The Sun – you might think we’d know quite a lot about this thing already, given how important it is for the sustaining of life on Earth, and well… given just how noticeable it is in the sky. All throughout history, the Sun has represented a cornerstone in mythology, worshipped (and rightly so) by many civilisations. Over the past two weeks we’ve started to scrape away at the surface of what there is to understand about the Sun, but the simple truth is that, despite our everlasting efforts, there’s so much more yet to uncover about this mystical being.
However, we are trying our best. The European Space Agency (ESA) is currently, as we speak, working on developing Solar Orbiter, and it is to be released from Cape Canaveral, Florida in early 2019. It will be the first satellite to orbit with such close proximity to the Sun, at nearly a quarter of the distance from the Sun to the Earth, which is much closer than the distance at which Mercury orbits. This means that the spacecraft will be subject to extreme conditions, and must be able to brave the fiery heat, facing sunlight about thirteen times as intense than what we feel on Earth (although seeing as its winter, thirteen times zero is still zero, right?). In fact, the spacecraft will be flying so close to the Sun that it will be able to be hit by the solar wind, bombarded by powerful bursts of charged particles.
New technologies have been developed which will (hopefully) equip the Solar Orbiter well enough to deal with these uncharted harsh environments. Since Solar Orbiter is specially designed to always point towards the Sun, the front is protected by a heat shield where temperatures will reach upwards of 500 °C. On the front of this shield, high-temperature solar arrays are positioned to supply energy to the instruments on board. The spacecraft is also kept cool by radiators which enable it to dissipate excess heat into space. On the other extreme, the central part of the satellite can reach temperatures of below -100 °C, so must be appropriately insulated.
So what exactly will it be doing? With gravity assists from Venus, the Solar Orbiter will be kicked into higher altitudes, eventually reaching an inclination of over 30°, relative to the Sun’s equator. This will allow close up, high resolution views of the Sun’s poles for the first time. Every five months, the orbiter will fly extremely close to the Sun along its orbit, and have an orbital period similar to that of the Sun’s rotational period. This means that the telescopes will be able to track the same patch of solar sky for an extended period of time, allowing for the study of magnetic activity in the atmosphere that can lead to the build up of solar storms. We will also be able to get data of the side of the Sun that is not visible from Earth.
All the information gathered will go towards answering four key questions:
- How and where do the solar wind and magnetic field from the corona originate?
- How do transient events, such as jets, influence variability in the heliosphere?
- How do solar eruptions produce energetic particle radiation in the heliosphere?
- How does the Sun’s magnetic field influence connections between the Sun and the heliosphere?
You don’t need to understand what these mean just yet, but in the near future we will expand further. For now, just sit back and try to appreciate the little bit of sunshine we do actually get at this time of year.