Parker Solar Probe’s Upcoming Close Encounter with a Highly Active Sun

As NASA’s Parker Solar Probe approaches its 13th perihelion, or close encounter, with the Sun on Sept. 6, it is heading into a much different solar environment than ever before.

An illustration of Parker Solar Probe's orbit shows the beginning of the spacecraft's thirteenth solar encounter on Sept. 1, 2022, at 22.8 million miles from the Sun. The space craft reaches its closest approach to the Sun on Sept. 6, 2022, at 5.3 million miles. The orbit ends on Sept. 11, 2022.
Parker Solar Probe began its thirteenth solar encounter on Sept. 1, 2022. Credit: NASA/Johns Hopkins APL

NASA reported earlier this summer that Solar Cycle 25 is already exceeding predictions for solar activity, even with solar maximum not to come for another three years. In recent days, a sunspot the size of Earth has rapidly developed on the Sun, and the star has given off multiple solar flares and geomagnetic storms.

“The Sun has changed completely since we launched Parker Solar Probe during solar minimum when it was very quiet,” said Nour Raouafi, Parker Solar Probe project scientist at the Johns Hopkins Applied Physics Laboratory (APL) in Laurel, Maryland. “When the Sun changes, it also changes the environment around it. The activity at this time is way higher than we expected.”

Raouafi expects the high level of solar activity to continue as Parker approaches this perihelion, just 5.3 million miles from the Sun. The spacecraft has yet to fly through a solar event like a solar flare or a coronal mass ejection (CME) during one of its close encounters, but that may change this coming month. The resulting data would be groundbreaking.

“Nobody has ever flown through a solar event so close to the Sun before,” Raouafi said. “The data would be totally new, and we would definitely learn a lot from it.”

Though the spacecraft has not flown through a solar event, Parker’s Wide-field Imager for Solar Probe (WISPR) instrument has imaged a small number of CMEs from a distance, including five during the spacecraft’s 10th encounter with the Sun in November 2021. These observations have already led to unexpected discoveries about the structure of CMEs.

Black and white gif image showing data taken with Parker Solar Probe's WISPR instrument. White particles shoot across a black and grayish background from left to right.
During Parker Solar Probe’s eighth orbit around the Sun, the spacecraft flew through structures in the corona called streamers. This movie shows the data captured from the WISPR instrument on Parker Solar Probe. Credit: NASA/Johns Hopkins APL/Naval Research Laboratory

All of Parker’s observations aid in the effort to understand the physics of the Sun, helping better predict space weather, which can affect electric grids, communications and navigation systems, astronauts and satellites in space, and more.

Although the Sun is much more active than during previous close encounters, Parker’s mission operators are not concerned about adverse effects to the spacecraft.

“Parker Solar Probe is built to withstand whatever the Sun can throw at it,” said Doug Rodgers, APL’s science operations center coordinator for the mission. “Every orbit is different, but the mission is a well-oiled machine at this point.”

While they will have very little contact with the spacecraft during its 10-day encounter, they have conducted routine operations to prepare, including readying the instruments, freeing up onboard memory space for new observations, and testing and pre-loading commands to operate the spacecraft while it’s out of contact. They have also coordinated observation times with Solar Orbiter, an ESA (European Space Agency)/NASA mission that will view the Sun from the same angle as Parker, but 58.5 million miles farther from the Sun’s surface.

Parker’s observations do not always overlap with those of other observatories, such as Solar Orbiter or Solar Terrestrial Relations Observatory-A (STEREO-A), another NASA solar probe. But when they do, it offers significant advantages.

“By combining the data from multiple space missions and even ground observatories, we can understand the bigger picture,” Raouafi said. “In this case, with both Parker and Solar Orbiter observing the Sun from different distances, we will be able to study the evolution of the solar wind, gathering data as it passes one spacecraft and then the other.”

This is not the first time Parker and Solar Orbiter have been in alignment for one of Parker’s perihelions. Scientists have used data from previous alignments of the two spacecraft to produce multiple peer-reviewed papers on solar phenomena observed by both missions.

While this perihelion promises to be exciting due to high solar activity, Raouafi is already looking ahead to future close encounters.

“While the Sun was quiet, we did three years of great science,” he said. “But our view of the solar wind and the corona will be totally different now, and we’re very curious to see what we’ll learn next.”

Parker Solar Probe is part of NASA’s Living with a Star program to explore aspects of the Sun-Earth system that directly affect life and society. The Living with a Star program is managed by the agency’s Goddard Space Flight Center in Greenbelt, Maryland, for NASA’s Science Mission Directorate in Washington. Johns Hopkins APL designed, built, and operates the spacecraft.

By Ashley Hume
Johns Hopkins University Applied Physics Lab

Parker Solar Probe Thriving Four Years after Launch

As it orbits the Sun, NASA’s Parker Solar Probe encounters some of the most challenging conditions ever faced by a spacecraft: temperatures up to nearly 1,500 degrees Fahrenheit (800 degrees Celsius), space dust that could easily degrade materials and instruments, and intense light and high-speed particles escaping from our closest star.

But four years after launch, the spacecraft is operating exceptionally well and sending back more than twice the planned amount of science data.

“Despite operating in such an extreme environment, Parker is performing well beyond our expectations,” said Helene Winters, Parker Solar Probe project manager at the Johns Hopkins Applied Physics Laboratory (APL) in Laurel, Maryland. “The spacecraft and its payload are making spectacular observations that will revolutionize our understanding of the Sun and the heliosphere, and that is a testament to the innovation and tireless dedication of the team.”

Parker Solar Probe By the Numbers: 2.76 billion miles traveled. 5 trips into the Sun's corona. 64 years since a solar probe mission was first proposed. 538 scientific papers citing Parker Solar Probe data. 2.8 terabytes of data returned to Earth. 62,047 images taken. 12 orbits of the Sun. 5.3 million miles from the Sun on Parker's closest approach to date (August 12, 2022)
As Parker Solar Probe continues its mission, it continues to break records and capture first-of-its-kind measurements of the Sun. Credit: NASA/Johns Hopkins APL/Magda Saina

Building a spacecraft to withstand these conditions for years was a monumental challenge. The mission team at APL had to prepare the spacecraft to operate in an environment that had never been explored before. Parker has weathered it all while flying approximately 2.7 billion miles (4.4 billion kilometers) — roughly the distance from the Sun to Neptune — and doing it faster than any mission before. By comparison, NASA’s New Horizons — the APL-led mission that captured the first images of Pluto — took 8 1/2 years to fly the same distance.

“We designed to worst-case assumptions for things like the thermal environment and the effects of solar radiation on the spacecraft,” said Jim Kinnison, the Parker Solar Probe mission systems engineer at APL. “We’re pleased that all the hard work during the design phase to define those worst-case assumptions has paid off.”

The spacecraft’s stellar performance has opened the door for the team to optimize the amount of science returned from the mission.

“Our telecommunications links are more robust than our worst-case predictions, allowing us to downlink at higher bit rates,” said Kinnison. “As a result, the scientists have been able to collect and downlink about three times more data than planned before launch. This means we’re able to study the Sun in more detail during each encounter but also greatly increase science return when we’re farther away. It also means we can collect data in special circumstances like Venus flybys, well beyond our basic science objectives.”

Over the course of the mission, Parker has sent back roughly 2.8 terabytes of scientific data, approximately equivalent to the amount of data in 200 hours of 4K video. Scientists worldwide will use this data for years to come to develop a better understanding of the Sun’s effects on Earth and our solar system.

“I couldn’t be happier with how the mission is going,” said John Wirzburger, the Parker spacecraft systems engineer at APL. “The spacecraft is operating normally, we’re well within all of our performance margins, and we have plenty of propellant to fly for a long time. Everything is working at least as well, if not better, than expected and modeled on the ground.”

Next month, Parker will complete its 13th perihelion, its closest approach to the Sun in this orbit. During that encounter, it will fly through the Sun’s upper atmosphere, the corona, for the sixth time.

That environment, though, is getting only more extreme. Parker makes its 13th approach as the Sun’s activity ramps up prior to solar maximum in 2025 — activity that NASA has reported is already exceeding predictions. This means there are more sunspots, solar flares, and solar eruptions than predicted. However, according to Wirzburger, the Parker team is not concerned about the spacecraft’s continued performance.

“Parker was designed to handle things like radiation and solar flares,” he said. “As some of the bigger solar flares have been released, the spacecraft has weathered the storm each time without issue.”

“Exploration is inherently risky, but the spacecraft has proven to be robust and able to autonomously keep itself safe,” added Kinnison. “We’re looking forward to the rest of the mission, and that closest perihelion at the end of the primary mission.”

By Ashley Hume
Johns Hopkins University Applied Physics Lab