Parker Solar Probe

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Parker Solar Probe
Digital model of a spacecraft with a bus attached to a larger Sun-shield. Two small solar panels are attached to the side of the bus, along with four rear-facing antennas.
Artist's impression of Parker Solar Probe
Names Solar Probe (–2002)
Solar Probe Plus (2010–17)
Mission type Solar heliophysics orbiter
Operator NASA · Applied Physics Laboratory
Mission duration 6 years, 321 days (planned)
Spacecraft properties
Manufacturer Applied Physics Laboratory
Launch mass 610 kg (1,340 lb)
Dry mass 555 kg (1,224 lb)
Payload mass 50 kg (110 lb)
Dimensions 1.0 m × 3.0 m × 2.3 m (3.3 ft × 9.8 ft × 7.5 ft)
Power 343 W (at closest approach)
Start of mission
Launch date July 31–August 19, 2018 (planned)[1]
Rocket Delta IV Heavy / Star-48BV[2]
Launch site Cape Canaveral SLC-37
Orbital parameters
Reference system Heliocentric
Perihelion 6.0 million km; 0.040 AU (3.7 million mi)
Apohelion 109.3 million km; 0.730 AU (67.9 million mi)
Inclination 3.4°
Period 88 days
Band Ka band
X band
Artwork of the spacecraft next to the Sun, enclosed in a circle with a yellow border. The words "Parker Solar Probe" are placed around the interior of the border, while the words "a mission to touch the Sun" are written inline in a smaller font in the bottom right of the image.
Official insignia for the Parker Solar Probe mission

Parker Solar Probe (previously Solar Probe, Solar Probe Plus, or Solar Probe+) is a planned NASA robotic spacecraft to probe the outer corona of the Sun.[4][5] It will approach to within 8.5 solar radii (5.9 million kilometers or 3.67 million miles) to the 'surface' (photosphere) of the Sun.[6] The project was announced as a new mission start in the fiscal 2009 budget year. On May 1, 2008 Johns Hopkins University Applied Physics Laboratory announced it will design and build the spacecraft, on a schedule to launch it in 2015.[7] The launch date has since been pushed back to 2018.[8] A Delta IV Heavy launch vehicle will enable the mission to become the fastest spacecraft to date.[2][9][10] On May 31, 2017 the probe was renamed after solar astrophysicist Eugene Parker.[4][11] This was the first time a NASA spacecraft was named after a living person.[12]


The Parker Solar Probe originates from a predecessor Solar Orbiter project conceived in the 1990s. Similar in design and objectives, the Solar Probe mission served as one of the centerpieces of the eponymous Outer Planet/Solar Probe (OPSP) program formulated by NASA. The first three missions of the program were planned to be the Solar Orbiter, the Pluto and Kuiper Belt reconnaissance mission Pluto Kuiper Express, and the Europa Orbiter astrobiology mission focused on Europa.[13][14] Following the appointment of Sean O'Keefe as Administrator of NASA, the entirety of the OPSP program was cancelled as part of President George W. Bush's request for the 2003 United States federal budget.[15] Administrator O'Keefe cited a need for a restructuring of NASA and its projects, falling in line with the Bush Administration's wish for NASA to refocus on "research and development, and addressing management shortcomings."[15]

The cancellation of the program also resulted in the initial cancellation of New Horizons, the mission that won the competition to replace Pluto Kuiper Express in the former OPSP program.[16] That mission, which would eventually be launched as the first mission of the New Frontiers program, a spiritual successor to the OPSP program, would undergo a lengthy political battle to secure funding for its launch, which occurred in 2006.[17] Plans for the Solar Probe mission would later manifest as the Solar Probe Plus in the early 2010s.[18]

Mission and trajectory[edit]

Apparent size of the Sun as seen from the orbit of the Parker Solar Probe compared to its apparent size seen from Earth.

The Parker Solar Probe mission design uses repeated gravity assists at Venus to incrementally decrease the orbital perihelion to achieve multiple passes of the Sun at approximately 8.5 solar radii, or about 6 million km (3.7 million mi; 0.040 AU).[19]

The spacecraft is designed to endure the harsh environment near the Sun, where the incident solar intensity is approximately 520 times the intensity at Earth orbit, by the use of a solar shadow-shield. The solar shield, at the front of the spacecraft, is made of reinforced carbon-carbon composite. The spacecraft systems and scientific instruments are located in the central portion of the shield's shadow, where direct radiation from the Sun is fully blocked. The primary power for the mission will be a dual system of solar panels (photovoltaic array). A primary photovoltaic array, used for the portion of the mission outside 0.25 AU, is retracted behind the shadow shield during the close approach to the Sun, and a much smaller secondary array powers the spacecraft through closest approach. This secondary array uses pumped-fluid cooling to maintain operating temperature.[20]

As the probe passes around the Sun, it will achieve a velocity of up to 200 km/s (120 mi/s) making it by any measure, the fastest manmade object ever, almost three times as fast as the current record holder, Helios-B.[21][22][23]

Scientific goals[edit]

  • Determine the structure and dynamics of the magnetic fields at the sources of solar wind.
  • Trace the flow of energy that heats the corona and accelerates the solar wind.
  • Determine what mechanisms accelerate and transport energetic particles.
  • Explore dusty plasma near the Sun and its influence on solar wind and energetic particle formation.


Year Events
2018 Jul 31
Sep 28
First flyby of Venus
(150 days)
Nov 1
Perihelion #1
2019 Mar 31
Perihelion #2
Aug 28
Perihelion #3
Dec 21
2nd flyby of Venus
(130 days)
2020 Jan 24
Perihelion #4
Jun 2
Perihelion #5
Jul 6
3rd flyby of Venus
(112.5 days)
Sep 22
Perihelion #6
2021 Jan 13
Perihelion #7
Feb 16
4th flyby of Venus
(102 days)
Apr 24
Perihelion #8
Aug 5
Perihelion #9
Oct 11
5th flyby of Venus
(96 days)
Nov 16
Perihelion #10
2022 Feb 21
Perihelion #11
May 28
Perihelion #12
Sep 1
Perihelion #13
Dec 6
Perihelion #14
2023 Mar 13
Perihelion #15
Jun 17
Perihelion #16
Aug 16
6th flyby of Venus
(92 days)
Sep 23
Perihelion #17
Dec 24
Perihelion #18
2024 Mar 25
Perihelion #19
Jun 25
Perihelion #20
Sep 25
Perihelion #21
Nov 2
7th flyby of Venus
(88 days)
Dec 19
Perihelion #22
1st close approach to Sun
2025 Mar 18
Perihelion #23
Jun 14
Perihelion #24
Perihelion #25
Perihelion #26

After the first Venus fly-by, the probe will be in an elliptical orbit with a period of 150 days (two-thirds the period of Venus), making three orbits while Venus makes two. On the second fly-by, the period shortens to 130 days. After less than two orbits (only 198 days later) it encounters Venus a third time at a point earlier in the orbit of Venus. This encounter shortens its period to half of that of Venus, or about 112.5 days. After two orbits it meets Venus a fourth time at about the same place, shortening its period to about 102 days. After 237 days it meets Venus for the fifth time and its period is shortened to about 96 days, three-sevenths that of Venus. It then makes seven orbits while Venus makes three. The sixth encounter, almost two years after the fifth, brings its period down to 92 days, two-fifths that of Venus. After five more orbits (two orbits of Venus) it meets Venus for the seventh and last time, decreasing its period to 88 or 89 days and allowing it to approach close to the Sun.[24]

See also[edit]


  1. ^ "Parker Solar Probe". NASA. Retrieved June 13, 2017. 
  2. ^ a b Clark, Stephen (March 18, 2015). "Delta 4-Heavy selected for launch of solar probe". Spaceflight Now. Retrieved March 18, 2015. 
  3. ^ "Parker Solar Probe Science Gateway | Parker Solar Probe Science Gateway". Retrieved 9 October 2017. 
  4. ^ a b Chang, Kenneth (May 31, 2017). "Newly Named NASA Spacecraft Will Aim Straight for the Sun". New York Times. Retrieved June 1, 2017. 
  5. ^ Applied Physics Laboratory (November 19, 2008). "Feasible Mission Designs for Solar Probe Plus to Launch in 2015, 2016, 2017, or 2018" (PDF). Johns Hopkins University. Archived from the original (.PDF) on April 18, 2016. Retrieved February 27, 2010. 
  6. ^ Tony Phillips (2010-06-10). "NASA Plans to Visit the Sun". NASA. Retrieved 2017-06-02. 
  7. ^ M. Buckley (2008-05-01). "NASA Calls on APL to Send a Probe to the Sun". Johns Hopkins University Applied Physics Laboratory. Retrieved 30 September 2010. 
  8. ^ M. Buckley (2012-03-05). "NASA Solar Study Mission Moves to Next Design Stage". Johns Hopkins University Applied Physics Laboratory. Retrieved 12 March 2012. 
  9. ^ Scharf, Caleb A. "The Fastest Spacecraft Ever?". Scientific American Blog Network. 
  10. ^ Bruno, Tory (21 July 2017). "PSP launch vehicle tweet". @torybruno. 
  11. ^ N. Davis (2017-05-31). "Nasa's hotly anticipated solar mission renamed to honour astrophysicist Eugene Parker". The Guardian. Retrieved 31 May 2017. 
  12. ^ "NASA Renames Solar Probe Mission to Honor Pioneering Physicist Eugene Parker". NASA. 31 May 2017. Retrieved 31 May 2017. 
  13. ^ "Mcnamee Chosen to Head NASA's Outer Planets/Solar Probe Projects". Jet Propulsion Laboratory. National Aeronautics and Space Administration (NASA). April 15, 1998. Archived from the original on January 2, 2017. Retrieved January 2, 2017. 
  14. ^ Maddock, R.W.; Clark, K.B.; Henry, C.A.; Hoffman, P.J. (March 7, 1999). "The Outer Planets/Solar Probe Project: "Between an ocean, a rock, and a hot place"". IEEE Xplore. Institute of Electrical and Electronics Engineers · Institution of Engineering and Technology. Archived from the original on January 2, 2017. Retrieved January 2, 2017. 
  15. ^ a b Berger, Brian (February 4, 2002). "NASA Kills Europa Orbiter; Revamps Planetary Exploration". Purch Group. Archived from the original on February 10, 2002. Retrieved January 2, 2017. 
  16. ^ Savage, Donald (November 29, 2001). "NASA Selects Pluto-Kuiper Belt Mission Phase B Study". National Aeronautics and Space Administration (NASA). Archived from the original on July 8, 2015. Retrieved July 9, 2015. 
  17. ^ Hand, Eric (June 25, 2015). "Feature: How Alan Stern's tenacity, drive, and command got a NASA spacecraft to Pluto". Science (journal). American Association for the Advancement of Science. Archived from the original on June 26, 2015. Retrieved July 8, 2015. 
  18. ^ Fazekas, Andrew (September 10, 2010). "New NASA Probe to Dive-bomb the Sun". National Geographic. 21st Century Fox / National Geographic Society. Archived from the original on January 2, 2017. Retrieved January 2, 2017. 
  19. ^ "Solar Probe Plus: A NASA Mission to Touch the Sun:". Johns Hopkins University Applied Physics Laboratory. 4 September 2010. Retrieved 30 September 2010. 
  20. ^ G.A. Landis, P. C. Schmitz, J. Kinnison, M. Fraeman, L. Fourbert, S. Vernon and M. Wirzburger, "Solar Power System Design for the Solar Probe+ Mission," AIAA Paper-2008-5712, International Energy Conversion Engineering Conference, Cleveland OH, 28–30 July 2008.
  21. ^ "Aircraft Speed Records". 13 November 2014. 
  22. ^ "Fastest spacecraft speed". 26 July 2015. Archived from the original on 2016-12-19. 
  23. ^ Parker Solar Probe - Check123, Video Encyclopedia, retrieved 2017-06-01 
  24. ^ See data and figure at "Solar Probe Plus: The Mission". Johns Hopkins University Applied Physics Laboratory. 2017. 

External links[edit]