NASA/Johns Hopkins APL/Steve Gribben 

The Parker Solar Probe, a spacecraft the size of a small car, was launched during solar minimum, a regular period of most minor solar activity in the Sun's 11-year solar cycle. That was back in 2018.

A lot has happened since then.

The spacecraft approached its 13th perihelion, or close encounter, with the Sun on September 6, at a time a sunspot the size of Earth had rapidly developed on the Sun, and the star had given off multiple solar flares and geomagnetic storms.

The solar environment is drastically different, but scientists are thrilled.

"Nobody has ever flown through a solar event so close to the Sun before," Nour Raouafi, Parker Solar Probe project scientist at the Johns Hopkins Applied Physics Laboratory (APL) in Laurel, Maryland, said in a statement. "The data would be totally new, and we would definitely learn a lot from it."

NASA had reported earlier this summer that Solar Cycle 25 was already exceeding predictions for solar activity, even with the expected solar maximum in 2025.

"When the Sun changes, it also changes the environment around it. The activity at this time is way higher than we expected," said Raouafi.

The scientist expects the high level of solar activity to continue as Parker approaches this perihelion, just 5.3 million miles from the Sun. The spacecraft is yet to fly through a solar flare or a coronal mass ejection (CME) during one of its close encounters, but that may change this coming month, reported NASA.

The resulting data would be groundbreaking.

NASA/Johns Hopkins APL/Steve Gribben 

Parker's observations will aid in understanding 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. Parker’s Wide-field Imager for Solar Probe (WISPR) instrument has already imaged a small number of CMEs from a distance, which has led to unexpected discoveries about the structure of CMEs.

However, though the Sun is more active than in previous encounters, mission operators are not concerned about unfavorable incidents 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."

Not only does Parker's custom heat shield and an autonomous system help protect the mission, but it also allows the coronal material to "touch" the spacecraft.

NASA/Johns Hopkins APL/Ed Whitman 

Parker was designed by the Johns Hopkins Applied Physics Laboratory and was built at Carbon-Carbon Advanced Technologies, using a carbon composite foam sandwiched between two carbon plates, according to a release. This lightweight insulation is replete with a finishing touch of white ceramic paint on the sun-facing plate to reflect as much heat as possible. Tested to withstand up to 3,000 F (1,650 C), the 'TPS can handle any heat the Sun can send its way, keeping almost all instrumentation safe'.

But, not all of the instruments are behind the TPS. The Solar Probe Cup — a sensor designed to measure the ion and electron fluxes and flow angles from the solar wind — is one of the instruments that the heat shield will not protect. Keeping the intensity of the solar atmosphere in mind, never-seen-before technologies had to be engineered to ensure that the instruments survive and transmit accurate readings.

Electronic wiring was another challenge - cables would generally melt from exposure to heat radiation in such proximity to the Sun. To overcome this, the team grew sapphire crystal tubes to suspend the wiring and made the wires from niobium.

And to ensure the instrument was ready for the harsh environment, the researchers mimicked the Sun’s intense heat radiation in a lab. Finally, cooling systems in the TPS will keep the solar arrays and instrumentation cool and functioning while in the heat of the Sun.

The spacecraft is also designed to keep itself safe and on track to the Sun autonomously. Several sensors that are attached to the body of the spacecraft along the edge of the shadow from the heat shield will alert the central computer if they detect sunlight. The spacecraft can then correct its position to protect the sensors and the rest of the instruments safely.

There's another factor that makes the 13th perihelion more special.

The Solar Orbiter, an ESA (European Space Agency)/NASA mission, will view the Sun from the same angle as Parker but 58.5 million miles farther from the Sun’s surface.

Though Parker’s observations do not always overlap with those of other observatories, it offers significant advantages when they do.

"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.”

However, this is not the first time Parker and Solar Orbiter have been in alignment for one of Parker’s perihelions.

Meanwhile, 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."