സൂര്യനെ സ്പര്‍ശിക്കുന്ന ആദ്യ പേടകമായി ‘പാര്‍ക്കര്‍’.സൂര്യന്റെ അന്തരീക്ഷത്തിലൂടെ മുകളിലത്തെ പാളിയിലേക്ക് പേടകം പ്രവേശിച്ചു

ഭൂമിയില്‍ നിന്നും 2018 ല്‍ അയച്ച ‘പാര്‍ക്കര്‍’ പേടകം സൂര്യനെ സ്പര്‍ശിച്ചു. നാസയുടെ പാര്‍ക്കര്‍ സോളാര്‍ പ്രോബ് ആണ് ഈ നേട്ടം കൈവരിച്ചത്. സൗരയൂഥത്തില്‍ സൂര്യന്റെ സ്വാധീനമെന്തെന്ന് ഉള്‍പ്പടെ സൂര്യന്റെ രഹസ്യങ്ങള്‍ തേടിയാണ് നാസയുടെ പാര്‍ക്കര്‍ സോളാര്‍ പ്രോബ്.കോറോണ എന്നറിയപ്പെടുന്ന സൂര്യന്റെ അന്തരീക്ഷത്തിലൂടെ മുകളിലത്തെ പാളിയിലേക്ക് പേടകം പ്രവേശിച്ചു. ഇവിടുത്തെ കണങ്ങളും കാന്തിക മണ്ഡലവും പഠനവിധേയമാക്കി. 78.69 ലക്ഷം കിലോമീറ്റര്‍ ഉയരത്തില്‍ വളരെ കുറച്ച് മണിക്കൂറുകള്‍ മാത്രമാണ് പേടകം കൊറോണയിലൂടെ സഞ്ചരിച്ചത്.സൂര്യന്റെ രഹസ്യങ്ങള്‍ കണ്ടെത്തുക എന്ന ലക്ഷ്യത്തോടെ 2018 ലാണ് പേടകം വിക്ഷേപിച്ചത്. എട്ടാമത്തെ തവണ സൂര്യനെ ചുറ്റുന്നതിനിടയില്‍ 1.30 കോടി കിലോമീറ്റര്‍ ഉയരത്തിലെത്തിയപ്പോള്‍ പേടകം പ്രത്യേക കാന്തിക, കണികാ അവസ്ഥകളിലൂടെ കടന്നുപോയപ്പോള്‍ ആണ് പേടകം സൂര്യന്റെ അന്തരീക്ഷത്തിലേക്ക് കടന്നതായി ശാസ്ത്രജ്ഞര്‍ അറിഞ്ഞത്.

 

NASA Enters the Solar Atmosphere for the First Time, Bringing New Discoveries

 

For the first time in history, a spacecraft has touched the Sun. NASA’s Parker Solar Probe has now flown through the Sun’s upper atmosphere – the corona – and sampled particles and magnetic fields there.

The new milestone marks one major step for Parker Solar Probe and one giant leap for solar science. Just as landing on the Moon allowed scientists to understand how it was formed, touching the very stuff the Sun is made of will help scientists uncover critical information about our closest star and its influence on the solar system.

“Parker Solar Probe “touching the Sun” is a monumental moment for solar science and a truly remarkable feat,” said Thomas Zurbuchen, the associate administrator for the Science Mission Directorate at NASA Headquarters in Washington. “Not only does this milestone provide us with deeper insights into our Sun’s evolution and it’s impacts on our solar system, but everything we learn about our own star also teaches us more about stars in the rest of the universe.”

As it circles closer to the solar surface, Parker is making new discoveries that other spacecraft were too far away to see, including from within the solar wind – the flow of particles from the Sun that can influence us at Earth. In 2019, Parker discovered that magnetic zig-zag structures in the solar wind, called switchbacks, are plentiful close to the Sun. But how and where they form remained a mystery. Halving the distance to the Sun since then, Parker Solar Probe has now passed close enough to identify one place where they originate: the solar surface.

The first passage through the corona – and the promise of more flybys to come – will continue to provide data on phenomena that are impossible to study from afar.

“Flying so close to the Sun, Parker Solar Probe now senses conditions in the magnetically dominated layer of the solar atmosphere – the corona – that we never could before,” said Nour Raouafi, the Parker project scientist at the Johns Hopkins Applied Physics Laboratory in Laurel, Maryland. “We see evidence of being in the corona in magnetic field data, solar wind data, and visually in images. We can actually see the spacecraft flying through coronal structures that can be observed during a total solar eclipse.”

Closer Than Ever Before
Parker Solar Probe launched in 2018 to explore the mysteries of the Sun by traveling closer to it than any spacecraft before. Three years after launch and decades after first conception, Parker has finally arrived.

Unlike Earth, the Sun doesn’t have a solid surface. But it does have a superheated atmosphere, made of solar material bound to the Sun by gravity and magnetic forces. As rising heat and pressure push that material away from the Sun, it reaches a point where gravity and magnetic fields are too weak to contain it.

That point, known as the Alfvén critical surface, marks the end of the solar atmosphere and beginning of the solar wind. Solar material with the energy to make it across that boundary becomes the solar wind, which drags the magnetic field of the Sun with it as it races across the solar system, to Earth and beyond. Importantly, beyond the Alfvén critical surface, the solar wind moves so fast that waves within the wind cannot ever travel fast enough to make it back to the Sun – severing their connection.

Until now, researchers were unsure exactly where the Alfvén critical surface lay. Based on remote images of the corona, estimates had put it somewhere between 10 to 20 solar radii from the surface of the Sun – 4.3 to 8.6 million miles. Parker’s spiral trajectory brings it slowly closer to the Sun and during the last few passes, the spacecraft was consistently below 20 solar radii (91 percent of Earth’s distance from the Sun), putting it in the position to cross the boundary – if the estimates were correct.

On April 28, 2021, during its eighth flyby of the Sun, Parker Solar Probe encountered the specific magnetic and particle conditions at 18.8 solar radii (around 8.1 million miles) above the solar surface that told scientists it had crossed the Alfvén critical surface for the first time and finally entered the solar atmosphere.

“We were fully expecting that, sooner or later, we would encounter the corona for at least a short duration of time,” said Justin Kasper, lead author on a new paper about the milestone published in Physical Review Letters, and deputy chief technology officer at BWX Technologies, Inc. and University of Michigan professor. “But it is very exciting that we’ve already reached it.” Even before the first trips through the corona, some surprising physics was already surfacing. On recent solar encounters, Parker Solar Probe collected data pinpointing the origin of zig-zag-shaped structures in the solar wind, called switchbacks. The data showed one spot that switchbacks originate is at the visible surface of the Sun – the photosphere.

By the time it reaches Earth, 93 million miles away, the solar wind is an unrelenting headwind of particles and magnetic fields. But as it escapes the Sun, the solar wind is structured and patchy. In the mid-1990s, the NASA-European Space Agency mission Ulysses flew over the Sun’s poles and discovered a handful of bizarre S-shaped kinks in the solar wind’s magnetic field lines, which detoured charged particles on a zig-zag path as they escaped the Sun. For decades, scientists thought these occasional switchbacks were oddities confined to the Sun’s polar regions.

In 2019, at 34 solar radii from the Sun, Parker discovered that switchbacks were not rare, but common in the solar wind. This renewed interest in the features and raised new questions: Where were they coming from? Were they forged at the surface of the Sun, or shaped by some process kinking magnetic fields in the solar atmosphere?

The new findings, in press at the Astrophysical Journal, finally confirm one origin point is near the solar surface.

The clues came as Parker orbited closer to the Sun on its sixth flyby, less than 25 solar radii out. Data showed switchbacks occur in patches and have a higher percentage of helium – known to come from the photosphere – than other elements. The switchbacks’ origins were further narrowed when the scientists found the patches aligned with magnetic funnels that emerge from the photosphere between convection cell structures called supergranules.

In addition to being the birthplace of switchbacks, the scientists think the magnetic funnels might be where one component of the solar wind originates. The solar wind comes in two different varieties – fast and slow – and the funnels could be where some particles in the fast solar wind come from.

“The structure of the regions with switchbacks matches up with a small magnetic funnel structure at the base of the corona,” said Stuart Bale, professor at the University of California, Berkeley, and lead author on the new switchbacks paper. “This is what we expect from some theories, and this pinpoints a source for the solar wind itself.”

Understanding where and how the components of the fast solar wind emerge, and if they’re linked to switchbacks, could help scientists answer a longstanding solar mystery: how the corona is heated to millions of degrees, far hotter than the solar surface below.

While the new findings locate where switchbacks are made, the scientists can’t yet confirm how they’re formed. One theory suggests they might be created by waves of plasma that roll through the region like ocean surf. Another contends they’re made by an explosive process known as magnetic reconnection, which is thought to occur at the boundaries where the magnetic funnels come together.

“My instinct is, as we go deeper into the mission and lower and closer to the Sun, we’re going to learn more about how magnetic funnels are connected to the switchbacks,” Bale said. “And hopefully resolve the question of what process makes them.”