London: New images from MESSENGER, the first spacecraft to orbit Mercury, support proposal for water ice near the planet’s south pole.
Two decades ago, radio telescope observations showed radar-bright features in Mercury’s polar regions.
The radar characteristics are similar to those of the icy satellites of Jupiter and at the south polar ice cap on Mars.
The radar-bright spots on Mercury were therefore believed to be water ice, and now images from MESSENGER provide new support for this idea.
MESSENGER has provided a view of Mercury’s south polar terrain over a full Mercury day that makes it possible to identify areas in permanent shadow.
Nancy L. Chabot of Johns Hopkins University Applied Physics Laboratory, Laurel, Maryland, USA and her team compared the MESSENGER images of craters in the south pole region with the distribution of radar-bright features from previous radio telescope studies.
They find that the radar-bright areas do correspond to areas in permanent shadow in the new images.
The researchers also applied thermal models to confirm that water ice could be stable in these craters if the ice is insulated by a thin covering layer of regolith.
The study supports the hypothesis that Mercury’s south polar region contains deposits of water ice in permanently shadowed craters.