Subsatellite Mini Forum, Tips, Tricks & Codes

A subsatellite, also known as a submoon or moonmoon, is a "moon of a moon" or a hypothetical natural satellite that orbits the moon of a planet.

It is inferred from the empirical study of natural satellites in the Solar System that subsatellites may be rare, albeit possible, elements of planetary systems. In the Solar System, the giant planets have hugecollections of natural satellites. The majority of detected exoplanets are giant planets; at least one, Kepler-1625b, may have a very large exomoon, named Kepler-1625b I, with speculations of a subsatellite. Nonetheless, aside from human-launched satellites in temporary lunar orbit, no notable subsatellite is known in the Solar System or beyond. In most cases, the tidal result of the planet would make such a system unstable.

Terminology

Rulesutilize in scientific literature for subsatellites include "submoons" and "moon-moons". Other rulesthat have been recommendedcontainmoonitos, moonettes, and moooons.

Possible natural instances

Rhea

The possible detection of a ring system around Saturn's natural satellite Rhea led to calculations that indicated that satellites orbiting Rhea would have stable orbits. The rings suspected were thought to be narrow, a phenomenon normally relatedwith shepherd moons; however, targeted photo taken by the Cassini spacecraft failed to detect any subsatellites or rings relatedwith Rhea, at least no particles huge than a few millimeters.

Iapetus

It has also been proposed that Saturn's satellite Iapetus possessed a subsatellite in the past; this is one of several hypotheses that have been put forward to accfor its unusual equatorial ridge.

Artificial subsatellites

Historical

Many spacecraft have orbited the Moon, including crewed craft of the Apollo program. As of 2020, none have orbited any other moons. In 1988, the Soviet Union unsuccessfully attempted to put two robotic probes on quasi-orbits around the Martian moon Phobos.

Current

Launched June 18, 2009, the Lunar Reconnaissance Orbiter (LRO) is a NASA robotic spacecraft currently orbiting the Moon in an eccentric polar mapping orbit. Data collected by LRO have been described as necessaryfor planning NASA's future human and robotic missions to the Moon. Its detailed mapping softwareis identifying safe landing page, locating potential resources on the Moon, characterizing the radiation environment, and demonstrating freshtechnologies.

Future designedartificial moon satellites

The interplanetary spacecraft JUICE currently in development will enter an orbit around Ganymede in 2032, becoming the first spacecraft to orbit a moon other than Earth's.

Additionally, the multi-agency supported Lunar Gateway human-rated zonestation is due to launchconstruction in 2024 in a near-rectilinear halo orbit (NRHO), primarily in assistanceof the later stage NASA Artemis program missions to Earth's moon. Lunar Gateway will also potentially assistancefuture missions to Mars and outlying asteroids.

CAPSTONE is a designedlate-2021 beginof a 12-unit collection of CubeSats intended to trythe viability of the designedNRHO of Lunar Gateway.

With a projected November 2021 launch, the Lunar Flashlight is designedlow-cost CubeSat lunar orbiter mission to explore, locate, and estimate size and composition of water ice deposits on the Moon for future exploitation by robots or humans from a polar orbit.

In fiction

• The Elder Scrolls series of video games takes territoryon the planet of Nirn, orbited by the satellite Masser, which in turn is orbited by the subsatellite Secunda.^{[citation needed]}
• In Planet 51, the titular planet is orbited by a moon with a Saturn-like ring system.
• Dumb Martian, a short story by John Wyndham, mostly takes territoryon Jupiter IV/II, a sub-moon of Callisto (see The Seeds of Time).
• In Star Wars, the moon Ajan Kloss has two moons of its own.

See also

• Media associatedto at Wikimedia Commons
• Position statement on the definition of a planet. (IAU)