India is planning to buy a small number of powerful Russian rocket engines called RD-191 to increase the lifting capacity of its space rockets. These engines are semi-cryogenic, meaning they use kerosene at room temperature and super-cooled liquid oxygen. If this deal happens, it will be the second time India buys rocket engines from Russia. In the 1990s, India had purchased seven cryogenic KVD-1 engines, which were used in the early GSLV rockets.

The possible agreement is expected to move forward during the visit of Russian President Vladimir Putin on December 4, when he meets Prime Minister Narendra Modi. Russian space agency Roscosmos has already indicated “good news” about cooperation with India, especially in rocket engines, astronaut missions, and space station development.

India and Russia already have a strong space partnership. Russia trained India’s four Gaganyaan astronaut candidates and also supplied the Sokol spacesuits they will use.

Why India wants the RD-191 engine

India’s biggest rocket, the LVM3, can lift only up to 4,000 kg to geosynchronous transfer orbit and around 8,000–10,000 kg to low Earth orbit. This is much lower compared to rockets from countries like the US, Europe, or China. Because of this limitation, India often has to rely on foreign companies, like SpaceX or Arianespace, to launch heavy satellites.

India’s future plans, such as the Gaganyaan human space mission, a proposed Indian space station, and a future moon landing, will require much more powerful rockets. Developing such engines in India will take many years. Although ISRO is working on its own semi-cryogenic engine (SE-2000), it is not ready yet. This is why India is considering importing the ready-for-use RD-191.

How India will use the engine

ISRO plans to install the RD-191 engine in the second stage (L110 stage) of the LVM3 rocket to immediately boost its lifting power. In the future, ISRO can also pair the Russian engine with its more advanced C32 cryogenic upper stage to carry heavier satellites from Indian soil.

The RD-191 is about 2.5 times more powerful than India’s Vikas engine. It can also adjust its thrust during flight, which helps in precise control and could support reusable rockets in the future. If India needs many such engines later, both countries may work together to manufacture the RD-191 in India under licence.