A space safety apparatus monitoring a volume of space encompassing a field of view (FOV) for detecting an intrusion including a gas or vapor, and includes a micro-electro-mechanical system (MEMS) having mirror elements in a mirror array for reflecting infra-red (IR) energy beam collected from the FOV and an IR energy detector for detecting the IR energy reflected by the MEMS array and converting the IR energy to an output signal. A processor adjusts an angle of an element of the MEMS mirror array by varying a control signal, or by switching from one to another focusing element. The method includes detection in a volume of space by positioning a MEMS mirror array to reflect IR signal with respect to active elements of an IR detector; and collecting IR energy from an i.sup.th portion of the FOV.