Difference between sub-orbital and orbital spaceflights

There sometimes appears to be confusion among the general public about the difference between sub-orbital and orbital spaceflights. This article is an attempt to clarify this issue. It also elaborates on the technical implications of the differences between orbital and sub-orbital spaceflights.

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A spaceflight is a flight into or through space. The craft which undertakes a spaceflight is called a spacecraft.

Related Topics:
Spaceflight - Flight - Space - Spacecraft

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The general public often thinks of orbital spaceflights as spaceflights and of sub-orbital spaceflights as "something less than actual spaceflights". This is not accurate; both orbital and sub-orbital spaceflights are true spaceflights.

Related Topics:
Orbital spaceflight - Sub-orbital spaceflight

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Strictly speaking, the term orbit means any trajectory in general. In common usage the term orbit refers to a closed trajectory around the Earth (or another central body). The term sub-orbital refers to a trajectory which intersects the central body before a complete orbit is achieved. An orbital spaceflight is one which completes an orbit fully around the central body.

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For a flight from Earth to be a spaceflight, the spacecraft has to ascend from Earth and at the very least go past the edge of space. The edge of space is, for the purpose of space flight, often accepted to lie at a height of 100 km (62 miles) above mean sea level.

Related Topics:
Edge of space - Sea level

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Any flight that goes higher than that is by definition a spaceflight. Where the Earth's atmosphere ends space begins but the atmosphere fades out gradually so the precise boundary is difficult to ascertain - hence the need for an arbitrary altitude for the edge of space.

Related Topics:
Earth's atmosphere - Edge of space

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