Instruments may record characteristics of phenomena close at hand, as with polarimetry; or at greater distances with remote-sensing instruments like radar imaging. These latter tools typically create images by analyzing round-trip times of radio signals reflected from objects.
Spacecraft are vehicles specifically designed to travel in and operate in outer space. Their complexity often depends on their mission objectives; typically manned or unmanned spacecraft may vary greatly in terms of complexity. Spacecraft are used for observation, meteorology, navigation and planetary exploration. Most require launch vehicles (carrier rockets) in order to reach space.
Spacecraft subsystems typically include attitude determination and control; navigation and guidance; communication; power; thermal control; structures and payload. Their selection generally depends on mission profile – for instance deep-space probes like Galileo and Cassini have thermoelectric generators which convert plutonium fuel heat emissions into electricity for powering their radioisotope thermoelectric generators – battery storage may also provide backup energy supply if necessary.
An onboard computer is responsible for overseeing overall spacecraft operations and management. It maintains timekeeping, interprets Earth commands, collects telemetry data for transmission back home, manages high-level fault protection protocols and safeguarding routines and is often referred to as the command and control system (CCS or C&DH).
Spacecraft use various telecommunications components that are selected based on anticipated distance, frequency bands, and transmitter power availability. A high-gain antenna is often utilized to communicate directly with Earth from interplanetary spacecraft.
Spacecraft are designed to meet their mission requirements in terms of shape and form; for instance, a space capsule or winged spaceplane. Their shape must match up with their chosen method for reentry into Earth’s atmosphere for either powered descent or parachute-aided glide. A manned spacecraft must also contain life support systems designed to maintain crew member health and comfort; these are usually housed within pressurized crew compartments and include subsystems like oxygen supply, drinking water supply, waste processing facilities, temperature regulation systems as well as ventilation controls.