Chaldene, also known as Jupiter XXI, is a retrograde irregular-satellite belonging to the outer planet of Jupiter. This satellite was founded by Scott S. Sheppard, David C. Jewett, Yanga R. Fernandez, and Eugene A. Magnier on November 23, 2000 at the Mauna Kea Observatory in Hawaii. This satellite belongs to the Carme group, a satellite group home to sixteen other satellites. This satellite makes one orbit around Jupiter in about 730 Earth days.
Common in the origin of many satellites in the Carme group, Chaldene was formed from the remains of the creation of the Carme group. It all started when a large D-type asteroid was pulled into Jupiter's gravitational pull. After suffering collisions, debris and pieces of the asteroids became the satellites of the Carme group. The D-type asteroid that was pulled in, the largest, was named "Carme".
All of the satellites in the Carme group, except Kalyke which is redder than the others, are light red. However, Chaldene is gray at the northern and southern poles, uncommon in the Carme group. In the Carme group, very few satellites, including this one, has mountainous areas. The surface contains few valleys and little to no craters, meaning it has suffered few impacts after its creation.