Solar Orbiter

Solar Orbiter. Solar Orbiter is a collaborative heliophysics mission between the European Space Agency and NASA designed to perform unprecedented close-up observations of the Sun. Launched in 2020, it aims to study the Sun's polar regions and the inner heliosphere, investigating the connections between solar activity and the space environment around our star. The mission represents a major step in understanding the Solar cycle and the origins of solar wind.

Mission overview

The primary goal of the mission is to address central questions in solar and heliospheric physics, focusing on how the Sun creates and controls the dynamic heliosphere. It builds upon the legacy of previous missions like SOHO and the Parker Solar Probe, but with a unique suite of instruments capable of both remote sensing and in-situ measurements. Managed from the European Space Operations Centre in Darmstadt, the mission involves a large consortium of scientific institutes across Europe and the United States. Its planned operational lifetime allows it to observe the Sun through a significant portion of increasing solar activity as part of Solar cycle 25.

Spacecraft design

The spacecraft was built by a consortium led by Airbus Defence and Space in the United Kingdom, featuring a robust design to withstand extreme thermal and radiation conditions. A key innovation is its large heat shield, made of titanium and coated with a special black calcium phosphate layer called "SolarBlack," which protects the bus and instruments from temperatures exceeding 500°C. The craft utilizes a novel "peephole" design in the shield, allowing remote-sensing instruments brief windows to observe the Sun. For propulsion and trajectory adjustments, it relies on a bi-propellant chemical system, while its power is supplied by solar panels that can be tilted to avoid overheating during close perihelion passes.

Scientific instruments

The payload consists of ten advanced instruments, split evenly between in-situ detectors and remote-sensing telescopes. The in-situ suite includes the Solar Wind Analyser (SWA), the Energetic Particle Detector (EPD), and the Magnetometer (MAG), which directly sample particles and fields. The remote-sensing package features the Extreme Ultraviolet Imager (EUI), the Polarimetric and Helioseismic Imager (PHI), and the Spectrometer/Telescope for Imaging X-rays (STIX). These instruments were developed by international teams led by institutions such as the Mullard Space Science Laboratory and the Max Planck Institute for Solar System Research. This combined approach enables the first-ever comprehensive, coordinated measurements of the Sun and its immediate environment from such a close vantage point.

Launch and trajectory

The spacecraft launched atop a United Launch Alliance Atlas V 411 rocket from Space Launch Complex 41 at Cape Canaveral Space Force Station on 10 February 2020. Its complex trajectory uses repeated gravity assist maneuvers from Venus and Earth to gradually increase its orbital inclination and decrease its perihelion. The first close solar pass occurred in June 2020, with the first Venus gravity assist following in December 2020. These maneuvers, planned by flight dynamics teams at ESOC, will eventually bring it within 0.28 AU of the Sun and tilt its orbit to provide the first high-latitude views of the Sun's poles, a perspective never before achieved.

Scientific objectives and findings

Key objectives include determining the origins of the solar wind, the acceleration mechanisms of solar energetic particles, and the dynamics of the Sun's corona and magnetic field. Early findings, published in journals like Astronomy & Astrophysics, have already been transformative. The mission has captured the first images of the Sun's elusive polar regions and identified numerous small-scale solar eruptions dubbed "campfires," which may contribute to coronal heating. Observations have also directly linked specific magnetic structures on the solar surface to the composition of the solar wind sampled in situ, providing crucial evidence for theories developed from data from earlier missions like Ulysses and Helios probes.

Category:European Space Agency spacecraft Category:NASA space probes Category:Solar spacecraft