"\"The surface gravity on Mars is only a little more than one third that of Earth's. It is not known if this level is high enough to prevent the health problems associated with weightlessness.\""@en . "\"The surface gravity on Mars is only a little more than one third that of Earth's. It is not known if this level is high enough to prevent the health problems associated with weightlessness.\""@en . . "Is there gravity on Mars"@en . . . . . .