NASA’s Parker Solar Probe completed its 21st close approach to the Sun on Sept. 30, equaling its own distance record by coming within about 4.51 million miles (7.26 million kilometers) of the solar surface.
The close approach (known as perihelion) occurred at 5:15 UTC — or 12:15 a.m. EDT — with Parker Solar Probe moving 394,700 miles per hour (635,300 kilometers per hour) around the Sun, again matching its own record. The spacecraft checked in on Oct. 3 with mission operators at the Johns Hopkins Applied Physics Laboratory in Laurel, Maryland — where the spacecraft was also designed and built — with a beacon tone indicating it was in good health and all systems were operating normally.
Parker Solar Probe’s 21st orbit included a perihelion that brought the spacecraft within 4.51 million miles of the Sun. Credit: NASA/Johns Hopkins APL/Steve Gribben
Perihelion marked the midpoint in the mission’s 21st solar encounter, which began Sept. 25 and runs through Oct. 5.
This week’s close approach marked the last time Parker will fly around the Sun at this distance and speed before it makes the first of its three final, closest approaches of its primary mission on Dec. 24. At that point, with its orbit shaped by the mission’s final Venus gravity assist-flyby on Nov. 6, the spacecraft will zip just 3.8 million miles from the solar surface, moving about 430,000 miles per hour.
By Michael Buckley
Johns Hopkins Applied Physics Laboratory
NASA’s Parker Solar Probe executed a short maneuver on Aug. 26 that kept the spacecraft on course for the mission’s seventh and final planned Venus flyby on Nov. 6.
Operating on preprogrammed commands, Parker fired its small directional thrusters for about 17 seconds, changing its velocity by less than a mile per hour, and setting its trajectory some 386 miles (593 kilometers) closer to a targeted approach point about 240 miles (380 kilometers) above the Venusian surface. The mission operations team at the Johns Hopkins Applied Physics Laboratory (APL) in Laurel, Maryland, where Parker was designed and built, monitored the activity through NASA’s Deep Space Network antenna station in Goldstone, California.
Yanping Guo, Parker Solar Probe mission design and navigation manager at APL, said precise positioning and timing are critical to the Venus flybys, in which Parker uses the planet’s gravity to tighten its orbit around the Sun. The upcoming flyby will be closer to Venus than the previous six gravity assists, and the final piece of a mission design that will swing Parker to within just 3.8 million miles of the Sun’s surface — the closest the spacecraft will come to our star.
During Parker Solar Probe’s fourth flyby of Venus, the spacecraft’s WISPR instrument captured these images, strung into a video, showing the nightside surface of the planet. Credits: NASA/APL/NRL
“Venus 7 is the critical gravity assist for Parker Solar Probe to eventually achieve its minimum solar distance,” Guo said, adding that the team will likely conduct an additional, smaller maneuver in late October or early November — after the mission’s Sept. 30 solar encounter — to shore up the spacecraft’s path to Venus.
After flying by Venus, Parker will make the first of at least three planned passes at that unprecedented distance — while whizzing past the Sun at a record 430,000 miles per hour — on Dec. 24, 2024.
Parker Solar Probe is currently in its 21st orbit, about to begin a science encounter that culminates on Sept. 30, 2024, with a close approach (known as perihelion) of about 4.51 million miles (7.26 million kilometers) from the solar surface.
NASA’s Parker Solar Probe completed its 20th close approach to the Sun on June 30, 2024, matching its own distance record by coming about 4.51 million miles (7.26 million kilometers) from the solar surface.
The close approach (known as perihelion) occurred at 3:47 UTC (11:47 p.m. EDT on June 29), with Parker Solar Probe moving 394,736 miles per hour (635,266 kilometers per hour) around the Sun, again matching its own record. On July 2, the spacecraft checked in with mission operators at the Johns Hopkins Applied Physics Laboratory in Laurel, Maryland (where the spacecraft was also designed and built), with a beacon tone indicating it was in good health and all systems were operating normally.
Parker Solar Probe’s 20th orbit included a perihelion that brought the spacecraft within 4.51 million miles of the Sun. Credit: NASA/Johns Hopkins APL/Steve Gribben
The milestone also marked the midpoint in the mission’s 20th solar encounter, which began June 25 and continues through July 5.
Parker will fly around the Sun at the same distance and speed one more time this year — on Sept. 30 — before making the first of its three final planned closest approaches on Dec. 24. At that point, with Parker’s orbit shaped by the mission’s final Venus gravity assist-flyby on Nov. 6, the spacecraft will zoom just 3.8 million miles from the solar surface, moving about 430,000 miles per hour.
By Michael Buckley Johns Hopkins Applied Physics Laboratory
NASA’s Parker Solar Probe completed its 19th close approach to the Sun on March 30, matching its own distance record by coming about 4.51 million miles (7.26 million kilometers) from the solar surface.
The close approach (known as perihelion) occurred at 2:21 UTC (10:21 EDT), March 29, with Parker Solar Probe moving 394,736 miles per hour (635,266 kilometers per hour) around the Sun – again equaling its own record. The spacecraft checked in on April 2 with mission operators at the Johns Hopkins Applied Physics Laboratory in Laurel, Maryland, where the spacecraft was also designed and built, with a beacon tone indicating it was in good health and all systems were operating normally.
Parker Solar Probe’s 19th orbit included a perihelion that brought the spacecraft within 4.51 million miles of the Sun. Credit: NASA/Johns Hopkins APL/Steve Gribben
The milestone also marked the midway point in the mission’s 19th solar encounter, which began March 25 and continued through April 4.
Parker is still on track to make its closest approach on Dec. 24. At that point, with its orbit shaped by the mission’s final Venus gravity assist-flyby on Nov. 6, the spacecraft will zoom just 3.8 million miles from the solar surface, moving about 430,000 miles per hour.
By Michael Buckley Johns Hopkins Applied Physics Laboratory
NASA’s Parker Solar Probe completed its 18th close approach to the Sun on Dec. 28, 2023, matching its own distance record by skimming just about 4.51 million miles (7.26 million kilometers) from the solar surface.
The close approach (known as perihelion) occurred at 7:56 p.m. EST, with Parker Solar Probe traveling at 394,736 miles per hour (635,266 kilometers per hour) around the Sun – also matching the speed record for the 17th solar encounter. The milestone also marked the midway point in the mission’s 18th solar encounter, which began Dec. 24, 2023, and continued through Jan. 2, 2024.
Parker Solar Probe’s 18th orbit included a perihelion that brought the spacecraft within 4.51 million miles of the Sun. Credit: NASA/Johns Hopkins APL/Steve Gribben
The spacecraft entered the encounter in good health, with all systems operating normally. Parker Solar Probe checked back in with mission operators at the Johns Hopkins Applied Physics Laboratory in Laurel, Maryland – where the spacecraft was also designed and built – by sending a status beacon tone on Jan. 5.
By Michael Buckley Johns Hopkins Applied Physics Laboratory
NASA’s Parker Solar Probe completed its 17th close approach to the Sun on Sept. 27, 2023, breaking its own distance record by skimming just 4.51 million miles (7.26 million kilometers) from the solar surface.
Set up by a gravity-assist flyby of Venus on Aug. 21, the close approach (known as perihelion) occurred at 7:28 p.m. EDT, with Parker Solar Probe moving 394,736 miles per hour (635,266 kilometers per hour) around the Sun – another record. The milestone also marked the midway point in the mission’s 17th solar encounter, which began Sept. 22 and continues through Oct. 3.
Parker Solar Probe’s 17th orbit included a perihelion that brought the spacecraft within 4.51 million miles of the Sun. Credit: NASA/Johns Hopkins APL/Steve Gribben
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 the spacecraft was also designed and built – by sending a stream of telemetry (status data) on Oct. 1.
The spacecraft will transmit science data from the encounter – largely covering the properties, structure, and behavior of the solar wind as it launches off the Sun – back to Earth from Oct. 4 – 19.
By Michael Buckley Johns Hopkins Applied Physics Laboratory
On Sept. 5, 2022, NASA’s Parker Solar Probe soared gracefully through one of the most powerful coronal mass ejections (CMEs) ever recorded – not only an impressive feat of engineering, but a huge boon for the scientific community. Parker’s journey through the CME is helping to prove a 20-year-old theory about the interaction of CMEs with interplanetary dust, with implications for space weather predictions. The results were recently published in The Astrophysical Journal.
A 2003 paper theorized that CMEs may interact with interplanetary dust in orbit around our star and even carry the dust outward. CMEs are immense eruptions from the Sun’s outer atmosphere, or corona, that help drive space weather, which can endanger satellites, disrupt communications and navigation technologies, and even knock out power grids on Earth. Learning more about how these events interact with interplanetary dust could help scientists better predict how quickly CMEs could travel from the Sun to Earth, forecasting when the planet could see their impact.
Parker has now observed this phenomenon for the first time.
“These interactions between CMEs and dust were theorized two decades ago, but had not been observed until Parker Solar Probe viewed a CME act like a vacuum cleaner, clearing the dust out of its path,” said Guillermo Stenborg, an astrophysicist at the Johns Hopkins Applied Physics Laboratory (APL) in Laurel, Maryland, and lead author on the paper. APL built and operates the spacecraft.
This dust is made up of tiny particles from asteroids, comets, and even planets, and is present throughout the solar system. A type of faint glow called zodiacal light, sometimes visible before sunrise or after sunset, is one manifestation of the cloud of interplanetary dust.
The CME displaced the dust all the way out to about 6 million miles from the Sun – about one-sixth of the distance between the Sun and Mercury – but it was replenished almost immediately by the interplanetary dust floating through the solar system.
In-situ observations from Parker were critical to this discovery, because characterizing dust dynamics in the wake of CMEs is challenging from a distance. According to the researchers, Parker’s observations could also provide insight into related phenomena lower down in the corona, such as coronal dimming caused by low-density areas in the corona that often appear after CMEs erupt.
Scientists observed the interaction between the CME and dust as decreased brightness in images from Parker’s Wide-field Imager for Solar Probe (WISPR) camera. This is because interplanetary dust reflects light, amplifying brightness where the dust is present.
Parker Solar Probe’s Wide Field Imagery for Solar Probe (WISPR) camera observes as the spacecraft passes through a massive coronal mass ejection on Sept. 5, 2022. Coronal mass ejections are immense eruptions of plasma and energy from the Sun’s corona that drive space weather. Credit: NASA/Johns Hopkins APL/Naval Research Lab
To locate this occurrence of decreased brightness, the team had to compute the average background brightness of WISPR images across several similar orbits – sifting out normal brightness variations that occur due to solar streamers and other changes in the solar corona.
“Parker has orbited the Sun four times at the same distance, allowing us to compare data from one pass to the next very well,” Stenborg said. “By removing brightness variations due to coronal shifts and other phenomena, we were able to isolate the variations caused by dust depletion.”
Because scientists have only observed this effect in connection with the Sept. 5 event, Stenborg and the team theorize that dust depletion may only occur with the most powerful CMEs.
Nevertheless, studying the physics behind this interaction may have implications for space weather prediction. Scientists are just starting to understand that interplanetary dust affects the shape and speed of a CME. But more studies are needed to understand these interactions better.
Parker completed its sixth Venus flyby, using the planet’s gravity to sling itself even closer to the Sun for its next five close approaches. This occurs as the Sun itself is approaching solar maximum, the period in the Sun’s 11-year cycle when sunspots and solar activity are most abundant. As the Sun’s activity increases, scientists hope to have the opportunity to see more of these rare phenomena and explore how they might affect our Earth environment and the interplanetary medium.
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, and operates the spacecraft and manages the mission for NASA.
By Ashley Hume Johns Hopkins Applied Physics Laboratory
NASA’s Parker Solar Probe zoomed past Venus on Aug. 21, using the planet’s gravity to aim toward a record-setting series of flights around the Sun that start next month.
Standing, from left, Parker Solar Probe Mission Operations Manager Nick Pinkine and Project Manager Helene Winters discuss the progress of Parker’s gravity assist flyby of Venus with members of the spacecraft operations team at the Johns Hopkins Applied Physics Laboratory on Aug. 21. Credit: NASA/ Johns Hopkins APL/Brooke Hammack
At just before 8:03 a.m. EDT, moving approximately 15 miles (more than 24 kilometers) per second, Parker Solar Probe passed 2,487 miles (4,003 kilometers) above the Venusian surface as it curved around the planet toward the inner solar system. The mission operations team at the Johns Hopkins Applied Physics Laboratory (APL) in Laurel, Maryland, kept in contact with the spacecraft during the flyby through NASA’s Deep Space Network – except for an expected 8 minutes at closest approach, when Venus was between Earth and Parker – and determined the spacecraft was on course and operating normally.
“Parker Solar Probe remains on track to make its closest flybys yet of the Sun,” said Nick Pinkine, Parker Solar Probe mission operations manager from APL. “Parker’s success is a tribute to the entire mission team, but I’m especially proud of the mission operators and the job they’ve done over the past five years to ensure the flawless operation of this incredible, history-making spacecraft.”
Guidance and Control Lead Sarah Hefter, of the Johns Hopkins Applied Physics Laboratory, monitors Parker Solar Probe’s trek around Venus in the Parker Mission Operations Center at APL on Aug. 21. Credit: NASA/Johns Hopkins APL/Brooke Hammack
Venus gravity assists are essential to guiding Parker Solar Probe progressively closer to the Sun; the spacecraft relies on the planet to reduce its orbital energy, which in turn allows it to travel closer to the Sun – where, since 2018, it has been exploring the origins and unlocking the secrets of the solar wind and other properties of the near-Sun environment at their source.
This was the Parker mission’s sixth of seven planned Venus gravity assists. This week’s flyby served as an orbit maneuver applying a velocity change – called “delta-V” – on Parker Solar Probe, reducing its orbital speed by about 5,932 miles per hour (9,547 kilometers per hour). The maneuver changed the spacecraft’s orbit and set Parker Solar Probe up for its next five close passes by the Sun, the first of which occurs on Sept. 27. On each close approach (known as perihelion), Parker Solar Probe will set or match its own speed and distance records when it comes to within just 4.5 million miles (7.3 million kilometers) from the solar surface, while moving close to 394,800 miles per hour.
An illustration of Parker Solar Probe passing Venus. Credit: NASA/Johns Hopkins APL/Steve Gribben
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, and operates the spacecraft and manages the mission for NASA.
By Michael Buckley Johns Hopkins Applied Physics Laboratory
On Aug. 12, 2018 – five years ago this week – NASA’s Parker Solar Probe blasted off atop a powerful Delta IV rocket from what is now Cape Canaveral Space Force Station. The predawn launch into the skies over the Florida coast marked the start of a game-changing mission to unlock the secrets of the solar wind – and the culmination of decades of development to craft a robotic explorer able to withstand the heat and radiation near the Sun like no other spacecraft before it.
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Designs for a “Solar Probe” started coming together in 1962, just four years after the National Research Council’s Space Studies Board first proposed a mission to explore the environment near the Sun. But the technology to pull off such a bold endeavor, especially the material ingredients for an effective heat shield, just wasn’t available – yet.
Evolution of a spacecraft: Designs for a Solar Probe changed through the decades, based on technologies and mission plans at the time. NASA’s directive for a Sun-skirting spacecraft led to the design of the Parker Solar Probe mission, which this week celebrates five years in space. Credits: NASA/Johns Hopkins APL
Material advances in the 1970s allowed NASA to begin considering a flyby close enough to directly sample the Sun’s upper atmosphere – the corona – and the solar wind. The initial mission science definition formed in a 1978 workshop at NASA’s Jet Propulsion Laboratory (JPL), but the means to implement the mission would take decades to come together – with JPL and the Johns Hopkins Applied Physics Laboratory (APL) developing concepts for a nuclear-powered Sun skimmer between 1982 and 2005.
In 2007, NASA asked APL to consider a concept for a spacecraft that could cozy up to the Sun, and from that – with the right combination of groundbreaking thermal-protection technologies and clever mission design – evolved the Parker Solar Probe mission that now marks its first half-decade.
“No matter its form, the core of the mission has always been a close encounter with the Sun,” said Jim Kinnison, Parker Solar Probe mission systems engineer at APL. “It took significant technology development, innovative mission design, and a risk-reducing engineering plan – and now, the Parker team is fulfilling an exploration vision laid out at the dawn of the Space Age.”
Protecting the probe: Engineers from the Johns Hopkins Applied Physics Laboratory prepare the Parker Solar Probe Thermal Protection System – one of the mission’s enabling technologies — for space-environment testing in a thermal vacuum chamber at NASA’s Goddard Space Flight Center, Maryland, in January 2018. Credits: NASA/Johns Hopkins APL/Ed Whitman
After five years of flying through thehottest and dustiest swaths of the inner solar system, Parker Solar Probe – which in 2021 became the first spacecraft to “touch the Sun” – isn’t just surviving, it’s thriving. The spacecraft has returned more than twice the amount of data that scientists expected, making discoveries critical to understanding thesource andproperties of the solar wind. The spacecraftrecently completed its 16th science orbit, out of 24 planned during the primary mission. And on Aug. 21 Parker will zoom past Venus for a gravity assist, a move that will tighten its orbit around the Sun and allow it to take measurements of theVenusian surface and atmosphere.
Thanks to that gravity assist, on Sept. 27, Parker Solar Probe will be traveling at 394,742 miles per hour when it comes within 4.5 million miles of the Sun’s surface – breaking its own speed and distance records around the Sun. It will ultimately dip to within just 3.8 million miles from the Sun, speeding by at 430,000 miles per hour, in December 2024.
The final design: The actual Parker Solar Probe spacecraft was prepped for launch in a cleanroom at Astrotech Space Operations in Titusville, Florida, in July 2018. Credits: NASA/Johns Hopkins APL/Ed Whitman
“We are in a golden era of heliophysics exploration,” said Nour Raouafi, Parker Solar Probe project scientist at APL. “In just five years, Parker Solar Probe has changed our understanding of the Sun and the activities that connect it to – and affect – life on Earth. As we speed closer and closer to the solar surface, we will learn more about the properties of the Sun itself, but that data will also significantly improve our knowledge of space weather and our ability to live and work in space.”
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, and operates the spacecraft and manages the mission for NASA.
By Michael Buckley Johns Hopkins Applied Physics Laboratory
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Background on Solar Probe design history comes from: J. Kinnison, M. K. Lockwood, N. Fox, R. Conde, and A. Driesman, “Solar Probe Plus: A mission to touch the sun,” 2013 IEEE Aerospace Conference, Big Sky, MT, USA, 2013, pp. 1-11, doi: 10.1109/AERO.2013.6496957.
Artist’s concept of Parker Solar Probe. Credit: NASA’s Goddard Space Flight Center
NASA’s Parker Solar Probe executed a short maneuver on Aug. 3, 2023, that kept the spacecraft on track to hit the aim point for the mission’s sixth Venus flyby on Monday, Aug. 21, 2023.
Operating on preprogrammed commands from mission control at the Johns Hopkins Applied Physics Laboratory (APL) in Laurel, Maryland, Parker fired its small thrusters for 4.5 seconds, enough to adjust its trajectory by 77 miles and speed up – by 1.4 seconds – its closest approach to Venus. The precise timing and position are critical to that flyby, the sixth of seven approaches in which Parker uses the planet’s gravity to tighten its orbit around the Sun.
“Parker’s velocity is about 8.7 miles per second, so in terms of changing the spacecraft’s speed and direction, this trajectory correction maneuver may seem insignificant,” said Yanping Guo, mission design and navigation manager at APL. “However, the maneuver is critical to get us the desired gravity assist at Venus, which will significantly change Parker’s speed and distance to the Sun”.
Parker Solar Probe will be moving 394,742 miles per hour when it comes within just 4.5 million miles from the Sun’s surface – breaking its own record for speed and solar distance – on Sept. 27, 2023. Follow the spacecraft’s journey through the inner solar system on the Parker Solar Probe website.
By Michael Buckley Johns Hopkins Applied Physics Laboratory
