Venus Flyby Sends Parker Solar Probe Toward Record-Setting Flights Around the Sun

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.

Several people sit in a control room filled with computer screens. One person points at something while talking to a few people sitting at a large desk.
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.”

A woman sits in front of a laptop and a computer screen, looking into the distance, with her hand on her chin.
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.
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

Durable Parker Solar Probe Going Strong After First Five Years

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.

8 drawings of iterations of Parker Solar Probe, labeled by year they were designed. The years start at 1982 and end at 2011.
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.”

People wearing protective white clothing stand around pieces of Parker Solar Probe in a dark room.
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 the hottest 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 the source and properties of the solar wind. The spacecraft recently 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 the Venusian 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.    

Parker Solar Probe spacecraft in an white room. It's mostly silver and shaped like a cone – smaller on the bottom toward the ground and getting wider toward the top. The top appears white and is flat.
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.”

Learn more at http://www.nasa.gov/parkersolarprobe and http://parkersolarprobe.jhuapl.edu.

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.

Course Correction Keeps Parker Solar Probe on Track for Venus Flyby

An illustration of Parker Solar Probe flying through solar material.
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