Parker Solar Probe

Parker Solar Probe flies through the solar corona at 690,000 km/h, studying the Sun.

Touching the Sun

Parker Solar Probe is named after Eugene Parker, who first predicted the solar wind in 1958. The spacecraft makes 24 orbits over 7 years, using 7 Venus gravity assiststo gradually tighten its orbit around the Sun. At closest approach, it travels at690,000 km/h (191 km/s) - the fastest human-made object ever, fast enough to go from Earth to the Moon in under an hour.

Spacecraft Specifications

• Launch mass: 635 kg
• Dimensions: 3.0 m × 2.3 m × 1.0 m (stowed)
• Power at closest approach: 343 W (from solar arrays retracted behind heat shield)
• Velocity at perihelion: 191 km/s (690,000 km/h)
• Perihelion: 6.1 million km from the Sun (8.5 solar radii)
• Orbital period at final orbit: 88 days
• Total orbits: 24
• Venus flybys: 7

Thermal Protection System (TPS)

The heart of Parker Solar Probe is its carbon-carbon composite Thermal Protection System (TPS) - an engineering marvel that keeps the spacecraft at room temperature while the Sun-facing side is heated to extreme temperatures:

• Heat shield diameter: 2.3 meters (7.5 feet)
• Thickness: 11.4 cm (4.5 inches)
• Material: Carbon-carbon composite (carbon fiber reinforced carbon) - maintains strength at extreme temperatures
• Mass: 73 kg
• Sun-facing temperature: up to 1,370°C at closest approach
• Shadow side temperature: approximately 29°C (room temperature)
• Temperature differential: over 1,340°C across 11.4 cm of material
• Tested to: 1,650°C in ground facilities (margin above operational maximum)
• Coating: White ceramic coating on the Sun-facing side to reflect maximum solar energy

The TPS allows the spacecraft's instruments and electronics to operate at approximately 29°C while the corona rages at millions of degrees just meters away. Without it, the spacecraft would be destroyed within seconds.

Communication

Parker Solar Probe uses 4 rear-facing antennas positioned behind the heat shield to communicate with Earth. The antennas are placed in the thermal shadow of the TPS to protect them from solar heating.

• Band: X-band (8 GHz)
• High-gain antenna: 0.6-meter dish, 42.3 dBi gain
• Data rate at closest approach: 167 kbps
• Data rate at farthest distance: 512 kbps
• Light time to Earth: approximately 8 minutes at maximum distance
• Daily data volume: up to 50 Gbit during closest approach

At closest approach, the spacecraft is limited to brief communication windows due to heat - the antenna must be pointed away from the Sun. Data is stored on onboard recorders and transmitted during safer portions of the orbit.

Science Goals

• Solar Wind Origin: Trace solar wind plasma from corona to Earth
• Energy Transport: Understand how the corona is heated to 1,000,000°C
• Particle Acceleration: Study how particles are accelerated to high energies
• Magnetic Fields: Map the Sun's magnetic field in the corona
• Dust Environment: Measure dust in the inner solar system, including the predicted "dust-free zone"

Discoveries

• Magnetic Switchbacks: Swooping zigzag structures in the solar wind, like "snakes" through space - sudden reversals in magnetic field direction
• Space Weather Origins: First direct measurements near solar wind source regions
• Dust Detection: Found the predicted "dust-free zone" near the Sun where solar radiation pressure blows dust away
• Coronal Mass Ejections: Observed CMEs up close with unprecedented detail
• Sub-Alfvénic Solar Wind: Parker entered the region where the solar wind is slower than the Alfvén speed - inside the Sun's magnetic atmosphere

Mission Profile

Parker Solar Probe will complete 24 orbits of the Sun between 2018 and 2025. The final orbit brings it within 6.1 million km of the solar surface- close enough to sample the corona directly. The mission ends when the spacecraft's hydrazine fuel is depleted, after which it will continue orbiting the Sun indefinitely as a man-made asteroid.

Communication System

Parker Solar Probe communicates via Ka-band (32 GHz) downlink through theDeep Space Network (DSN) 70-meter antennas at Goldstone, Madrid, and Canberra. The 70-meter dishes are essential for capturing the weak signals from a spacecraft deep within the solar corona, where solar plasma can introduce signal scintillation.

• Transmitter: 16-watt Traveling Wave Tube Amplifier (TWTA) for science data downlink
• Data rate at closest approach (perihelion): 154 kbps - limited by thermal constraints and antenna pointing restrictions
• Data rate at aphelion: 169 kbps - slightly higher due to reduced solar interference and longer communication windows
• Solid-state recorder: 32 GB flash memory buffer stores science and engineering data during brief perihelion passes when direct communication is impossible, then downlinks during safer orbital segments
• Antenna configuration: 4 rear-facing low-gain antennas positioned behind the heat shield, maintaining thermal protection during transmission
• Daily data volume: up to 50 Gbit during closest approach phases

Thermal Protection System

The Thermal Protection System (TPS) is the critical technology enabling Parker Solar Probe to survive within the solar corona. The 4.5-inch (11.4 cm) thick carbon-composite heat shield maintains a temperature differential of over 1,340°Cacross its thickness - the Sun-facing side reaches 1,370°C while the spacecraft side remains at approximately 29°C.

• Heat shield orientation: The spacecraft continuously reorients behind the TPS, keeping all instruments and electronics in the thermal shadow - attitude control thrusters adjust the probe's pointing throughout each orbit
• Solar panel cooling system: The two solar panels deploy during cruise phases but retract behind the heat shield during perihelion, with only small segments exposed to generate approximately 343 W of power
• Instrument cooling: Active heat pipes circulate coolant from the instrument bay to radiator panels on the spacecraft's cold side, maintaining sensitive detectors within operational temperature ranges
• Material science: The carbon-carbon composite maintains structural integrity at extreme temperatures - tested to 1,650°C in ground facilities, well above the operational maximum
• White ceramic coating: Applied to the Sun-facing side to maximize solar energy reflection and minimize heat absorption

Mission Operations

Parker Solar Probe operates a 7-year mission with 24 orbitsof the Sun and 24 Venus flybysthat gradually reduce its perihelion distance. Each Venus gravity assist removes orbital energy, tightening the spacecraft's path closer to the Sun.

• Orbital evolution: Initial perihelion of 35.7 solar radii (24.8 million km) gradually decreases to 6.16 solar radii (6.1 million km) at final orbit
• 2024 close approaches: Parker made its closest solar approaches, reaching within 6.1 million km of the Sun's surface - closer than any previous human-made object
• 2025 operations: Final Venus flybys and closest solar passes before mission conclusion
• Plasma measurements: The FIELDS instrument suite measures electric and magnetic fields, plasma waves, and solar wind density directly in the corona
• Particle detection: SWEAP (Solar Wind Electrons Alphas and Protons) instrument counts particles and measures their properties, providing the first in-situ sampling of the solar wind at its source
• Solar energetic particles: ISʘIS (Integrated Science Investigation of the Sun) detects high-energy particles accelerated by solar flares and coronal mass ejections
• Imaging: WISPR (Wide-field Imager for Solar Probe) captures images of the corona and solar wind structure from within the atmosphere itself