A missionary is a member of a religion who works to convert those who do not share the missionary's faith; someone who proselytizes. The word "mission" is derived from the Latin missionem (nom. missio), meaning "act of sending" or mitto, mittere, literally meaning "to send" or "to dispatch," the equivalent of the Greek-derived word "apostle" from apostolos, meaning "messenger". In Christian cultures the term is most commonly used for Christian missions, but it applies equally to any proselytizing creed or ideology. Buddhism launched 'the first large-scale missionary effort in the history of the world's religions'.

Spaceflight is the use of space technology to fly a spacecraft into and through outer space.

Spaceflight is used in space exploration, and also in commercial activities like space tourism and satellite telecommunications. Additional non-commercial uses of spaceflight include space observatories, reconnaissance satellites and other earth observation satellites.

A spaceflight typically begins with a rocket launch, which provides the initial thrust to overcome the force of gravity and propels the spacecraft from the surface of the Earth. Once in space, the motion of a spacecraft -- both when unpropelled and when under propulsion -- is covered by the area of study called astrodynamics. Some spacecraft remain in space indefinitely, some disintegrate during atmospheric reentry, and others reach a planetary or lunar surface for landing or impact.

The Church of Jesus Christ of Latter-day Saints (LDS Church) is one of the most active modern practitioners of missionary work, with over 50,000 full-time missionaries worldwide. Commonly referred to as Mormon missionaries, most LDS Church missionaries are single young men and women in their early twenties and are assigned to a mission of the church that is usually far from the missionary's home. Mormon missionaries do not receive a salary for any of the work they undertake.