Technology glossary

Lunar Hopper

A robotic lunar vehicle that moves by making controlled powered hops rather than relying only on wheels. This allows it to cross steep crater rims or rough terrain that conventional rovers may not reach.

Lunar Ice Prospecting

The use of orbital or surface measurements to locate, estimate and characterize possible water-ice deposits on the Moon.

Lunar Impact Ejecta

Dust, soil and rock thrown away from the lunar surface when an object strikes it. The height, speed and distribution of this material help scientists estimate the impact energy and properties of the Moon's upper layers.

Lunar Regolith

The loose layer of dust, broken rock and impact debris that covers the Moon's solid bedrock.

M-Code(M-Code)

M-Code is an encrypted military GPS signal designed to improve security, power and resistance to jamming for authorized users. Modern GPS satellites, including GPS III, broadcast M-Code alongside civilian signals.

Machine-Readable Mark

Metadata, a watermark, a cryptographic signal or another technical indicator that software can detect to identify content as artificially generated or manipulated. It differs from a visible disclosure intended primarily for a human viewer.

Macrophage

An immune cell that engulfs microbes, damaged cells and other material.

Magnetic Transistor

A transistor that uses magnetic states or spin-dependent behavior to switch or store information.

Magnetoelectric Nanoparticle

A nanoscale material that can convert magnetic stimulation into a local electrical effect.

Magnetoencephalography(MEG)

A non-invasive technique that records the extremely small magnetic fields produced by synchronized neural activity. It offers high temporal resolution but usually requires sensitive, expensive equipment and a magnetically shielded environment.

Magnetoplasmadynamic Thruster(MPD thruster)

An electric spacecraft thruster that uses electric current and magnetic fields to accelerate an ionized gas, or plasma, and produce thrust. It can offer high exhaust velocity and potentially high power, but requires substantial electrical energy and faces electrode-lifetime and thermal challenges.

Magnon Polariton

A hybrid excitation formed when a magnetic spin wave strongly couples with an electromagnetic mode inside a resonator.

Main Engine Cutoff(MECO)

The commanded shutdown of a rocket stage's main engines after they have completed their planned burn. It normally occurs before stage separation and does not by itself mean the vehicle has reached orbit.

Mandrel

A temporary form around which another material is shaped, deposited or wound before the form is removed.

Marginal Ice Zone

The narrow transitional band where open ocean meets melting sea ice, marked by high biological and chemical activity compared with surrounding areas.

Marine Heatwave

A prolonged period when ocean temperatures remain unusually high relative to the normal range for a place and season. Marine heatwaves can disrupt ecosystems, trigger coral bleaching and increase mortality when they are intense or persistent.

Market Data Feed

A structured stream of prices, events, or other information supplied to financial systems and market participants.

Marketing Granted Order(MGO)

An FDA order allowing a specific tobacco product to be marketed after premarket review; it is not a declaration that the product is safe or approved as medicine.

Marketplace Listing Audit

A structured review of product listings to identify inconsistent, missing or potentially misleading information. A credible audit defines its sample, testing procedure and decision criteria, and distinguishes a warning signal from a confirmed violation.

Martensitic Transformation

A diffusionless change between crystal structures in which atoms shift cooperatively, enabling shape-memory and elastocaloric behavior.

Mathematical Construction

An explicit method for creating a mathematical object that satisfies specified properties, using a finite procedure, formula, algorithm, geometric steps, or proof of existence with defined ingredients. A construction provides more information than merely asserting that the object exists.

Maximum Dynamic Pressure(Max Q)

The point during atmospheric flight when a vehicle experiences its greatest aerodynamic load. It occurs when increasing speed and decreasing air density combine to produce the highest dynamic pressure, so rockets often reduce thrust around this phase.

Mechanical Emergency Release

A physical lever, cable or handle that opens a latch without depending on the vehicle's electrical system. Its location and operation must be obvious enough for occupants or rescuers to use quickly after a crash.

Mechanosensing

The ability of a cell, material or device to detect force, pressure or deformation.

Median Overall Survival(mOS)

The time from a defined starting point at which half the participants in a study are still alive and half have died. It describes the middle of the observed survival distribution, not how long every person will live.

Mediation Analysis

A statistical method that estimates whether part of an association between an exposure and an outcome may operate through an intermediate variable. It does not by itself prove the causal pathway.

Medium Earth Orbit(MEO)

Medium Earth Orbit (MEO) is the region of space between low Earth orbit and geostationary orbit. GPS and several other global navigation constellations operate in MEO, balancing broad coverage with manageable signal travel time.

Mesophotic Coral Ecosystem

A light-dependent coral ecosystem found below shallow reefs, typically at depths where sunlight is limited but still present.

Messenger RNA Vaccine(mRNA vaccine)

A vaccine that delivers messenger RNA instructions prompting cells to temporarily produce an antigen, which trains the immune system to recognize a target. The mRNA does not need to enter the cell nucleus and is broken down after delivering its instructions.

Meteorite Contamination Control

Procedures used to prevent, measure, and document the introduction of terrestrial material into a meteorite sample during recovery, handling, storage, and analysis. Controls can include clean tools, protective packaging, environmental blanks, chain-of-custody records, and comparisons with local soil or air.