The Parker Solar Probe will fly within 6.2 million kilometres of the Sun's surface Johns Hopkins University Applied Physics Laboratory/NASA/PA

Nasa has announced a historic mission that will send a

 probedirectly into the Sun's atmosphere.

The US space agency has revealed the probe will 

"touch the Sun" as it flies within 3.9 million miles 

(6.2 million kilometres) of the star's surface into the 

solar atmosphere, which is known as the corona.

Originally called the Solar Probe Plus, Nasa also revealed 

it has renamed the spacecraft to Parker Solar Probe to honour

 astrophysicist Eugene Parker - whose work has been crucial 

to our understanding about how stars interact with the 

planets that orbit them.

The solar probe is set to launch in the summer of 2018 and its

aim will be to better understand how stars work and answer 

questions like why the Sun's corona is hotter than its surface.

"Parker Solar Probe is going to answer questions about solar 

physics that we've puzzled over for more than six decades,"

 said Nicola Fox, of Johns Hopkins University, one of the 

scientists involved in the mission project.

It is seen as a landmark mission in space exploration 

(Johns Hopkins University Applied Physics Laboratory/NASA)

"It's a spacecraft loaded with technological breakthroughs 

that will solve many of the largest mysteries about our star, 

including finding out why the Sun's corona is so much hotter

 than its surface.

"And we're very proud to be able to carry Gene's name with 

us on this amazing voyage of discovery."

The probe is expected to travel at 430,000 miles 

(69,000 kilometres) an hour and is expected to do 24 orbits, 

according to Dr Fox.

The spacecraft will be subjected to extreme heat and radiation 

from the corona, where temperatures are nearly 1,377C (2,500F).

The announcement was made during a ceremony to honour Dr Parker, 

a professor emeritus at the University of Chicago.

"The solar probe is going to a region of space that has 

never been explored before," said the solar astrophysicist. 

"It's very exciting that we'll finally get a look.

"One would like to have some more detailed measurements 

of what's going on in the solar wind. I'm sure that there will be 

some surprises. There always are."

The probe, which is expected to come within the orbit of Mercury, 

will be more than seven times closer to the Sun than any spacecraft to date.

The last time a spacecraft came close to the star's surface was 

in 1976, when Helios 2 achieved perihelion - point of the orbit at 

which it was closest to the Sun - at 27 million miles (43 million kilometres).

(The Evening Standard, London)