Solar Orbiter makes Venus flyby as it heads towards the Sun
Image credit: ESA
The UK-built Solar Orbiter spacecraft is making a flyby of Venus, using the planet’s gravitational field to slingshot itself closer to the Sun.
The spacecraft, which launched in February, will make its closest approach to the planet just after midday on 27 December. It will fly some 7,500 km from the Venus cloud tops while tilting its orbit so that it can observe the Sun from a different perspective.
As it will be facing the Sun the whole time, Solar Orbiter will not be able to take any photos of Venus, although it will use some of the onboard instruments to record the magnetic, plasma, and particle environment around it.
Following completion of its commissioning phase, the spacecraft is undertaking its main science phase which will see it get as close as 42 million km from the Sun’s surface, closer than the planet Mercury.
Its initial mission is intended to last seven years, during which it will keep coming into close contact with Venus which it will use to alter or tilt its orbit. The next close approach of the planet is expected to take place in August 2021, and each encounter will increase its orbital inclination.
In order to align for the flyby, specialists from the European Space Agency’s ground stations and flight dynamics teams conducted a so-called ‘Delta-DOR’ campaign, using a sophisticated technique (Delta-Differential One-Way Ranging) to precisely determine the spacecraft's position and trajectory.
In Delta-DOR, a set of widely separated ground stations on Earth are used to receive the spacecraft's radio signals, giving a first result for its location. This result is compared to locations of known stellar radio sources previously mapped by other missions, resulting in a corrected and ultra-precise final plot. The Delta-DOR technique allows operators to determine where a spacecraft is to within a few hundred metres, even at a distance of 100 million km.
In July, the Solar Orbiter revealed its first images of the Sun, taken from 47 million miles of the star’s surface. It was the closest images ever taken of the Sun, revealing “campfires”, or mini solar flares, dotted across its surface.
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