Mach
Mach was a unit of measure to describe high speeds within an atmosphere. Mach 1 was equal to the speed of sound.

When the mining shuttle Nenebek passed through the atmosphere of Lambda Paz in preparation for a crash-landing in 2367, the crew had to manually trip the bypass from the main engine to the thrusters to maintain a controlled entry, which was performed when the shuttle had slowed to below Mach 1. ()

When the Sacajawea made its descent through the atmosphere of the Nezu colony planet in 2373, Tuvok noted that the Type 6 shuttlecraft was traveling at an altitude of fifteen kilometers, at a velocity of Mach 2.1. ()

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Measurements