Technology glossary

Radioisotope Thermoelectric Generator (RTG)

A device that converts the heat released by the natural radioactive decay of a material, such as plutonium-238, directly into electricity, with no moving parts. Spacecraft traveling far from the Sun, such as Voyager 1 and 2 and other outer-planet missions, rely on RTGs because solar panels become impractical at those distances. Output declines gradually each year as the radioactive fuel decays.

Raman Spectroscopy

An analytical technique that identifies molecules and materials by measuring how monochromatic light, usually from a laser, changes energy when scattered by molecular vibrations. It can provide a chemical fingerprint with little sample preparation and may be used microscopically.

Randomized Controlled Trial(RCT)

A study in which participants are assigned by chance to an intervention group or one or more comparison groups. Randomization helps balance known and unknown confounding factors, making differences in outcomes more credibly attributable to the intervention when the trial is well designed and conducted.

RAS Inhibitor

A drug designed to block signaling driven by RAS proteins or specific mutated forms such as KRAS. Because abnormal RAS signaling promotes growth in many cancers, inhibitors can slow selected tumors, but effectiveness depends on the exact mutation, cancer type, resistance mechanisms, and treatment combination.

Reaction Latency

Reaction latency is the elapsed time between detecting a relevant change or event and producing the corresponding system response. In robotics, it includes sensing, inference, communication, and actuation delays.

Real-Time Decision Support

A system that analyzes current or rapidly arriving data and presents timely information, predictions, or recommendations to help a person make a decision. It supports human judgment rather than necessarily making the final decision automatically.

Real-Time Kinematic Positioning(RTK)

Real-Time Kinematic positioning (RTK) uses carrier-phase satellite measurements plus corrections from a reference station or network to achieve centimetre-level positioning, widely used in surveying, construction, agriculture and autonomous machines.

Real-Time Rendering

The generation of visual frames quickly enough to respond interactively to user input or changing data. It is used in games, simulations, design tools, and extended reality, where each frame must typically be produced within milliseconds.

Real-World Fuel Consumption

The amount of fuel a vehicle uses under actual driving conditions rather than in a standardized laboratory test. It varies with traffic, speed, weather, load, driving style, route, maintenance, and, for plug-in hybrids, how often the vehicle is charged.

Reasoning Model

A type of AI model designed to work through a problem step by step before producing a final answer, rather than generating an instant response.

Reasoning Trace

A sequence of intermediate computational or textual steps associated with how an AI model reaches an output, distinct from the final answer shown to a user.

Rebound Effect

A market or behavioral response in which an efficiency improvement lowers the cost of a service and encourages greater use, offsetting some or all of the expected resource or emissions saving.

Receiver Autonomous Integrity Monitoring(RAIM)

Receiver Autonomous Integrity Monitoring (RAIM) is a technique in which a GNSS receiver uses redundant satellite measurements to check whether its navigation solution is internally consistent and to detect certain faulty measurements.

Recombinant Spider Silk

Spider-silk proteins produced using engineered cells rather than harvested from spiders.

Reconfigurable Electronics

Electronic systems whose physical arrangement, electrical behavior, or computational function can be changed after fabrication. Reconfiguration may use software, programmable circuits, movable components, or materials that respond to external stimuli.

Recurrence-free survival(RFS)

A clinical-trial endpoint measuring the time after treatment during which a patient remains alive without the cancer returning. It does not necessarily show that a treatment extends overall survival, which counts death from any cause.

Regolith

The loose layer of dust, broken rock, and soil covering the solid bedrock of a planet, moon, or asteroid. On the Moon, regolith was formed by billions of years of meteorite impacts and can trap ice in permanently shadowed, extremely cold regions near the poles.

Relativistic Correction

A relativistic correction accounts for differences in clock rates caused by satellite speed and weaker gravity at orbital altitude. GPS must correct for effects predicted by special and general relativity or positioning errors would accumulate rapidly.

Remote Assistance

Human support provided from a control centre to help an autonomous vehicle interpret an unusual situation without directly driving it continuously.

Remote Code Execution(RCE)

A security impact in which an attacker can make a target computer or service run commands or program code from a remote location. The required access and consequences vary by vulnerability; unauthenticated remote code execution is especially severe because an attacker may not need a valid account.

Remotely Operated Vehicle(ROV)

An underwater robot controlled by operators through a tether or communication link.

Renewable Methanol

Methanol made with renewable energy and non-fossil carbon, commonly by reacting clean hydrogen with carbon dioxide captured from air, biomass or industrial sources.

Reservoir Engineering

In quantum science, the deliberate design of a system's surrounding environment, or reservoir, to control dissipation, decoherence, and steady states. By tailoring these interactions, researchers can prepare, protect, or manipulate quantum states.

Resiquimod(R848)

An experimental immune-stimulating compound that activates Toll-like receptors 7 and 8 and is studied as a way to shift innate immune cells toward a more inflammatory response.

Retainer Sacrifice

The deliberate killing and burial of attendants, officials or servants in connection with the death and funeral of a ruler or elite person.

Retinal Prosthesis

An implanted visual device that stimulates retinal cells to provide limited artificial vision.

Retrieval-Augmented Generation(RAG)

A method that searches a selected collection of documents for relevant passages and supplies them to a generative model as context before it produces an answer.

Reusable Launch Vehicle(RLV)

A rocket designed so that part of it, usually the first stage or booster, can return to Earth intact after launch and fly again on a later mission, instead of being discarded. Reusability can cut launch costs because the same hardware carries multiple payloads over its lifetime.

Robot Interoperability

The ability of software, tools and control systems to work across robots from different manufacturers or with different hardware.

Robot-Assisted Bronchoscopy

A physician-controlled procedure that uses robotic navigation to guide a flexible bronchoscope and biopsy tools through branching airways toward small or difficult lung lesions.