Funds were released in 2017 to complete preliminary studies, and solicitations for instruments were announced.[17][18] The orbiter was expected to have a science payload capability of approximately 100 kilograms (220 lb) with 500 W available power.[1] The initial elliptical orbit around Venus is expected to be 500 km (310 mi) at periapsis & 60,000 km (37,000 mi) at apoapsis.[1][19]
In 2017, ISRO made an 'Announcement of Opportunity' (AO) seeking science payload proposals from Indian academia.[1] In 2018, ISRO made another 'Announcement of Opportunity' inviting payload proposals from the international scientific community. The available science payload capacity with a science payload of 100 kg.[28][29]
ISRO and the FrenchNational Centre for Space Studies (CNES) held collaboration discussions in 2018, including the Venus mission and autonomous navigation and aerobraking technologies.[30]FrenchastrophysicistJacques Blamont expressed interest to ISRO chairmanUdupi Ramachandra Rao to use balloons to help study the Venusian atmosphere. Similar to the Vega missions, these instrumented balloons could be deployed from an orbiter and take prolonged observations while floating in the planet's relatively mild upper atmosphere.[22][31] ISRO agreed to consider the proposal to use a balloon probe carrying a 10 kilograms (22 lb) payload to study the Venusian atmosphere at a 55 kilometres (34 mi) altitude.[3][32]
As of November 2020, ISRO had shortlisted 20 international proposals that include collaboration with institutions from Russia, France, Sweden and Germany.[34] Mission could be launched no earlier than 2028, with an alternate launch window in 2031.[35][36][4]
S. Somanath, the chairman of ISRO, stated that engineers are aiming to lower the cost of some high-value components and that India's maiden mission to Venus is probably going to launch in 2028 while speaking with reporters during India International Science Festival 2024. Venus Orbiter Mission development, however, will take longer than expected because Gaganyaan project has taken precedence.[37][38]
Science payload
The 100 kg (220 lb) science payload would consist of instruments from India and other countries. As of December 2019[update], 16 Indian and 7 international payloads had been shortlisted.[39][5][40]
^ abcdBagla, Pallava (21 November 2018). "India seeks collaborators for a mission to Venus, the neglected planet". Science. doi:10.1126/science.aaw1484. S2CID134327421. Astrophysicist Jacques Blamont, a former head of France's National Center for Space Studies in Paris, several years ago proposed producing metallic balloons that could dip in and out of Venus's hot atmosphere to study its chemistry. ISRO has adopted that idea, says Sivan, but will develop the balloon in-house. It will carry 10 kilograms of instruments and float down to 55 kilometers above the surface.
^Laxman, Srinivas (24 April 2017). "Venus mission: Isro invites proposals for space experiments". The Times of India. Retrieved 9 October 2017. An Isro official told TOI that though it is an approved mission, the date of the launch is yet to be firmed up.
^"Department of Space, Annual Report 2016-17"(PDF). 22 February 2017. Archived from the original(PDF) on 18 March 2017. Retrieved 8 November 2018. Both agencies have also agreed to conduct a joint experiment to study Venus atmosphere by collecting signals from JAXA's Akatsuki mission by ISRO's ground stations (IDSN).
^"India-France Joint Vision for Space Cooperation (New Delhi, 10 March 2018)". www.mea.gov.in. Retrieved 21 November 2018. 3.6 Exploring the solar system and beyond: ISRO and CNES would work together on (i) autonomous navigation of rovers in Moon, Mars and other planets; (ii) aero braking technologies for planetary exploration; (iii) modeling of Mars and Venus atmosphere; and (iv) inflatable systems for Venus exploration. Both sides can embark on complex high technology space science and planetary exploration missions in future.