It is unfortunate that Nasa’s “Solar Probe Plus” mission got put back from 2015 to a 2018 launch, however once it gets going it will have been worth waiting for.  After doing seven fly-bys of Venus first, it will make its initial close approach to the Sun on 19th December 2024, getting within 8.5 solar radii, or less than 6 million km away (here on Earth we are 150 million km away).  And fittingly, the primary power source for the craft will be a dual system of photovoltaic arrays - in other words the energy of the Sun itself will drive it.  The primary objective is to answer two questions: Why is the Sun's atmosphere - the  corona - so much hotter than its visible surface, the photosphere? And how is the solar wind accelerated?
 
In pursuit of new scientific information, Solar Probe Plus will: determine the structure and dynamics of the magnetic fields at the sources of solar wind; trace the flow of energy that heats the corona and accelerates the solar wind; determine what mechanisms accelerate and transport energetic particles; and explore dusty plasma near the Sun and its influence on solar wind and energetic particle formation. The spacecraft will go close enough to the Sun to watch the solar wind speed up from subsonic to supersonic, and it will fly though the birthplace of the highest-energy solar particles.
 
Ultimately it will revolutionize our knowledge of the origin and evolution of the solar wind, which I believe carries not only visible particles but also the Pneuma – the very life force that vivifies us.
 
Credit for Featured image at top of page:
http://clasp-research.engin.umich.edu/dailyplanet/2014/spring/images/banner3a-solar-probe-plus.jpg