First Spacecraft Orbit of Mercury

Abstract

After a 7.9‐billion‐kilometer flight since its launch on 3 August 2004—which included flybys of Earth, Venus, and Mercury—NASA's MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft entered a planned, highly elliptical orbit around the closest planet to our Sun on 17 March. Engineers in the mission operations center at the Johns Hopkins University Applied Physics Laboratory (JHU/APL) in Laurel, Md., which manages the mission for NASA, received radiometric signals indicating a successful orbit insertion at 9:10 P.M. local time. “Tonight we will have orbited the fifth planet in the solar system. This is a major accomplishment,” Ed Weiler, NASA assistant administrator for the Science Mission Directorate, said at a 17 March public forum at JHU/APL, noting that spacecraft have previously entered orbit around several other planets. “You only go into orbit for the first time around Mercury once in human history, and that is what was accomplished tonight.”