Zefiro-40 for Smile at the Vega-C launch pad

A view of the fiery end of a second stage for Vega-C at the launch pad at Europe's Spaceport as it is prepared to be hoisted to the top of the Vega-C first stage building the rocket from the ground up, 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: two metal platforms on either side of a black cylinder in horizontal position can be seen. At the end of the cylinder facing the camera is a black cone that is the rocket engine nozzle extender. Two yellow lines can be seen extending upwards that is the hoist. A launch technician in a hard had stands close by with a control box.]