LUME GRAVITY Reach

REACH / NASA · JOHNS HOPKINS APL

Parker
Solar Probe.

A spacecraft inside a star’s atmosphere.

Explore the mission
Sun image · NASA/GSFC/Solar Dynamics Observatory
10 September 2025 · Cropped for display · Not Parker imagery ↗

01 / THE QUESTION

Why is the corona
so hot?

The Sun’s visible surface is about 5,500 °C. Its outer atmosphere reaches millions of degrees. Parker measures plasma, magnetic fields and energetic particles close to where the solar wind begins.

The mission investigates how energy heats the corona, accelerates the solar wind and drives energetic particles. These processes shape space weather across the solar system.

NASA · mission overview

02 / A RECORD IN PERSPECTIVE

692,000 km/h.
Made on Earth.

The record was first set on 24 December 2024. It is speed relative to the Sun, reached near perihelion, rather than a constant cruising speed.

RECORD SPEED · APPROXIMATE430,000 mphABOUT 692,000 KM/H
ABOVE THE SOLAR SURFACE3.8 million milesABOUT 6.1 MILLION KM
THERMAL PROTECTION11.5 cmCARBON-COMPOSITE HEAT SHIELD
NASA · record encounter

03 / FOUR MOMENTS

A journey closer.

01

Leaving Earth

Parker launched toward the Sun. Repeated Venus flybys reshaped its orbit.

02

Inside the corona

The spacecraft first crossed into the magnetically dominated solar atmosphere.

03

A new record

About 692,000 km/h, roughly 6.1 million kilometres above the visible solar surface.

04

Returning to the frontier

Its 29th close approach matched those records. NASA has extended the mission into 2029.

NASA · September 2026 encounter and extension

04 / THE ENGINEERING

A few centimetres.
A world of difference.

A carbon-composite shield roughly 11.5 centimetres thick protects the spacecraft. Behind it, much of the instrumentation stays near 30 °C. Some sensors must face the Sun directly and need their own heat-resistant materials.

Temperature and heat transfer are different things. The corona’s particles are extremely energetic, but sparse. Solar radiation still presents a formidable engineering challenge; the shield, cooling and autonomous pointing work together.

NASA · why Parker does not melt