Solar Orbiter prepares for unprecedented Venus flyby

Solar Orbiter prepares for unprecedented Venus flyby
by Erica Marchand
Paris, France (SPX) Feb 20, 2025

ESA's Solar Orbiter, a collaborative mission with NASA, is poised for its closest-ever approach to Venus, marking a pivotal moment in its mission to study the Sun's polar regions.

The spacecraft's maneuver will alter its orbital trajectory, granting scientists a rare opportunity to observe the Sun's poles, a perspective unattainable from Earth. Insights gained from this unique vantage point will enhance our understanding of solar dynamics, space weather, and their impact on Earth.

A record-breaking approach to Venus

Since its launch in 2020, Solar Orbiter has used a series of gravity assists from Earth and Venus to refine its orbit. On February 18, 2025, the spacecraft reached an unprecedented proximity to Venus, coming within 379 km of the planet at 21:48 CET. For comparison, astronauts aboard the International Space Station orbit Earth at an altitude of about 408 km.

"Flying this close to Venus allows us to leverage its gravitational pull to alter the spacecraft's trajectory with minimal fuel consumption," explained ESA Flight Dynamics expert Julia Schwartz.

"The planets in our Solar System orbit the Sun within a relatively flat plane. Today's encounter will utilize Venus' gravity to significantly tilt Solar Orbiter's orbit, enabling a superior view of the Sun's polar regions, which are otherwise obscured."

Future flybys, including another in December 2026, will further adjust the spacecraft's trajectory, progressively improving its ability to capture high-resolution images of the Sun's poles. This mission is expected to refine our knowledge of solar activity and help mitigate risks posed by solar storms to Earth's technological infrastructure.

Navigating extreme conditions

The team at ESA's European Space Operations Centre (ESOC) in Germany has meticulously planned the flyby to maximize scientific gains while ensuring the spacecraft remains at a safe altitude above Venus' atmosphere.

"The maneuver has been optimized to get close enough to benefit from Venus' gravity while avoiding atmospheric drag," said Sam Bammens of the Solar Orbiter Flight Control Team.

Despite maintaining a safe distance, the spacecraft will still be exposed to thermal radiation from Venus as it passes.

"We expect the spacecraft to heat up considerably during this encounter," noted Bammens. "To mitigate risks, we conducted extensive simulations to predict and account for temperature fluctuations. While some components will experience notable heating, all will remain within safe operational limits."

"For several of us on the control team, this marks our first flyby experience. Through the planning process, we have gained invaluable insights into interplanetary navigation, and we are eagerly anticipating tonight's event."

Venus flyby and scientific opportunities

During the approach, Solar Orbiter will maintain its usual Sun-facing orientation, with its heat shield protecting sensitive instruments. This positioning means that its cameras will not be able to capture images of Venus, but the encounter still holds scientific value.

Unlike Earth, Venus lacks a global magnetic field, yet its upper atmosphere, known as the ionosphere, interacts uniquely with the solar wind. To investigate these interactions, the spacecraft's Magnetometer and Radio and Plasma Waves sensors will be active during the flyby, collecting data on Venus' plasma and magnetic environment. These findings will contribute to ongoing studies of how solar wind influences planetary atmospheres across the Solar System.

ESA's ongoing exploration of Venus

Solar Orbiter is not the only ESA mission visiting Venus this year. The Juice spacecraft, currently en route to Jupiter's icy moons, is also scheduled for a Venus flyby in August. These two encounters will occur just 194 days apart-less than one Venusian day, which lasts 243 Earth days.

While Solar Orbiter and Juice are only making brief stopovers, other ESA missions have dedicated their entire focus to Venus. From 2006 to 2014, ESA's Venus Express extensively analyzed the planet's atmosphere and surface temperature. Looking ahead, the EnVision mission, set for launch in the early 2030s, will provide a comprehensive study of Venus, examining its evolution in comparison to Earth and offering crucial insights into planetary development.