Volcanoes on Other Planets

Volcanoes exist on planets other than Earth.

A Hawaiian-Style Volcano on Io

This is a high-resolution image of part of Prometheus, an active volcano on Jupiter's volcanic moon Io. In earlier, lower resolution images, it appeared that all the dark material at Prometheus comprised a single, long lava flow. The new image shows for the first time that the northeastern end of this dark feature is actually a lava-filled caldera 28 kilometers (17 miles) long and 14 kilometers (9 mile s) wide. The underground source of the Prometheus lava is probably beneath this newly discovered caldera. Galileo scientists are intrigued also by the snowfield containing hummocks, seen to the east of the Prometheus caldera.

November 5, 1999 - NASA

New images from Galileo reveal unexpected details of the Prometheus volcano on Io including a caldera and lava flowing through fields of sulfur dioxide snow.

A volcanic crater several times larger than one found at Hawaii's Kilauea volcano has been photographed on Jupiter's moon Io during a close flyby performed by NASA's Galileo spacecraft.

"It appears that the Prometheus volcano on Io has characteristics remarkably similar to those of the Kilauea volcano in Hawaii, although Prometheus is much larger," said Dr. Laszlo Keszthelyi (KEST-ay), a Galileo research associate at the University of Arizona, Tucson, AZ. "Both volcanoes are long- lived eruptions, with flows that apparently travel through lava tubes and produce plumes when they interact with cooler materials."

The sharp images of Prometheus released today come from two of Galileo's onboard instruments -- the camera, and the near- infrared mapping spectrometer which observes in wavelengths not visible to the naked eye. The images were taken during the close flyby of Io by Galileo on October 10, 1999, and are part of a large batch of data currently being transmitted to Earth.

"We've been having a feast looking at the material from Io," said Dr. Rosaly Lopes-Gautier NASA's Jet Propulsion Laboratory, Pasadena, CA. "We have been waiting for such high-resolution images of Io for more than 10 years." Scientists will present an assortment of new images and describe their latest discoveries at a press briefing scheduled for November 19 at NASA Headquarters, Washington, DC.

Prometheus is the "Old Faithful" of Io's many volcanoes. It has been active during every observation over the past 20 years by NASA's Voyager and Galileo spacecraft and the Hubble Space Telescope. The new spectrometer images show two distinct hot spots at Prometheus -- a large one to the west and a fainter, cooler one to the east. The images reveal numerous lava flows near the western hot spot and enable scientists to identify a crater, or caldera, 28 kilometers (17 miles) long and 14 kilometers (9 miles) wide near the hot spot to the east.

Previously, it was thought that the 50 to 100 kilometer- (30 to 60 mile-) tall plume observed at Prometheus formed where the lava erupts onto the surface. Now, however, it now appears that the plume forms at the far end of the lava flows. The caldera and eastern hot spot are thought to be associated with the vent where the molten rock rises to the surface. It appears that after the lava reaches the surface, it is transported westward through lava tubes for about 100 kilometers (60 miles) before breaking out onto the surface again. Here, numerous lava flows wander across a plain covered with sulfur dioxide-rich snow. The plume is created by the interaction of the hot lava with the snow.

This plume feature is just one of several similarities between Prometheus and Hawaii's Kilauea. Volcanologists say that Prometheus has been erupting for more than 20 years and Kilauea has been erupting for more than 16 years. The current vent at Kilauea consists of a small lava lake about 100 meters (330 feet) across that produces a relatively small thermal hot spot. From this vent, lava is transported 10 kilometers (6 miles) in lava tubes to the Pacific Ocean where large steam plumes are generated by the interaction between the hot lava and the ocean. Galileo scientists believe the plume seen on the western end of Prometheus is similar to this Hawaiian steam plume, except the Ionian plume is composed largely of sulfur dioxide and rises much higher because of Io's low atmospheric density and gravity.

Another Io flyby, this time at an altitude of 300 kilometers (186 miles), is planned for November 25 at 8:40 p.m. Pacific Time (11:40 p.m. Eastern Time). (Times given are in Earth-received time -- or the time when the signal of the event is received on Earth.) The Io flybys are challenging and risky, because Io lies in an area of intense radiation from Jupiter's radiation belts, and that radiation can harm spacecraft components. Because of the risk, the flybys were scheduled for the final portion of Galileo's extended mission.

Galileo sweeps over Io's volcanoes

Scientists hope Galileo will have flown through a volcanic plume

October 11, 1999 - BBC Online

At 0600 GMT on Monday, the Galileo spacecraft swept within a few hundred kilometres of Io, the innermost moon of Jupiter. It was its closest ever approach to this strange volcanic moon.

Galileo remained in contact with ground controllers at Nasa's Jet Propulsion Laboratory in California and appears to be making its science observations. If all goes as planned, it will return data to Earth over the coming weeks.

A volcano erupts on Io

Io is one of the wonders of the Solar System - a world like no other. About the same size as our Moon, it is covered in vast orange and yellow deposits of sulphur that give the world a unique appearance.

The sulphur is billowed hundreds of kilometres up into the sky by at least a dozen active volcanoes, making Io the most volcanically-active world in the Solar System.

As well as the active vents scattered over its surface, there are extensive frozen plains, mountain ranges and volcanic rings the size of England.

Io's activity comes from a gravitational tug-of-war with mighty Jupiter.

Jupiter's gravity raises tides in Io that are trying to drive the world further away from the giant planet. But Io is locked in place by the gravity of Jupiter's three other main moons.

The result is a massive input of energy into the world that becomes heat inside it providing the volcanic energy.

In 1979, the Voyager spaceprobe that flew through the system detected these alien volcanoes. More recently, the Hubble Space Telescope has been able to observe plumes above them.

Galileo arrived at Jupiter in december 1995

It is the first time that Galileo has flown so close to Io. Until now the closest images taken of the volcanic moon were from a distance of 129,000 km (80,000 miles).

When Galileo passes within 600 km (380 miles), objects as small as 12 metres (40 feet) will be visible.

Successive images of volcanic activity in the Pillan Patera region

A second Io flyby is planned for 25 November as the finale to Galileo's two-year, extended mission orbiting Jupiter.

Galileo reached Jupiter in December 1995, entering orbit and dropping a probe into the Jovian atmosphere. It completed its main mission in December 1997 and then began its current extended mission.

Engineers hope that it will go on, if it survives the intense radiation field around Io. Its fuel will run out towards the end of next year but before that it will be moved into a wide circular orbit around Jupiter where its sensors could continue working for many years.

Mars experienced a period of volcanic activity that peaked a few billion years ago. The planet has the largest volcano in the solar system, Olympus Mons. At a height of 17 miles (27 kilometers), the volcano is three times higher than Earth's Mount Everest and covers an area the size of the state of Arizona. It sits on the Tharsis Plateau, a broad, elevated plain dotted with large volcanoes and fractures. The largest fracture system is Valles Marineris, a huge valley about 2,500 miles (4,000 kilometers) long and varying from 21/2 to 6 miles (4 to 10 kilometers) in depth. The Tharsis Plateau may have been formed by a rising plume of hot mantle material, but no plate-tectonic activity accompanied this process--the Martian surface consists of a single plate. Other regions on Mars include smooth plains, densely cratered areas, mesas, and rolling hills formed by various combinations of fracturing, volcanism, and atmospheric-related erosion and deposition.