Category Archives: Solar Science

Voyager 2 reaches interstellar space

NASA’s Voyager 2 spacecraft, launched in 1977, joins Voyager 1 in leaving the Sun’s heliosphere and entering interstellar space:

NASA’s Voyager 2 Probe Enters Interstellar Space

For the second time in history, a human-made object has reached the space between the stars. NASA’s Voyager 2 probe now has exited the heliosphere – the protective bubble of particles and magnetic fields created by the Sun.

Members of NASA’s Voyager team will discuss the findings at a news conference at 11 a.m. EST (8 a.m. PST) today at the meeting of the American Geophysical Union (AGU) in Washington. The news conference will stream live on the agency’s website.

Comparing data from different instruments aboard the trailblazing spacecraft, mission scientists determined the probe crossed the outer edge of the heliosphere on Nov. 5. This boundary, called the heliopause, is where the tenuous, hot solar wind meets the cold, dense interstellar medium. Its twin, Voyager 1, crossed this boundary in 2012, but Voyager 2 carries a working instrument that will provide first-of-its-kind observations of the nature of this gateway into interstellar space.

This illustration shows the position of NASA’s Voyager 1 and Voyager 2 probes, outside of the heliosphere, a protective bubble created by the Sun that extends well past the orbit of Pluto. Credits: NASA/JPL-Caltech

Voyager 2 now is slightly more than 11 billion miles (18 billion kilometers) from Earth. Mission operators still can communicate with Voyager 2 as it enters this new phase of its journey, but information – moving at the speed of light – takes about 16.5 hours to travel from the spacecraft to Earth. By comparison, light traveling from the Sun takes about eight minutes to reach Earth.

The most compelling evidence of Voyager 2’s exit from the heliosphere came from its onboard Plasma Science Experiment (PLS), an instrument that stopped working on Voyager 1 in 1980, long before that probe crossed the heliopause. Until recently, the space surrounding Voyager 2 was filled predominantly with plasma flowing out from our Sun. This outflow, called the solar wind, creates a bubble – the heliosphere – that envelopes the planets in our solar system. The PLS uses the electrical current of the plasma to detect the speed, density, temperature, pressure and flux of the solar wind. The PLS aboard Voyager 2 observed a steep decline in the speed of the solar wind particles on Nov. 5. Since that date, the plasma instrument has observed no solar wind flow in the environment around Voyager 2, which makes mission scientists confident the probe has left the heliosphere.

“Working on Voyager makes me feel like an explorer, because everything we’re seeing is new,” said John Richardson, principal investigator for the PLS instrument and a principal research scientist at the Massachusetts Institute of Technology in Cambridge. “Even though Voyager 1 crossed the heliopause in 2012, it did so at a different place and a different time, and without the PLS data. So we’re still seeing things that no one has seen before.”

In addition to the plasma data, Voyager’s science team members have seen evidence from three other onboard instruments – the cosmic ray subsystem, the low energy charged particle instrument and the magnetometer – that is consistent with the conclusion that Voyager 2 has crossed the heliopause. Voyager’s team members are eager to continue to study the data from these other onboard instruments to get a clearer picture of the environment through which Voyager 2 is traveling.

“There is still a lot to learn about the region of interstellar space immediately beyond the heliopause,” said Ed Stone, Voyager project scientist based at Caltech in Pasadena, California. 

Together, the two Voyagers provide a detailed glimpse of how our heliosphere interacts with the constant interstellar wind flowing from beyond. Their observations complement data from NASA’s Interstellar Boundary Explorer (IBEX), a mission that is remotely sensing that boundary. NASA also is preparing an additional mission – the upcoming Interstellar Mapping and Acceleration Probe (IMAP), due to launch in 2024 – to capitalize on the Voyagers’ observations.

“Voyager has a very special place for us in our heliophysics fleet,” said Nicola Fox, director of the Heliophysics Division at NASA Headquarters. “Our studies start at the Sun and extend out to everything the solar wind touches. To have the Voyagers sending back information about the edge of the Sun’s influence gives us an unprecedented glimpse of truly uncharted territory.”

While the probes have left the heliosphere, Voyager 1 and Voyager 2 have not yet left the solar system, and won’t be leaving anytime soon. The boundary of the solar system is considered to be beyond the outer edge of the Oort Cloud, a collection of small objects that are still under the influence of the Sun’s gravity. The width of the Oort Cloud is not known precisely, but it is estimated to begin at about 1,000 astronomical units (AU) from the Sun and to extend to about 100,000 AU. One AU is the distance from the Sun to Earth. It will take about 300 years for Voyager 2 to reach the inner edge of the Oort Cloud and possibly 30,000 years to fly beyond it.

The Voyager probes are powered using heat from the decay of radioactive material, contained in a device called a radioisotope thermal generator (RTG). The power output of the RTGs diminishes by about four watts per year, which means that various parts of the Voyagers, including the cameras on both spacecraft, have been turned off over time to manage power.

“I think we’re all happy and relieved that the Voyager probes have both operated long enough to make it past this milestone,” said Suzanne Dodd, Voyager project manager at NASA’s Jet Propulsion Laboratory (JPL) in Pasadena, California. “This is what we’ve all been waiting for. Now we’re looking forward to what we’ll be able to learn from having both probes outside the heliopause.”

Voyager 2 launched in 1977, 16 days before Voyager 1, and both have traveled well beyond their original destinations. The spacecraft were built to last five years and conduct close-up studies of Jupiter and Saturn. However, as the mission continued, additional flybys of the two outermost giant planets, Uranus and Neptune, proved possible. As the spacecraft flew across the solar system, remote-control reprogramming was used to endow the Voyagers with greater capabilities than they possessed when they left Earth. Their two-planet mission became a four-planet mission. Their five-year lifespans have stretched to 41 years, making Voyager 2 NASA’s longest running mission.

The Voyager story has impacted not only generations of current and future scientists and engineers, but also Earth’s culture, including film, art and music. Each spacecraft carries a Golden Record of Earth sounds, pictures and messages. Since the spacecraft could last billions of years, these circular time capsules could one day be the only traces of human civilization.

Voyager’s mission controllers communicate with the probes using NASA’s Deep Space Network (DSN), a global system for communicating with interplanetary spacecraft. The DSN consists of three clusters of antennas in Goldstone, California; Madrid, Spain; and Canberra, Australia.

The Voyager Interstellar Mission is a part of NASA’s Heliophysics System Observatory, sponsored by the Heliophysics Division of NASA’s Science Mission Directorate in Washington. JPL built and operates the twin Voyager spacecraft. NASA’s DSN, managed by JPL, is an international network of antennas that supports interplanetary spacecraft missions and radio and radar astronomy observations for the exploration of the solar system and the universe. The network also supports selected Earth-orbiting missions. The Commonwealth Scientific and Industrial Research Organisation, Australia’s national science agency, operates both the Canberra Deep Space Communication Complex, part of the DSN, and the Parkes Observatory, which NASA has been using to downlink data from Voyager 2 since Nov. 8.

For more information about the Voyager mission, visit:

More information about NASA’s Heliophysics missions is available online at:

Videos: ULA Delta IV rocket launches NASA’s Parker Solar Probe

Early this morning, a United Launch Alliance Delta IV Heavy rocket successfully launched NASA’s Parker Solar Probe from Cape Canaveral on a unique mission to study the Sun’s corona up close NASA, ULA Launch Parker Solar Probe on Historic Journey to Touch Sun | NASA

“The United Launch Alliance Delta IV Heavy rocket launches NASA’s Parker Solar Probe to touch the Sun, Sunday, Aug. 12, 2018, from Launch Complex 37 at Cape Canaveral Air Force Station, Florida.” – NASA

Few get to see a spacecraft named after themselves launched on a grand rocket. A clip of Dr. Eugene Newman Parker watching the launch last night:

The spacecraft is carrying a chip with the names of 1.1 million public participants etched on it.

See previous postings here and here on the Parker mission.

More resources at the Parker Solar Probe Mission HQ at Johns Hopkins Univ. Applied Physics Lab.



Videos: NASA Parker Solar Probe set for early morning launch from the Cape on Aug.11

NASA’s Parker Solar Probe is ready for its launch early Saturday morning. NASA’s Parker Solar Probe is About to Lift Off | NASA

At [ 3:33 a.m. EDT  (0733 GMT) ] on Aug. 11, while most of the U.S. is asleep, NASA’s Kennedy Space Center in Florida will be abuzz with excitement. At that moment, NASA’s Parker Solar Probe, the agency’s historic mission to touch the Sun, will have its first opportunity to lift off.

Launching from Cape Canaveral Air Force Station in Florida, Parker Solar Probe will make its journey all the way to the Sun’s atmosphere, or corona — closer to the Sun than any spacecraft in history.

The spacecraft will ride the massive United Launch Alliance Delta IV Heavy rocket, which is powered by liquid hydrogen and liquid oxygen. United Launch Alliance to Launch NASA’s Parker Solar Probe – ULA.

The liftoff of a Delta IV is always fun to watch. A sheet of flame will surround the vehicle just at liftoff caused by the burn off of hydrogen gas that’s emitted from the engines before they ignite.

Here is a new video about the mission:

Here’s the orbit that the probe will follow to bring it into the Sun’s atmosphere or corona:

Parker uses a highly elliptical orbit with Venus gravity assists to get closer to the Sun. Credits: NASA/JPL/WISPR Team

A video about the Sun’s corona, which is actually hotter than the surface of the Sun, a mystery the Parker probe will investigate: The Curious Case of the Sun’s Hot Corona | NASA

More videos about the Parker mission: GMS: Parker Solar Probe Science Briefing – Visual Resources

Some interesting items about the mission: Parker Solar Probe preview: 10 hot facts about NASA’s cool mission to the Sun | The Planetary Society



Videos: Parker Solar Probe set to launch on mission to study the Sun up close

On August 4th, United Launch Alliance (ULA) aims to launch a big Delta IV Heavy rocket from Cape Canaveral to send NASA’s Parker Solar Probe into an orbit that will bring it far closer to our home star than any previous spacecraft has dared go. (Perhaps your name is aboard the probe.) A cutting-edge heat shield enables the probe to fly directly through the corona, which is the extremely hot ionized plasma that surrounds the Sun.

Here is a new NASA video about the mission:

More about the mission at Parker Solar Probe: Humanity’s First Visit to a Star | NASA:

In order to unlock the mysteries of the Sun’s atmosphere, Parker Solar Probe will use Venus’ gravity during seven flybys over nearly seven years to gradually bring its orbit closer to the Sun. The spacecraft will fly through the Sun’s atmosphere as close as 3.8 million miles to our star’s surface, well within the orbit of Mercury and more than seven times closer than any spacecraft has come before. (Earth’s average distance to the Sun is 93 million miles.)

Flying into the outermost part of the Sun’s atmosphere, known as the corona, for the first time, Parker Solar Probe will employ a combination of in situ measurements and imaging to revolutionize our understanding of the corona and expand our knowledge of the origin and evolution of the solar wind. It will also make critical contributions to our ability to forecast changes in Earth’s space environment that affect life and technology on Earth.

A simulation of the orbit that will bring the probe closer and closer to the sub at perigee:



Send your name to the Sun on the Parker Solar Probe

NASA’s Parker Solar Probe mission offers you the opportunity to launch your name this summer on a spaceship heading for the sun :

Public Invited to Come Aboard NASA’s First Mission to Touch the Sun

Want to get the hottest ticket this summer without standing in line?

NASA is inviting people around the world to submit their names online to be placed on a microchip aboard NASA’s historic Parker Solar Probe mission launching in summer 2018. The mission will travel through the Sun’s atmosphere, facing brutal heat and radiation conditions — and your name will go along for the ride.

“This probe will journey to a region humanity has never explored before,” said Thomas Zurbuchen, the associate administrator for the Science Mission Directorate at NASA Headquarters in Washington. “This mission will answer questions scientists have sought to uncover for more than six decades.”

Understanding the Sun has always been a top priority for space scientists. Studying how the Sun affects space and the space environment of planets is the field known as heliophysics. The field is not only vital to understanding Earth’s most important and life-sustaining star, it supports exploration in the solar system and beyond.

Submissions will be accepted until April 27, 2018. Learn more and add your name to the mission here: 

Star Trek’s William Shatner, on behalf of NASA, invites you to send your name where it’s never gone before: the Sun, by way of NASA’s Parker Solar Probe. Credits: NASA’s Goddard Space Flight Center/Rich Melnick

The spacecraft, about the size of a small car, will travel directly into the Sun’s atmosphere about 4 million miles from the star’s surface. The primary science goals for the mission are to trace how energy and heat move through the solar corona and to explore what accelerates the solar wind as well as solar energetic particles. The mission will revolutionize our understanding of the Sun, where changing conditions can spread out into the solar system, affecting Earth and other worlds.

To perform these unprecedented investigations, the spacecraft and instruments will be protected from the Sun’s heat by a 4.5-inch-thick carbon-composite shield, which will need to withstand temperatures outside the spacecraft that reach nearly 2,500 F. This state-of-the-art heat shield will keep the four instrument suites designed to study magnetic fields, plasma and energetic particles, and image the solar wind at room temperature.

The spacecraft speed is so fast, at its closest approach it will be going at approximately 430,000 mph. That’s fast enough to get from Washington, D.C., to Tokyo in under a minute.

“Parker Solar Probe is, quite literally, the fastest, hottest — and, to me, coolest — mission under the Sun,” said project scientist Nicola Fox, of the Johns Hopkins Applied Physics Laboratory. “This incredible spacecraft is going to reveal so much about our star and how it works that we’ve not been able to understand.”

Honoring a Science Legend

Eugene Parker, professor emeritus at the University of Chicago, visits the spacecraft that bears his name, NASA’s Parker Solar Probe, on Oct. 3, 2017. Engineers in the clean room at the Johns Hopkins Applied Physics Laboratory in Laurel, Maryland, where the probe was designed and built, point out the instruments that will collect data as the mission travels directly through the Sun’s atmosphere. Credits: NASA/Johns Hopkins University Applied Physics Laboratory

In May 2017, NASA renamed the spacecraft from the Solar Probe Plus to the Parker Solar Probe in honor of astrophysicist Eugene Parker. The announcement was made at a ceremony at the University of Chicago, where Parker serves as the S. Chandrasekhar Distinguished Service Professor Emeritus, Department of Astronomy and Astrophysics.

This was the first time NASA named a spacecraft for a living individual.

NASA missions are most often renamed after launch and certification. In this case, given Parker’s accomplishments within the field, and how closely aligned this mission is with his research, the decision was made to honor him prior to launch, in order to draw attention to his important contributions to heliophysics and space science.

In the 1950s, Parker proposed a number of concepts about how stars — including our Sun — give off energy. He called this cascade of energy the solar wind, and he described an entire complex system of plasmas, magnetic fields and energetic particles that make up this phenomenon. Parker also theorized an explanation for the superheated solar atmosphere, the corona, which is — contrary to what was expected by physics laws — hotter than the surface of the Sun itself. Many NASA missions have continued to focus on this complex space environment defined by our star.

Parker Solar Probe is part of NASA’s Living with a Star Program, or LWS, to explore aspects of the Sun-Earth system that directly affect life and society. LWS is managed by the NASA’s Goddard Space Flight Center in Greenbelt, Maryland, for NASA’s Science Mission Directorate in Washington. The Johns Hopkins Applied Physics Laboratory, in Laurel, Maryland, manages the Parker Solar Probe mission for NASA. APL is designing and building the spacecraft and will also operate it.

Illustration of the Parker Solar Probe spacecraft approaching the Sun.
Credits: Johns Hopkins University Applied Physics Laboratory