Il sole

Knocking on the Sun's door

Two projects developed to study our star in depth.

by Stefano Bevacqua
27 August 2020
4 min read
by Stefano Bevacqua
27 August 2020
4 min read

You can’t get anywhere near the Sun because our star is too hot for a human being. The Ancient Greeks warned about that with the myth of Daedalus and Icarus.

It’s been thousands of years since then and technology has made giant leaps forward. Now man can attempt to get to know the sun better from close up, to get unprecedented information on its behaviour.

There are two new projects on the go that are separate but sure whose results will be coordinated. One is the Parker Solar Probe, which NASA launched in August 2018. The other is the European Space Agency’s Solar Orbiter, which set off on 10 February and is Italian in much of its design and content.

What are they going to do up there?

The aims of the two missions are manifold and ambitious. They include getting to grips with certain phenomena that till now have been a mystery, like the sun’s electromagnetic interference, which damages broadcasting tools and systems on earth, and predicting in greater detail the sun’s behaviour, which can determine climate change on our planet.

We’ve never been so near to the Sun

Even in the first phase of its mission, the Parker Solar Probe cleared up, at least partly, the confusion over the dynamics of two very important space phenomena: so-called solar wind and the expulsion of material from the sun’s corona.

The smallest particles, which are essentially electrons, are shaved off the sun almost at the speed of light, and reach earth in under an hour. This is a kind of energy storm that can wreak serious havoc on human aeronautic and space activity. To better protect ourselves from these ups and downs we need to study their physical characteristics in depth, which is impossible on earth. The American probe was subjected to a rigorous test to see how it could withstand the enormous heat of the European solar furnace at Odeillo. It has now managed to gather much more detailed information and get within 24 million km of the sun (the distance between the earth and the sun is 152 million km).

Similar research has been done by the Solar Orbiter, and the overall collective work effort has been extremely fruitful. The technicians explain that the relative positions of the two probes, far from each other’s orbits, lets them take coordinated measures and observe the same material from different distances, thereby distinguishing spatial effects from earthly ones.

The Italian machine watching the corona

The Solar Orbiter has a range of measuring equipment on board, one piece of which unveils the many mysteries surrounding the solar corona, the outermost part of the sun’s atmosphere. Effective observation demands that you catch only the peripheral effects, without getting hit by the star’s entire light flow. It’s what happens regularly with solar eclipses, but the data for those are blighted by all the distortions that come with the distance between the earth and its star. But the Solar Orbiter, because it can get about 42 million km near, will be able to give us precious information using Metis, the Italian made coronagraph installed on board the probe.

This machine was made in such a way as to stop the light from the solar disk getting into its telescope, which means it can observe the regions of the corona that unleash storms of particles and so-called eruptions, or humongous, terrifying ejections of boiling hot gaseous mass.

What makes Metis unique is that it can record, at the same time, on a wide scale, in both visibility and ultraviolet, the evolution over time of phenomena all over the corona, at multiple electromagnetic frequencies.

The Solar Orbiter will remain at a reasonable distance, so to speak, from the sun, but follow its rotations, so that it can observe the more widespread phenomena over periods. The Solar Parker Probe, for its part, will get far nearer to our star, almost skimming it by 2025, just 6 million km away. It will therefore offer data to integrate with the Solar Orbiter’s and reframe our entire knowledge of the sun.

We’ll never know what Icarus would have made of it all...