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.

WASHINGTON, Oct. 29 (UPI) -- A U.S. spacecraft has, for the second time this year, transmitted data about previously unseen areas of Mercury.

WASHINGTON, Oct. 1 (UPI) -- The U.S. space agency says its Messenger spacecraft will make the second of three flybys of Mercury next week to collect more science data.

GREENBELT, Md., July 3 (UPI) -- The U.S. space agency says it has determined Mercury's smooth plains were produced by volcanoes and its magnetic field is produced in the planet's core.

BALTIMORE, Jan. 14 (UPI) -- For the first time in 33 years, a space probe Monday zipped close to Mercury, snapping photos as it went by.

LAUREL, Md., Aug. 2 (UPI) -- NASA's Messenger spacecraft swung by Earth for a Tuesday gravity assist that propelled it deeper into space on its long journey toward Mercury.

WASHINGTON, May 5 (UPI) -- A series by UPI examining the human exploration of space. This week: The turf war between engineers and scientists over government funding erupted again last week with the release of an interim National Research Council report criticizing NASA for canceli

WASHINGTON, Aug. 4 (UPI) -- Given everything known about planetary geology, atmospheric chemistry and biology, there is almost no chance the planet Mercury harbors any kind of life. Yet on Tuesday, NASA launched -- within a window that lasted only 12 seconds -- its MESSENGER spacecr

CAPE CANAVERAL, Fla., Aug. 3 (UPI) -- After a 24-hour weather delay, the United States launched its Messenger spacecraft early Tuesday from Florida on its 7-year mission to explore Mercury.