At just before 1:50 p.m. EDT on Sept. 1, 2019, NASA’s Parker Solar Probe completed its third close approach of the Sun, called perihelion. At the time of perihelion, the spacecraft was about 15 million miles from the Sun’s surface, traveling at more than 213,200 miles per hour.
Mission controllers at the Johns Hopkins Applied Physics Laboratory in Laurel, Maryland, received a green “A” beacon from the spacecraft soon after perihelion, meaning all systems were performing as designed and that the spacecraft was in good health.
This third encounter, which was at approximately the same distance from the Sun and speed as the first two, differs in that the spacecraft’s four instrument suites have been on and gathering data for a longer period than other perihelia.
For this third solar encounter, the mission team turned on the instruments when the spacecraft was around 0.45 astronomical units from the Sun on the inbound side of its orbit. (One astronomical unit, or AU, is about 93 million miles, the average distance between the Sun and Earth.) The instruments will be turned off when Parker Solar Probe is about 0.5 AU from the Sun on the outbound side, which will occur on about Sept. 20. For the prior two perihelia, the instruments were on from 0.25 AU prior to and after completing the close approach.
After Parker Solar Probe’s successful first year in space, the mission team has decided to extend science observations as the spacecraft approaches its third solar encounter.
Parker Solar Probe turned on its four instrument suites on Aug. 16, 2019 — earlier than during its previous two solar encounters, extending the observation period from 11 days to about 35 days.
During the spacecraft’s first two solar encounters, the science instruments were turned on when Parker was about 0.25 AU from the Sun and powered off again at the same distance on the outbound side of the orbit. (One AU, or astronomical unit, is about 93 million miles, the average distance between the Sun and Earth.) For this third solar encounter, the mission team turned on the instruments when the spacecraft was around 0.45 AU from the Sun on the inbound side of its orbit and will turn them off when the spacecraft is about 0.5 AU from the Sun on the outbound side.
“We’ve seen very intriguing phenomena below 0.25 AU, and are confident we will see interesting things all the way out to 0.5 AU,” said Nour Raouafi, Parker Solar Probe project scientist at the Johns Hopkins Applied Physics Laboratory in Laurel, Maryland. “We cannot wait to see how this extended campaign data will compare to our previous data collected during the shorter periods and to the data from previous missions, such as Helios.”
The extended observation time before and after Parker Solar Probe’s perihelion — its closest approach to the Sun during a given orbit — will let scientists capture the evolution of the solar wind over greater distances as it travels away from the Sun. They also hope the additional data will yield more insight into the energetic particles surrounding the Sun, the corona and the overall solar environment.
The data gathered during this period will start downlinking immediately at the end of the extended campaign. The data from the first two encounters will be released to the public in 2019. Parker Solar Probe’s third perihelionwill occur on Sept. 1.
As NASA’s Parker Solar Probe approaches its third encounter with the Sun, mission scientists are hard at work poring over data from the spacecraft’s first two flybys of our star — and thanks to excellent performance by the spacecraft and the mission operations team, they’re about to get something extra.
On May 6, 2019, just over a month after Parker Solar Probe completed its second solar encounter, the final transmission of 22 gigabytes of planned science data — collected during the first two encounters — was downlinked by the mission team at the Johns Hopkins Applied Physics Laboratory, or APL, in Laurel, Maryland.
This 22 GB is 50% more data than the team had estimated would be downlinked by this point in the mission — all because the spacecraft’s telecommunications system is performing better than pre-launch estimates. After characterizing the spacecraft’s operations during the commissioning phase, which began soon after launch, the Parker mission team determined that the telecom system could effectively deliver more downlink opportunities, helping the team maximize the download of science data.
The team has capitalized on the higher downlink rate, instructing Parker Solar Probe to record and send back extra science data gathered during its second solar encounter. This additional 25 GB of science data will be downlinked to Earth between July 24 and Aug. 15.
“All of the expected science data collected through the first and second encounters is now on the ground,” said Nickalaus Pinkine, Parker Solar Probe mission operations manager at APL. “As we learned more about operating in this environment and these orbits, the team did a great job of increasing data downloads of the information gathered by the spacecraft’s amazing instruments.”
There are four instrument suites on Parker, gathering data on particles, waves, and fields related to the Sun’s corona and the solar environment. Scientists use this information — gathered closer to the Sun than any previous measurements — along with data from other satellites and scientific models to expand on what we currently know about the Sun and how it behaves. Data collected during the first two perihelia will be made available to the public later this year.
Parker Solar Probe continues on its record-breaking exploration of the Sun with its third solar encounter beginning Aug. 27, 2019; the spacecraft’s third perihelion will occur on Sept. 1.
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. “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.
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.
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.
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.”
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.
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.
“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.
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.
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.
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.
Parker Solar Probe will repeatedly break its own records, achieving a top speed of about 430,000 miles per hour in 2024.
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.