Shukrayaan: ISRO's Venus mission attracts international payload proposals

The Indian Space Research Organisation (ISRO) has shortlisted 20 space-based experiment proposals for its proposed Venus orbiter mission 'Shukrayaan' to study the planet for more than four years. Here are the key things that you must know.

It comes as "collaborative contributions" from Russia, France, Sweden and Germany, sources in the Bengaluru-headquartered space agency said. ISRO has been eyeing June 2023 for the country's first mission to Venus.

The optimal launch window (when Venus is closest to the Earth) comes about every 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 shortlisted 20.

The 20 payload (scientific instruments) proposals, including collaborative contributions from Russia, France, Sweden and Germany, are currently under review, an ISRO official said.

The ones 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.

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.

Exploration of Venus began in the early 1960s. Venus has been explored by fly-by, orbiter, a few lander missions and atmospheric probes.
"In spite of great progress made in exploring Venus, there still exist gaps in our basic understanding about surface/sub-surface features and processes, super rotation of Venusian atmosphere and its evolution and interaction with solar radiation/solar wind," ISRO had said.

The payload capability of the proposed 2,500kg satellite, planned to be launched onboard GSLV Mk II rocket, is likely to be 175 kg with 500W of power. The proposed orbit is expected to be around 500 x 60,000 km around Venus. This orbit is likely to be reduced gradually over several months to a lower apoapsis (farthest point).