Zefiro-40 on the road to the Vega-C launch pad

Aerial view of the second stage for Vega-C as it is transported to the launch pad at Europe's Spaceport, 25 February 2026.

The Zefiro-40 solid-propellant rocket motor is used as the second stage for the Vega-C rocket flight VV29 that will take ESA's Smile mission to orbit.

Vega-C is a single-body rocket nearly 35 m tall with that weighs 210 tonnes on the launch pad. The Zefiro-40 second stage contains 36.2 t of solid propellant, providing an average thrust of 1304 kN.

Smile (the Solar wind Magnetosphere Ionosphere Link Explorer) is a joint mission between the European Space Agency (ESA) and the Chinese Academy of Sciences (CAS).

Smile will use four science instruments to study how Earth responds to the solar wind from the Sun. In doing so, Smile will improve our understanding of solar storms, geomagnetic storms and the science of space weather.

ESA is responsible for providing Smile’s payload module (which carries three of the four science instruments), one of the spacecraft’s four science instruments (the soft X-ray imager, SXI), the launcher, and the Assembly Integration and Testing facilities and services. ESA contributes to a second science instrument (the ultraviolet imager, UVI) and the mission operations once Smile is in orbit.

CAS provides the other three science instruments and the spacecraft platform, and is responsible for operating the spacecraft in orbit.

[Image description: A blue truck is transporting a black cylinder along a road leading from bottom-right to top-left. Above is the trucks destination: a tall white building that is the Vega-C launch tower. The area around the road and launch pad is tropical forest to the horizon.]