Posted: Fri, Mar 7, 2003, 10:38 AM ET (1538 GMT)
Planetary scientists reported Thursday that they believe the planet Mars has a molten core like the Earth and Venus, a discovery that could mean the planet is more geologically active than once thought. JPL scientists closely watched the orbit of the Mars Global Surveyor spacecraft as solid-body tides caused by the Sun made minute changes in the spacecraft's orbit. The planet's tidal bulge is large enough, they found, that the planet's core must be at least partially liquid and not completely solid, as some scientists believed. That data, combined with archived data from the Mars Pathfinder mission, also showed that the planet's core is about half the size of the planet itself, similar to the Earth and Venus, and also contains some lighter elements, such as sulfur, in addition to heavier elements like iron. A liquid core could provide an internal heat source for volcanic activity and keep subterranean deposits of water from freezing.

Related Links:

•  NASA press release
•  New York Times article
•  SPACE.com article