Civil Rights
Movements, leaders, victories and the continuing fight for equality.
q2K BHP
Black History Portal
THE BHP WIRE —
HIDDEN TRUTHS
What's New!
Explore the people, places, events, achievements, struggles and stories that shaped our journey.
Movements, leaders, victories and the continuing fight for equality.
Innovation, patents, science, technology and world-changing contributions.
Pioneers, champions, Negro Leagues, records, activism and excellence.
Meet the people whose lives, choices and achievements shaped the journey.
Black towns, communities, institutions and places where history happened.
Moments that changed communities, movements, institutions and the nation.
Katherine Johnson’s mathematical calculations helped guide some of America’s most important early space missions while she confronted the racial and gender barriers faced by Black women in twentieth-century America.
MORE →Reflects the personal views, recollections, and perspective of the author, Mike Davis.
This is a personal recollection on the Move fire on May 13, 1985
A subsatellite, also known as a submoon, moonlet or informally a moonmoon, is a "moon of a moon" or a hypothetical natural satellite that orbits the moon of a planet.[3]
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 large collections 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, which could theoretically host a subsatellite.[1][2][4][5] Nonetheless, aside from human-launched satellites in temporary lunar orbit, no subsatellite is known in the Solar System or beyond. In most cases, the tidal effects of the planet would make such a system unstable on an astronomical timescale.
Terms used in scientific literature for subsatellites include "submoons" and "moon-moons". Colloquial terms that have been suggested include moonitos (compare plutino), moonettes, and moons.[6]
There is a possible detection[7] of a ring system around Saturn's natural satellite Rhea that led to calculations that indicated that satellites orbiting Rhea would have stable orbits. The rings suspected were thought to be narrow,[8] a phenomenon normally associated with shepherd moons; however, targeted images taken by the Cassini spacecraft failed to detect any subsatellites or rings associated with Rhea, at least no particles larger than a few millimeters, making the chance of a ring system around Rhea slim.[9]
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 account for its unusual equatorial ridge.[10] An ancient giant impact on Iapetus could have produced a subsatellite; as Saturn despun Iapetus, the subsatellite's orbit would then decay until it crossed Iapetus' Roche limit, forming a transient ring which then impacted Iapetus to form a ridge. Such a scenario could have happened on the other giant-planet satellites as well, but only for Iapetus and perhaps Oberon would the resulting ridge have formed after the Late Heavy Bombardment and thus survived to the present day.[11]
Light-curve analysis suggests that Saturn's irregular satellite Kiviuq is extremely prolate, and is likely a contact binary or even a binary moon.[12] Other candidates among the Saturnian irregulars include Bestla, Erriapus, and Bebhionn.[13]
Many spacecraft have orbited the Moon, with the first being Luna 10 in 1966.
As of 2026[update], no spacecraft has successfully orbited any natural satellite other than the Moon. In 1988, the Soviet Union unsuccessfully attempted to put two robotic probes on quasi-orbits around the Martian moon Phobos.[14]
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 essential for planning NASA's future human and robotic missions to the Moon. Its detailed mapping program is identifying safe landing sites, locating potential resources on the Moon, characterizing the radiation environment, and demonstrating new technologies.
Different classes of lunar orbits are selected according to mission objectives. Low polar orbits are typically used for global mapping and surface observations, while near-rectilinear halo orbits (NRHOs) provide long-term stability and continuous communication with Earth, making them well suited for sustained lunar exploration missions.[15][16]
CAPSTONE is a project that successfully launched on June 28, 2022. Composed of a 12-unit collection of CubeSats which spent a few months in transit to the Moon to arrive on November 14, 2022. It has spent over 2 years in the Moon's Near-rectilinear halo orbit. CAPSTONE is testing and verifying the viability of the planned NRHO of planned future Lunar Gateway and its communication efficiency.[17]
The interplanetary spacecraft JUICE launched in 2023 will enter an orbit around Ganymede in 2034, becoming the first spacecraft to orbit a moon other than Earth's.[18]
The Lunar Gateway was a planned space station to be constructed in a near-rectilinear halo orbit (NRHO), primarily in support of the later stage NASA Artemis program missions to the Moon. As of March 2026, the focus of the project has shifted towards a lunar surface base, but the station may be considered later.[19]
Media related to Extrasolar moons at Wikimedia CommonsNatural satellites of the Solar System | |||||||||||||||||||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| |||||||||||||||||||||||||||||||||||||
| |||||||||||||||||||||||||||||||||||||
| |||||||||||||||||||||||||||||||||||||
| |||||||||||||||||||||||||||||||||||||
| |||||||||||||||||||||||||||||||||||||
| |||||||||||||||||||||
Solar System → Local Interstellar Cloud → Local Bubble → Gould Belt → Orion Arm → Milky Way → Milky Way subgroup → Local Group → Local Sheet → Local Volume → Virgo Supercluster → Laniakea Supercluster → Pisces–Cetus Supercluster Complex → Local Hole → Observable universe → Universe | |||||||||||||||||||||
Source: Wikipedia. Article content is retrieved live through the MediaWiki API.
A subsatellite, also known as a submoon, moonlet or informally a 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 large collections 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, which could theoretically host a subsatellite. Nonetheless, aside from human-launched satellites in temporary lunar orbit, no subsatellite is known in the Solar System or beyond. In most cases, the tidal effects of the planet would make such a system unstable on an astronomical timescale.
Apollo 15 (July 26 – August 7, 1971) was the ninth crewed mission in the Apollo program and the fourth Moon landing. It was the first J mission, with a longer stay on the Moon and a greater focus on science than earlier landings. Apollo 15 saw the first use of the Lunar Roving Vehicle. The mission began on July 26 and ended on August 7, with the lunar surface exploration taking place between July 30 and August 2. Commander David Scott and Lunar Module Pilot James Irwin landed near Hadley Rille and explored the local area using the rover, allowing them to travel further from the Lunar Module than had been possible on previous missions. They spent 181⁄2 hours on the Moon's surface on four extravehicular activities (EVA), and collected 170 pounds (77 kg) of surface material. At the same time, Command Module Pilot Alfred Worden orbited the Moon, operating the sensors in the scientific instrument module (SIM) bay of the service module. This suite of instruments collected data on the Moon and its environment using a panoramic camera, a gamma-ray spectrometer, a mapping camera, a laser altimeter, a mass spectrometer, and a lunar subsatellite deployed at the end of the moonwalks. The Lunar Module returned safely to the command module and, at the end of Apollo 15's 74th lunar orbit, the engine was fired for the journey home. During the return trip, Worden performed the first spacewalk in deep space. The Apollo 15 mission splashed down safely on August 7 despite the partial opening of one of its three parachutes. The mission accomplished its goals and also saw the collection of the Genesis Rock, thought to be part of the Moon's early crust, and Scott's use of a hammer and a feather to validate Galileo's theory that when there is no air resistance, objects fall at the same rate due to gravity regardless of their mass. The mission received negative publicity the following year when it emerged that the crew had carried unauthorized postal covers to the lunar surface, some of which were sold by a West German stamp dealer. The members of the crew were reprimanded for poor judgment, and did not fly in space again.
Apollo 16 (April 16–27, 1972) was the tenth crewed mission in the United States Apollo space program, administered by NASA, and the fifth and penultimate to land on the Moon. It was the second of Apollo's "J missions", with an extended stay on the lunar surface, a focus on science, and the use of the Lunar Roving Vehicle (LRV). The landing and exploration were in the Descartes Highlands, a site chosen because some scientists expected it to be an area formed by volcanic action, though this proved not to be the case. The mission was crewed by Commander John Young, Lunar Module Pilot Charles Duke and Command Module Pilot Ken Mattingly. Launched from the Kennedy Space Center in Florida on April 16, 1972, Apollo 16 experienced a number of minor glitches en route to the Moon. These culminated with a problem with the spacecraft's main engine that resulted in a six-hour delay in the Moon landing as NASA managers contemplated having the astronauts abort the mission and return to Earth, before deciding the problem could be overcome. Although they permitted the lunar landing, NASA had the astronauts return from the mission one day earlier than planned. After flying the Lunar Module to the Moon's surface on April 21, Young and Duke spent 71 hours—just under three days—on the lunar surface, during which they conducted three extravehicular activities or moonwalks, totaling 20 hours and 14 minutes. The pair drove the lunar rover, the second used on the Moon, for 26.7 kilometers (16.6 mi). On the surface, Young and Duke collected 95.8 kilograms (211 lb) of lunar samples for return to Earth, including Big Muley, the largest Moon rock collected during the Apollo missions. During this time Mattingly orbited the Moon in the command and service module (CSM), taking photos and operating scientific instruments. Mattingly, in the command module, spent 126 hours and 64 revolutions in lunar orbit. After Young and Duke rejoined Mattingly in lunar orbit, the crew released a subsatellite from the service module (SM). During the return trip to Earth, Mattingly performed a one-hour spacewalk to retrieve several film cassettes from the exterior of the service module. Apollo 16 returned safely to Earth on April 27, 1972.
After the Apollo 15 LM Falcon lifted from the lunar surface on August 2, 1971, it rendezvoused and docked with the CSM Endeavour. After transferring across the lunar samples and other equipment, Falcon was jettisoned. It would fire its rocket engine to cause it to impact the lunar surface. Apollo 15 spent one more day in lunar orbit, continuing Worden's observations. After releasing a subsatellite, they ignited their service propulsion system to put them on a trajectory back to Earth. The next day, Worden performed an EVA to retrieve the film cassettes from the scientific instrument module (SIM) bay cameras. The twelfth day in space was uneventful, with Mission Control holding a press conference where the astronauts were asked questions submitted by the news media. On their 13th and final day they prepared for reentry. During descent one of their three parachutes failed, and they splashed down successfully with only two.
Before the 1921 destruction of Tulsa’s Greenwood District, Black residents had created a remarkable center of business and community life. The district included stores, professional offices, entertainment venues and homes owned by Black citizens. Understanding Greenwood means learning what was built—not only what was burned.
MORE →The Greenwood District.
