Space and Solar Definitions - T

TAU - Thousand AU Mission.

TCM - Trajectory Correction Maneuver, spacecraft propulsive maneuver.

TDM - Time-division multiplexing.

Termination shock - Shock at which the solar wind is thought to slow to subsonic speed, well inside the heleopause.

Terrestrial planet - One of the four inner Earth-like planets.

Three-way - Coherent communications mode wherein a DSS receives a downlink whose frequency is based upon the frequency of an uplink provided by another DSS.

THz - Terahertz (1012 Hz).

TLM - DSN Telemetry System. Also, telemetry data.

TMOD - PL's Telecommunications and Mission Operations Directorate.

TOS - Transfer Orbit Stage, upper stage.

Transducer - Device for changing one kind of energy into another, typically from heat, position, or pressure into a varying electrical voltage or vice-versa, such as a microphone or speaker.

Transponder - Electronic device which combines a transmitter and a receiver.

TRC - NASA's Teacher Resource Centers. Obsolete, now called Educator Resource Centers, ERC.

TRK - DSN Tracking System. Also, Tracking data.

TRM - Transmission Time, UTC Earth time of uplink.

True anomaly - The angular distance of a point in an orbit past the point of periapsis, measured in degrees.

TWNC - Two-Way Non-Coherent mode, in which a spacecraft's downlink is not based upon a received uplink from DSN.

Two-Ribbon Flare - A flare that has developed as a pair of bright strands (ribbons) on both sides of the main inversion ("neutral") line of the magnetic field of the active region.

Two-way - Communications mode consisting of downlink received from a spacecraft while uplink is being received at the spacecraft. See also coherent.

TWT - Traveling Wave Tube, downlink power amplifier in a spacecraft telecommunications subsystem, the final stage of amplification for downlink (same unit as TWTA).

TWTA - Traveling Wave Tube Amplifier, downlink power amplifier in a spacecraft telecommunications subsystem, the final stage of amplification for downlink (same unit as TWT).

TXR - DSN's DSCC Transmitter assembly.