NASA’s Parker Solar Probe – Journey to the Sun’s Corona

The Sun is the closest star to us and building an understanding of this huge big ball of nuclear fusion will allow us to improve this planet’s own resilience to Sun’s infrequent burbs of high energy particles that can create havoc to do with satellites and power grids. It will also allow us to understand the mechanisms that may be going on around other stars, given the Sun is the easiest to study because it’s significantly closer than the other stars (4.3 light years being th next closest). The Parker Solar Probe will fly in the Sun’s corona, the launch point of the solar wind, to help us understand why these particles accelerate so quickly in this region and why the corona is so hot.

NASA plans to launch the Parker Solar Probe from 31 July this year from the Kennedy Space Centre on a United Launch Alliance Delta IV Heavy rocket. This probe will go closer to the Sun more than anything that humans have built before. The previous record holder was Helios 2 in 1976, which got as close as 43.5 million kilometres. The Parker Probe will smash that record by getting as close as 6.1 million kilometres, about 10 times as close as Mercury to the Sun. This will put the spacecraft under extreme stress with the surface getting as hot as as nearly 1400 degrees Celsius. To survive these enourmous temperatures and keep the sensors protected, the spacecraft will have an 11.5 cm thick heat shield made from a carbon composite. Not only will the spacecraft have to endure very high temperatures, it will also be travelling incredibly fast at about 700,000 kilometres per hour (still only 0.06% of the speed of light).

The Parker Solar Probe (Credit: NASA)

Why do we want to know more about the Sun? The main reason is that the weather on the Sun can have a significant impact on our own lives. We have become very dependent on satellites for communications, remote sensing and positioning and high energy particles from the Sun can detrimentally affect these services. We don’t know a lot about the processes that cause these streams of high energy particles, scientists want to understand more about why the corona of the Sun is so much hotter than the surface and why the solar wind is accelerated to such a high speed. The more that we can understand about the Sun, the better we will be able to predict solar weather and hopefully avoid the outages of satillite communications and the potential damaging effects that large streams of high energy particles can have on power grids. The high energy particles from the Sun in the solar wind can not only damage satellites and power grids, but also degrade pipelines, and effect air travellers and astronauts.

The corona is an outer layer of the Sun that extends millions of kilometres into space around the Sun and is quite variable in its nature depending on the current state of the solar cycle. The corona is extremely hot being over 1 million degrees Celsius and scientists are not certain of the mechanism as to why the corona is so hot. It’s the part of the Sun that is visible in photographs of Solar Eclipses that show large loops of structure extending well beyond the Sun, like the image below.

The Sun’s Corona (Credit: Luc Viatour)

The Parker Solar Probe will make its way to the sun via seven flypasts of Venus over seven years to slowly shrink the orbit around the sun until it’s well within the corona and doing the first close flypast on 19 Dec 2024. The instruments on the space craft are based around 4 main investigations. The first is the FIELDS experiment which will examine the different fields in the corona, including the Sun’s magnetic field, electric fields, waves, plasma density, electron temperature, density fluctuations and radio emissions. The second instrument is the Intergrated Science Investigation of the Sun which will measure energetic electrons, protons and heavy ions as they are accelerated in the corona. The third instrument is the Widefield Imager for the Solar Probe which will image the corona and the Inner Heliosphere. The final instrument set is the Solar Wind Electrons Alpha and Protons which will measure velocity, temperature and density of electrons, protons and helium atoms in the corona.

The Parker Solar Probe is name after the prominent US astrophysicist Eugene Parker, professor emeritus from the University of Chicago. He proposed that there was a constant outflow of material from the sun, now called the solar wind. Such was the significance of his work that it was decided to name the probe after him.

It will be a few years before we see the results of this mission as, even through the Sun is quite close in astronomical terms, it is still a huge distance from the Earth and the mechanics of getting the probe into the right orbit require multiple orbits and positioning. All of this will put the probe into the perfect position to help us get a better understanding of the processes occurring in the corona of the Sun. If you want to get your name on the spacecraft then go to this website at NASA and register your name, you have until 27 April.