Sentence:  The direct evidence on the micrometeorite environment near the Earth is obtained from piezoelectric sensors ( essentially microphones ) and from wire gages ; these instruments are installed on rockets , satellites , and <WSD>space</WSD> probes . 
Meaning of the word marked with <WSD> tags:  a rocket-propelled guided missile that can escape the earth's atmosphere; makes observations of the solar system that cannot be made by terrestrial observation