Parker Solar Probe Completes Second Close Approach to the Sun

Parker Solar Probe has successfully completed its second close approach to the Sun, called perihelion, and is now entering the outbound phase of its second solar orbit. At 6:40 p.m. EDT on April 4, 2019, the spacecraft passed within 15 million miles of our star, tying its distance record as the closest spacecraft ever to the Sun; Parker Solar Probe was traveling at 213,200 miles per hour during this perihelion.

The Parker Solar Probe mission team at the Johns Hopkins Applied Physics Laboratory, or APL, in Laurel, Maryland scheduled a contact with the spacecraft via the Deep Space Network for four hours around the perihelion and monitored the health of the spacecraft throughout this critical part of the encounter. Parker Solar Probe sent back beacon status “A” throughout its second perihelion, indicating that the spacecraft is operating well and all instruments are collecting science data.

“The spacecraft is performing as designed, and it was great to be able to track it during this entire perihelion,” said Nickalaus Pinkine, Parker Solar Probe mission operations manager at APL.Animation of Parker Solar Probe passing close to the Sun “We’re looking forward to getting the science data down from this encounter in the coming weeks so the science teams can continue to explore the mysteries of the corona and the Sun.”

Parker Solar Probe began this solar encounter on March 30, and it will conclude on April 10. The solar encounter phase is roughly defined as when the spacecraft is within 0.25 AU — or 23,250,000 miles — of the Sun. One AU, or astronomical unit, is about 93 million miles, the average distance from the Sun to Earth.

By Geoff Brown

Johns Hopkins University Applied Physics Lab

Parker Solar Probe Approaches Second Solar Encounter

On March 30, 2019, Parker Solar Probe begins the second solar encounter phase of its mission, culminating in its closest approach to the Sun, called perihelion, on April 4 at 6:40 p.m. EDT.

During this solar encounter phase, which lasts until April 10, the spacecraft’s four suites of science instruments are fully operational and storing science data collected from within the Sun’s corona. As designed, Parker Solar Probe will be out of contact with Earth for several days during the solar encounter. This allows the spacecraft to prioritize keeping its heat shield, called the Thermal Protection System, oriented towards the Sun, rather than pointing its transmitter towards Earth. Science data from this second solar encounter phase will downlink to Earth over several weeks later in spring 2019.

Plot showing Parker Solar Probe's speed & position as of March 28, 2019.
Parker Solar Probe begins its second solar encounter phase on March 30, 2019. Track the spacecraft’s speed and position online.

Like the mission’s first orbit, Parker Solar Probe will reach a perihelion of about 15 million miles from the Sun’s surface — meeting its own record for closest-ever approach to the Sun, a little more than half the previous record distance of about 27 million miles set by Helios 2 in 1976. The spacecraft’s top speed of about 213,200 miles per hour is also the same as the first solar encounter of the mission. In December 2019, Parker Solar Probe will perform the second of seven Venus gravity assists of its mission, setting up the trajectory that will carry the spacecraft closer to the Sun and to a higher top speed.

Editor’s note: This post was updated on April 3, 2019, to include the time of Parker Solar Probe’s perihelion.

By Sarah Frazier

NASA’s Goddard Space Flight Center

All Systems Go As Parker Solar Probe Begins Second Sun Orbit

On Jan. 19, 2019, just 161 days after its launch from Cape Canaveral Air Force Station in Florida, NASA’s Parker Solar Probe completed its first orbit of the Sun, reaching the point in its orbit farthest from our star, called aphelion. The spacecraft has now begun the second of 24 planned orbits, on track for its second perihelion, or closest approach to the Sun, on April 4, 2019.

Parker Solar Probe entered full operational status (known as Phase E) on Jan. 1, with all systems online and operating as designed. The spacecraft has been delivering data from its instruments to Earth via the Deep Space Network, and to date more than 17 gigabits of science data has been downloaded. The full dataset from the first orbit will be downloaded by April.

“It’s been an illuminating and fascinating first orbit,” said Parker Solar Probe Project Manager Andy Driesman, of the Johns Hopkins University Applied Physics Laboratory. “We’ve learned a lot about how the spacecraft operates and reacts to the solar environment, and I’m proud to say the team’s projections have been very accurate.” APL designed, built, and manages the mission for NASA.

“We’ve always said that we don’t know what to expect until we look at the data,” said Project Scientist Nour Raouafi, also of APL. “The data we have received hints at many new things that we’ve not seen before and at potential new discoveries. Parker Solar Probe is delivering on the mission’s promise of revealing the mysteries of our Sun.”

Parker Solar Probe's position, speed and round-trip light time as of Jan. 28, 2019.
Parker Solar Probe’s position, speed and round-trip light time as of Jan. 28, 2019. Track the spacecraft online.

The Parker Solar Probe team is not only focused on analyzing the science data but also preparing for the second solar encounter, which will take place in about two months.

In preparation for that next encounter, the spacecraft’s solid state recorder is being emptied of files that have already been delivered to Earth. In addition, the spacecraft is receiving updated positional and navigation information (called ephemeris) and is being loaded with a new automated command sequence, which contains about one month’s worth of instructions.

Like the mission’s first perihelion in November 2018, Parker Solar Probe’s second perihelion in April will bring the spacecraft to a distance of about 15 million miles from the Sun – just over half the previous close solar approach record of about 27 million miles set by Helios 2 in 1976.

The spacecraft’s four instrument suites will help scientists begin to answer outstanding questions about the Sun’s fundamental physics — including how particles and solar material are accelerated out into space at such high speeds and why the Sun’s atmosphere, the corona, is so much hotter than the surface below.

By Geoff Brown

Johns Hopkins University Applied Physics Lab

Parker Solar Probe Reports First Telemetry, Acquisition of Science Data Since Perihelion

On Nov. 16, Parker Solar Probe reported that all systems are operating well in the first detailed performance and health update sent to Earth by the spacecraft since its first solar encounter.

At about 6:00 p.m. EST on Friday, Nov. 16, mission controllers at the Johns Hopkins Applied Physics Lab in Laurel, Maryland, received the report from the spacecraft, which also included information about the data collected by the four instrument suites during its first solar encounter. Parker Solar Probe’s first solar encounter phase took place Oct. 31 – Nov. 11, culminating in its first close approach to the Sun — called perihelion — on Nov. 6 at just 15 million miles from the Sun’s surface, the closest any spacecraft has ever come to our star.

All Parker Solar Probe systems are operating well and as designed. The solid state recorder on the spacecraft indicated that, as planned, the four instrument suites had recorded a significant amount of data, which is scheduled to be downloaded to Earth via the Deep Space Network over several weeks starting Dec. 7. In addition to helping scientists begin to explore fundamental questions about the physics of our star, the data from this initial perihelion — collected closer to the Sun than any before — will help instrument teams calibrate Parker Solar Probe’s instruments and plan future observations.

Illustration of Parker Solar Probe approaching the Sun.
Illustration of Parker Solar Probe approaching the Sun. Credits: NASA/Johns Hopkins APL/Steve Gribben

“The team is extremely proud to confirm that we have a healthy spacecraft following perihelion,” said APL’s Nick Pinkine, mission operations manager for Parker Solar Probe. “This is a big milestone, and we’re looking forward to some amazing science data coming down in a few weeks.”

During the 11-day solar encounter, the spacecraft executed only one autonomous momentum dump – a procedure in which small thrusters are used to adjust the speed of Parker’s reaction wheels. The rate of spin of the wheels is adjusted to maintain the desired orientation of the spacecraft relative to the Sun. Momentum dumps are expected during solar encounters, as the wheels spin up to counter increasing torque from the gravitational effects of the solar environment. Executing only one dump indicates that the spacecraft is well balanced, minimizing the need for these dumps during future solar encounters, which will save propellant.

Parker Solar Probe’s second perihelion will occur on April 4, 2019. During the seven-year mission, the spacecraft will perform a total of 24 perihelia, with the last three bringing the spacecraft to less than 4 million miles from the Sun’s surface.

By Geoff Brown

Johns Hopkins University Applied Physics Lab

Parker Solar Probe Starts First Solar Encounter

On Oct. 31, 2018, Parker Solar Probe began its first of 24 solar encounters. This period — which lasts until Nov. 11 — is the time during which the spacecraft is within 0.25 astronomical units, or 23.2 million miles, of the Sun’s center. Parker Solar Probe’s four suites of science instruments are on and collecting data throughout this phase, giving scientists their closest-yet look at this dynamic region of the Sun’s outer atmosphere.

This solar encounter encompasses the first perihelion of the mission, the point at which Parker Solar Probe is closest to the Sun. Perihelion is expected at about 10:28 p.m. EST on Nov. 5. The spacecraft will come within 15 million miles of the Sun’s surface and clock in at a top speed of 213,200 miles per hour relative to the Sun — setting new records for both closest solar approach and top heliocentric speed by a spacecraft. At perihelion, Parker Solar Probe will fly through material at about 3.6 million degrees Fahrenheit — but because material in this region is so tenuous, it doesn’t influence the temperature of the spacecraft. However, the Sun’s intense radiation heats the Sun-facing side of the spacecraft’s heat shield, called the Thermal Protection System, to about 820 F.

A plot of Parker Solar Probe's speed, position and round-trip light time on Oct. 31 at 14:00 UTC.
Parker Solar Probe’s speed, position and round-trip light time as of Oct. 31. Track Parker Solar Probe’s speed and position online.

For several days around the Nov. 5 perihelion, Parker Solar Probe will be completely out of contact with Earth because of interference from the Sun’s overwhelming radio emissions.

Parker Solar Probe employs a host of autonomous systems to keep the spacecraft safe without guidance from Earth — including automatic retraction of the solar panels to regulate their temperature, attitude control using solar limb sensors that ensures all of the instruments remain in the heat shield’s shadow, and a sophisticated guidance and control system that keeps the spacecraft pointed correctly. This autonomy is key not only during no-contact phases around the 24 planned perihelia but also throughout the mission, when the round-trip light time — the time it takes for radio signals to go back and forth between Earth and Parker Solar Probe — can be up to 31 minutes.

During the solar encounter phase, Parker Solar Probe’s four instrument suites measure the properties of material directly within the Sun’s outer atmosphere. These observations, gathered closer to the Sun than ever before, will help scientists begin to answer outstanding questions about the Sun’s fundamental physics — including how particles and solar material are accelerated out into space at such high speeds and why the Sun’s atmosphere, the corona, is so much hotter than the surface below.

Because of the spacecraft’s distance from Earth and position relative to the Sun, it will be several weeks after the end of the solar encounter before Parker Solar Probe begins transmitting this science data back to Earth.

Parker Solar Probe Becomes Fastest-Ever Spacecraft

At about 10:54 p.m. EDT, Parker Solar Probe surpassed 153,454 miles per hour — as calculated by the mission team — making it the fastest-ever human-made object relative to the Sun. This breaks the record set by the German-American Helios 2 mission in April 1976.

Illustration of Parker Solar Probe approaching the Sun.
Illustration of Parker Solar Probe approaching the Sun. Credits: NASA/Johns Hopkins APL/Steve Gribben

Parker Solar Probe will repeatedly break its own records, achieving a top speed of about 430,000 miles per hour in 2024.

Read more about Parker Solar Probe’s record-making mission.

Parker Solar Probe Looks Back at Home

On Sept. 25, 2018, Parker Solar Probe captured a view of Earth as it sped toward the first Venus gravity assist of the mission. Earth is the bright, round object visible in the right side of the image.

The view from Parker Solar Probe's WISPR instrument on Sept. 25, 2018, shows Earth, the bright sphere near the middle of the right-hand panel.
The view from Parker Solar Probe’s WISPR instrument on Sept. 25, 2018, shows Earth, the bright sphere near the middle of the right-hand panel. The elongated mark toward the bottom of the panel is a lens reflection from the WISPR instrument.
Credits: NASA/Naval Research Laboratory/Parker Solar Probe

Read more on NASA.gov.

In First for a Spacecraft, Parker Solar Probe Autonomously Manages Heat Load on Solar Arrays

Two people in bunny suits stand on either end of a solar array and examine it.
Members of the Parker Solar Probe team examine and align one of the spacecraft’s two solar arrays on May 31, 2018. Credit: NASA/Johns Hopkins APL/Ed Whitman

Two days after Parker Solar Probe flew past Venus toward its rendezvous with the Sun, the spacecraft had drawn close enough to our star that its power-generating solar array wings began to tilt themselves inward – a task directed by the spacecraft itself, based on the rising temperatures – away from the Sun and behind the spacecraft’s heat shield. This is the first time that autonomous, closed-loop solar array angle control based on temperature has taken place on a spacecraft.

This solar array movement, controlled by software within the spacecraft’s main processor, began on Oct. 5, soon after Parker Solar Probe’s distance from the Sun dropped below about 65 million miles.

Read more from the Johns Hopkins University Applied Physics Lab.

Parker Solar Probe Successfully Completes First Venus Flyby

On Oct. 3, Parker Solar Probe successfully completed its flyby of Venus at a distance of about 1,500 miles during the first Venus gravity assist of the mission. These gravity assists will help the spacecraft tighten its orbit closer and closer to the Sun over the course of the mission.

The orbit design for the Parker Solar Probe mission.
The orbit design for the Parker Solar Probe mission. Credit: NASA/Johns Hopkins APL

Detailed data from the flyby will be assessed over the next few days. This data allows the flight operations team to prepare for the remaining six Venus gravity assists which will occur over the course of the seven-year mission.

 

Fall 2018 Milestones for Parker Solar Probe

We like to call Parker Solar Probe the coolest, hottest, fastest mission under the Sun — and fall 2018 will prove why. Here are a few mission milestones to look forward to over the coming months.

Oct. 3, 2018 (about 4:45 a.m. EDT) — Parker Solar Probe performs its first Venus gravity assist. This maneuver — to be repeated six more times over the lifetime of the mission — will change Parker Solar Probe’s trajectory to take the spacecraft closer to the Sun.

An illustration of Parker Solar Probe passing Venus.
An illustration of Parker Solar Probe passing Venus. Credit: NASA/Johns Hopkins APL/Steve Gribben

Oct. 29, 2018 — Parker Solar Probe is expected to come within 27 million miles of the Sun. This is the record currently held by Helios 2, set in 1976.

Oct. 30, 2018 — Parker Solar Probe is expected to surpass a heliocentric speed of 153,454 miles per hour. This is the record for fastest spacecraft measured relative to the Sun, set by Helios 2 in 1976.

These speed and distance estimates could change after Parker Solar Probe performs its Venus gravity assist on Oct. 3.

Oct. 31 – Nov. 11, 2018 — Parker Solar Probe performs its first solar encounter. Throughout this period, the spacecraft will gather valuable science data. It will not be in contact with Earth because of the Sun’s interference and the orientation needed to keep the spacecraft’s heat shield between it and the Sun. The spacecraft is expected to reach its closest approach on Nov. 5. Like the distance and speed records, this estimate could change after the Venus gravity assist.

December 2018 — Parker Solar Probe will downlink the science data gathered during its first solar encounter.

You can keep up with Parker Solar Probe’s real-time speed and position online, with updates every hour. More mission milestones are also available.

Editor’s note: This post was updated on Oct. 3, 2018, to correct the expected date of first perihelion.