Glossary

The volume of space between Earth and the Moon — increasingly contested operational space as lunar programs scale.

An orbit at ~35,786 km altitude where a satellite's period matches Earth's rotation, so it appears stationary above one longitude.

Orbits below roughly 2,000 km altitude; where most communications, Earth-observation, and human spaceflight occur.

The altitude band between LEO and GEO — roughly 2,000–35,786 km — most famous as the home of GPS and other GNSS constellations.

A near-polar LEO inclined so the satellite passes over each part of Earth at the same local solar time every orbit.

Orbits below ~450 km where atmospheric drag is significant; emerging for high-resolution imaging and low-latency comms.

Missions that capture and de-orbit existing debris objects — defunct satellites, spent stages — to reduce collision risk in LEO.

A standardized small-satellite form factor built from 10 cm × 10 cm × 10 cm units (1U).

Satellite links that talk to unmodified handheld phones directly, without ground gateways or special antennas.

Thrusters that ionize propellant and accelerate it electrostatically or electromagnetically — high specific impulse, low thrust.

Imaging across hundreds of narrow, contiguous spectral bands so each pixel has a full reflectance spectrum — enabling material identification.

On-orbit operations that refuel, upgrade, repair, assemble, or build spacecraft — extending lifetimes and enabling larger structures than any rocket fairing.

Using local resources — lunar ice, regolith, Mars CO₂ — instead of shipping everything from Earth.

A satellite constellation of hundreds to tens of thousands of spacecraft providing global coverage, typically in LEO.

Free-space optical links between satellites, replacing RF cross-links with higher-bandwidth, harder-to-jam laser communications.

Launch vehicles where some or all stages return for refurbishment and reflight, dropping marginal launch cost.

A launch arrangement where multiple customer payloads share a single rocket — the dominant cost-per-kg path for SmallSats.

An active radar imaging technique that synthesizes a large antenna aperture from the satellite's motion to produce high-resolution images day or night, through clouds.

The base spacecraft platform — power, propulsion, attitude control, comms — onto which mission payloads bolt.

Satellites under ~500 kg — the size class that drove the post-2015 commercial space boom.

Imaging or sensing the Earth from orbit — optical, SAR, hyperspectral, RF, GNSS-RO — for commercial, government, and scientific use.

Low-bandwidth, low-power satellite connectivity for sensors, asset trackers, and remote machinery — the M2M layer of space.

Tracking objects in orbit, characterizing their behavior, and forecasting collisions — the air-traffic-control layer for space.

NASA's program to return humans to the Moon and establish a sustained presence — the anchor demand-pull for cislunar industry.

NASA's commercial program that buys lunar surface delivery as a service from a pool of pre-qualified providers.

A commercial service that captures and lowers a defunct satellite to controlled atmospheric re-entry — meeting end-of-life regulations.

A secondary payload that flies as a passenger on someone else's satellite — typically a commercial bus carrying a government or partner sensor.

Transferring propellant to a satellite in orbit so it can extend its mission, change orbits, or perform high-Δv maneuvers.