Nasa's daring mission to 'touch the sun' explained

Nasa is preparing to embark on a daring mission to "touch the sun" on Saturday, aiming to go closer than any other spacecraft has ventured.
The Parker Solar Probe will endure wicked heat while zooming through the solar corona to study this outermost part of the stellar atmosphere that gives

rise to the solar wind.
The launch is currently targeted for August 11 at 3:33 a.m. EDT (8.33am BST), with an extended launch window through to August 23.
"To send a probe where you haven't been before is ambitious. To send it into such brutal conditions is highly ambitious," Nicola Fox, a project scientist from the Johns Hopkins University Applied Physics Laboratory, said.

The mission
The project, with a $1.5 billion price tag, is the first major mission under Nasa's Living With a Star programme.
Nasa is hoping to use the data collected from the probe to help astronomers predict solar storms and explain some of the deepest mysteries surrounding our source of light and heat.
According to a statement from Nasa, the probe is due to orbit within 4 million miles of the sun's "surface," where the probe will "[face] heat and radiation unlike any spacecraft in history".
The probe, named after American solar astrophysicist Eugene Newman Parker, is set to use seven Venus flybys over nearly seven years to steadily reduce its orbit around the Sun, using instruments designed to image the solar wind and study electric and magnetic fields, coronal plasma and energetic particles.
Nasa aims to collect data about the inner workings of the highly magnetized corona.

The risk
Although 4 million miles sounds like a long way by our tiny standards here on Earth, being that close to the sun is likely to be a risk for the spacecraft.
For example, by orbiting the sun at a distance of between 28 and 43 million miles, Mercury's surface and atmosphere have been completely changed by the constant stream of radiation and particles from the sun.
It has been outfitted with a heat shield designed to keep its instruments at a tolerable 29 degrees Celsius even as the spacecraft faces temperatures reaching nearly 1,370 degrees Celsius at its closest pass.

Previous missions
The closest a spacecraft has been before is when Helios 2 came within 27 million miles of the sun in 1976.
By way of comparison, the average distance from the Sun for Earth is 93 million miles.

How it will help us
The information collected from the probe is likely to help future generations of humans, who may one day live outside the Earth's atmosphere.
Our world has since grown ever more dependent on a network of technology – both in orbit and on our planet's surface – that's vulnerable to a threat we barely understand.
These people will need the knowledge to protect themselves from severe winds of charged particles and radiation.
"[Solar Probe Plus] will explore the sun's outer atmosphere and make critical observations that will answer decades-old questions about the physics of how stars work," the statement from Nasa said.
"The resulting data will improve forecasts of major space-weather events that impact life on Earth, as well as satellites and astronauts in space."
Alex Young, a solar scientist at NASA's Goddard Space Flight Centre in Maryland, said it was "of fundamental importance for us to be able to predict this space weather, much like we predict weather here on Earth".
"In the most extreme cases of these space weather events, it can actually affect our power grids here on Earth," he added.