Tonga’s huge blast

How the Tonga eruption is helping space scientists to understand Mars

NASA scientists say that the eruption of a submarine volcano in Tonga is helping them to understand how certain features formed on the surfaces of Mars and Venus.

The unusual explosion of the Hunga Tonga–Hunga Ha‘apai volcano has been calculated at more than 500 times the force of the atom bomb dropped on Hiroshima, Japan, in 1945.

Studying the volcano and its evolution in recent weeks is “important for planetary science”, says Petr Brož, a planetary volcanologist at the Institute of Geophysics of the Czech Academy of Sciences in Prague. The knowledge “might help us to reveal results of water–lava interactions on the red planet and elsewhere across the Solar System”, he says.

The volcanic island, which began to form from ash and lava expelled from an undersea volcano in early 2015, piqued the interest of researchers including James Garvin, chief scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, because of its similarity to structures on Mars and possibly Venus. “We don’t normally get to see islands form,” explains Garvin, but this one offered “a front-row seat”.

Volcanic islands typically last for just months before being eroded away. But Hunga Tonga–Hunga Ha‘apai survived for years, allowing Garvin’s team to use satellite observations and sea-floor surveys to study how such islands form, erode and persist. The researchers wanted to use that knowledge to understand how small conical volcanoes found on Mars might have formed in the presence of water billions of years ago.

Many volcanoes on Mars are thought to have erupted with steady flows of lava, but some could have been explosive, like Hunga Tonga–Hunga Ha‘apai, says Joseph Michalski, a planetary scientist at the University of Hong Kong.

The marine environment also mimics some aspects of the low-gravity settings on small planets such as Mars and “can shed unique light on Martian features that formed in lower gravity”, he adds. A