From the days of the early explorers like Christopher Columbus and Magellan, there has always been an inherent desire in humanity to explore its surroundings. From the exploits of those early knowledge seekers, many incredible discoveries were made. So it was fitting and understandable that the first spacecraft launched by the Army Ballistic Missile Agency on Jan. 31, 1958 was named “Explorer”.
Since the first mission, more than 70 U.S. and cooperative international scientific space missions have been part of the much celebrated Explorer program. Explorer satellites have made impressive discoveries: Earth’s magnetosphere and the shape of its gravity field; the solar wind; properties of micrometeoroids raining down on the earth; much about ultraviolet, cosmic, and X-rays from the solar system and universe beyond; ionospheric physics; solar plasma; energetic particles; and atmospheric physics. These missions have also investigated air density, radio astronomy, geodesy, and gamma ray astronomy. Some Explorer spacecraft have even traveled to other planets, and some have monitored the Sun.
The mission of the Explorers program is to provide frequent flight opportunities for scientific investigations from space. The Explorers program enables the definition, development and implementation of mission concepts through a variety of modes to meet the need of the scientific community and the NASA space science enterprise.
The Explorers Program Office at Goddard Space Flight Center in Greenbelt, MD, provides management of the multiple scientific exploration missions in the Explorer space flight program. The missions are characterized by relatively moderate cost, and by small to medium sized missions that are capable of being built, tested and launched in a short time interval compared to the large observatories.