Closer to Venus than ever before

Since launch in 2020, Solar Orbiter has carried out a number of gravity assists at Earth and Venus to gradually shrink its orbit and bring it closer to the Sun, but never before has it come as close to a planet as it will today, 18 February 2025.

At 21:48 CET, the spacecraft will pass within just 379 km of Venus. For comparison, astronauts aboard the International Space Station orbit Earth at an average altitude of 408 km.

“Getting so close to the planet allows us to use its gravity to significantly change the spacecraft’s orbit without using much fuel,” says ESA Flight Dynamics expert Julia Schwartz.

“The planets in our Solar System orbit the Sun in the same roughly flat plane. Today’s encounter with Venus will use the planet’s gravity to significantly ‘tilt’ Solar Orbiter’s orbit with respect to that plane. This will grant Solar Orbiter a much better view of the Sun’s polar regions, which cannot be seen from within the plane.”

Future Venus flybys, such as the one in December 2026, will further tilt the spacecraft’s orbit and enable high-resolution imaging of the Sun’s entire polar regions.

From its unique orbit, the mission will help us refine our understanding of solar activity and improve our ability to safeguard technology on Earth from powerful solar outbursts and erratic space weather.

Cool under pressure

Passing so close to Venus presents a number of challenges for the team at ESA’s European Space Operations Centre (ESOC) in Germany. Precise calculations and minor course corrections are necessary before and after the flyby to keep the spacecraft on track.

“The flyby has been carefully planned to get close enough to Venus to get the most out of the encounter while keeping the spacecraft safely above the planet’s atmosphere to avoid it experiencing drag,” says Sam Bammens from the Solar Orbiter Flight Control Team.

However, Solar Orbiter will still be bathed in the thermal radiation emitted by the planet as it passes.

“We expect Solar Orbiter to heat up significantly during the flyby. To prepare for this, the team carried out a detailed simulation of the heating effect of the Venus gravity assist manoeuvre. Several parts of the spacecraft will experience a significant temperature increase, but all components will stay well within their design limits.”

“For a few of us in the control team, it is our first flyby. During the planning, we learned a lot about what it takes to navigate the Solar System, and we are very excited for tonight.”

Cloudy with a chance for science

During the manoeuvre, Solar Orbiter will continue to point its ‘front’ – its instruments and, more importantly, its heat shield – towards the Sun to keep the spacecraft safe. That means it won’t be able to point any of its cameras towards Venus and its cloud tops during the flyby, but it is still an opportunity to gather some scientific data.

Unlike Earth, Venus lacks a global magnetic field to interact with the charged particles of the solar wind. However, a layer of its atmosphere known as the ionosphere interacts with the solar wind in unique ways.

Solar Orbiter’s Magnetometer and Radio and Plasma Waves sensors will be switched on as the spacecraft passes Venus to record the planet’s magnetic and plasma environment. The data they collect will contribute to ongoing research on how the solar wind affects planetary atmospheres beyond Earth.

ESA at Venus

Solar Orbiter is not the only ESA mission visiting Venus this year. ESA’s Juice spacecraft, en route to Jupiter to explore its icy moons, will also fly past the planet in August.

Solar Orbiter and Juice will pass Venus just 194 days apart – that’s less than one day on Venus, which lasts 243 Earth days. The frequent visits highlight the planet’s important role as a waypoint for ESA's interplanetary voyagers.

However, while Solar Orbiter and Juice are making just brief visits to Earth’s neighbour, for some ESA missions, Venus is the final destination. From arrival in 2006 until the end of the mission in 2014, ESA’s Venus Express studied the planet’s atmosphere and clouds in detail and mapped its surface temperature.

Looking ahead, ESA’s Envision is set to launch in the early 2030s. Envision will be the first mission to provide a comprehensive view of Venus from its inner core to its upper atmosphere. In doing so, it will help scientists determine how and why, despite starting off similar, Venus and Earth evolved in such different ways.