Amazing Achievements From Parker Solar Probe

In 2018, NASA launched Parker Solar Probe on an unprecedented mission to study the Sun up close. The mission was defined with three key scientific goals:

    1. To trace the flow of energy that heats the Sun’s outer atmosphere.
    2. To shed light on the sources of the solar wind, the constant flow of solar material escaping from the Sun.
    3. To explore how solar energetic particles – which can make the 93-million mile (150 million kilometer) journey to Earth in under an hour – are transported and accelerated.

Now four years after launch, the mission has officially met its Mission Success criteria, making inroads towards achieving these key goals and more. As Parker Solar Probe continues its mission, it continues to break records and capture first-of-its-kind measurements of the Sun.

Here are the need-to-know facts about NASA’s historic mission to touch the Sun.

1. Parker Solar Probe was the first NASA mission named for a living person.

In honor of Eugene Parker, eminent physicist who first predicted the solar wind, NASA announced in May 2017, that it would rename the Solar Probe Plus mission to Parker Solar Probe. Parker witnessed the spacecraft’s launch in person and the discoveries made in the mission’s few years. He passed away on March 15, 2022, at age 94.

2. The spacecraft carries revolutionary technology.

The mission was conceived in 1958, but it took 60 years to develop the technology to make it happen. Designed and built at the Johns Hopkins Applied Physics Laboratory in Laurel, Maryland, Parker Solar Probe carries a heat shield, autonomous onboard “smarts” to keep the spacecraft facing the Sun, and an efficient cooling system.

3. It’s a repeated record-breaker.

Just a few months after launch, Parker Solar Probe became the closest human-made object to the Sun, passing within 26.55 million miles (42.72 million kilometers) from the Sun’s surface, and became the fastest human-made object, reaching speeds of 153,454 miles per hour. Since then, it has repeatedly broken both of those records, and will reach a top speed of about 430,000 miles per hour (700,000 kilometers per hour) as it flies to within 3.9 million miles (6.2 million kilometers) of the Sun’s surface in 2024. See where Parker Solar Probe is in real time here.

4. Parker Solar Probe has officially sampled the Sun.

In December 2021, NASA announced that Parker Solar Probe had achieved its cornerstone objective: making the first measurements from within the atmosphere of a star.

5. It’s made game-changing discoveries.

Parker Solar Probe carries four instrument suites, and each is now credited with several groundbreaking discoveries. A small sample of them is described below.

The Solar Wind Electrons Alphas and Protons investigation (SWEAP)
Surveying where Sun becomes solar wind

When Parker Solar Probe entered the solar atmosphere, it made the first-ever crossing of what’s known as the Alfvén critical surface – the boundary where solar material anchored to the Sun first escapes and becomes the solar wind.

Until this crossing, no one knew what that boundary would look like. During its first pass close enough to cross the boundary, Parker Solar Probe passed into and out of the corona several times. This revealed key information about the boundary’s shape, revealing that the Alfvén critical surface wasn’t shaped like a smooth ball. Rather, it has spikes and valleys that wrinkle the surface.

The SWEAP instrument established that the wrinkles were due to coronal streamers – giant plumes of solar material rising through the Sun’s atmosphere. Streamers have long been observed by Sun-watching spacecraft near Earth, but never before measured directly. The results are reshaping what we know about the Sun’s atmosphere and how it transforms into the solar wind.

The boundary that marks the edge of the corona is the Alfvén critical surface. Inside that surface (circle at left), plasma is connected to the Sun by waves that travel back and forth to the surface. Beyond it (circle at right), the Sun’s magnetic fields and gravity are too weak to contain the plasma and it becomes the solar wind, racing across the solar system so fast that waves within the wind cannot ever travel fast enough to make it back to the Sun. The results suggest that the Alfvén critical surface has a wrinkled structure that is connected to giant plumes of solar material called coronal streamers. Credits: NASA/Johns Hopkins APL/Ben Smith

The Wide-Field Imager for Parker Solar Probe (WISPR)
The first hints of a dust-free zone

Dust is just about everywhere in our solar system — the remnants of collisions that formed planets, asteroids, comets and other celestial bodies billions of years ago. Almost a century ago, astronomer Henry Norris Russell predicted that there should be a region around the Sun where dust particles should get hot enough to sublimate and thus disappear, creating a dust-free zone. People looked for evidence of the sublimation zone for decades but there was no consistent evidence for its existence whatsoever.

The WISPR instrument made the first detection of dust depleting close to the Sun, observing the light reflected from dust dimming at about 19 solar radii (8.2 million miles, or 13.2 million kilometers, away from the Sun). Models of the results suggest that a dust-free zone should exist starting at about 5 solar radii (2.2 million miles, or 3.5 million kilometers, from the Sun).

Parker Solar Probe saw cosmic dust (illustrated here) — scattered throughout our solar system — begin to thin out close to the Sun, supporting the idea of a long-theorized dust-free zone near the Sun. Credits: NASA’s Goddard Space Flight Center/Scott Wiessinger

Tracking down the Sun’s magnetic reversals 

When Parker Solar Probe sent back the first observations from its voyage to the Sun, scientists found their magnetic field measurements spiked with what became known as switchbacks: rapid flips in the Sun’s magnetic field that reversed direction like a zig-zagging mountain road.

FIELDS has since helped narrow down their origins.  During Parker Solar Probe’s 6th flyby of the Sun, FIELDS data revealed that the switchbacks aligned with magnetic “funnels” in the solar surface. These funnels emerge from between structures called supergranules – giant bubbles on the Sun in which hot plasma from the solar interior rises up, spreads out across the surface, cools and then sinks back down. The magnetic geometry of these regions suggests that magnetic reconnection powers the solar wind.

While the new findings locate where switchbacks are made, the question of how they’re formed is still a matter of active research.

Data from Parker Solar Probe has traced the origin of switchbacks – magnetic zig-zag structures in the solar wind – back to the solar surface. At the surface, magnetic funnels emerge from the photosphere between convection cell structures called supergranules. Switchbacks form inside the funnels and rise into the corona and are pushed out on the solar wind. Credit: NASA GSFC/CIL/Jonathan North.

The Integrated Science Investigation of the Sun (ISʘIS)
Rewriting the book on solar energetic particles

ISʘIS, pronounced “ee-sis” and including the symbol for the Sun in its acronym, measures solar energetic particles, the most energetic particles that escape the Sun. Measured near Earth, solar energetic particles events are relatively rare and hard to predict. But detecting SEPs close to the Sun, ISʘIS has changed just about everything we know about these speedy particles. ISʘIS has found that SEPs are much more common than expected, that they contain a wider range of types of particles than expected, and that their paths from the Sun are not as direct as previously thought – they can be disrupted by the switchbacks detected by fields and can at times follow a path twice as long as expected. By measuring these events so close to the Sun, ISʘIS is detecting events so small that all trace of them is lost before they reach Earth, helping scientists develop a fuller picture of where they come from and how they’re accelerated away from the Sun.

Energetic particle detections during the first 10 orbits or Parker Solar Probe by the Integrated Science Investigation of the Sun (ISʘIS) instrument. Credits: NASA/Princeton/David McComas, Jamie Rankin, Mitchell Shen, Jamey Szalay

…And the results keep coming.

Each new dataset expands the limits of space science – and it’s not just about the Sun. Parker Solar Probe has also studied comets, detected radio emissions from Venus’ atmosphere, and even captured the first-ever images of Venus’ surface in visible wavelengths.

With its closest pass of the Sun still ahead in 2024, only time will tell what new discoveries await.

Telescopes Trained on Parker Solar Probe’s Latest Pass Around the Sun

As NASA’s Parker Solar Probe completes its latest swing around the Sun, it’s doing so in full view of dozens of other spacecraft and ground-based telescopes.

These powerful instruments can’t actually see Parker itself – the van-sized spacecraft is far too small for visible detection – but they offer from a distance what the probe is sensing close-up, as it samples and analyzes the solar wind and magnetic fields from as close as 5.3 million miles (8.5 million kilometers) from the Sun’s surface.

The view from Earth: The red line indicates path of NASA’s Parker Solar Probe across the face of the Sun, as seen from Earth, from Feb. 24-27, 2022. The red dots indicate an hour along the trajectory, and the appearance of the path heading into the Sun at right accounts for Earth’s own movement around our star. The image of the Sun was captured by NASA’s Solar Dynamics Observatory.
Credit: NASA/Johns Hopkins APL/Steve Gribben/SDO

Occurring at 10:36 a.m. EST (15:36 UTC) on Feb. 25, this was the 11th close approach – or perihelion in the spacecraft’s orbit around the Sun – of 24 planned for Parker Solar Probe’s primary mission. Most of these passes occur while the Sun is between the spacecraft and Earth, blocking any direct lines of sight from home. But every few orbits, the dynamics work out to put the spacecraft in Earth’s view – and the Parker mission team seizes these opportunities to organize broad observation campaigns that not only include telescopes on Earth, but several spacecraft as well.

More than 40 observatories around the globe, including the recently commissioned Daniel K. Inouye Solar Telescope in Hawaii, among other major installations in the southwestern United States, Europe and Asia, are training their visible, infrared and radio telescopes on the Sun over the several weeks around the perihelion. About a dozen spacecraft, including NASA’s STEREO, Solar Dynamics Observatory, TIMED and Magnetospheric Multiscale missions, ESA’s and NASA’s Solar Orbiter, ESA’s BepiColombo, the JAXA-led Hinode, and even NASA’s MAVEN at Mars are making simultaneous observations of activity stretching from the Sun to Earth and beyond.

The pass also marked the midway point in the mission’s 11th solar encounter, which began Feb. 20 and continues through March 2. The spacecraft checked in with mission operators at APL – where Parker Solar Probe was designed and built – on Feb. 28 to report that it was healthy and operating as expected.

Most of the data from this encounter will stream back to Earth from March 30 through May 1, though the team will get a glimpse of some readings when the spacecraft sends a limited amount of data this week.

Solar Activity Picks Up

Parker Solar Probe is expected to dip back into the Sun’s outer atmosphere – the corona – continuing the solar wind and magnetic field readings it has taken since before it first “touched the Sun” last year.

Along with that data, scientists eagerly anticipate a look at what Parker Solar Probe recorded from the large solar prominence on Feb. 15 that blasted tons of charged particles in the spacecraft’s direction. Project Scientist Nour Raouafi of the Space Exploration Sector, said it was the largest event Parker Solar Probe has experienced during its first three-and-a-half years in flight.

“The shock from the event hit Parker Solar Probe head-on, but the spacecraft was built to withstand activity just like this – to get data in the most extreme conditions,” he said. “And with the Sun getting more and more active, we can’t wait to see the data that Parker Solar Probe gathers as it gets closer and closer.”

Assisted by a pair of orbit-shaping Venus flybys in August 2023 and November 2024, Parker Solar Probe will eventually come within 4 million miles (6.2 million kilometers) of the solar surface in December 2024 at speeds topping 430,000 miles per hour. Follow the probe’s trek through the inner solar system​.

Parker Solar Probe Completes a Record-Setting Swing by the Sun

Blazing along at space-record speeds that would get it from Earth to the Moon in under an hour, NASA’s Parker Solar Probe completed its 10th close approach to the Sun on Nov. 21, coming within 5.3 million miles (8.5 million kilometers) of the solar surface.

Parker Solar Probe is in the 10th of 24 planned, progressively closer orbits around the Sun. the spacecraft, built and operated at the Johns Hopkins Applied Physics Laboratory in Laurel, Maryland, launched on Aug. 12, 2018. Credit: NASA/Johns Hopkins APL

The close approach (known as perihelion), also at a record distance, occurred at 4:25 a.m. EST (8:25 UTC), with Parker Solar Probe moving 364,660 miles per hour (586,864 kilometers per hour). The milestone also marked the midway point in the mission’s 10th solar encounter, which began Nov. 16 and continues through Nov. 26.

The spacecraft entered the encounter in good health, with all systems operating normally. Parker Solar Probe is scheduled to check back in with mission operators at the Johns Hopkins Applied Physics Laboratory in Laurel, Maryland – where it was also designed and built – on Nov 24.

The spacecraft will transmit science data from the encounter – largely covering the properties and structure of the solar wind as well as the dust environment near the Sun – back to Earth from Dec. 23-Jan. 9.

Space Dust Presents Opportunities, Challenges as Parker Solar Probe Speeds Back toward the Sun

Illustration of Parker Solar Probe facing the Sun
Artist’s concept of Parker Solar Probe approaching the Sun. Credit: NASA/Johns Hopkins APL/Steve Gribben

Propelled by a recent swing past Venus, NASA’s Parker Solar Probe is healthy and performing normally as it heads toward its next closest approach to the Sun on Nov. 21.

Parker Solar Probe will break its own distance and speed records on that approach – the 10th of 24 planned, progressively closer trips around the Sun – when it comes about 5.3 million miles (8.5 million kilometers) from the Sun’s surface, while reaching top speeds of 101 miles (163 kilometers) per second, or 364,621 miles per hour. The probe’s science instruments are already queued up to measure the properties of the solar wind near its source, but the spacecraft is also making other critical, if not unexpected, discoveries.

“We’re observing higher than expected amounts of dust near the Sun,” said Nour Raouafi, Parker Solar Probe project scientist at the Johns Hopkins Applied Physics Laboratory (APL) in Laurel, Maryland. “What’s exciting about this is it’s greatly improving our understanding of the innermost regions of our heliosphere, giving us insight into an environment that, until now, was a total mystery.”

Parker Solar Probe designed, built and now operated at APL, does not carry a dust detector. But as dust grains pelt the spacecraft along its path, the high-velocity impacts create clouds of plasma. These clouds produce unique electrical charges that are picked up by several sensors on the probe’s FIELDS instrument, which is designed to measure the electric and magnetic fields near the Sun. Mission scientists have used this data, for example, to construct comprehensive pictures of the structure and behavior of the large cloud of dust that swirls through the innermost solar system.

The visible imaging camera, WISPR, also picks up bits of material expelled from the spacecraft’s structures after impact with those dust grains. But it also images dust structures far away from the spacecraft, such as the dust ring that shares Venus’ orbit. While learning about space dust isn’t a prime mission science goal, the WISPR and FIELDS have planned for specifically investigating near-Sun dust – in a region of the solar system where no mission has ever operated.

The Parker Solar Probe team did prepare for the spacecraft’s precarious trek through this potentially hazardous environment – as early as the initial mission concept phase – at least as well as our scientific community understood it before the probe’s 2018 launch.

“We designed materials and components that survive hypervelocity dust impacts and the effects of the even smaller particles created in these impacts,” said Jim Kinnison, Parker Solar Probe mission systems engineer at APL. “We modeled the makeup and effects of the dust environment, tested how materials react to the dust particles, and installed fault-tolerant onboard systems that are keeping Parker Solar Probe safe in this unexplored region.”

The spacecraft team has noticed that occasionally, the star tracking cameras used as part of the guidance and control system see reflected light from dust and shattering particles that can momentarily disrupt their ability to see stars. Kinnison noted, however, that this doesn’t compromise the safety of spacecraft or instrument operations, and the star trackers aren’t the spacecraft’s only method of controlling where it points. The guidance and control software uses data from the star trackers in tandem with an inertial measurement unit and solar-limb sensors to keep the Thermal Protection System – the heat shield – pointed toward the Sun.

“Because the system was built to be robust and highly autonomous, loss of data from any one source doesn’t affect the ability to control the spacecraft attitude, and in a worst-case situation, can work indefinitely with just the Solar Limb Sensors that watch for unexpected solar illumination on the spacecraft due to attitude errors,” he said. “With PSP now in its 10th orbit around the Sun, the spacecraft is proving it can handle this unexpected dust environment.”

And that’s good news, he added, with Parker Solar Probe only set to move closer to – and faster around – the Sun. Assisted by two more Venus flybys, in August 2023 and November 2024, Parker Solar Probe will eventually come within 4 million miles (6.2 million kilometers) of the solar surface in December 2024, at speeds topping 430,000 miles per hour.

Parker Solar Probe Heads Toward Second Venus Flyby

After nearly 17 months in space culminating with the release of new science data, Parker Solar Probe is right on course for its second Venus gravity assist maneuver. This flyby will set the spacecraft up for its fourth perihelion of the Sun, during which it will set records for spacecraft speed and closest solar distance, while continuing to gather groundbreaking data from within the Sun’s corona to help scientists make new discoveries.

Diagram of the locations and dates of Parker Solar Probe’s first four Venus gravity assists. The upcoming Venus gravity assist on Dec. 26, 2019, will be the second such maneuver of the mission.

On Dec. 26, at 1:14 p.m. EST, Parker Solar Probe will perform its second Venus flyby, during which the spacecraft will fly within 1,870 miles of Venus, using the planet to slow itself down and adjust its trajectory for an optimal path toward the Sun. This move allows Parker Solar Probe to precisely position itself for a fourth orbit around Earth’s star—with its next close approach, or perihelion, on January 29, 2020—when it will break its own speed and distance records, flying within 11.6 million miles of the Sun’s surface, 20 percent closer than its first three perihelia.

“These gravity assist maneuvers create the enormous orbit reduction required to get Parker Solar Probe close to the Sun,” said Yanping Guo, mission and navigation design manager for Parker Solar Probe at the Johns Hopkins Applied Physics Lab (APL) in Laurel, Maryland. “The seven Venus flybys are connected in a unique sequence, and each of the flybys is chosen not only to make the necessary orbit reductions, but also to hit the subsequent flybys.”

To prepare for this planetary maneuver, the Parker Solar Probe mission operations team at APL performed a small trajectory correction maneuver (TCM) on the spacecraft on Dec. 8. This TCM very accurately lined up the spacecraft for the rendezvous with Venus. After the flyby, the team will perform another TCM to fine-tune Parker Solar Probe’s final approach for its fourth perihelion.

The spacecraft will complete five more of these critical Venus flybys in the coming years in order to gradually pull it closer to the Sun.

By Justyna Surowiec

Johns Hopkins Applied Physics Lab