WASHINGTON, April 30 (UPI) -- Data from a U.S. space agency probe flying over Mercury's surface suggest the planet has greater levels of activity that scientists suspected.
The National Aeronautics and Space Administration's Mercury Surface, Space Environment, Geochemistry and Ranging spacecraft, known as Messenger, has measured the planet's atmosphere, the interaction of its surrounding magnetic field with the solar wind, and its geological past. The probe also discovered a previously unknown impact basin about 430 miles in diameter.