Parker Solar Probe Encounters

Parker Solar Probe science is conducted in a series of “encounters” centered around each perihelion, as well as during multiple flybys of Venus. The table below provides the times and distances of each perihelion, and information about each encounter and Venus flyby are given in sections below. To facilitate coordination between other missions and Parker Solar Probe during these encounters, the Parker team releases footpoint predictions (see these slides and the Badman et al. (2023) paper for information on the footpoint preditions). For information on coordinating with Parker for an encounter, or to be added to the footpoint distribution list, please contact Robert C. Allen (Robert.Allen@jhuapl.edu).

Venus Flyby 1

On the way into the first encounter, Parker Solar Probe conducted a Venus Flyby on 2018 October 3rd, in which measurements were taken of the Venusian bowshock. These flybys provide much needed information into the near-Venus space environment and allow for exciting research outside of the primary mission of Parker Solar Probe.

Encounter 1

The first perihelion of Parker Solar Probe reached a solar distance of 0.17 au (35.6 R_S), breaking the record as the closest human-made object to the Sun. Findings from the first two encounters were reported in four Nature articles (1, 2, 3, 4) and as a set of over 50 articles in a special issue of The Astrophysical Journal Supplement series (ApJS).

See also ENLIL predictions from Helioweather for Encounter 1.

Encounter 2

The second Parker Solar Probe encounter also reached a solar distance of 0.17 au (35.6 R_S) and provided additional insight into the structure of the solar wind in the inner heliosphere. Findings from the first two encounters were reported in four Nature articles (1, 2, 3, 4) and as a set of over 50 articles in a special issue of ApJS.

See ENLIL predictions from Helioweather for Encounter 2.

Encounter 3

The third encounter of Parker Solar Probe provided an additional snapshot of the inner heliosphere down to 0.17 au (35.6 R_S), complementing those from the first two encounters.

See ENLIL predictions from Helioweather for Encounter 3.

Venus Flyby 2

The second Venus flyby, on 2019 December 26th, provided additional measurements of the bowshock of Venus, and allowed Parker Solar Probe to lower its perihelion to 27.8 R_S for Encounter 4.

Encounter 4

The orbit of Parker Solar Probe (Parker) during the 4^th encounter with the Sun presented a unique opportunity for a multi-mission and multi-observatory collaboration as the 4th perihelion occurred nearly at the Sun-Earth line. This unprecedented configuration allowed ground-based solar observatories to measure the solar surface that Parker was magnetically connected to while Parker simultaneously measured the near-Sun environment at the closest distance to the Sun recorded to date (27.8 R_S). Additionally, near-Earth missions (e.g., ACE, ARTEMIS, and MMS) could then measure this solar wind once it reached 1 au to study the evolution of solar wind structures as they propagate radially outward from the Sun. Probes within the magnetosphere of Earth, and observatories focused on the ionosphere, could then study how these structures affect the near-Earth environment. To take advantage of this great opportunity for large-scale coordinated science, the Parker Project Science team and the Whole Heliosphere and Planetary Interactions (WHPI) group organized a campaign that has brought together observatories and missions from across the world. This page is meant to contain information and links relevant to the Parker Solar Probe Encounter 4 campaign. For more information, please contact Robert C. Allen (Robert.Allen@jhuapl.edu), the Parker Project Science team coordinator for this effort.

Contributing Missions and Observatories

In all, 50 missions and observatories took part in this campaign. The table below provides information on the number of missions/observatories by type. A full list of missions and observatories involved can be found here.

Footpoint Predictions

To facilitate targeted measurements from the solar observatories, predictions of the Parker footpoints were generated daily and provided via the WHPI website by the Parker modeling team (leads: Pete Riley and Sam Badman). Consensus predictions were generated using several PFSS models and MHD simulations.

Conjunction with In Situ Observations

In addition to magnetic footpoint mapping for solar observers, ballistic mappings were performed to estimate when solar wind observed at Parker may reach 1 au at either STEREO-A or near-Earth observers. This shows that the footpoints of STEREO-A and Parker may have been near each other from Jan 26^th, 2020 to Jan 28^th, 2020 (where the red lines cross the black horizontal line at 0), while the footpoints of Earth and Parker may have been close from Jan 29^th, 2020 until Jan 31^st, 2020 (where the blue lines cross the zero-line).

Encounter 4 Coordination Planning Presentations

• Planning Telecon from Dec 20^th, 2019
• Planning Telecon from Jan 10^th, 2020
• Planning Telecon from Jan 24^th, 2020

Ongoing Efforts

Sessions have been proposed related to Encounter 4 activities and subsequent observations for the upcoming 2020 SHINE meeting and the joint GEM/SHINE day this summer. Additionally, this encounter were discussed at the upcoming WHPI workshop on September 14 – 18, 2020.

Links to Websites Related to Encounter 4

See the WHPI website for Encounter 4

See ENLIL predictions from Helioweather for Encounter 4

Encounter 5

The fifth encounter of Parker Solar Probe provides measurements of the inner heliosphere down to 0.13 au (27.8 R_S), the same distance as Encounter 4. The orbit configuration of Parker and Earth allowed footpoint observations at the limb starting near the time of the Parker perihelion.

Ballistic Propagation

Ballistic propagation predictions, provided by Sam Badman, give an early prediction of when the Parker footpoint may cross into view from Earth. Below is a movie showing the (left) helioprojective viewpoint and (right) Carrington coordinates of Parker during encounter 5. The orange dashed line represents the limb from the point of view of Earth. Ballistic footpoints for solar wind speeds of 200 (blue), 400 (orange), and 600 (red) km/s speeds are shown in both plots (unless they are not visible from Earth in the left panel). The Carrington meridian is shown with the blue curve in the left panel and is dashed when on the opposite side of the Sun as Earth. These estimates predict that the ballistic footpoint of Parker crossed over the East limb on June 7th (0600 UTC for 200 km/s, 1200 UTC for 400 km/s, and 1800 UTC for 600 km/s). This is remarkably close to the perihelion (June 7th, 0800 UTC).

Using data from the movie above, the panels in the image below show the course of predicted Parker footpoint locations during Encounter 5. The blue circles in the left panel mark, with the dates labeled, when the Parker footpoints are in view of the Earth for a solar wind speed of 400 km/s. This is shown in the helioprojective frame. The predicted footpoints in the right panel are shown in Carrington coordinates over the full encounter. For this solar wind speed, these ballistic estimates predict that the Parker footpoints was visible from the Earth by June 8th. Please note that these ballistic footpoints just show the orbital position of Parker mapped down to solar surface using a Parker Spiral to correct the longitude and includes no modeling of the corona. Therefore these do not indicate probable sources on the photosphere but do give a good idea of when the footpoints are on disk and approximately which solar meridian they were on.

Consensus footpoint predictions

Most recent consensus predictions (CSV table of coordinates):

Update 2020/06/19: This is the last modeling update for E5. Today Parker is at 86 R_S and heading back out for its next Venus flyby. Parker's footpoints are now moving slowly and drifting towards the West Limb. Parker has remained close to the HCS and will continue to do so, connecting to the boundaries of polar coronal holes. In this update, HMI and some GONG realizations suggest that there may have been some southern polar coronal hole connectivity in the last week and for the next couple of days. However, the consensus for the coming week is northern polar coronal hole connectivity. GONG maps predict a HCS crossing back to the southern polar coronal hole on June 23rd. We suggested last week that Parker might be in the vicinity of AR 12764, but, since then, this AR has diffused in EUV and is no longer showing a strong impact on the coronal magnetic field. We also note that right now the predictions towards the end of the month connect to low latitude regions which do not appear to correspond to a physical coronal hole, and therefore we suggest to only trust the footpoints given here through June 26th.

Venus Flyby 3

Parker flew behind Venus on her third Venus flyby on 2020 July 11th, lowering the perihelion to 20.3 R_S for Encounter 6.

Encounter 6

The sixth encounter of Parker Solar Probe provide the first observations down to 0.09 au (20.3 R_S).

Ballistic Propagation

Ballistic propagation predictions, provided by Sam Badman, show that the majority of Parker’s footpoints during encounter map to the opposite side of the Sun at Earth. Below is a movie showing the (left) helioprojective viewpoint and (right) Carrington coordinates of Parker during encounter 6. The orange dashed line represents the limb from the point of view of Earth. Ballistic footpoints for solar wind speeds of 200 (blue), 400 (orange), and 600 (red) km/s speeds are shown in both plots (unless they are not visible from Earth in the left panel). The Carrington meridian is shown with the blue curve in the left panel and is dashed when on the opposite side of the Sun as Earth. These estimates predict that the ballistic footpoint of Parker will pass behind the West limb on September 25th. The footpoints of Parker are then expected to reemerge on the East limb between October 2nd and 4th.

Using data from the movie above, the panels in the image below show the course of predicted Parker footpoint locations during Encounter 6. The blue circles in the left panel mark, with the dates labeled, when the Parker footpoints are in view of the Earth for a solar wind speed of 400 km/s. This is shown in the helioprojective frame. The predicted footpoints in the right panel are shown in Carrington coordinates over the full encounter. For this solar wind speed, these ballistic estimates predict that the Parker footpoints will be visible from the Earth until September 25th, when they will pass behind the Sun until reemerging around October 4th. Please note that these ballistic footpoints just show the orbital position of Parker mapped down to solar surface using a Parker Spiral to correct the longitude and includes no modeling of the corona. Therefore, these do not indicate probable sources on the photosphere but do give a good idea of when the footpoints are on disk and approximately which solar meridian they will lie on.

Below is an ecliptic view of the trajectory sitting in the frame rotating with the Earth with several Parker spirals drawn (assuming 400 km/s solar wind).

Due to the majority of the encounter occurring on the far side of the Sun, the Parker modeling team will not be providing consensus mappings for this encounter. Instead we advise observers to target interesting West limb sources in the few days up to September 25th and target East limb sources starting on October 3rd.

Encounter 7

The seventh encounter of Parker Solar Probe provides observations down to 0.09 au (20.3 R_S). Because of the favorable alignment between Parker and Earth, the Parker mission has teamed with the Whole Heliosphere and Planetary Interactions (WHPI) group to orgnanize another multi-observatory campaign similar to the fourth encounter of Parker. From 2021 January 10 - 20, Parker footpoint predictions will be issued on a daily basis to the community. For more information, please contact Robert C. Allen (Robert.Allen@jhuapl.edu), the Parker Project Science team coordinator for this effort.

Ballistic Propagation

Ballistic propagation predictions, courtesy of Sam Badman, estimate that the footpoints of Parker will be connected to the Earth-facing side of the Sun for more than half of the orbit spanning from aphelion (2020 November 22) through perihelion (2021 January 17) until about 2021 January 19. The movie below shows the ballistic predictions for three different solar wind velocities during orbit 7.

Using a nominal 400 km/s solar wind velocity, the following figures show the ballistic mapping in a helioprojective and heliographic frame, followed by an ecliptic view of the trajectory in the frame rotating with the Earth. Several Parker spirals are drawn, showing the possible magnetic connection to the Earth near the orbit 7 perihelion.

Additional information regarding the encounter 7 coordination and footpoint predictions can be found on the WHPI website.

Encounter 8

The eighth encounter of Parker Solar Probe provides observations down to 0.074 au (15.9 R_S). The Parker mission has again teamed with the Whole Heliosphere and Planetary Interactions (WHPI) group to orgnanize a short multi-observatory campaign. From 2021 April 28 - May 7, Parker footpoint predictions will be issued on a weekly basis to the community. For more information, please contact Robert C. Allen (Robert.Allen@jhuapl.edu), the Parker Project Science team coordinator for this effort.

Ballistic Propagation

Ballistic propagation predictions, courtesy of Sam Badman, estimate that the footpoints of Parker will be connected to the Earth-facing side of the Sun for more than half of the orbit spanning from near perihelion (2021 April 29) until about 2021 May 7. The movie below shows the ballistic predictions for three different solar wind velocities during orbit 8.

Using a nominal 400 km/s solar wind velocity, the following figures show the ballistic mapping in a helioprojective and heliographic frame, followed by an ecliptic view of the trajectory in the frame rotating with the Earth. Several Parker spirals are drawn, showing the possible magnetic connection to the Earth near May 9th.

Additional information regarding the encounter 8 coordination and footpoint predictions can be found on the WHPI website.

Encounter 9

The ninth encounter of Parker Solar Probe provides observations down to 0.074 au (15.9 R_S). Due to the majority of the encounter having footpoints on the far side of the Sun, there was no footpoint prediction campaign for this encounter.

Encounter 10

The tenth encounter of Parker Solar Probe provides observations down to 0.062 au (13.3 R_S). Due to the orbital configuraton for this Encounter, two sets of footpoint predictions will be issued prior to perihelion on 2021 November 8 and 2021 November 15. For more information, please contact Robert C. Allen (Robert.Allen@jhuapl.edu), the Parker Project Science team coordinator for this effort.

Ballistic Propagation

Ballistic propagation predictions, courtesy of Sam Badman, estimate that the footpoints of Parker will be connected near the disk center early in the Enounter, before quickly moving off the West limb through perihelion (passing the terminator near perihelion). We can therefore expect to be connected to limb sources and be in quadrature with Earth at perihelion at ~13 Solar radii. The movie below shows the ballistic predictions for three different solar wind velocities during orbit 10.

Using a nominal 400 km/s solar wind velocity, the following figures show the ballistic mapping in a helioprojective and heliographic frame, followed by an ecliptic view of the trajectory in the frame rotating with the Earth. Several Parker spirals are drawn, showing the possible magnetic connection to the Earth near November 20th.

Encounter 11

The eleventh encounter of Parker Solar Probe provides observations down to 0.062 au (13.3 R_S). Since the footpoints of Parker will be visible from Earth when it is near perihelion, the Parker team has again partnered with the Whole Heliosphere and Planetary Interactions (WHPI) group to coordinate remote observing during this encounter. The first footpoint prediction will be issued on February 18th followed by daily updates form February 21st through 28th, 2022. For more information, please contact Robert C. Allen (Robert.Allen@jhuapl.edu), the Parker Project Science team coordinator for this effort and visit the WHPI page for this campaign.

Ballistic Propagation

Ballistic propagation predictions, courtesy of Sam Badman, estimate that the footpoints of Parker will be at the East limb on June 2nd. The movie below shows the ballistic predictions for three different solar wind velocities during orbit 12.

Using a nominal 400 km/s solar wind velocity, the following figures show the ballistic mapping in a helioprojective and heliographic frame, followed by an ecliptic view of the trajectory in the frame rotating with the Earth.

Encounter 12

The twelfth encounter of Parker Solar Probe provides observations down to 0.062 au (13.3 R_S). Due to the limited viewing geometry from Earth, the Parker team will only have a limited footpoint prediction campign for this encounter. Footpoint predictions will be published on May 30th, June 1st, June 3rd, and a final prediction on June 13th. For more information, please contact Robert C. Allen (Robert.Allen@jhuapl.edu) to be added to the Parker footpoint campaign email list.

Ballistic Propagation

Ballistic propagation predictions, courtesy of Sam Badman, estimate that the footpoints of Parker will be at the East limb on June 2nd. The movie below shows the ballistic predictions for three different solar wind velocities during orbit 12.

Using a nominal 400 km/s solar wind velocity, the following figures show the ballistic mapping in a helioprojective and heliographic frame, followed by an ecliptic view of the trajectory in the frame rotating with the Earth.

Encounter 13

The thirteenth encounter of Parker Solar Probe provides observations down to 0.062 au (13.3 R_S). Due to the limited viewing geometry from Earth, the Parker team will only have a limited footpoint prediction campign for this encounter. Footpoint predictions will be published on August 29th and September 7th. For more information, please contact Robert C. Allen (Robert.Allen@jhuapl.edu) to be added to the Parker footpoint campaign email list.

Ballistic Propagation

Ballistic propagation predictions, courtesy of Sam Badman. The movie below shows the ballistic predictions for three different solar wind velocities during orbit 13.

Using a nominal 400 km/s solar wind velocity, the following figures show the ballistic mapping in a helioprojective and heliographic frame, followed by an ecliptic view of the trajectory in the frame rotating with the Earth.

Encounter 14

The fourteenth encounter of Parker Solar Probe provides observations down to 0.062 au (13.3 R_S). Footpoint predictions for this campaign were issued on December 2nd and December 9th. For more information, please contact Robert C. Allen (Robert.Allen@jhuapl.edu) to be added to the Parker footpoint campaign email list.

Ballistic Propagation

Ballistic propagation predictions, courtesy of Sam Badman. The movie below shows the ballistic predictions for three different solar wind velocities during orbit 14.

Using a nominal 400 km/s solar wind velocity, the following figures show the ballistic mapping in a helioprojective and heliographic frame, followed by an ecliptic view of the trajectory in the frame rotating with the Earth.

Encounter 15

The fifteenth encounter of Parker Solar Probe provides observations down to 0.062 au (13.3 R_S). An initial footpoint prediction for this encounter was issued on March 13th 2023 with daily predictions released from March 16th through March 21st 2023. This campaign has been archived on the Encounter 15 WHPI website. For more information, please contact Robert C. Allen (Robert.Allen@jhuapl.edu) to be added to the Parker footpoint campaign email list.

Ballistic Propagation

Ballistic propagation predictions, courtesy of Sam Badman. The movie below shows the ballistic predictions for three different solar wind velocities during orbit 15.

Using a nominal 400 km/s solar wind velocity, the following figures show the ballistic mapping in a helioprojective and heliographic frame, followed by an ecliptic view of the trajectory in the frame rotating with the Earth.

Encounter 16

The sixteenth encounter of Parker Solar Probe provides observations down to 0.062 au (13.3 R_S). Due to the limited viewing geometry from Earth for this perihelion, footpoint predictions will only be issued on June 21st, 2023. For more information, please contact Robert C. Allen (Robert.Allen@jhuapl.edu) to be added to the Parker footpoint campaign email list.

Ballistic Propagation

Ballistic propagation predictions, courtesy of Sam Badman. The movie below shows the ballistic predictions for three different solar wind velocities during orbit 16.

Using a nominal 400 km/s solar wind velocity, the following figures show the ballistic mapping in a helioprojective and heliographic frame, followed by an ecliptic view of the trajectory in the frame rotating with the Earth.

Encounter 17

The seventeenth encounter of Parker Solar Probe provides observations down to 0.053 au (11.4 R_S) for the first time. Due to the limited viewing geometry from Earth for this perihelion, footpoint predictions will only be issued on 2023 September 25th, 26th, and 30th and October 2nd. For more information, please contact Robert C. Allen (Robert.Allen@jhuapl.edu) to be added to the Parker footpoint campaign email list.

Ballistic Propagation

Ballistic propagation predictions, courtesy of Sam Badman. The movie below shows the ballistic predictions for three different solar wind velocities during orbit 17.

Using a nominal 400 km/s solar wind velocity, the following figures show the ballistic mapping in a helioprojective and heliographic frame, followed by an ecliptic view of the trajectory in the frame rotating with the Earth.