Glossary - L
L band
frequency range from 0.5 to 1.5 GHz
(communications)
Large Magellanic Cloud (LMC)
the larger of two small satellite galaxies which orbit the Milky Way; only visible from the southern hemisphere
(astronomy)
Latitude
the angle from the plane of the equator, measured from the centre of the Earth, of a location on the surface of the Earth
(orbital geometry)
Launcher
rocket designed to lift one or more spacecraft from the surface of the Earth into space (usually into orbit)
(launcher technology)
Launcher adapter
the structure which is used to attach one or more spacecraft to the top of the launcher
(launcher technology)
Life support system
a system designed to maintain the environment in a spacecraft or spacesuit so that it is comfortable for human crew members by controlling atmospheric composition and pressure, temperature and humidity, managing waste and the supply of drinkable water, as well as fire detection and suppression
(human spaceflight)
Liftoff
the moment a launcher or spacecraft leaves a launchpad or planetary surface and begins its flight
(launcher technology, spacecraft technology)
Light time
the time it takes electromagnetic radiation to travel a given distance at light speed
(physics)
Light year
the distance travelled by light in one year (about 63,197 au or 9.46 x 106 km)
(astronomy)
Link budget
standard way of calculating the performance that can be achieved by a particular link, for example from an earth station, through a satellite to a second earth station
(communications)
Liquid propellant
the liquid fuel and oxidiser used in most rockets; liquid propellants are generally classified as being "storable" which can be stored at room temperature or "cryogenic" which are liquefied gases; examples are: storable fuels - UDMH and hydrazine, cryogenic fuels - liquid hydrogen (LH2), storable oxidiser - nitrogen tetroxide, cryogenic oxidiser - liquid oxygen (LOX)
(launcher technology)
Little LEO
low earth orbit satellite for only data communications
(orbits)
Longitude
the angle from the plane of the Greenwich meridian (the International Reference Meridian), measured from the centre of the Earth along the equator towards the East, of a plane containing the Earth’s axis of rotation and a location on the surface of the Earth
(orbital geometry)
Low Earth Orbit (LEO)
an orbit of altitude between 200 and 1000 km above the Earth
(orbits)
Low Noise Amplifier (LNA)
a preamplifier, generally located as near to the antenna feed as possible, which has a very low noise figure and which is used to boost the receive signal level for transmission across the site to the receiver(s); ensures that signals are received with the minimum of additional noise
(communications, spacecraft technology, earth station technology)
Low noise block downconverter
a combined low noise amplifier and downconverter in a single device which is mounted on an antenna feed
(earth station technology)
Lunar Gateway
a space station planned as part of the Artemis program which will be placed in lunar orbit which is intended to be used as a staging post for astronauts travelling to and from the lunar surface, a communications hub, an orbiting science laboratory and as a holding area for lunar rovers and robots
(human spaceflight, space exploration)
