Science & Technology

NASA’s Parker Solar Probe Touches the Sun for the First Time – Bringing New Discoveries

NASA's Parker Solar Probe Touches Sun

For the first time in historical past, a spacecraft has touched the Sun. NASA’s Parker Solar Probe has now flown by way of the Sun’s higher ambiance – the corona – and sampled particles and magnetic fields there.

The brand new milestone marks one main step for Parker Solar Probe and one large leap for photo voltaic science. Simply as touchdown on the Moon allowed scientists to know the way it was shaped, touching the very stuff the Sun is manufactured from will assist scientists uncover essential details about our closest star and its affect on the photo voltaic system.

A significant milestone and new outcomes from NASA’s Parker Solar Probe had been introduced on Dec. 14 in a press convention at the 2021 American Geophysical Union Fall Assembly in New Orleans. The outcomes have been revealed in Bodily Evaluation Letters and accepted for publication in the Astrophysical Journal.

“Parker Solar Probe “touching the Sun” is a monumental second for photo voltaic science and a very outstanding feat,” stated Thomas Zurbuchen, the affiliate administrator for the Science Mission Directorate at NASA Headquarters in Washington. “Not solely does this milestone present us with deeper insights into our Sun’s evolution and it’s impacts on our photo voltaic system, however all the things we find out about our personal star additionally teaches us extra about stars in the remainder of the universe.”

Because it circles nearer to the photo voltaic floor, Parker is making new discoveries that different spacecraft had been too far-off to see, together with from inside the photo voltaic wind – the stream of particles from the Sun that may affect us at Earth. In 2019, Parker found that magnetic zig-zag constructions in the photo voltaic wind, known as switchbacks, are plentiful near the Sun. However how and the place they type remained a thriller. Halving the distance to the Sun since then, Parker Solar Probe has now handed shut sufficient to establish one place the place they originate: the photo voltaic floor.

The primary passage by way of the corona – and the promise of extra flybys to return – will proceed to supply information on phenomena which might be unimaginable to review from afar.

Artist’s idea of the Parker Solar Probe spacecraft approaching the solar. Credit score: NASA

“Flying so near the Sun, Parker Solar Probe now senses situations in the magnetically dominated layer of the photo voltaic ambiance – the corona – that we by no means may earlier than,” stated Nour Raouafi, the Parker venture scientist at the Johns Hopkins Utilized Physics Laboratory in Laurel, Maryland. “We see proof of being in the corona in magnetic subject information, photo voltaic wind information, and visually in pictures. We will really see the spacecraft flying by way of coronal constructions that may be noticed throughout a complete photo voltaic eclipse.”

Parker Solar Probe launched in 2018 to discover the mysteries of the Sun by touring nearer to it than any spacecraft earlier than. Three years after launch and many years after first conception, Parker has lastly arrived.

Not like Earth, the Sun doesn’t have a stable floor. Nevertheless it does have a superheated ambiance, manufactured from photo voltaic materials sure to the Sun by gravity and magnetic forces. As rising warmth and strain push that materials away from the Sun, it reaches some extent the place gravity and magnetic fields are too weak to comprise it.

That time, often called the Alfvén essential floor, marks the finish of the photo voltaic ambiance and starting of the photo voltaic wind. Solar materials with the vitality to make it throughout that boundary turns into the photo voltaic wind, which drags the magnetic subject of the Sun with it because it races throughout the photo voltaic system, to Earth and past. Importantly, past the Alfvén essential floor, the photo voltaic wind strikes so quick that waves inside the wind can not ever journey quick sufficient to make it again to the Sun – severing their connection.

Till now, researchers had been not sure precisely the place the Alfvén essential floor lay. Primarily based on distant pictures of the corona, estimates had put it someplace between 10 to twenty photo voltaic radii from the floor of the Sun – 4.3 to eight.6 million miles. Parker’s spiral trajectory brings it slowly nearer to the Sun and through the previous few passes, the spacecraft was persistently under 20 photo voltaic radii (91 p.c of Earth’s distance from the Sun), placing it in the place to cross the boundary – if the estimates had been appropriate.

On April 28, 2021, throughout its eighth flyby of the Sun, Parker Solar Probe encountered the particular magnetic and particle situations at 18.8 photo voltaic radii (round 8.1 million miles) above the photo voltaic floor that informed scientists it had crossed the Alfvén essential floor for the first time and eventually entered the photo voltaic ambiance.

“We had been absolutely anticipating that, eventually, we might encounter the corona for a minimum of a brief length of time,” stated Justin Kasper, lead creator on a brand new paper about the milestone revealed in Bodily Evaluation Letters, and deputy chief expertise officer at BWX Applied sciences, Inc. and College of Michigan professor. “However it is vitally thrilling that we’ve already reached it.”

Throughout the flyby, Parker Solar Probe handed into and out of the corona a number of occasions. That is proved what some had predicted – that the Alfvén essential floor isn’t formed like a easy ball. Moderately, it has spikes and valleys that wrinkle the floor. Discovering the place these protrusions line up with photo voltaic exercise coming from the floor might help scientists find out how occasions on the Sun have an effect on the ambiance and photo voltaic wind.

At one level, as Parker Solar Probe dipped to simply beneath 15 photo voltaic radii (round 6.5 million miles) from the Sun’s floor, it transited a characteristic in the corona known as a pseudostreamer. Pseudostreamers are large constructions that rise above the Sun’s floor and will be seen from Earth throughout photo voltaic eclipses.

As Parker Solar Probe handed by way of the corona on encounter 9, the spacecraft flew by constructions known as coronal streamers. These constructions will be seen as vibrant options transferring upward in the higher pictures and angled downward in the decrease row. Such a view is simply potential as a result of the spacecraft flew above and under the streamers inside the corona. Till now, streamers have solely been seen from afar. They’re seen from Earth throughout whole photo voltaic eclipses.
Credit: NASA/Johns Hopkins APL/Naval Analysis Laboratory

Passing by way of the pseudostreamer was like flying into the eye of a storm. Inside the pseudostreamer, the situations quieted, particles slowed, and variety of switchbacks dropped – a dramatic change from the busy barrage of particles the spacecraft often encounters in the photo voltaic wind.

For the first time, the spacecraft discovered itself in a area the place the magnetic fields had been sturdy sufficient to dominate the motion of particles there. These situations had been the definitive proof the spacecraft had handed the Alfvén essential floor and entered the photo voltaic ambiance the place magnetic fields form the motion of all the things in the area.

The primary passage by way of the corona, which lasted just a few hours, is one among many deliberate for the mission. Parker will proceed to spiral nearer to the Sun, finally reaching as shut as 8.86 photo voltaic radii (3.83 million miles) from the floor. Upcoming flybys, the subsequent of which is occurring in January 2022, will possible carry Parker Solar Probe by way of the corona once more.

“I’m excited to see what Parker finds because it repeatedly passes by way of the corona in the years to return,” stated Nicola Fox, division director for the Heliophysics Division at NASA Headquarters. “The chance for new discoveries is boundless.”

The scale of the corona can also be pushed by photo voltaic exercise. As the Sun’s 11-year exercise cycle – the solar cycle – ramps up, the outer fringe of the corona will increase, giving Parker Solar Probe a higher probability of being inside the corona for longer durations of time.

“It’s a actually necessary area to get into as a result of we expect all kinds of physics probably activate,” Kasper stated. “And now we’re entering into that area and hopefully going to begin seeing a few of these physics and behaviors.”

Even earlier than the first journeys by way of the corona, some stunning physics was already surfacing. On latest photo voltaic encounters, Parker Solar Probe collected information pinpointing the origin of zig-zag-shaped constructions in the photo voltaic wind, known as switchbacks. The info confirmed one spot that switchbacks originate is at the seen floor of the Sun – the photosphere.

By the time it reaches Earth, 93 million miles away, the photo voltaic wind is an unrelenting headwind of particles and magnetic fields. However because it escapes the Sun, the photo voltaic wind is structured and patchy. In the mid-Nineteen Nineties, the NASA-European Area Company mission Ulysses flew over the Sun’s poles and found a handful of weird S-shaped kinks in the photo voltaic wind’s magnetic subject strains, which detoured charged particles on a zig-zag path as they escaped the Sun. For many years, scientists thought these occasional switchbacks had been oddities confined to the Sun’s polar areas.

In 2019, at 34 photo voltaic radii from the Sun, Parker found that switchbacks weren’t uncommon, however common in the solar wind. This renewed curiosity in the options and raised new questions: The place had been they coming from? Had been they solid at the floor of the Sun, or formed by some course of kinking magnetic fields in the photo voltaic ambiance?

The brand new findings, in press at the Astrophysical Journal, lastly verify one origin level is close to the photo voltaic floor.

The clues got here as Parker orbited nearer to the Sun on its sixth flyby, lower than 25 photo voltaic radii out. Information confirmed switchbacks happen in patches and have a better proportion of helium – recognized to return from the photosphere – than different parts. The switchbacks’ origins had been additional narrowed when the scientists discovered the patches aligned with magnetic funnels that emerge from the photosphere between convection cell constructions known as supergranules.

Along with being the birthplace of switchbacks, the scientists suppose the magnetic funnels could be the place one element of the photo voltaic wind originates. The photo voltaic wind is available in two completely different varieties – quick and gradual – and the funnels might be the place some particles in the quick photo voltaic wind come from.

“The construction of the areas with switchbacks matches up with a small magnetic funnel construction at the base of the corona,” stated Stuart Bale, professor at the College of California, Berkeley, and lead creator on the new switchbacks paper. “That is what we anticipate from some theories, and this pinpoints a supply for the photo voltaic wind itself.”

Understanding the place and the way the parts of the quick photo voltaic wind emerge, and in the event that they’re linked to switchbacks, may assist scientists reply a longstanding solar mystery: how the corona is heated to thousands and thousands of levels, far hotter than the photo voltaic floor under.

As Parker Solar Probe ventures nearer to the Sun, it’s crossing into uncharted regimes and making new discoveries. This picture represents Parker Solar Probe’s distances from the Sun for a few of these milestones and discoveries.
Credit: NASA’s Goddard Area Flight Heart/Mary P. Hrybyk-Keith

Whereas the new findings find the place switchbacks are made, the scientists can’t but verify how they’re shaped. One principle suggests they could be created by waves of plasma that roll by way of the area like ocean surf. One other contends they’re made by an explosive course of often called magnetic reconnection, which is assumed to happen at the boundaries the place the magnetic funnels come collectively.

“My intuition is, as we go deeper into the mission and decrease and nearer to the Sun, we’re going to study extra about how magnetic funnels are linked to the switchbacks,” Bale stated. “And hopefully resolve the query of what course of makes them.”

Now that researchers know what to look for, Parker’s nearer passes could reveal much more clues about switchbacks and different photo voltaic phenomena. The info to return will permit scientists a glimpse right into a area that’s essential for superheating the corona and pushing the photo voltaic wind to supersonic speeds. Such measurements from the corona will likely be essential for understanding and forecasting excessive house climate occasions that may disrupt telecommunications and harm satellites round Earth.

“It’s actually thrilling to see our superior applied sciences reach taking Parker Solar Probe nearer to the Sun than we’ve ever been, and to have the ability to return such superb science,” stated Joseph Smith, Parker program govt at NASA Headquarters. “We look ahead to seeing what else the mission discovers because it ventures even nearer in the coming years.”

Reference: “I Enters the Magnetically Dominated Solar Corona” by J. C. Kasper et al., 14 December 2021, Bodily Evaluation Letters.
DOI: 10.1103/PhysRevLett.127.255101

Parker Solar Probe is a part of NASA’s Dwelling with a Star program to discover features of the Sun-Earth system that immediately have an effect on life and society. The Dwelling with a Star program is managed by the company’s Goddard Area Flight Heart in Greenbelt, Maryland, for NASA’s Science Mission Directorate in Washington. The Johns Hopkins College Utilized Physics Laboratory in Laurel, Maryland, manages the Parker Solar Probe mission for NASA and designed, constructed, and operates the spacecraft.

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