Editing Spacecraft Event Time (section)

===Spacecraft control===

Since it takes time for a radio transmission to reach a spacecraft from [[Earth]], the usual operation of a spacecraft is controlled with an uploaded command script containing SCET markers to ensure a certain timeline of events. Because of the delay between the sending of instructions from Earth and their receipt and execution by the spacecraft, real-time commanding of robotic spacecraft is done rarely: usually only in response to an emergency event, when changes in spacecraft operations must be made as soon as possible.  For example, a spacecraft could be instructed to go into [[Safe mode (spacecraft)|safe mode]] to protect it during a [[Coronal mass ejection|coronal mass ejection (CME)]] from the [[Sun]].