The Solar Orbiter is preparing for the first of many flyers to help gravity Venus December 27, to start bringing it closer to the Sun and tilting its orbit to observe our star from different perspectives.
Just like most of us will surely stay at home under miscellaneous COVID-19 pandemic closure measures during the traditional holiday season, the overflight – a routine event in the world of flying spacecraft – will also be overseen by spacecraft operations managers.
The closest approach will take place at 12:39 UTC (13:39 CET) on December 27 and will see the spacecraft flying some 7,500 km from the tops of Venus’ clouds. Later flyers, from 2025, will see much closer encounters at just a few hundred miles.
Over the coming summer, several in-situ scientific instruments – MAG, RPW and some EPD sensors – will be included to record magnetic, plasma and the environment of particles around a spacecraft as it encounters Venus. (It is not possible to capture Venus during flight, as the spacecraft must remain facing the Sun.)
In order to properly position themselves for passage, experts from ESA’s ground stations and flight dynamics teams conducted a so-called “Delta-DOR” campaign, using an advanced technique – Delta-Differential One-Way Range – to pinpoint the spacecraft’s position in the universe and its orbits.
In Delta-DOR, a set of widely separated Earth stations on Earth is used to receive the spacecraft’s radio signal, giving the first result for its location. This result is then compared with the locations of known stellar radio sources that have previously mapped other missions, resulting in a corrected and ultra-precise final plot. The Delta-DOR technique allows operators to determine where a spacecraft is located at several hundred meters, even at a distance of 100 million km.
As of December 17, the solar orbiter is 235 million kilometers away from the Earth, and about 10.5 million from Venus. It takes about 13 minutes for the signals to travel to (or from) the spacecraft.
The path of the Sun’s orbit around the Sun has been chosen to be ‘in resonance’ with Venus, meaning it will return close to the planet every few orbits and will again be able to use planetary gravity to change or tilt its orbit. The next meeting will be in August 2021, which is also within days of BepiColomb’s next assistance for the gravity of Venus. Initially, the Solar Orbit will be limited to the same plane as the planets, but each encounter of Venus will increase its orbital inclination. By 2025, it will make its first solar passage at an inclination of 17 °, increasing to 33 ° by the end of the decade, bringing even more polar regions into direct view. This will result in a spacecraft being able to capture the first images of the Sun’s polar regions, crucial for understanding how the Sun ‘functions’, for exploring the Sun-Earth connection and how we can better predict periods of stormy space time.
Solar Orbiter is a space mission of international cooperation between ESA and NASA.
Track the location of Solar Orbiter with this interactive map.