Parker Solar Probe
NASA's Sun-grazer — the fastest object humans have ever built, diving repeatedly into the solar corona.
Vital statistics
01
Overview
Parker Solar Probe is the first spacecraft built to fly through the Sun's corona — the searing outer atmosphere that astronomers have observed remotely for centuries but never sampled in situ. Launched on a Delta IV Heavy in August 2018, the probe uses seven gravity assists from Venus to shrink its perihelion progressively closer to the Sun. On December 24, 2024, it set a new record by approaching within 6.9 million kilometres — about 4 percent of the Earth-Sun distance — at a speed of nearly 700,000 km/h. Its measurements are rewriting our understanding of how the solar wind is heated and accelerated.
02
Composition
A 1×3 metre hexagonal carbon-composite heat shield, just 11.4 cm thick, blocks the full thrust of solar radiation while the spacecraft bus stays at room temperature behind it. Two retractable solar arrays angle in and out as the probe nears perihelion. Four instrument suites — FIELDS (electric/magnetic), SWEAP (solar wind particles), ISʘIS (energetic particles), and WISPR (wide-field imager) — sample the corona during each close pass. Power, thermal, and communications systems are radiation-hardened far beyond typical JPL spacecraft.
05
Exploration
Parker has so far completed 21 perihelia and 7 Venus gravity assists, each one shrinking its closest approach. In 2021 it became the first spacecraft to "touch" the Sun, crossing the Alfvén critical surface — the boundary inside which plasma is gravitationally bound to the corona. Findings include detailed maps of "switchbacks" (kinked magnetic-field reversals in the solar wind) and the first in-situ evidence of how those structures form. The mission was extended in 2024 and is expected to operate until its heat-shield protection finally degrades, sometime after 2027.
Did you know?
Parker is the first NASA mission named after a living scientist — Eugene Parker, who predicted the solar wind in 1958.
Its top speed of 692,000 km/h is fast enough to cross the contiguous United States in less than a second.
Behind the heat shield, the spacecraft bus stays at roughly room temperature even at 1,400 °C external heat.
Each Venus flyby steals a tiny bit of orbital energy from the planet — slowing Venus by an unmeasurably small amount.
Parker carries a memory chip with 1.1 million names of solar-physics enthusiasts who signed up for the trip.
During perihelion passes, the round-trip communication delay with Earth is short enough (~16 minutes) that NASA can intervene during anomalies.
It will eventually be vaporised by the Sun — but only after its 2030s end-of-mission, when station-keeping fuel is exhausted.
Timeline
- 20182018
Parker Solar Probe launches on a Delta IV Heavy from Cape Canaveral on August 12.
- 20182018
First Venus gravity assist on October 3 reshapes the orbit toward the Sun.
- 20182018
First perihelion (Encounter 1) on November 5 sets a new closest-approach record.
- 20212021
On April 28, Parker becomes the first spacecraft to fly through the solar corona, crossing the Alfvén surface.
- 20242024
Final Venus flyby on November 6 sets up the closest perihelion at 6.9 million km on December 24.
- 20252025
Mission officially extended through additional close perihelia.