Mission M into the Sun
We’ve visited Pluto and the outer reaches of the Solar System, and our rovers are trundling over the surface of Mars. Yet the Sun has remained stubbornly out of reach… until now
Our star defies the laws
nature. It’s time to find out why.
This summer, NASA will launch one of its most ambitious space missions to date: the Parker Solar Probe. Travelling at a blistering 720,000km/h (450,000mph), the spacecraft will repeatedly dive closer to the Sun than any previous spacecraft in history. It will venture so close that the Parker Solar Probe team refers to it as touching the
Sun. In fact, it will dive in and out of the Sun’s atmosphere, known as its corona. And it’s not going to be alone up there.
In February 2019, the European Space Agency (ESA) will launch a solar mission of its own, called Solar Orbiter. This craft will not go as close to the Sun as its NASA counterpart but it will still be bathed in intense sunlight, almost 500 times that experienced by a spacecraft in Earth’s orbit. Unlike Parker
Solar Probe, which spends only a short amount of time in the fierce heat as it dives in and out, Solar Orbiter will stay put for years, watching and measuring the Sun.
Both of these missions have a single goal: to find out more about the way electrified gas known as plasma is launched from the Sun’s atmosphere out into space. This continuous stream is known as the solar wind. It carries energy and the Sun’s magnetic field through space, and understanding it could solve a problem that’s been mystifying scientists for decades and could be the key to safeguarding our technological society.
WHAT A WIND
When the solar wind collides with Earth, it can disrupt or even destroy electrical technology in orbit and on the ground. One recent study by the US National Academy of Sciences found that without advance warning, a huge solar flare, carried by the solar wind, could cause $2tr worth of damage in the US alone, and it would not be quick to fix. The report found that such an enormous solar flare could cause so much damage to power stations that the US eastern seaboard could be left without power for a year. Europe is similarly vulnerable. Yet while something of this magnitude would only happen once every couple of hundred years, smaller storms happen more frequently. Most of these cause little disruption, but all have an effect. In March 1989, for example, a small solar storm severely damaged a power transformer on the Hydro- Québec power system. It took down their power grid for more than nine hours as emergency repairs were carried out. And more recently, in 2003, a series of solar storms that took place around the Halloween period caused more than half of NASA’s satellites to malfunction in some way, while aeroplanes had to be re-routed away from polar latitudes because of the large amounts of radiation associated with the intense aurora.
So while studying the Sun has never been more timely, the desire to do so stretches back before the space age to the 19th Century, when a solar mystery was uncovered. On 7 August 1869, astronomers gathered across Russia and North America to observe a total solar eclipse. In those fleeting minutes of darkness, the scientists got to see something not visible at any other time: the ghostly veils of the solar corona, the Sun’s outer atmosphere. It was an object of fascination for the astronomers of the day. Two of the astronomers, Charles Augustus Young and William Harkness, were using spectroscopes to split the coronal light into its constituent wavelengths. They knew that the various chemical elements gave out light at specific wavelengths, and by measuring these ‘spectral lines’ they would be able to establish the chemical components of the corona. Working independently, they both discovered a green spectral line with a wavelength of 530.3nm. It caused great excitement at the time because there was no known chemical related to this wavelength, so the astronomers thought they had discovered a new element. They named it coronium.
It turned out that Young and Harkness were wrong, yet it wasn’t until the 1930s that scientists understood