The mission, Solar Probe Plus, is scheduled to launch in the summer of 2018. Placed in orbit within four million miles of the sun’s surface, and facing heat and radiation unlike any spacecraft in history, the spacecraft 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 resulting data will improve forecasts of major space weather events that impact life on Earth, as well as satellites and astronauts in space.
This is not the first time NASA has sent a probe to study the Sun. In 1976, a probe called ‘Helios 2’ passed within 27 million miles of the Sun’s surface to study solar winds and cosmic rays.
“The Sun is the primary puzzle in the universe,” said Eugene Parker, astrophysicist and professor emeritus at the University of Chicago, who is the leading authority on the solar wind and the effects of magnetic fields in the heliosphere. “Because it’s the one star we can observe in detail, and stars are complicated things. You can’t imagine all the strange things that have been discovered in the Sun.”
Our world has since grown ever more dependent on a network of technology – both in orbit and on our planet's surface – that is vulnerable to a threat we barely understand.
Not only can our modern technology suffer enormous damage from extreme solar activity, humans who might one day live outside the Earth’s atmosphere will also need protection from severe winds of charged particles and radiation.
The Solar Probe Plus – now named the Parker Solar Probe after Prof Parker, the first time NASA has named an instrument after a space researcher while they are still alive - will have to endure temperatures up to 1,400°C while keeping its payload at room temperature.
“The materials haven’t existed before to allow us to do this,” explained Nicola Fox, mission project scientist at the Johns Hopkins University Applied Physics Laboratory. “Our heat shield, an 11.5cm-thick carbon-carbon-composite, was developed by APL and many other contributors to withstand repeated extreme hot and cold as we go closer and further away from the sun.”
In addition to the heat shield, the $1.5 billion Parker Solar Probe will use an active water circulation system to help protect instruments that will measure the corona's electric and magnetic fields, electron temperatures, and plasma density.
Fox added: “The craft is being built and tested so we know it will be able to withstand these temperatures. The instruments in the shadow, behind the heat shield will be operating at room temperature.”
Understanding how particles are whipped into high speeds will also give researchers a better idea about how objects move through space. The Kepler Space Telescope, for example, is steered by solar winds. Understanding the solar winds in greater detail will help in the development of spacecraft that are powered by them, such as the proposed Light Sail project.
Another puzzling phenomena NASA wishes to shed some more light on is why the Sun’s corona is so much hotter than its surface. The Sun's photosphere is just over 5,500°C, yet this increases to several million degrees as it turns into the corona. While there are hypotheses as to why this radical heating occurs, more evidence could establish the cause.
Though this mission will travel seven times closer to the Sun than any other mission, at speeds of up to 430,000 mph (118 miles per second), the NASA scientists would love to get even closer. However, Fox said: “We can’t go any closer because we need to use Venus’ orbit to trim the orbit of the probe. If we get any closer, we won’t be able to do this and we will lose the probe.”
The probe is currently being built and tested and will go through final testing by the end of 2017. It will then be transported to Florida where it will be launched next year by a three-stage Delta IV Heavy rocket to propel it towards the Sun where four flybys will take place over the next seven years.
