The Indian Space Research Organisation (ISRO) has short-listed 20 space-based experiment proposals, including from France, for its proposed Venus orbiter mission ‘Shukrayaan’ to study the planet for more than four years. These include “collaborative contributions” from Russia, France, Sweden and Germany, sources in the Bengaluru-headquartered space agency said.19 months. Of the Indian and international payload proposals it received in response to an announcement of opportunity for novel space-based experiments to study Venus, ISRO has short-listed 20. “These 20 payload (scientific instruments) proposals, including collaborative contributions from Russia, France, Sweden and Germany, are currently under review”, the ISRO official said. The one already selected, according to French space agency CNES, is France’s VIRAL instrument (Venus Infrared Atmospheric Gas Linker) co-developed with the Russian space agency Roscosmos, and the LATMOS atmospheres, environments and space observations laboratory attached to the French national scientific research centre CNRS. “Swedish Institute of Space Physics is engaged with India’s mission to Venus”, sources said.According to ISRO, scientific objectives of ISRO’s Venus mission are 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. Venus is often described as the “twin sister” of the Earth because of the similarities in size, mass, density, bulk composition and gravity. It is believed that both planets share a common origin, forming at the same time out of a condensing nebulosity around 4.5 billion years ago, ISRO had noted in its announcement of opportunity. Venus is around 30 per cent closer to the Sun as compared to Earth resulting in much higher solar flux. Exploration of Venus began in the early 1960s. Venus has been explored by flyby, orbiter, a few lander missions and atmospheric probes.