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. For information on coordinating with PSP for an encounter, please contact Robert C. Allen (Robert.Allen@jhuapl.edu).

 

Event

Time (UT)

Distance from Center of Sun

Venus Flyby 1

Closest Approach: 2018-10-03/08:44

0.7 au

Encounter 1

Perihelion: 2018-11-06/03:27

0.17 au (35.6 RS)

Encounter 2

Perihelion: 2019-04-04/22:39

0.17 au (35.6 RS)

Encounter 3

Perihelion: 2019-09-01/17:50

0.17 au (35.6 RS)

Venus Flyby 2

Closest Approach: 2019-12-26/18:14

0.7 au

Encounter 4

Perihelion: 2020-01-29/09:37

0.13 au (27.8 RS)

Encounter 5

Perihelion: 2020-06-07/08:23

0.13 au (27.8 RS)

Venus Flyby 3

Closest Approach: 2020-07-11

0.7 au

Encounter 6

Perihelion: 2020-09-27/09:16

0.09 au (20.3 RS)

 

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 RS), 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.

PSP Orbit for Encounter 1

 

Encounter 2

 

The second Parker Solar Probe encounter also reached a solar distance of 0.17 au (35.6 RS) 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.

PSP Encounter Orbit 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 RS), complementing those from the first two encounters.

 

See ENLIL predictions from Helioweather for Encounter 3.

PSP Encounter Orbit 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 RS for Encounter 4.

 

Encounter 4

 

The orbit of Parker Solar Probe (PSP) during the 4th 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 PSP was magnetically connected to while PSP simultaneously measured the near-Sun environment at the closest distance to the Sun recorded to date (27.8 RS). 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 PSP 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 PSP 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.

Observatory/mission type

Number contributing to encounter 4

Ground-based optical observatories

22

Ground-based radio observatories

13

Space-based missions

9

Ground-based geospace observatories

6

 

Footpoint Predictions

 

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

Heliographic Carrington footpoints of PSP

Heliographic Carrington footpoints of PSP on the day of Perihelion 4: one footpoint per day plotted in Carrington coordinates (latitude-longitude) and with error bars in latitude and longitude for ensemble predictions. Also shown in this plot is the most recent GONG-ADAPT current sheet generated by the UCB model (red), and the date-stamped PSP trajectory in Carrington coordinates (grey) (Courtesy of Sam Badman; SDO/AIA 193A synoptic map produced by David Stansby).

Helioprojective PSP predicted footpoints on the day of Perihelion 4: one footpoint per day plotted on the solar disk. Colored dots show predictions from a range of models (Courtesy of Sam Badman).

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 PSP may reach 1 au at either STEREO-A or near-Earth observers. This shows that the footpoints of STEREO-A and PSP may have been near each other from Jan 26th, 2020 to Jan 28th, 2020 (where the red lines cross the black horizontal line at 0), while the footpoints of Earth and PSP may have been close from Jan 29th, 2020 until Jan 31st, 2020 (where the blue lines cross the zero-line).

Difference in the Carrington longitude

 

Difference in the Carrington longitude of footpoints between PSP and Earth (blue) and between PSP and STEREO-A (red) for different solar wind velocities from a ballistic propagation (Courtesy of Sam Badman).

 

Movie showing the footpoint locations from ballistic mapping of PSP (yellow), STEREO-A (red), and Earth (blue) for 300 and 600 km/s solar wind during encounter 4 (Courtesy of Sam Badman; SDO/AIA 193A synoptic map produced by David Stansby).

Encounter 4 Coordination Planning Presentations

 

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 will be 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 RS), the same distance as Encounter 4. The orbit configuration of PSP and Earth will allow for footpoint observations at the limb starting near the time of the PSP perihelion.

 

PSP Encounter Orbit 5

 

Ballistic Propagation

 

Ballistic propagation predictions, provided by Sam Badman, give an early prediction of when the PSP footpoint may cross into view from Earth. Below is a movie showing the (left) helioprojective viewpoint and (right) Carrington coordinates of PSP 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 PSP will cross 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 PSP footpoint locations during Encounter 5. The blue circles in the left panel mark, with the dates labeled, when the PSP 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 PSP footpoints will be visible from the Earth by June 8th. Please note that these ballistic footpoints just show the orbital position of PSP 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.

 

PSP Orbit for Encounter 5

 

Consensus footpoint predictions

 

Most recent consensus predictions (CSV table of coordinates):

Update 2020/06/19: This is the last modeling update for E5. Today PSP is at 86 RS and heading back out for its next Venus flyby. PSP's footpoints are now moving slowly and drifting towards the West Limb. PSP 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 PSP 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.

 

Heliographic Carrington footpoints of PSP

Heliographic Carrington footpoints of PSP for most recent prediction: one footpoint per day plotted in Carrington coordinates (latitude-longitude) and with error bars in latitude and longitude for ensemble predictions. The diamonds with white date labels and squares with grey labels show ADAPT HMI and ADAPT GONG predictions, respectively. The smaller colored dots show the underlying ensemble. Also shown in this plot is the most recent GONG-ADAPT current sheet generated by the UCB model (red), and the date-stamped PSP trajectory in Carrington coordinates (grey) (Courtesy of Sam Badman; SDO/AIA 193A synoptic map produced by David Stansby).

Helioprojective footpoints of PSP

Helioprojective PSP predicted footpoints for most recent prediction: one footpoint per day plotted on the solar disk. Colored dots show predictions from a range of models (Courtesy of Sam Badman).

 

Venus Flyby 3

 

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

 

Encounter 6

 

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

 

PSP Encounter Orbit 6

 

Ballistic Propagation

 

Ballistic propagation predictions, provided by Sam Badman, show that the majority of PSP’s footpoints during encounter will map to the opposite side of the Sun at Earth. Below is a movie showing the (left) helioprojective viewpoint and (right) Carrington coordinates of PSP 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 PSP will pass behind the West limb on September 25th. The footpoints of PSP 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 PSP footpoint locations during Encounter 6. The blue circles in the left panel mark, with the dates labeled, when the PSP 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 PSP 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 PSP 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.

 

PSP Footpoints for Encounter 6

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).

 

PSP Footpoints for Encounter 6

Due to the majority of the encounter occurring on the far side of the Sun, the PSP 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.

 



Page Last Modified: September 18, 2020