A plunge towards the Sun

By 2018, NASA plans to launch a spacecraft which will “skim” our star from 2024.

 

Illustration showing Solar Probe Plus approaching at only 5.9 million kilometres from the sun - a record! As a comparison, the closest planet to our star, Mercury is still at least 46 million kilometres away. Credit: JHU/APL

Although the Sun might seem to be an ordinary yellow dwarf type star, its importance is undeniable for us humans: without it and its energy, no life form would have been able to develop on Earth. Furthermore, while astronomers understand the basic principles of its internal mechanisms (nuclear fusion where hydrogen becomes helium), many details still remain a mystery.

7 fly overs of Venus!
An annoying situation when we know that solar activity has direct effects on our civilisation since some eruptions are capable of causing magnetic storms which disrupt telecommunications, satellite operations and even sometimes overload electric networks on the ground.  In addition, we wonder about the potential influence of the Sun’s cycles on major variations in climate. This is why the number of satellites dedicated to the observation of the sun has recently increased. For example, Picard by the French Space Agency CNES or NASA's Solar Dynamics Observatory. The U.S. agency plans to go even further by launching a spacecraft called Solar Probe Plus in 2018 and on 2 September it announced the instruments that will be on board: priority is given to high precision 3D imagery and the study of the solar corona and solar winds.  It must be said that this robotic explorer will have a unique perspective since it will approach at only 5.9 million kilometres from the Sun, which is 8 times closer than the current record (44 million kilometres for Helios 2 in 1976). At such a short distance, Solar Probe Plus will be subjected to intense heat and will be protected by a thermal shield 2.4 m in diameter capable of withstanding up to 1,400°C.

Solar Probe Plus (illustration) should complete 7 fly overs of Venus to reach the sun in the current mission scenario: 27 September 2018, 21 December 2019, 5 July 2020, 15 February and 10 October 2021, 15 August 2023 and finally 31 October 2024 for an initial fly over of our sun on 19 December 2024! Credit: JHU/APL

However, this mission also has another, just as surprising aspect, namely its long journey to its objective. Going so close to the sun without using excessive fuel (otherwise the spacecraft would be too big and too expensive) requires a journey of 6 years and no less than 7 trips to Venus in order to take advantage of this planet’s gravitational pull to gradually "bend” the spacecraft’s trajectory towards the ideal path and the desired fly overs of our star. Without a doubt, Solar Probe Plus will have earned its place in the Sun!

Published 3 September 2010