Data Collected On Venus Suggest The Planet Is Volcanically Active

There may be significant volcanic activity on Venus based on a recent study of data gathered there more than 30 years ago.

Volcanic Lava In Venus

Two regions with a volcanic lava flow have been discovered by an Italian study team led by David Sulcanese of the Università d'Annunzio in Pescara, Italy, using data from a radar scan of Venus's surface obtained in the early 1990s.

The finding supports earlier indirect evidence that there is volcanic activity on Venus by indicating that it may be more broad and active than previously believed.

Venus is tagged as "Earth's twin sister." Its surface bakes at roughly 465°C (870°F), despite being only slightly smaller than Earth due to the huge greenhouse effect caused by its CO2-dominated atmosphere.

Venus's surface and atmosphere were probably similar to Earth's billions of years ago in that they both contained liquid water, but the planet's temperature was so high due to volcanic activity and the sun's constant brightness that all of the water was evaporated, creating a runaway greenhouse effect.

The planet is dried out today, scorching hot and almost lifeless, encircled by thick sulfuric acid clouds.

Launched from NASA's space shuttle in 1989, the Magellan spacecraft orbited Venus between 1990 and 1992 carrying a variety of scientific instruments, descending as low as 295 km above the planet's surface.

The researchers adjusted backscatter for various viewing angles and compared Magellan's first cycle of radar scans, which was taken from January to September 1992 [Earth time], to the third cycle, which was taken from September 1990 to May 1991, both of which had a mean resolution of 150 meters.

While the second scan cycle approached from the right, the first two cycles had a left-view angle from the satellite.

The first area includes lava flow characteristics on the western flank of Sif Mons, a low-profile shield volcano on Venus that is located at 22° north latitude and resembles a flat shield in profile. The second area was the western portion of Niobe Planitia, which is located at a similar latitude of 21° north. It is distinguished by its level topography, numerous shield volcanoes, and volcanic debris associated with shields.

The group notes that their "best interpretation" of the observations is that Venus's surface scattering properties, such as its composition and roughness, changed between the first and third scan cycles, or roughly 16 months apart, after looking into a wide range of alternative scenarios.

They write that the new lava flows that occurred during the Magellan expedition most likely account for the altered features that were noticed.

"Our study covered only about 16% of Venus's surface due to the limitation of comparing images from just the two left-look cycles," said lead author Sulcanese, who works at his university's International Research School of Planetary Sciences.

Volcanic Activity

This discovery validates earlier research that deduced recent volcanic activity on Venus through indirect evidence, including variations in sulfuric acid levels in the atmosphere, shifts in thermal emissivity data (a measure of an area's capacity to emit electromagnetic radiation, primarily infrared), and morphological examination of features on the surface that resemble volcanoes.

Venus is known to experience up to 42 volcanic eruptions annually, of which 20 are thought to last longer than 1,000 Earth days. This current analysis suggests that there could be as many as 120 distinct eruptions every Earth year.

By assuming that the flows' thickness falls between 3 and 20 meters, using the regions' reported flow areas, and known terrestrial values, estimates of the volcanic flow rates were calculated for each of the two regions.

The greatest flow rates on Sif Mons are 25 km3/Earth-year and 38 km3/Earth-year, respectively, on Niobe Planitia. Venus may be more volcanically active than previously believed, with volcanic activity reaching the order of magnitude of Earth's based on the total of the greatest flow rates.