Watching the Sun and Mercury: Eight Probes From Sakigake to Solar Orbiter

Sakigake launched on January 7, 1985, and was Japan's first interplanetary spacecraft. Its job was to observe the interplanetary medium and magnetic field, and it also served as a reference probe for Halley's Comet, so its early measurements could help the later Suisei mission.

Ulysses, launched on October 6, 1990, was a joint European Space Agency and NASA probe built to orbit the Sun and study it at all latitudes. It made three fast latitude scans, in 1994 and 1995, 2000 and 2001, and 2007 and 2008, and its operations ended on June 30, 2009.

Genesis, launched on August 8, 2001, collected particles of solar wind and returned them to Earth for laboratory study. Its parachute failed to deploy and the capsule crash-landed in Utah on September 8, 2004, contaminating many collectors, though some were recovered and studied.

Double Star was a joint China National Space Administration and European Space Agency mission, launched on December 29, 2003, and China's first space mission to investigate Earth's magnetosphere. Its two satellites, TC-1 and TC-2, studied the effects of the Sun on Earth's environment, and the mission was extended twice until the end of September 2007.

MESSENGER launched on August 3, 2004, and orbited Mercury between 2011 and 2015, studying its chemical composition, geology and magnetic field. It was the first spacecraft to orbit the planet, after Mariner 10 had only flown past it.

Parker Solar Probe, built by the Johns Hopkins Applied Physics Laboratory and launched on August 12, 2018, studies the Sun's outer corona and solar wind at closer range than any earlier spacecraft. It is the first NASA spacecraft named for a living person, physicist Eugene Parker.

BepiColombo, a joint European Space Agency and Japan Aerospace Exploration Agency mission launched in October 2018, carries two orbiters, one from each agency, to Mercury. It uses repeated gravity assist flybys of Earth, Venus and Mercury to slow down enough to be captured, rather than spending prohibitive amounts of fuel.

Solar Orbiter, launched in February 2020 by the European Space Agency in partnership with NASA, studies the Sun and inner heliosphere from closer than any earlier imaging mission. Venus flybys raise its orbital inclination, which let it capture the first images of the Sun's polar regions.