Embodiments of the present disclosure are directed to techniques for autonomously transitioning a spacecraft from a power-saving state to a power-consuming state at a time after launch of the spacecraft on a launch vehicle. Because the spacecraft can autonomously detect conditions for transitioning to the power-consuming state, commands received via an umbilical connection to the launch vehicle, or detecting the presence or absence of such a connection, is unnecessary, thereby removing several technical barriers to eliminating such umbilical connections altogether. In some embodiments, low-cost vacuum detection devices that use very small amounts of power may be used by the spacecraft to detect when the spacecraft has reached an altitude suitable for transitioning to the power-consuming state.