Parker Solar Probe

This article is about the NASA in-situ heliophysics orbiter. For the European Space Agency in-situ heliophysics orbiter, see Solar Orbiter.

Parker Solar Probe

Parker Solar Probe artist rendering
Names	Solar Probe (before 2002) Solar Probe Plus (2010–17) Parker Solar Probe (since 2017)
Mission type	Heliophysics
Operator	NASA · Applied Physics Laboratory
COSPAR ID	2018-065A
SATCAT no.	43592
Website	solarprobe.jhuapl.edu
Mission duration	Planned: 6 years, 321 days
Spacecraft properties
Manufacturer	Applied Physics Laboratory
Launch mass	685 kg (1,510 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	Planned August 12 07:31 UTC, 2018
Rocket	Delta IV Heavy / Star-48BV
Launch site	Cape Canaveral SLC-37
Orbital parameters
Reference system	Heliocentric
Perihelion altitude	0.040 AU (6.0 million km; 3.7 million mi)
Aphelion altitude	0.730 AU (109.3 million km; 67.9 million mi)
Inclination	3.4°
Period	88 days
Transponders
Band	Ka band X band
Instruments SWEAP Solar Wind Electrons Alphas and Protons Investigation SPC Solar Probe Cup SPAN Solar Probe Analyzers WISPR Wide-field Imager for Solar Probe FIELDS Electromagnetic Fields Investigation IS☉IS‒EPI Integrated Science Investigation of the Sun Energetic Particle Instruments
Official insignia for the Parker Solar Probe mission

Parker Solar Probe (previously Solar Probe, Solar Probe Plus, or Solar Probe+, abbreviated PSP) is a planned NASA robotic spacecraft to probe the outer corona of the Sun. It will approach to within 8.86 solar radii (6.2 million kilometers or 3.85 million miles) from the "surface" (photosphere) of the Sun and will travel, at closest approach, as much as 700,000 km/h (430,000 mph).

The project was announced in the fiscal 2009 budget year. Johns Hopkins University Applied Physics Laboratory designed and built the spacecraft, which was originally scheduled to launch in 2015. The launch date was then rescheduled to the summer of 2018. This was the first time a NASA spacecraft was named after a living person, honoring physicist Eugene Parker.

A memory card containing the names of over 1.1 million people was mounted on a plaque and installed below spacecraft’s high-gain antenna on May 18, 2018. The card also contained photos of Parker, professor emeritus at the University of Chicago, and a copy of his 1958 scientific paper.

History

Light bar testing in the Astrotech processing facility

The Parker Solar Probe concept 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. 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. 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."

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

In May 2017, the spacecraft was renamed Parker Solar Probe in honor of astrophysicist Eugene Parker.

Overview

NASA's Parker Solar Probe receives intense environmental testing

The Parker Solar Probe will be the first spacecraft to fly into the low solar corona. It will determine the structure and dynamics of the Sun's coronal magnetic field, understand how the solar corona and wind are heated and accelerated, and determine what processes accelerate energetic particles. The Parker Solar Probe mission design uses repeated gravity assists at Venus to incrementally decrease its 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).

The spacecraft's systems are designed to endure the extreme radiation and heat 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 is 11.4 cm (4.5 in) thick and is made of reinforced carbon–carbon composite, which is designed to withstand temperatures outside the spacecraft of about 1,377 °C (2,511 °F). The shield is hexagonal and is mounted at the Sun-facing side of the spacecraft. 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. If the shield is not between the spacecraft and the sun, the probe will become damaged and inoperative within tens of seconds. As radio communication with Earth will take about eight minutes, the Parker Solar Probe will have to act autonomously and rapidly to protect itself. According to project scientist Nicky Fox, the team describe it as "the most autonomous spacecraft that has ever flown".

The primary power for the mission is 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.

Trajectory

Animation of Parker Solar Probe's trajectory from August 7, 2018 to August 29, 2025
  Parker Solar Probe ·   Sun ·   Mercury ·   Venus ·   Earth

Velocity and distance from Sun of Parker Solar Probe

Plot of Voyager 2's heliocentric velocity against its distance from the Sun, illustrating the use of gravity assist to accelerate the spacecraft by Jupiter, Saturn and Uranus. Using the same technique but with Venus, Parker Solar Probe will decelerate to lower its orbit.

The spacecraft trajectory will include seven Venus flybys over nearly seven years to gradually shrink its elliptical orbit around the Sun, for a total of 24 orbits. The science phase will take place during those 7 years, focusing on the periods when the spacecraft is closest to the Sun. The near Sun radiation environment is predicted to cause spacecraft charging effects, radiation damage in materials and electronics, and communication interruptions, so the orbit will be highly elliptical with short times spent near the Sun.

The trajectory requires high launch energy, so the probe will be launched on a Delta IV Heavy class launch vehicle and an upper stage based on the STAR 48BV solid rocket motor. Interplanetary gravity assists will provide further deceleration relative to its heliocentric orbit, which may result in a heliocentric speed record at perihelion. As the probe passes around the Sun, it will achieve a velocity of up to 200 km/s (120 mi/s), which will temporarily make it the fastest manmade object, almost three times as fast as the current record holder, Helios-B. Like every object in an orbit, due to gravity the spacecraft will accelerate as it nears perihelion, then slow down again afterwards until it reaches its aphelion.

Scientific goals

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

The goals of the mission are:

• Trace the flow of energy that heats the corona and accelerates the solar wind.
• Determine the structure and dynamics of the magnetic fields at the sources of solar wind.
• Determine what mechanisms accelerate and transport energetic particles.

Investigations

In order to achieve these goals, the mission will perform five major experiments or investigations:

• Electromagnetic Fields Investigation (FIELDS) — This investigation will make direct measurements of electric and magnetic fields, radio waves, Poynting flux, absolute plasma density, and electron temperature. Its main instrument is a flux-gate magnetometer. The Principal investigator is Stuart Bale, at the University of California, Berkeley.
• Integrated Science Investigation of the Sun (ISIS)— This investigation will measure energetic electrons, protons and heavy ions. The instrument suite is composed of two independent instruments, EPI-Hi and EPI-Lo. The Principal investigator is David McComas, at the Princeton University.
• Wide-field Imager for Solar PRobe (WISPR)— These optical telescopes will acquire images of the corona and inner heliosphere. The Principal Investigator is Russell Howard, at the Naval Research Laboratory.
• Solar Wind Electrons Alphas and Protons (SWEAP)— This investigation will count the electrons, protons and helium ions, and measure their properties such as velocity, density, and temperature. Its main instruments are two electrostatic analyzers and a Faraday cup. The Principal Investigator is Justin Kasper at the University of Michigan and the Smithsonian Astrophysical Observatory.
• Heliospheric origins with Solar Probe Plus (HeliOSPP) is a theory and modeling investigation to maximize the scientific return from the mission. The Principal Investigator is Marco Velli at UCLA and the Jet Propulsion Laboratory (JPL)

Planned timeline

Perihelion means the point in the PSP's orbit closest to the Sun

Year	Events
	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
2018								NET Aug 12 Postponed launch			Nov 1 Perihelion #1
									Sep 28 First flyby of Venus (period 150 days)
2019			Mar 31 Perihelion #2					Aug 28 Perihelion #3				Dec 21 Second flyby of Venus (period 130 days)
2020	Jan 24 Perihelion #4					Jun 2 Perihelion #5			Sep 22 Perihelion #6
							Jul 6 Third flyby of Venus (period 112.5 days)
2021	Jan 13 Perihelion #7			Apr 24 Perihelion #8				Aug 5 Perihelion #9			Nov 16 Perihelion #10
		Feb 16 Fourth flyby of Venus (period 102 days)								Oct 11 Fifth flyby of Venus (period 96 days)
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			Sep 23 Perihelion #17			Dec 24 Perihelion #18
								Aug 16 Sixth flyby of Venus (period 92 days)
2024			Mar 25 Perihelion #19			Jun 25 Perihelion #20			Sep 25 Perihelion #21			Dec 19 Perihelion #22 First close approach to the Sun
											Nov 2 Seventh flyby of Venus (period 88 days)
2025			Mar 18 Perihelion #23			Jun 14 Perihelion #24			Sep 10 Perihelion #25			Dec 7 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.

Mission timeline

The original planned launch on 11 August, 2018 was missed after two delays resulted in the daily launch window expiring. The full window includes one opportunity per day from 11 August to 23 August 2018. The launch is currently planned for 12 August 2018.

See also

• Advanced Composition Explorer (ACE), launched 1997
• List of vehicle speed records
• MESSENGER, Mercury orbiter (2011-2015)

Sun observation spacecraft

• Helios, a pair of spacecraft launched in the 1970s to approach the Sun inside the orbit of Mercury, 63 R_☉
• Solar Orbiter, 45 R_☉
• STEREO, launched 2006
• WIND, launched 1994
• Ulysses, solar polar orbiter (1990-2009)

Spacecraft design

• Spacecraft thermal control
• Sunshield (JWST)

External links

• Parker Probe Plus at the Johns Hopkins Applied Physics Laboratory
• Solar Probe Plus Mission Engineering Study Report
• NASA – Heliophysics Research
• Explorers and Heliophysics Projects Division (EHPD)
• NASA, Parker Solar Probe data & news