Denise Hill – Parker Solar Probe

Scientists Shed Light on the Unusual Origin of a Familiar Meteor Shower

Editor’s note: This blog post was updated to include more information about the paper published in The Planetary Science Journal.

Each winter, the Geminid meteors light up the sky as they race past Earth, producing one of the most intense meteor showers in the night sky. Now, NASA’s Parker Solar Probe mission is providing new evidence that a violent, catastrophic event created the Geminids.

Most meteor showers come from comets, which are made of ice and dust. When a comet travels close to the Sun, the ice evaporates and releases gas, dislodging small pieces of the comet and creating a trail of dust. Slowly, this repeated process fills the comet’s orbit with material that produces a meteor shower when Earth passes through the stream.

However, the Geminid stream seems to originate from an asteroid – a chunk of rock and metal – called 3200 Phaethon. Asteroids like Phaethon are not typically affected by the Sun’s heat the way comets are, leaving scientists to wonder what caused the formation of Phaethon’s stream across the night sky.

“What’s really weird is that we know that Phaethon is an asteroid, but as it flies by the Sun, it seems to have some kind of temperature-driven activity. Most asteroids don’t do that,” said Jamey Szalay, a research scholar at Princeton University. Szalay was an author, with Wolf Cukier as the lead author, on the science paper recently published in The Planetary Science Journal.

The research builds on previous work by Szalay and several of his Parker Solar Probe mission colleagues, including the Geminids direct images captured by Karl Battams’ team, to assemble a picture of the structure and behavior of the large cloud of dust that swirls through the innermost solar system. Taking advantage of Parker’s flight path – an orbit that swings it just millions of miles from the Sun, closer than any spacecraft in history – the scientists were able to get the best direct look yet at the dust grains shed from passing comets and asteroids.

Built and operated by the Johns Hopkins Applied Physics Laboratory (APL) in Laurel, Maryland, Parker Solar Probe does not carry a dedicated dust counter that would give it accurate readings on grain mass, composition, speed, and direction. However, dust grains pelt the spacecraft along its path, and the high-speed impacts create unique electrical signals, or plasma clouds. These impact clouds produce unique electrical signals that are picked up by several sensors on the probe’s FIELDS instrument, which measures electric and magnetic fields near the Sun.

To learn about the origin of the Geminid stream, the scientists used this Parker data to model three possible formation scenarios, and then compared these models to existing models created from Earth-based observations. They found that violent models were most consistent with the Parker data. This means it was likely that a sudden, powerful event – such as a high-speed collision with another body or a gaseous explosion, among other possibilities – that created the Geminid stream.

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 program is managed by NASA’s Goddard Space Flight Center for the Heliophysics Division of NASA’s Science Mission Directorate. APL manages the Parker Solar Probe mission for NASA.

By Desiree Apodaca
Goddard Space Flight Center, Greenbelt, MD

NASA Notes Parker Solar Probe Instrument Temporarily Offline

An instrument on NASA’s Parker Solar Probe was powered off by the spacecraft autonomy system on Feb. 12. It happened during the application of an approved flight software patch to the Energetic Particle Instrument (EPI-Hi). The instrument team determined the instrument was power cycled prematurely before the patch was completely loaded.

The instrument will remain off for several weeks as the geometry between the spacecraft, Sun, and Earth currently prevents a good uplink. The EPI-Hi is expected to return to normal operations after this blackout period, before the spacecraft begins its 15th close encounter with the Sun on March 12.

The overall spacecraft remains healthy and is functioning as expected and the operation of other Parker instruments has not been impacted.

Parker Solar Probe Embarks on 14th Close Encounter with the Sun

On Dec. 6, NASA’s Parker Solar Probe began the 14^th of 24 planned close approaches to the Sun, eventually coming within 5.3 million miles of the solar surface.

The closest approach – called perihelion – occurred on Dec. 11 at 8:16 a.m. EST, during which the spacecraft traveled at 364,639 miles per hour – fast enough to fly from New York to Tokyo in just over a minute. This is just under Parker’s record speed of 364,660 mph, set on Nov. 21, 2021.

During the spacecraft’s previous close encounter with the Sun on Sept. 5, it flew through one of the most powerful coronal mass ejections in recorded history. As the Sun’s activity continues to increase on its approach toward solar maximum – the period of greatest activity during the Sun’s 11-year cycle – scientists expect Parker to fly through and observe more exciting phenomena from its unprecedented vantage point.

“It’s a very exciting time to have a spacecraft flying so close to the Sun and observing its activity,” said Nour Raouafi, Parker Solar Probe project scientist at Johns Hopkins Applied Physics Laboratory (APL) in Laurel, Maryland. “The first part of the mission was during the solar cycle minimum, when we learned so much about the relatively quiet conditions in the solar atmosphere. Now Parker Solar Probe embarks on a renewed journey where the Sun is more active. Every close encounter opens up new opportunities to understand better how the Sun works and how it affects us here on Earth and beyond.”

During the encounter, which ends Dec. 16, the European Space Agency’s Solar Orbiter, NASA’s Solar Terrestrial Relations Observatory-A (STEREO-A), and radar telescopes on Earth will view the Sun from the same angle as Parker at the beginning of the encounter. They will slowly progress to an approximately 90-degree angle from Parker on the inbound side of the encounter. ESA’s BepiColombo mission will start out viewing the Sun from the same angle as Parker and progress to observing the Sun from an approximately 90-degree angle from Parker on the outbound side of the encounter. This orientation could provide an opportunity to observe a solar event from all sides.

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 Johns Hopkins APL – where it was also designed and built – on Dec. 17.

Parker Solar Probe was developed as 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. APL designed, built, manages, and operates the spacecraft.

By Ashley Hume
Johns Hopkins Applied Physics Laboratory

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

As NASA’s Parker Solar Probe approaches its 13^th 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 10^th 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 Completes Its Fifth Venus Flyby

NASA’s Parker Solar Probe is speeding in toward the Sun after a swing past Venus on Oct. 16, successfully using the planet’s gravity to shape its path for its next closest approach to our star.

At just after 5:30 a.m. EDT, moving about 15 miles (24 kilometers) per second, the spacecraft swooped 2,370 miles (3,814 kilometers) above Venus’ surface. Such gravity assists are essential to the mission to bring Parker Solar Probe progressively closer to the Sun; the spacecraft counts on the planet to reduce its orbital energy, which in turn allows it to travel closer to the Sun and measure the properties of the solar wind near its source.

This was the fifth of seven planned Venus gravity assists. The flyby reduced Parker Solar Probe’s orbital speed by about 6,040 miles per hour (9,720 kilometers per hour), and set it up for its 10th close pass (or perihelion) by the Sun, on Nov. 21.

animated image showing parker solar probe flying by Venus — NASA’s Parker Solar Probe is speeding in toward the Sun after a swing past Venus on Oct. 16, 2021, successfully using the planet’s gravity to shape its path for its next closest approach to our star. This was the fifth of seven planned Venus gravity assists. The flyby reduced Parker Solar Probe’s orbital speed by about 6,040 miles per hour (9,720 kilometers per hour), and set it up for its 10th close pass (or perihelion) by the Sun, on Nov. 21, 2021. Credit: NASA/Johns Hopkins APL/Steve Gribben

Parker Solar Probe will break its own distance and speed records on that closest approach, when it comes approximately 5.3 million miles (8.5 million kilometers) from the Sun’s surface — some 1.2 million miles (1.9 million kilometers) closer than the previous perihelion on Aug. 13 – while reaching 101 miles (163 kilometers) per second, or 364,621 miles per hour. 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.

Parker Solar Probe, which was designed and built at the Johns Hopkins Applied Physics Laboratory in Laurel, Maryland, is healthy and its systems are operating normally after the Oct. 16 Venus flyby. The flyby operation was monitored by the spacecraft and mission operations teams at APL, through NASA’s Deep Space Network.

By Mike Buckley
Johns Hopkins University Applied Physics Lab