ESA’s Solar Orbiter To Perform Closest Ever Flyby of Venus Today!

The European Space Agency (ESA) is set to navigate the ESA/NASA Solar Orbiter spacecraft through its closest encounter with Venus to date; this historic gravity-assist maneuver will bring the spacecraft within just 379 kilometers (235 miles) of the planet’s surface—closer than the altitude of the International Space Station above Earth.

Beyond being a precise feat of celestial mechanics, today’s flyby marks a critical milestone for the mission, allowing Solar Orbiter to gradually alter its trajectory and gain a unique vantage point of the Sun’s elusive polar regions. This new perspective is expected to yield groundbreaking insights into solar activity, space weather, and the Sun-Earth connection.

A Crucial Flyby: Closer to Venus Than Ever Before

Since its launch in February 2020, Solar Orbiter has utilized gravity assists from Earth and Venus to refine its orbit, steadily bringing it closer to the Sun. However, today’s encounter represents the closest planetary flyby the spacecraft has ever attempted.

At 21:48 CET (20:48 UTC), Solar Orbiter will pass just 379 km (235 miles) above Venus—a mere fraction of the planet’s 12,104-kilometer (7,521-mile) diameter.

Why Fly So Close?

By leveraging Venus’s gravity, the mission team can significantly tilt the spacecraft’s orbit without expending much fuel.

“The planets in our Solar System orbit the Sun in roughly the same 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 us a much better view of the Sun’s polar regions, which cannot be seen from within the plane.” - Julia Schwartz, ESA Flight Dynamics Expert

Understanding the Sun’s poles is crucial to decoding the solar cycle, predicting space weather events, and safeguarding Earth’s technological infrastructure from potential solar storms.

Future Venus flybys, including a December 2026 encounter, will progressively increase the tilt of Solar Orbiter’s orbit, enabling even higher-resolution imaging of the Sun’s polar dynamics.

Keeping Cool Under Pressure

Executing a gravity-assist maneuver at such close range presents formidable technical challenges. The team at ESA’s European Space Operations Centre (ESOC) in Darmstadt, Germany, has meticulously calculated the spacecraft’s trajectory and performed minor course corrections to ensure the flyby goes precisely as planned.

“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 experiencing drag,” - Sam Bammens, Solar Orbiter Flight Control Team.

Despite this cautious approach, thermal management is a major concern. As Solar Orbiter passes Venus, it will be bathed in the planet’s intense infrared radiation, leading to a noticeable temperature increase.

“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. Several parts of the spacecraft will experience a temperature increase, but all components will stay well within their design limits.” - Sam Bammens, Solar Orbiter Flight Control Team.

For some members of the mission control team, this marks their first-ever planetary flyby—a thrilling introduction to interplanetary navigation.

Studying Venus’s Mysterious Plasma Environment

While Solar Orbiter’s primary objective is the Sun, today’s flyby presents an opportunity to conduct valuable research on Venus as well.

During the maneuver, the spacecraft will maintain its Sun-facing orientation to keep its instruments and heat shield protected. This means that Solar Orbiter’s cameras will not be able to capture images of Venus. However, several instruments will still gather crucial plasma and magnetic field data.

Unlike Earth, Venus lacks a global magnetic field, making its interaction with the solar wind unique. Instead, Venus has an ionosphere—a charged layer of its atmosphere—that interacts with the solar wind in complex ways.

To investigate these interactions, Solar Orbiter’s Magnetometer (MAG) and Radio and Plasma Waves (RPW) sensors will be switched on as the spacecraft passes through Venus’s magnetic environment.

The data will help scientists further understand:
- How the solar wind shapes planetary atmospheres
- The effects of solar radiation on planets without magnetic protection
- How these findings relate to other unmagnetized planets, such as Mars

Venus: A Popular Stop for ESA’s Interplanetary Voyagers

Solar Orbiter’s visit to Venus is just one of several ESA missions making a pit stop at Earth’s enigmatic neighbor.

Later this year, ESA’s Jupiter Icy Moons Explorer (Juice) will also fly past Venus in August 2025 as it continues its journey to the Jovian system. The two spacecraft will pass Venus just 194 days apart—less than a single day on Venus, which lasts 243 Earth days.

This underscores Venus’s crucial role as a gravity-assist waypoint for spacecraft on deep-space trajectories.

Meanwhile, ESA remains committed to dedicated Venus exploration:

- Venus Express (2006-2014): Delivered groundbreaking insights into Venus’s thick atmosphere, cloud layers, and surface temperature.

- EnVision (early 2030s): Set to be ESA’s next major Venus mission, EnVision will explore Venus from its core to its atmosphere, providing unprecedented data on its geology, climate history, and atmospheric composition.

Venus is often called Earth’s twin, but the two worlds evolved in radically different ways...EnVision will help us understand why Earth became a habitable paradise while Venus turned into a scorching inferno.” - Dr. Valentina Cardoso, ESA Planetary Scientist

Looking Ahead: A New Perspective on the Sun

With today’s flyby complete, Solar Orbiter will continue its mission, inching closer to the Sun and preparing for its next gravity assist in 2026.

As its orbit tilts higher, the spacecraft will provide unprecedented views of the Sun’s poles, unlocking new insights into:
- The origins of the solar wind
- The behavior of the Sun’s magnetic field
- The mechanisms driving space weather

Ultimately, the findings will enhance our ability to predict solar storms, which can disrupt power grids, satellites, and communications on Earth.