Zamama is an active volcanic center on Jupiter 's moon Io. [1] [2] This volcanic center erupted after the Voyager 1 flyby in 1979, making it one of the few planetary volcanoes known to have activated during this generation's lifetime. Further analysis and study by the Galileo spacecraft helped with the overall study of Io's volcanism. Galileo located it on Io at 21°N173°W / 21°N 173°W [1] [3] . Zamama has a fissure-fed-type flow that is 150 km (93 mi) long with temperatures of 1,100 K (830 °C; 1,520 °F), [1] and the volcanic center site has explosive and effusive eruption characteristics. [4] The flow appears to be emanating from the Promethean-type volcano.
Remote sensing instruments built on the Galileo spacecraft—the Near-Infrared Mapping Spectrometer (NIMS), Solid-State Imager (SSI), Photopolarimeter-Radiometer (PPR)—collect and analyze volcanism on Io's surface. Since there are no samples collected from Io, all of the interpretations are made by studying albedo effects, morphology and/or spectral variations in Galileo data. Furthermore, Geomorphologic analysis is strictly used to study such specific planetary structures. [1] [5]
Most of the data acquired from the Jovian moon Io was derived from geomorphologic interpretations of orbital imaging. Voyager 1 and Galileo both used thermal remote sensing to accomplish this task. Thermal remote sensing is a branch of remote sensing which deals with processing and interpretations of data in the thermal infrared (TIR) region of the electromagnetic (EM) spectrum. Zamama is a hotspot/volcanic center among 61 active volcanic centers on Io. [6] These were observed by the Voyager flybys, by Galileo, and by ground-based observations. Zamama was first observed by Galileo, [6] which identified two types of volcanic activity: persistent and sporadic. [6] The NIMS instrument detected activity at Zamama lasting longer than one year; therefore, it is considered the persistent type. [6] It has only been NIMS-detected five times, but NIMS-observed nine times. This lower incidence of detection could be due to observational constraints or temporary waning of activity. [6]
Io is one of the most challenging Jovian moons for which to establish topography. A couple techniques aided in the making of Io's topography, such as "3D" stereo photogrammetry (SP) and "2D" photoclinometry (PC). [4] Ionian volcanoes have been poorly characterized because of their volcanic construct, which is different from well-studied planetary volcanoes such as those on Mars. Two common flow field morphologies have been identified on Io: [4]
The Zamama active volcanic center is characterized morphologically by a radially centered flow field. Multiple steep-sided shield volcanoes lie in this area:
Zamama appears to have been inactive during the 1979 Voyager 1 visit, or, it may have been buried by the Volund deposits. In contrast, Zamama appeared as a very active hot spot during the Galileo observations. Zamama has shown three notable surface changes in the SSI collected images. Images show them as bright rings, placed within the dark lava flows, with diameters of about 370 km (230 mi). In addition, new black rings were deposited north and northeast of the central prominent eruption. This most prominent central eruption was the first to take place (18° N, 171° W). The total area changed was about 136,000 km2 (53,000 sq mi). Second, a new eruption caused broadening in the central dark deposits of the western side and new bright rings were deposited along the margins of the lava flows. The total area effected was about 37,000 km2 (14,000 sq mi). Third, Zamama's third plume was actively erupting while Galileo was on its 14th orbit around Jupiter. New deposits enlarged to 150 ± 5 km (93.2 ± 3.1 mi) and are centered east of the eruptive center. Total affected area was about 96,000 km2 (37,000 sq mi). [8]
Galileo's NIMS instrument collected data on volcanic emissions to analyze the power output. A two-temperature model is used to determine the temperature and power output. Models have shown that Zamama has a temperature of 1,173 ± 243 K (900 ± 243 °C; 1,652 ± 437 °F). Pyroclastic flows with high silica content can have temperatures as high as 1,200 °C (1,470 K; 2,190 °F). Since Zamama volcanoes have such high temperatures, this indicates siliceous magma. No actual samples of Zamama's magma have been retrieved and processed for composition. [9]
Lava flows at Zamama suggest that it is a shield volcano with a central vent and a rift zone. The rift zone seems to feed the dark flow field, which appeared in the Galileo visit. The flow field appeared narrow/thin closer to the center, and wide/broad away from the center. This behavior might be due to a change in slope from the volcano rim to the nearby plains. The central vent emanates bright flows, due to sulfurous lava composition or silicate lava coated by sulfurous deposits. The composition of the lava emitted from the volcano is still mysterious. [7]
NIMS data analysis was conducted to determine the variability of thermal emissions from volcanoes on Io—particularly Zamama—for 1,038 days (28 June 1996 to 2 May 1999) and the results showed: [5]
Most Ionian volcanoes start as steep-sided shield volcanoes. After an eruptive construct-building phase, the central region collapses to form a caldera. Since steep-sided shield volcanoes have not been observed inside collapsed calderas, this indicates a failure to reform steep-sided volcanoes after the collapse, which can be associated with various variables such as change in temperature, eruptive rate, and/or lava composition. Failure to reform shield volcanoes is caused by failure to supply magma through the magma chamber. These interpretations might be a sign that current shield volcanoes will follow this pattern and transform to caldera-forming eruptive sites. [4]
Williams (2013) suggests the need for a variety of methods for observing Io in the future: "Future Io exploration is recommended to include: 1) a Jupiter-orbiting Io Observer spacecraft of either Discovery-class or New Frontiers-class; 2) a space-based UV telescope with diffraction-limited capability; 3) space-based missions that enable long-term monitoring of Io over a variety of time scales (seconds, minutes, hours, days, months, years); and 4) expanded time for Io observation on ground-based 8- to 10-m class telescopes, particularly those with nighttime Adaptive Optics capability." [10]
A volcano is a rupture in the crust of a planetary-mass object, such as Earth, that allows hot lava, volcanic ash, and gases to escape from a magma chamber below the surface. The process that forms volcanoes is called volcanism.
Volcanism, vulcanism, volcanicity, or volcanic activity is the phenomenon where solids, liquids, gases, and their mixtures erupt to the surface of a solid-surface astronomical body such as a planet or a moon. It is caused by the presence of a heat source, usually internally generated, inside the body; the heat is generated by various processes, such as radioactive decay or tidal heating. This heat partially melts solid material in the body or turns material into gas. The mobilized material rises through the body's interior and may break through the solid surface.
A stratovolcano, also known as a composite volcano, is a conical volcano built up by many layers (strata) of hardened lava and tephra. Unlike shield volcanoes, stratovolcanoes are characterized by a steep profile with a summit crater and periodic intervals of explosive eruptions and effusive eruptions, although some have collapsed summit craters called calderas. The lava flowing from stratovolcanoes typically cools and solidifies before spreading far, due to high viscosity. The magma forming this lava is often felsic, having high to intermediate levels of silica, with lesser amounts of less viscous mafic magma. Extensive felsic lava flows are uncommon, but have traveled as far as 15 km (9 mi).
Io, or Jupiter I, is the innermost and second-smallest of the four Galilean moons of the planet Jupiter. Slightly larger than Earth's moon, Io is the fourth-largest moon in the Solar System, has the highest density of any moon, the strongest surface gravity of any moon, and the lowest amount of water by atomic ratio of any known astronomical object in the Solar System. It was discovered in 1610 by Galileo Galilei and was named after the mythological character Io, a priestess of Hera who became one of Zeus's lovers.
Loki Patera is the largest volcanic depression on Jupiter's moon Io, 202 kilometres (126 mi) in diameter. It contains an active lava lake, with an episodically overturning crust. The level of activity seen is similar to a superfast spreading mid-ocean ridge on Earth. It is the largest volcano on Io, producing about 10% of Io’s total thermal emission. Temperature measurements of thermal emission at Loki Patera taken by Voyager 1's Infrared Interferometer Spectrometer and Radiometer (IRIS) instrument were consistent with sulfur volcanism.
Pele is an active volcano on the surface of Jupiter's moon Io. It is located on Io's trailing hemisphere at 18.7°S 255.3°W. A large, 300-kilometer (190 mi) tall volcanic plume has been observed at Pele by various spacecraft starting with Voyager 1 in 1979, though it has not been persistent. The discovery of the Pele plume on March 8, 1979 confirmed the existence of active volcanism on Io. The plume is associated with a lava lake at the northern end of the mountain Danube Planum. Pele is also notable for a persistent, large red ring circling the volcano resulting from sulfurous fallout from the volcanic plume.
Volcanism on Io, a moon of Jupiter, is represented by the presence of volcanoes, volcanic pits and lava flows on the surface. Io's volcanic activity was discovered in 1979 by Linda Morabito, an imaging scientist working on Voyager 1. Observations of Io by passing spacecraft and Earth-based astronomers have revealed more than 150 active volcanoes. As of 2024, up to 400 such volcanoes are predicted to exist based on these observations. Io's volcanism makes the satellite one of only four known currently volcanically or cryovolcanically active worlds in the Solar System
Surt is an active volcano on Jupiter's moon Io. It is located on Io's Jupiter-facing hemisphere at 45.21°N 336.49°W. Surt consists of an oblong volcanic pit, 75 by 40 kilometres in diameter, surrounded by reddish sulfur and bright sulfur dioxide deposits to its south and east. The volcano was first observed in images acquired by the Voyager 1 spacecraft in March 1979. Later that year, the International Astronomical Union named this feature after Surtr, a leader of the fire giants of Norse mythology.
Prometheus is an active volcano on Jupiter's moon Io. It is located on Io's hemisphere facing away from Jupiter at 1.52°S 153.94°W.
Amirani is an active volcano on Jupiter's moon Io, the inner-most of the Galilean Moons. It is located on Io's leading hemisphere at 24.46°N 114.68°W. The volcano is responsible for the largest active lava flow in the entire Solar System, with recent flows dwarfing those of even other volcanos on Io.
Volcanic activity, or volcanism, has played a significant role in the geologic evolution of Mars. Scientists have known since the Mariner 9 mission in 1972 that volcanic features cover large portions of the Martian surface. These features include extensive lava flows, vast lava plains, and the largest known volcanoes in the Solar System. Martian volcanic features range in age from Noachian to late Amazonian, indicating that the planet has been volcanically active throughout its history, and some speculate it probably still is so today. Both Mars and Earth are large, differentiated planets built from similar chondritic materials. Many of the same magmatic processes that occur on Earth also occurred on Mars, and both planets are similar enough compositionally that the same names can be applied to their igneous rocks.
Masubi is an active volcano on Jupiter's moon Io. It is located on Io's leading hemisphere at 49.6°S 56.18°W within a bright terrain region named Tarsus Regio. A volcanic plume has been observed at Masubi by various spacecraft starting with Voyager 1 in 1979, though it has not been persistent like similar Ionian volcanoes Amirani and Prometheus. Masubi is also notable for having one of the largest active lava flows on Io, with an additional 240 km (150 mi) flow forming between 1999 and 2007.
Tupan Patera is an active volcano on Jupiter's moon Io. It is located on Io's anti-Jupiter hemisphere at 18.73°S 141.13°W. Tupan consists of a volcanic crater, known as a patera, 79 kilometers across and 900 meters deep. The volcano was first seen in low-resolution observations by the two Voyager spacecraft in 1979, but volcanic activity was not seen at this volcano until June 1996 during the Galileo spacecraft's first orbit. Following this first detection of near-infrared thermal emission and subsequent detections by Galileo during the next few orbits, this volcano was formally named Tupan Patera, after the thunder god of the Tupí-Guaraní indigenous peoples in Brazil, by the International Astronomical Union in 1997.
Tawhaki Patera is an active volcano on Jupiter's moon Io. It is located on Io's leading hemisphere at 3.32°N 76.18°W within the equatorial plains of western Media Regio. Tawhaki is an Ionian patera, a type of volcanic crater similar to a caldera, 49.8 kilometers (30.9 mi) wide and 550 meters (1,800 ft) deep.
The exploration of Io, Jupiter's innermost Galilean and third-largest moon, began with its discovery in 1610 and continues today with Earth-based observations and visits by spacecraft to the Jupiter system. Italian astronomer Galileo Galilei was the first to record an observation of Io on January 8, 1610, though Simon Marius may have also observed Io at around the same time. During the 17th century, observations of Io and the other Galilean satellites helped with the measurement of longitude by map makers and surveyors, with validation of Kepler's Third Law of planetary motion, and with measurement of the speed of light. Based on ephemerides produced by astronomer Giovanni Cassini and others, Pierre-Simon Laplace created a mathematical theory to explain the resonant orbits of three of Jupiter's moons, Io, Europa, and Ganymede. This resonance was later found to have a profound effect on the geologies of these moons. Improved telescope technology in the late 19th and 20th centuries allowed astronomers to resolve large-scale surface features on Io as well as to estimate its diameter and mass.
Thor is an active volcano on Jupiter's moon Io. It is located on Io's anti-Jupiter hemisphere at 39.15°N 133.14°W. A major eruption with high thermal emission and a large, volcanic plume was observed during a Galileo flyby on August 6, 2001, when the spacecraft flew through the outer portions of the plume allowing for direct sampling. The eruption continued into Galileo's next flyby in October 2001. As seen during high-resolution images taken during the eruption, Thor consists of a series of dark lava flows emanating from a set of nearby volcanic depressions. Before the eruption, the area consisted of red-brown plains, composed of irradiated sulfur, typical of Io's mid- to high-northern latitudes and a set of yellow flows, possibly consisting of sulfur or silicate flows covered by diffuse sulfur deposits. During the New Horizons encounter in February 2007, Thor was still active, with the spacecraft observing thermal emission in the near-infrared and a volcanic plume at the volcano.
Kanehekili Fluctus is a lava flow field on Jupiter's moon, Io. This fluctus is located in the sub-Jovian hemisphere at 17.68°S 33.56°W as shown in the picture on the right. Also in the picture is the Kanehekili volcanic center located at 18.21°S 33.6°W. This lava field covers roughly 34,500 square kilometres (13,300 sq mi). The hotspot was detected by the Galileo Solid State Imaging experiment (SSI) on orbits by Galileo.
The Chaac-Camaxtli region is a volcanic region on Jupiter's moon Io, located from approximately 5 to 20°N and 130 to 160°W in its anti-Jovian hemisphere. It consists mainly of the hummocky bright plains that occupy the surface. This area is defined on the west by Chaac Patera, and on the east by Camaxtli Patera. At least 10 distinct volcanic centers are located in the region, making it a volcanically active region on Io's surface. Most of the volcanism here is expressed as paterae, which range in size from circular to elliptical. A patera is defined by the International Astronomical Union as "irregular or complex craters with scalloped edges." The largest volcanic structure here is the Chaac Patera. The paterae found in the Chaac-Camaxtli region are Chaac, Balder Patera, Grannos, Ababinili, Ruaumoko, Steropes, Camaxtli, Tien Mu, Utu, and Mentu.
Volcanism on the Moon is represented by the presence of volcanoes, pyroclastic deposits and vast lava plains on the lunar surface. The volcanoes are typically in the form of small domes and cones that form large volcanic complexes and isolated edifices. Calderas, large-scale collapse features generally formed late in a volcanic eruptive episode, are exceptionally rare on the Moon. Lunar pyroclastic deposits are the result of lava fountain eruptions from volatile-laden basaltic magmas rapidly ascending from deep mantle sources and erupting as a spray of magma, forming tiny glass beads. However, pyroclastic deposits formed by less common non-basaltic explosive eruptions are also thought to exist on the Moon. Lunar lava plains cover large swaths of the Moon's surface and consist mainly of voluminous basaltic flows. They contain a number of volcanic features related to the cooling of lava, including lava tubes, rilles and wrinkle ridges.