Record-breaking probe embarks on closest approach to the sun in history. Science news.

Record-breaking probe embarks on closest approach to the sun in history.

Dr. Eugene Parker is pictured with a model of the Parker Solar Probe on May 31, 2017. 

Scott Olson/Getty Images

Parker was the first living person to have a spacecraft named in his honor. The renowned astrophysicist, whose groundbreaking research transformed humanity's understanding of the sun and interplanetary space, passed away at the age of 94 in March 2022. However, he lived to see how the spacecraft bearing his name could unravel long-standing mysteries about the sun, more than 65 years after the mission was first envisioned.

In December 2021, the Parker Solar Probe achieved a historic milestone by becoming the first spacecraft to "touch the sun," successfully flying through the sun's corona — its upper atmosphere — to sample particles and study the star's magnetic fields.

Over the past six years of its seven-year mission, the Parker Solar Probe has collected invaluable data, shedding light on some of the sun's greatest enigmas. Heliophysicists have long been puzzled by how the solar wind — a continuous stream of charged particles emitted by the sun — is generated and why the sun's corona is significantly hotter than its surface. The probe's observations are helping to answer these enduring questions.

Scientists are also striving to unravel the structure of coronal mass ejections — massive clouds of ionized gas, or plasma, combined with magnetic fields that erupt from the sun’s outer atmosphere.

When these ejections are directed toward Earth, they can trigger geomagnetic storms, powerful disruptions to the planet’s magnetic field that have the potential to interfere with satellites, power grids, and communication systems.

Now, Parker Solar Probe is entering its final and closest flybys, which could provide the answers to these enduring questions while uncovering new mysteries by exploring uncharted solar territory.

“Parker Solar Probe is revolutionizing the field of heliophysics,” said Helene Winters, the project manager for the mission at Johns Hopkins University’s Applied Physics Laboratory. “After years of withstanding the heat and dust of the inner solar system and enduring blasts of solar energy and radiation that no spacecraft has ever encountered, Parker Solar Probe continues to thrive.”

A Fiery Flyby Close to the Sun

Parker’s flyby on Christmas Eve at approximately 6:53 a.m. ET marked the first of the spacecraft’s final three closest approaches to the sun. The remaining two are scheduled for March 22 and June 19.

At this extraordinary proximity, if the distance between Earth and the sun were scaled to the length of an American football field, Parker would be just 4 yards from the end zone, according to NASA.

From this vantage point, the spacecraft is expected to fly directly through plumes of plasma and could even pass within a solar eruption, should one be released during its approach.

The Parker Solar Probe was engineered to endure the sun's extreme conditions and has previously flown through coronal mass ejections without sustaining any damage, according to project scientist Nour Raouafi.

The spacecraft features a robust carbon foam shield measuring 4.5 inches (11.4 centimeters) thick and 8 feet (2.4 meters) wide. Before its launch, the shield was rigorously tested on Earth and proven capable of withstanding temperatures of nearly 2,500 degrees Fahrenheit (about 1,400 degrees Celsius). During its Christmas Eve flyby, the shield is expected to endure temperatures of up to 1,800 degrees Fahrenheit (980 degrees Celsius).

Despite the intense heat, the interior of the spacecraft remains at a comfortable room temperature, ensuring the proper functioning of its electronics and scientific instruments. To maintain this temperature stability, a specialized cooling system developed by the Applied Physics Laboratory circulates water through the spacecraft’s solar arrays, keeping them at a steady 320 degrees Fahrenheit (160 degrees Celsius), even during its closest encounters with the sun.

The Parker Solar Probe conducted its flyby autonomously, as its proximity to the sun temporarily prevents mission control from maintaining contact with the spacecraft.

Following its closest approach, which occurred around midnight between Thursday and Friday, the probe was expected to transmit a signal known as a beacon tone back to mission control, according to project scientist Nour Raouafi. This tone provides a brief summary of the spacecraft’s overall status, confirming the success of the flyby.

The extensive data and images collected during the flyby won’t reach mission control until Parker moves farther away from the sun in its orbit, a process expected to take about three weeks. The data is anticipated to arrive in mid-January, Raouafi said.

Perfect Timing to Observe an Active Sun

Just over a year after the Parker Solar Probe’s launch, the sun entered a new solar cycle. Now, as the spacecraft performs its closest approach, the sun is at its solar maximum, the period of peak activity. This timing has allowed Parker to observe nearly an entire solar cycle, including its transitions between periods of high and low activity, said Dr. C. Alex Young, associate director for science in the Heliophysics Science Division at NASA’s Goddard Space Flight Center in Greenbelt, Maryland.

In October, scientists from NASA, the National Oceanic and Atmospheric Administration, and the international Solar Cycle Prediction Panel announced that the sun has reached solar maximum, the peak of activity in its 11-year solar cycle.

At this point in the cycle, the sun's magnetic poles flip, marking a transition from a calmer phase to a more active one. Experts track the rise in solar activity by counting the number of sunspots visible on the sun's surface. The sun is expected to remain highly active for the next year or so.

This surge in solar activity became evident earlier this year during two significant auroral displays on Earth in May and October, when coronal mass ejections (CMEs) released by the sun were directed at our planet. These solar storms generate auroras, or bands of light, that dance around Earth's poles — the northern lights (aurora borealis) in the north and the southern lights (aurora australis) in the south. When the energized particles from the CMEs collide with Earth's magnetic field, they interact with atmospheric gases to produce vibrant displays of colored light in the sky.

“Both of those storms made auroras visible as far south as the bottom of the United States,” said Young. “However, the May storm was particularly intense. We believe it could be a once-in-a-100- to possibly 500-year event, causing auroras to appear as far south as the equator, which is extremely rare. It was a global phenomenon that millions — hopefully billions — of people witnessed, and it may not happen again.”

The data collected by the Parker Solar Probe could help scientists gain a deeper understanding of solar storms and potentially improve their ability to predict them, Young explained.

“The sun is the only star we can observe in such detail, and it’s the only one we can visit and measure directly,” Young said. “It serves as a natural laboratory in our solar system, offering insights into all the other stars in the universe and how they interact with the countless planets, some of which may resemble our own, orbiting them.”

With that in mind, Rawafi expressed hope that the sun will put on a remarkable display during the probe’s close approaches, allowing scientists to gain valuable insights into its activity.

“Sun, please do your best,” Rawafi said. “Give us the strongest event you can, and the Parker Solar Probe is ready for it.”

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