerobraking — using Venus's thick atmosphere as a natural brake to lower the spacecraft's orbit without expending propellant. After Venus Orbit Insertion, ISRO plans to use repeated passes through the upper atmosphere, allowing drag to gradually circularise the orbit. This is a high-risk, high-reward manoeuvre ISRO will be attempting at Venus for the first time — saving hundreds of kilograms of propellant mass while requiring extremely precise navigation to avoid going too deep into the atmosphere.