Solar Probe Plus

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Solar Probe Plus
Digital model of a spacecraft with a hexagonal bus and large heat shield oriented to the surface of the sun
Artist’s impression of NASA’s Solar Probe Plus spacecraft on approach to the Sun
Names Solar Probe+
NASA Solar Probe
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
Dry mass 555 kg
Payload mass ~50 kg
Dimensions 1 m wide, 3 m tall, 2.3 m heat shield
Power 343 Watts at closest approach
Start of mission
Launch date July 31, 2018 (2018-07-31) (planned).[1]
Rocket Delta IV Heavy
Launch site Cape Canaveral SLC-37
Orbital parameters
Reference system Heliocentric
Perihelion 6.0 Gm (3,700,000 mi)
Apohelion 109.3 Gm (67,900,000 mi)
Inclination 3.4°
Period 88 days
Flyby of Venus
Closest approach September 27, 2018
Flyby of Venus
Closest approach December 21, 2019
Flyby of Venus
Closest approach July 5, 2020
Flyby of Venus
Closest approach February 15, 2021
Flyby of Venus
Closest approach October 10, 2021
Flyby of Venus
Closest approach August 15, 2023
Flyby of Venus
Closest approach October 31, 2024
Sun orbiter
Orbital insertion December 19, 2024 (first close approach)
Band Ka band
X band
SWEAP suite: Solar Wind Electrons Alphas and Protons Investigation
SPC: Solar Probe Cup
SPAN: Solar Probe Analyzers
WISPR: Wide-field Imager for Solar Probe
FIELDS suite: Electromagnetic Fields Investigation
Electric Field Antennas (4)
Fluxgate Magnetometers (2)
Search Coil Magnetometer
ISIS‒EPI suite: Integrated Science Investigation of the Sun Energetic Particle Instruments
I‒EPI‒Hi: ISIS Energetic Particle Instrument — High
I‒EPI‒Lo: ISIS Energetic Particle Instrument — Low

Solar Probe Plus or Solar Probe+, previously NASA Solar Probe, is a planned robotic spacecraft to probe the outer corona of the Sun. 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.[2] 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.[3] The launch date has since been pushed back to 2018,[4] with the Delta IV Heavy as the launch vehicle.[1]

Trajectory and mission[edit]

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

Early conceptual designs for the Solar Probe mission used a gravity assist maneuver at Jupiter to cancel the orbital speed of the probe launched from Earth, in order to drop onto a trajectory close to the Sun. The Solar Probe Plus mission design simplifies this trajectory by using repeated gravity assists at Venus, to incrementally decrease the orbital perihelion to achieve multiple passes to approximately 8.5 solar radii, or about 6,000,000 km (3,700,000 mi).[5]

The mission is designed to survive 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 the scientific instruments, are located in the umbra of the shield, where direct light from the sun is fully blocked. The primary power for the mission will be by use of a dual system of photovoltaic arrays. 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.[6]

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 faster than the current record holder, Helios 2.[7][8]

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.

See also[edit]


  1. ^ a b Clark, Stephen (Mar 18, 2015). "Delta 4-Heavy selected for launch of solar probe". Spaceflight Now. Retrieved Mar 18, 2015. 
  2. ^ Tony Phillips. "NASA Plans to Visit the Sun". NASA. Retrieved 30 September 2010. 
  3. ^ 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. 
  4. ^ M. Buckley (2012-03-05). "NASA Solar Study Mission Moves to Next Design Stage". Johns Hopkins University Applied Physics Laboratory. Retrieved 12 March 2012. 
  5. ^ "Solar Probe Plus: A NASA Mission to Touch the Sun:". JHU/APL. 4 September 2010. Retrieved 30 September 2010. 
  6. ^ 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.
  7. ^ "Aircraft Speed Records". 13 November 2014. 
  8. ^ "Fastest spacecraft speed". 26 July 2015. 

External links[edit]