Short answers, pulled from the story.
Adrastea was discovered by David C. Jewitt and G. Edward Danielson in photographs taken by the Voyager 2 spacecraft on the 8th of July, 1979. It received the provisional designation S/1979 J 1 and was the first natural satellite discovered by an interplanetary spacecraft rather than a telescope.
Adrastea is officially named after the Greek nymph Adrastea, described in mythology as the daughter of Zeus and his lover Ananke. The name was formally assigned in 1983. Zeus is the Greek equivalent of the Roman god Jupiter, after whom the planet is named.
Adrastea measures roughly 20 kilometres across, making it the smallest of Jupiter's four inner moons. Its bulk composition and mass are not directly known; estimates of its mass rely on an assumed density similar to that of the inner moon Amalthea.
Adrastea is considered the largest contributor of material to Jupiter's ring system. Meteorite impacts on its surface eject debris that escapes into space due to the moon's low gravity, and the densest part of Jupiter's ring, the main ring, is located at and within Adrastea's orbital path.
Tidal forces are gradually causing Adrastea's orbit to decay because it orbits inside Jupiter's synchronous orbit radius. Over time this orbital decay will cause the moon to impact Jupiter. Adrastea's orbit may already lie within Jupiter's fluid Roche limit, though the moon has not broken apart, indicating it still sits outside the rigid Roche limit.
A close flyby of Adrastea is planned for the 3rd of June, 2026, during Juno's 84th perijove pass. At closest approach, the spacecraft will be 11,747 kilometres from the moon, the nearest any mission has been scheduled to pass.