SCIENCE LAB SCULPTS : MARS

TRACK FROM QUAKES

The boulder of Mars may not be finished bouncing

If rock falls on Mars, and no one is there to see it, does it leave a trace? Yes, and it's a beautiful herringbone-like pattern, new research reveals.

Scientists have now spotted thousands of tracks created by tumbling boulders on the planet. Delicate chevron-shaped piles of Martian dust and sand from the tracks, the team showed, and most fade in a few years.

Such traces have been spotted elsewhere in the solar system. They have been spotted on the moon and even on a comet. But a big question is the timing of these rockfalls - are they going on now, or were they predominantly left in the past?

A study of these ephemeral features on Mars, published recently in Geophysical Research Letters, says that such boulder tracks can be used to pinpoint recent seismic activity.

The new evidence runs contrary to the notion that Mars is geologically inert, said Ingrid Daubar, a planetary scientist at Brown University who was not involved in the study.

''For a long time, we thought that Mars was this cold, dead planet.''

To arrive at this finding, Vijayan, a planetary scientist in Ahmedabad, India, who uses a single name, and his colleagues pored over thousands of images of Mar's equatorial region.

The imagery was captured from 2006 through 2020 by a camera onboard NASA's Mars Reconnaissance Orbiter.

Roughly one third of the tracks the researchers studied were absent in early images, meaning that they must have formed since 2006. [ Katherine Korne ]