A Close Look at Sun and Solar Orbiter

By - Dr. S. S. VERMA; Department of Physics, S.L.I.E.T.


Sun as the central point to our solar system is respected as one of the most powerful GOD in almost all mythologies of the world over due to its important role in the survival of life on planet earth. Most of us only feel concerned for sun as a source of light and heat energy (less heat in winter and more heat in summer), exhibiting rainbows and eclipses and take it as a guaranteed entity to our existence. As the sun is far away, we are least informed or concerned about the activities taking place on the surface of sun and how they affect our survival as well as well being on the Earth. As humans, we have always been familiar with the importance of the Sun to life on Earth, observing it and investigating how it works in detail, but we have also long known it has the potential to disrupt everyday life should we be in the firing line of a powerful solar storm. Therefore, scientists and engineers with inquisitive minds are always trying their best to know SUN more closely for its surface activities like sun spots, sun flares, solar corona and solar winds etc. for their affect on Earth beings.

A Close Look

Fig.: The first ultraviolet images from the
Solar Orbiter spacecraft (Credit: SOLAR

Recently,new and closest ever pictures of SUN from the Solar Orbiter spacecraft have been released by scientists of the Royal Observatory of Belgium in Brussels which reveal ‘campfire’ flares on the surface of sun. These never-before-seen campfire flares are thought to be little relatives of larger solar flares, powerful magnetic outbursts that shoot bright spurts of radiation into space. Campfire flares are a million to a billion times as small as typical solar flares. The smallest ones in the Solar Orbiter images are a few hundred kilometers across. It’s not clear yet whether the flickers are just scaled-down solar flares, or if the two phenomena have different driving mechanisms. Earlier, other spacecraft have swooped closer to the sun than the present e.g., the Parker Solar Probe has gotten as close as 24 million kilometers, collecting data but no direct photos because it gets too close. The new images were taken on May 30 with the Extreme Ultraviolet Imager camera when the spacecraft was 77 million kilometers from the sun, about half the distance from Earth. It will eventually reach 6 million kilometers from the sun’s surface. Ultimately, Solar Orbiter will come within about 42 million kilometers of the sun, and will be the first spacecraft to fly over the sun’s poles.

Solar Orbiter

Fig.: Solar Orbiter

Solar Orbiter is a new sun-watching spacecraft that’s a joint project between NASA and the European Space Agency. Solar Orbiter was launched on February 10, 2020 with a suite of scientific instruments to observe the sun and its surroundings. According to the scientists behind the mission, it is to see phenomena that were not observable in detail before hints at the enormous potential of Solar Orbiter, which has only just finished its early phase of technical verification known as commissioning. Solar Orbiter carries six remote-sensing instruments, or telescopes, that image the Sun and its surroundings, and four in situ instruments that monitor the environment around the spacecraft. New and fine images received from the space orbiter is the result of  how ten scientific instruments complement each other, providing a holistic picture of the Sun and the surrounding environment. The unique aspect of the Solar Orbiter mission is that no other spacecraft has been able to take images of the Sun’s surface from a closer distance.

The Solar Orbiter

Fig.: European Space Agency’s Solar Orbiter spacecraft launch and deployment © PA Graphics

which aims to unlock the secrets of the Sun – was constructed by Airbus in Stevenage and blasted off from NASA’s Cape Canaveral site in Florida on 10 February, 2020. It has been designed to withstand the scorching heat from the Sun that will hit one side, while maintaining freezing temperatures on the other side of the spacecraft as the orbit keeps it in shadow. Solar Orbiter launch is a mission for a generation satellite on its way to the Sun. The satellite will orbit the star, beaming back high-resolution photos and measuring the solar wind as part of the mission led by the European Space Agency (ESA) and partly funded by the the UK Space Agency. Solar Orbiter will have to endure temperatures of more than 500°C – hot enough to melt lead. Its heat shield, with a coating called SolarBlack, will continually face the Sun in order to protect the sensitive instruments behind it. The spacecraft will make a close approach to the Sun every five months, and at its closest will only be 26 million miles away, closer than the planet Mercury. It will use the gravitational force of Venus and Earth to adjust its trajectory, before getting into operational orbit in November 2021. The mission is expected to last 11 years and once the Solar Orbiter runs out of fuel and power, scientists will lose all communication with the spacecraft. It will then continue to orbit around the Sun somewhere between Mercury and Venus as a piece of space junk.

Catching the solar wind

Solar flares are brief eruptions of high-energy radiation from the Sun’s surface, which can cause radio and magnetic disturbances on the Earth. During solar flares, the Sun releases bursts of energetic particles that enhance the solar wind that constantly emanates from the star into the surrounding space. When these particles interact with Earth’s magnetosphere, they can cause magnetic storms that can disrupt telecommunication networks and power grids on the ground. The four in situinstruments on Solar Orbiter then characterize the magnetic field lines and solar wind as it passes the spacecraft. The Polarimetric and Helioseismic Imager (PHI) is another cutting-edge instrument aboard Solar Orbiter. It makes high-resolution measurements of the magnetic field lines on the surface of the Sun. It is designed to monitor active regions on the Sun, areas with especially strong magnetic fields, which can give birth to solar flares. The magnetograms, showing how the strength of the solar magnetic field varies across the Sun’s surface, could be then compared with the measurements from the in situ instruments.

Scientific outcome

The first images have revealed omnipresent miniature solar flares, dubbed ‘campfires’, near the surface of our closest star. The campfires are little relatives of the solar flares that we can observe from Earth, million or billion times smaller. The scientists do not know yet whether the campfires are just tiny versions of big flares, or whether they are driven by different mechanisms. There are, however, already theories that these miniature flares could be contributing to one of the most mysterious phenomena on the Sun, the coronal heating. According to scientists, these small campfires are totally insignificant each by themselves, but summing up their effect all over the sun, they might be the dominant contribution to the heating of the solar corona. The solar corona is the outermost layer of the Sun’s atmosphere that extends millions of kilometres into outer space. Its temperature is more than a million degrees Celsius, which is orders of magnitude hotter than the surface of the Sun, a ‘cool’ 5500 °C. After many decades of studies, the physical mechanisms that heat the corona are still not fully understood, but identifying them is considered the ‘holy grail’ of solar physics. By comparing the data from both sets of instruments, scientists will get insights into the generation of the solar wind, the stream of charged particles from the Sun that influences the entire Solar System. Solar physicists think campfires could help explain one of the biggest solar mysteries: why the solar corona, the sun’s wispy outer atmosphere, is millions of degrees hotter than the solar surface. Together, the small but ubiquitous flares could be a source of energy to the corona that astronomers haven’t accounted for.  It’s obviously way too early to tell but hope that by connecting these observations with measurements from other instruments that feel the solar wind as it passes the spacecraft, scientists will eventually be able to answer some of these mysteries. Understanding more about solar activity could also help scientists make predictions on space weather events, which can damage satellites in orbit and disrupt the infrastructure on Earth that mobile phones, transport, GPS signals and the electricity networks rely on. Further, the science will allow us to start improving our operational capability to predict the space weather, just like to predict the weather here on Earth.

Acknowledgement: The use of information retrieved through various references/sources of internet in this article is highly acknowledged.

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