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Orbiter Solar

Solar Orbiter returns first data, snaps closest pictures of the Sun – Phys.org

Solar Orbiter Returns First Data, Snaps Closest Pictures of the Sun
Solar Orbiter spots ‘campfires’ on the Sun. Locations of campfires are annotated with white arrows. Credits: Solar Orbiter/EUI Team (ESA & NASA); CSL, IAS, MPS, PMOD/WRC, ROB, UCL/MSSL

The first images from ESA/NASA’s Solar Orbiter are now available to the public, including the closest pictures ever taken of the Sun.

Solar Orbiter is an international collaboration between the European Space Agency, or ESA, and NASA, to study our closest star, the Sun. Launched on Feb. 9, 2020 (EST), the spacecraft completed its first close pass of the Sun in mid-June.

“These unprecedented pictures of the Sun are the closest we have ever obtained,” said Holly Gilbert, NASA project scientist for the mission at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “These amazing images will help scientists piece together the Sun’s atmospheric layers, which is important for understanding how it drives space weather near the Earth and throughout the .”

“We didn’t expect such great results so early,” said Daniel Müller, ESA’s Solar Orbiter project scientist. “These images show that Solar Orbiter is off to an excellent start.”

Getting to this point was no simple feat. The novel coronavirus forced at the European Space Operations Center, or ESOC, in Darmstadt, Germany to close down completely for more than a week. During commissioning, the period when each instrument is extensively tested, ESOC staff were reduced to a skeleton crew. All but essential personnel worked from home.

“The pandemic required us to perform critical operations remotely—the first time we have ever done that,” said Russell Howard, principal investigator for one of Solar Orbiter’s imagers.

Solar Orbiter Returns First Data, Snaps Closest Pictures of the Sun
The first images from the Solar and Heliospheric Imager, or SoloHI instrument, reveal the zodiacal light (the bright blob of light on the right protruding towards the center). Mercury is also visible as a bright dot on the image left. The straight bright feature on the very edge of the image is a baffle illuminated by reflections from the spacecraft’s solar array. Credits: Solar Orbiter/SoloHI team (ESA & NASA), NRL

But the team adapted, even readying for an unexpected encounter with comet ATLAS’s ion and dust tails on June 1 and 6, respectively. The spacecraft completed commissioning just in time for its first close solar pass on June 15. As it flew within 48 million miles of the Sun, all 10 instruments flicked on, and Solar Orbiter snapped the closest pictures of the Sun to date. (Other spacecraft have been closer, but none have carried Sun-facing imagers.)

Solar Orbiter carries six imaging instruments, each of which studies a different aspect of the Sun. Normally, the first images from a spacecraft confirm the instruments are working; scientists don’t expect new discoveries from them. But the Extreme Ultraviolet Imager, or EUI, on Solar Orbiter returned data hinting at solar features never observed in such detail.

Principal investigator David Berghmans, an astrophysicist at the Royal Observatory of Belgium in Brussels, points out what he calls “campfires” dotting the Sun in EUI’s images.

“The campfires we are talking about here are the little nephews of solar flares, at least a million, perhaps a billion times smaller,” Berghmans said. “When looking at the new high resolution EUI images, they are literally everywhere we look.”

It’s not yet clear what these campfires are or how they correspond to solar brightenings observed by other spacecraft. But it’s possible they are mini-explosions known as nanoflares—tiny but ubiquitous sparks theorized to help heat the Sun’s outer atmosphere, or corona, to its temperature 300 times hotter than the solar surface.

To know for sure, scientists need a more precise measurement of the campfires’ temperature. Fortunately, the Spectral Imaging of the Coronal Environment, or SPICE instrument, also on Solar Orbiter, does just that.

Solar Orbiter Returns First Data, Snaps Closest Pictures of the Sun
This animation shows a sequence of images from the Polarimetric and Helioseismic Imager (PHI) on ESA/NASA’s Solar Orbiter. PHI measures the magnetic field near the Sun’s surface and allows the investigation of the Sun’s interior via the technique of helioseismology. Credits: Solar Orbiter/ PHI Team/ESA & NASA

“So we’re eagerly awaiting our next data set,” said Frédéric Auchère, principal investigator for SPICE operations at the Institute for Space Astrophysics in Orsay, France. “The hope is to detect nanoflares for sure and to quantify their role in coronal heating.”

Other images from the spacecraft showcase additional promise for later in the mission, when Solar Orbiter is closer to the Sun.

The Solar and Heliospheric Imager, or SoloHI, led by Russell Howard of the Naval Research Laboratory in Washington, D.C., revealed the so-called zodiacal light, light from the Sun reflecting off of interplanetary dust—a light so faint that the bright face of the Sun normally obscures it. To see it, SoloHI had to reduce the Sun’s light to one trillionth of its original brightness.

“The images produced such a perfect zodiacal light pattern, so clean,” Howard said. “That gives us a lot of confidence that we will be able to see solar wind structures when we get closer to the Sun.”

Images from the Polar and Helioseismic Imager, or PHI, showed it is also primed for later observations. PHI maps the Sun’s , with a special focus on its poles. It will have its heyday later in the mission as Solar Orbiter gradually tilts its to 24 degrees above the plane of the planets, giving it an unprecedented view of the Sun’s poles.

“The magnetic structures we see at the visible surface show that PHI is receiving top-quality data,” said Sami Solanki, PHI’s principal investigator at the Max Planck Institute for Solar System Research in Göttingen, Germany. “We’re prepared for great science as more of the Sun’s poles comes into view.”

Today’s release highlights Solar Orbiter’s imagers, but the mission’s four in situ instruments also revealed initial results. In situ instruments measure the space environment immediately surrounding the spacecraft. The Solar Wind Analyser, or SWA instrument, shared the first dedicated measurements of heavy ions (carbon, oxygen, silicon, iron, and others) in the solar wind from the inner heliosphere.



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Solar Orbiter returns first data, snaps closest pictures of the Sun (2020, July 17)
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Orbiter Solar

Solar Orbiter: Incredible images of the Sun reveal a new solar phenomenon – Inverse

After traveling 48 million miles in outer space toward our nearest star, the Solar Orbiter has captured the closest-ever images of the Sun. These breathtaking shots reveal never before seen features on the solar surface.

These images, released Thursday by NASA and the European Space Agency (ESA) mission, are a result of the spacecraft’s first close approach to the Sun, which occurred in mid-June. The spacecraft’s groundbreaking proximity to the star’s surface enabled it to document miniatures solar flares — which scientists have dubbed “campfires.”

The spacecraft launched on February 9, 2020, with the Sun as its destination. It’s job: Getting up close and personal with our host star in order to resolve some of the lingering mysteries regarding the Sun’s magnetic field, solar storms, and how the star affects its surrounding space environment.

The Solar Orbiter travels in an elliptical orbit around the Sun, completing one orbit every 168 days. In mid-June, the spacecraft completed its first perihelion, the point in orbit closest to the Sun, and used its six telescopes to capture the star in unprecedented detail.

The different imaging instruments onboard the Solar Orbiter captured the Sun at different wavelengths. Solar Orbiter/EUI Team (ESA & NASA); CSL, IAS, MPS, PMOD/WRC, ROB, UCL/MSSL

After observing the first batch of images, scientists noticed this “campfire” phenomenon. These are believed to be are relatives of solar flares — only a million (or billion) times smaller. Solar flares are fiery eruptions of high-energy radiation that burst from the Sun’s surface.

The miniature solar flares, or campfires, are indicated by a white arrow at the top of the image, with the size of the Earth used to scale.Solar Orbiter/EUI Team (ESA & NASA)

Spotting “campfires” — David Berghmans, a space physicist at the Royal Observatory of Belgium, and principal investigator of one of the instruments onboard Solar Orbiter, was not expecting much from the Solar Orbiter’s initial set of data.

“We couldn’t believe it when we first saw this and we started giving it crazy names like campfires and dark fibrils and ghosts and whatever we saw,” Berghmans said during a press conference on Thursday. “There is so much new small phenomena going on on the smallest scale.”

The scientists investigating the images are still not sure whether the “campfires” are driven by the same mechanism as the solar flares or if they are fueled entirely differently. They do think that this newly observed phenomenon may be contributing to one of the Sun’s unsolved mysteries — the heating of the Sun’s corona.

“We couldn’t believe it when we first saw this.”

Temperatures of the Sun’s core can reach 15 million degrees Celsius. Things get relatively cooler the further you move away from the center of the Sun — it’s a balmy 5,700 degrees C at the solar surface. In the outermost part of the solar atmosphere, known as the corona, temperatures start to rise, reaching more than one million degrees C.

For years, scientists have been looking for an answer to this heating of the corona.

“These 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,” Frédéric Auchère, of the Institut d’Astrophysique Spatiale (IAS), France, and co-principal investigator of the Extreme Ultraviolet Imager, explained during the press conference.

The closest ever images of the Sun may unravel one of the star’s biggest mysteries. Solar Orbiter/EUI Team (ESA & NASA); CSL, IAS, MPS, PMOD/WRC, ROB, UCL/MSSL

What comes next — Using the Solar Orbiter’s Spectral Imaging of the Coronal Environment, or SPICE instrument, scientists will measure the temperatures of these “campfires” in order to help them better understand their origin.

The scientists behind the mission hope to uncover more mysteries of the Sun as the Solar Orbiter continues its journey — it will make its second perihelion in early 2021. A year later, the mission will officially commence its science phase with its first close approach scheduled for early 2022. At that time, the spacecraft will be as close as 26 million miles to the Sun’s surface (getting closer to the Sun than the Solar System’s innermost planet, Mercury).

The Solar Orbiter joins another spacecraft currently orbiting around the Sun: NASA’s Solar Parker Probe, which launched in August 2018. The Solar Parker Probe will get even closer to the Sun, a record-breaking distance of around 4 million miles from the Sun’s surface. But alas, the spacecraft does not carry telescopes that are capable of capturing close-up images of the star — leaving the Solar Orbiter as the only paparazzi covering our favorite star.

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