Glossary

ablation

removal of the outer layers of an object by erosion, melting, or vaporization

abort-to-orbit

emergency procedure planned for the space shuttle and other spacecraft if the spacecraft reaches a lower than planned orbit

accretion

the growth of a star or planet through the accumulation of material from a companion star or the surrounding interstellar matter

adaptive optics

the use of computers to adjust the shape of a telescope's optical system to compensate for gravity or temperature variations

aeroballistic

describes the combined aerodynamics and ballistics of an object, such as a spacecraft, in flight

aerobraking

the technique of using a planet's atmosphere to slow down an incoming spacecraft; its use requires the spacecraft to have a heat shield, because the friction that slows the craft is turned into intense heat

aerodynamic heating

heating of the exterior skin of a spacecraft, aircraft, or other object moving at high speed through the atmosphere

Agena

a multipurpose rocket designed to perform ascent, precision orbit injection, and missions from low Earth orbit to interplanetary space; also served as a docking target for the Gemini spacecraft

algae

simple photosynthetic organisms, often aquatic

alpha proton X-ray

analytical instrument that bombards a sample with alpha particles (consisting of two protons and two neutrons); the X rays are generated through the interaction of the alpha particles and the sample

altimeter

an instrument designed to measure altitude above sea level

amplitude

the height of a wave or other oscillation; the range or extent of a process or phenomenon

angular momentum

the angular equivalent of linear momentum; the product of angular velocity and moment of inertia (moment of inertia = mass × radius²)

angular velocity

the rotational speed of an object, usually measured in radians per second

anisotropy

a quantity that is different when measured in different directions or along different axes

annular

ring-like

anomalies

phenomena that are different from what is expected

anorthosite

a light-colored rock composed mainly of the mineral feldspar (an aluminum silicate); commonly occurs in the crusts of Earth and the Moon

anthropocentrism

valuing humans above all else

antimatter

matter composed of antiparticles, such as positrons and antiprotons

antipodal

at the opposite pole; two points on a planet that are diametrically opposite

aperture

an opening, door, or hatch

aphelion

the point in an object's orbit that is farthest from the Sun

Apollo

American program to land men on the Moon; Apollo 11, 12, 14, 15, 16, and 17 delivered twelve men to the lunar surface between 1969 and 1972 and returned them safely back to Earth

asthenosphere

the weaker portion of a planet's interior just below the rocky crust

astrometry

the measurement of the positions of stars on the sky

astronomical unit

the average distance between Earth and the Sun (152 million kilometers [93 million miles])

atmospheric probe

a separate piece of a spacecraft that is launched from it and separately enters the atmosphere of a planet on a one-way trip, making measurements until it hits a surface, burns up, or otherwise ends its mission

atmospheric refraction

the bending of sunlight or other light caused by the varying optical density of the atmosphere

atomic nucleus

the protons and neutrons that make up the core of an atom

atrophy

condition that involves withering, shrinking, or wasting away

auroras

atmospheric phenomena consisting of glowing bands or sheets of light in the sky caused by high-speed charged particles striking atoms in Earth's upper atmosphere

avionics

electronic equipment designed for use on aircraft, spacecraft, and missiles

azimuth

horizontal angular distance from true north measured clockwise from true north (e.g., if North = 0 degrees; East = 90 degrees; South = 180 degrees; West = 270 degrees)

ballast

heavy substance used to increase the stability of a vehicle

ballistic

the path of an object in unpowered flight; the path of a spacecraft after the engines have shut down

basalt

a dark, volcanic rock with abundant iron and magnesium and relatively low silica common on all of the terrestrial planets

base load

the minimum amount of energy needed for a power grid

beacon signal generator

a radio transmitter emitting signals for guidance or for showing location

berth space

the human accommodations needed by a space station, cargo ship, or other vessel

Big Bang

name given by astronomers to the event marking the beginning of the universe when all matter and energy came into being

biocentric

notion that all living organisms have intrinsic value

biogenic

resulting from the actions of living organisms; or, necessary for life

bioregenerative

referring to a life support system in which biological processes are used; physiochemical and/or nonregenerative processes may also be used

biosignatures

the unique traces left in the geological record by living organisms

biosphere

the interaction of living organisms on a global scale

bipolar outflow

jets of material (gas and dust) flowing away from a central object (e.g., a protostar) in opposite directions

bitumen

a thick, almost solid form of hydrocarbons, often mixed with other minerals

black holes

objects so massive for their size that their gravitational pull prevents everything, even light, from escaping

bone mineral density

the mass of minerals, mostly calcium, in a given volume of bone

breccia

mixed rock composed of fragments of different rock types; formed by the shock and heat of meteorite impacts

bright rays

lines of lighter material visible on the surface of a body and caused by relatively recent impacts

brown dwarf

star-like object less massive than 0.08 times the mass of the Sun, which cannot undergo thermonuclear process to generate its own luminosity

calderas

the bowl-shaped crater at the top of a volcano caused by the collapse of the central part of the volcano

Callisto

one of the four large moons of Jupiter; named for one of the Greek nymphs

Caloris basin

the largest (1,300 kilometers [806 miles] in diameter) well-preserved impact basin on Mercury viewed by Mariner 10

capsule

a closed compartment designed to hold and protect humans, instruments, and/or equipment, as in a spacecraft

carbon-fiber composites

combinations of carbon fibers with other materials such as resins or ceramics; carbon fiber composites are strong and lightweight

carbonaceous meteorites

the rarest kind of meteorites, they contain a high percentage of carbon and carbon-rich compounds

carbonate

a class of minerals, such as chalk and limestone, formed by carbon dioxide reacting in water

cartographic

relating to the making of maps

Cassini mission

a robotic spacecraft mission to the planet Saturn scheduled to arrive in July 2004 when the Huygens probe will be dropped into Titan's atmosphere while the Cassini spacecraft studies the planet

catalyst

a chemical compound that accelerates a chemical reaction without itself being used up; any process that acts to accelerate change in a system

catalyze

to change by the use of a catalyst

cell culture

a means of growing mammalian (including human) cells in the research laboratory under defined experimental conditions

cellular array

the three-dimensional placement of cells within a tissue

centrifugal

directed away from the center through spinning

centrifuge

a device that uses centrifugal force caused by spinning to simulate gravity

Cepheid variables

a class of variable stars whose luminosity is related to their period. Their periods can range from a few hours to about 100 days and the longer the period, the brighter the star

Ĉerenkov light

light emitted by a charged particle moving through a medium, such as air or water, at a velocity greater than the phase velocity of light in that medium; usually a faint, eerie, bluish, optical glow

chassis

frame on which a vehicle is constructed

chondrite meteorites

a type of meteorite that contains spherical clumps of loosely consolidated minerals

cinder field

an area dominated by volcanic rock, especially the cinders ejected from explosive volcanoes

circadian rhythm

activities and bodily functions that recur every twenty-four hours, such as sleeping and eating

Clarke orbit

geostationary orbit; named after science fiction writer Arthur C. Clarke, who first realized the usefulness of this type of orbit for communication and weather satellites

coagulate

to cause to come together into a coherent mass

comet matrix material

the substances that form the nucleus of a comet; dust grains embedded in frozen methane, ammonia, carbon dioxide, and water

cometary outgassing

vaporization of the frozen gases that form a comet nucleus as the comet approaches the Sun and warms

communications infrastructure

the physical structures that support a network of telephone, Internet, mobile phones, and other communication systems

convection

the movement of heated fluid caused by a variation in density; hot fluid rises while cool fluid sinks

convection currents

mechanism by which thermal energy moves because its density differs from that of surrounding material. Convection current is the movement pattern of thermal energy transferring within a medium

convective processes

processes that are driven by the movement of heated fluids resulting from a variation in density

coronal holes

large, dark holes seen when the Sun is viewed in X-ray or ultraviolet wavelengths; solar wind emanates from the coronal holes

coronal mass ejections

large quantities of solar plasma and magnetic field launched from the Sun into space

cosmic microwave background

ubiquitous, diffuse, uniform, thermal radiation created during the earliest hot phases of the universe

cosmic radiation

high energy particles that enter Earth's atmosphere from outer space causing cascades of mesons and other particles

cosmocentric ethic

an ethical position that establishes the universe as the priority in a value system or appeals to something characteristic of the universe that provides justification of value

cover glass

a sheet of glass used to cover the solid state device in a solar cell

crash-landers

or hard-lander; a spacecraft that collides with the planet, making no—or little—attempt to slow down; after collision, the spacecraft ceases to function because of the (intentional) catastrophic failure

crawler transporter

large, tracked vehicles used to move the assembled Apollo/Saturn from the VAB to the launch pad

cryogenic

related to extremely low temperatures; the temperature of liquid nitrogen or lower

cryptocometary

another name for carbonaceous asteroids—asteroids that contain a high percentage of carbon compounds mixed with frozen gases

cryptoendolithic microbial

microbial ecosystems that live inside sandstone in extreme environments such as Antarctica

crystal lattice

the arrangement of atoms inside a crystal

crystallography

the study of the internal structure of crystals

dark matter

matter that interacts with ordinary matter by gravity but does not emit electromagnetic radiation; its composition is unknown

density-separation jigs

a form of gravity separation of materials with different densities that uses a pulsating fluid

desiccation

the process of drying up

detruents

microorganisms that act as decomposers in a controlled environmental life support system

diffuse

spread out; not concentrated

DNA

deoxyribonucleic acid; the molecule used by all living things on Earth to transmit genetic information

docking system

mechanical and electronic devices that work jointly to bring together and physically link two spacecraft in space

doped

semiconductor such as silicon with an addition of small amounts of an impurity such as phosphorous to generate more charge carriers (such as electrons)

dormant comet

a comet whose volatile gases have all been vaporized, leaving behind only the heavy materials

downlink

the radio dish and receiver through which a satellite or spacecraft transmits information back to Earth

drag

a force that opposes the motion of an aircraft or spacecraft through the atmosphere

dunites

rock type composed almost entirely of the mineral olivine, crystallized from magma beneath the Moon's surface

dynamic isotope power

the decay of isotopes such as plutonium-238, and polonium-210 produces heat, which can be transformed into electricity by radioisotopic thermoelectric generators

Earth-Moon LaGrange

five points in space relative to Earth and the Moon where the gravitational forces on an object balance; two points, 60 degrees from the Moon in orbit, are candidate points for a permanent space settlement due to their gravitational stability

eccentric

the term that describes how oval the orbit of a planet is

ecliptic

the plane of Earth's orbit

EH condrites

a rare form of meteorite containing a high concentration of the mineral enstatite (a type of pyroxene) and over 30 percent iron

ejecta

the pieces of material thrown off by a star when it explodes; or, material thrown out of an impact crater during its formation

ejector ramjet

engine design that uses a small rocket mounted in front of the ramjet to provide a flow of heated air, allowing the ramjet to provide thrust when stationary

electrodynamic

pertaining to the interaction of moving electric charges with magnetic and electric fields

electrolytes

a substance that when dissolved in water creates an electrically conducting solution

electromagnetic spectrum

the entire range of wavelengths of electromagnetic radiation

electron

a negatively charged subatomic particle

electron volts

units of energy equal to the energy gained by an electron when it passes through a potential difference of 1 volt in a vacuum

electrostatic separation

separation of substances by the use of electrically charged plates

elliptical

having an oval shape

encapsulation

enclosing within a capsule

endocrine

system in the body that creates and secretes substances called hormones into the blood

equatorial orbit

an orbit parallel to a body's geographic equator

equilibruim point

the point where forces are in balance

Europa

one of the large satellites of Jupiter

eV

an electron volt is the energy gained by an electron when moved across a potential of one volt. Ordinary molecules, such as air, have an energy of about 3x10^-2 eV

event horizon

the imaginary spherical shell surrounding a black hole that marks the boundary where no light or any other information can escape

excavation

a hole formed by mining or digging

expendable launch vehicles

launch vehicles, such as a rocket, not intended to be reused

extrasolar planets

planets orbiting stars other than the Sun

extravehicular activity

a space walk conducted outside a spacecraft cabin, with the crew member protected from the environment by a pressurized space suit

extremophiles

microorganisms that can survive in extreme environments such as high salinity or near boiling water

extruded

forced through an opening

failsafe

a system designed to be failure resistant through robust construction and redundant functions

fairing

a structure designed to provide low aerodynamic drag for an aircraft or spacecraft in flight

fault

a fracture in rock in the upper crust of a planet along which there has been movement

feedstock

the raw materials introduced into an industrial process from which a finished product is made

feldspathic

rock containing a high proportion of the mineral feldspar

fiber-optic cable

a thin strand of ultrapure glass that carries information in the form of light, with the light turned on and off rapidly to represent the information sent

fission

act of splitting a heavy atomic nucleus into two lighter ones, releasing tremendous energy

flares

intense, sudden releases of energy

flybys

flight path that takes the spacecraft close enough to a planet to obtain good observations; the spacecraft then continues on a path away from the planet but may make multiple passes

fracture

any break in rock, from small "joints" that divide rocks into planar blocks (such as that seen in road cuts) to vast breaks in the crusts of unspecified movement

freefall

the motion of a body acted on by no forces other than gravity, usually in orbit around Earth or another celestial body

free radical

a molecule with a high degree of chemical reactivity due to the presence of an unpaired electron

frequencies

the number of oscillations or vibrations per second of an electromagnetic wave or any wave

fuel cells

cells that react a fuel (such as hydrogen) and an oxidizer (such as oxygen) together; the chemical energy of the initial reactants is released by the fuel cell in the form of electricity

fusion

the act of releasing nuclear energy by combining lighter elements such as hydrogen into heavier elements

fusion fuel

fuel suitable for use in a nuclear fusion reactor

G force

the force an astronaut or pilot experiences when undergoing large accelerations

galaxy

a system of as many as hundreds of billions of stars that have a common gravitational attraction

Galilean satellite

one of the four large moons of Jupiter first discovered by Galileo

Galileo mission

succesful robot exploration of the outer solar system; this mission used gravity assists from Venus and Earth to reach Jupiter, where it dropped a probe into the atmosphere and studied the planet for nearly seven years

gamma rays

a form of radiation with a shorter wavelength and more energy than X rays

Ganymede

one of the four large moons of Jupiter; the largest moon in the solar system

Gemini

the second series of American-piloted spacecraft, crewed by two astronauts; the Gemini missions were rehearsals of the spaceflight techniques needed to go to the Moon

general relativity

a branch of science first described by Albert Einstein showing the relationship between gravity and acceleration

geocentric

a model that places Earth at the center of the universe

geodetic survey

determination of the exact position of points on Earth's surface and measurement of the size and shape of Earth and of Earth's gravitational and magnetic fields

geomagnetic field

Earth's magnetic field; under the influence of solar wind, the magnetic field is compressed in the Sunward direction and stretched out in the downwind direction, creating the magnetosphere, a complex, teardrop-shaped cavity around Earth

geospatial

relating to measurement of Earth's surface as well as positions on its surface

geostationary

remaining above a fixed point above Earth's equator

geostationary orbit

a specific altitude of an equatorial orbit where the time required to circle the planet matches the time it takes the planet to rotate on its axis. An object in geostationary orbit will always remain over the same geographic location on the equator of the planet it orbits

geosynchronous

remaining fixed in an orbit 35,786 kilometers (22,300 miles) above Earth's surface

geosynchronous orbit

a specific altitude of an equatorial orbit where the time required to circle the planet matches the time it takes the planet to rotate on its axis. An object in geostationary orbit will always remain over the same geographic location on the equator of the planet it orbits

gimbal motors

motors that direct the nozzle of a rocket engine to provide steering

global change

a change, such as average ocean temperature, affecting the entire planet

global positioning systems

a system of satellites and receivers that provide direct determination of the geographical location of the receiver

globular clusters

roughly spherical collections of hundreds of thousands of old stars found in galactic haloes

grand unified theory

(GUT) states that, at a high enough energy level (about 10²⁵ eV), the electromagnetic force, strong force, and weak force all merge into a single force

gravitational assist

the technique of flying by a planet to use its energy to "catapult" a spacecraft on its way—this saves fuel and thus mass and cost of a mission; gravitational assists typically make the total mission duration longer, but they also make things possible that otherwise would not be possible

gravitational contraction

the collapse of a cloud of gas and dust due to the mutual gravitational attraction of the parts of the cloud; a possible source of excess heat radiated by some Jovian planets

gravitational lenses

two or more images of a distant object formed by the bending of light around an intervening massive object

gravity assist

using the gravity of a planet during a close encounter to add energy to the motion of a spacecraft

gravity gradient

the difference in the acceleration of gravity at different points on Earth and at different distances from Earth

gravity waves

waves that propagate through space and are caused by the movement of large massive bodies, such as black holes and exploding stars

greenhouse effect

process by which short wavelength energy (e.g., visible light) penetrates an object's atmosphere and is absorbed by the surface, which reradiates this energy as longer wavelength infrared (thermal) energy; this energy is blocked from escaping to space by molecules (e.g., H₂O and CO₂) in the atmosphere; and as a result, the surface warms

gyroscope

a spinning disk mounted so that its axis can turn freely and maintain a constant orientation in space

hard-lander

spacecraft that collides with the planet or satellite, making no attempt to slow its descent; also called crash-landers

heliosphere

the volume of space extending outward from the Sun that is dominated by solar wind; it ends where the solar wind transitions into the interstellar medium, somewhere between 40 and 100 astronomical units from the Sun

helium-3

a stable isotope of helium whose nucleus contains two protons and one neutron

hertz

unit of frequency equal to one cycle per second

high-power klystron tubes

a type of electron tube used to generate high frequency electromagnetic waves

hilly and lineated terrain

the broken-up surface of Mercury at the antipode of the Caloris impact basin

hydrazine

a dangerous and corrosive compound of nitrogen and hydrogen commonly used in high powered rockets and jet engines

hydroponics

growing plants using water and nutrients in solution instead of soil as the root medium

hydrothermal

relating to high temperature water

hyperbaric chamber

compartment where air pressure can be carefully controlled; used to gradually acclimate divers, astronauts, and others to changes in pressure and air composition

hypergolic

fuels and oxidizers that ignite on contact with each other and need no ignition source

hypersonic

capable of speeds over five times the speed of sound

hyperspectral

imaging technique in remote sensing that uses at least sixteen contiguous bands of high spectral resolution over a region of the electromagnetic spectrum; used in NASA spacecraft Lewis' payload

ilmenite

an important ore of titanium

Imbrium Basin impact

largest and latest of the giant impact events that formed the mare-filled basins on the lunar near side

impact craters

bowl-shaped depressions on the surfaces of planets or satellites that result from the impact of space debris moving at high speeds

impact winter

the period following a large asteroidal or cometary impact when the Sun is dimmed by stratospheric dust and the climate becomes cold worldwide

impact-melt

molten material produced by the shock and heat transfer from an impacting asteroid or meteorite

in situ

in the natural or original location

incandescence

glowing due to high temperature

indurated rocks

rocks that have been hardened by natural processes

information age

the era of our time when many businesses and persons are involved in creating, transmitting, sharing, using, and selling information, particularly through the use of computers

infrared

portion of the electromagnetic spectrum with waves slightly longer than visible light

infrared radiation

radiation whose wavelength is slightly longer than the wavelength of light

infrastructure

the physical structures, such as roads and bridges, necessary to the functioning of a complex system

intercrater plains

the oldest plains on Mercury that occur in the highlands and that formed during the period of heavy meteoroid bombardment

interferometers

devices that use two or more telescopes to observe the same object at the same time in the same wavelength to increase angular resolution

interplanetary trajectories

the solar orbits followed by spacecraft moving from one planet in the solar system to another

interstellar

between the stars

interstellar medium

the gas and dust found in the space between the stars

ion propulsion

a propulsion system that uses charged particles accelerated by electric fields to provide thrust

ionization

removing one or more electrons from an atom or molecule

ionosphere

a charged particle region of several layers in the upper atmosphere created by radiation interacting with upper atmospheric gases

isotopic ratios

the naturally occurring ratios between different isotopes of an element

jettison

to eject, throw overboard, or get rid of

Jovian

relating to the planet Jupiter

Kevlar®

a tough aramid fiber resistant to penetration

kinetic energy

the energy an object has due to its motion

KREEP

acronym for material rich in potassium (K), rare earth elements (REE), and phosphorus (P)

L-4

the gravitationally stable Lagrange point 60 degrees ahead of the orbiting planet

L-5

the gravitationally stable Lagrange point 60 degrees behind the orbiting planet

Lagrangian point

one of five gravitationally stable points related to two orbiting masses; three points are metastable, but L4 and L5 are stable

laser-pulsing

firing periodic pulses from a powerful laser at a surface and measuring the length of time for return in order to determine topography

libration point

one of five gravitationally stable points related to two orbiting masses; three points are metastable, but L4 and L5 are stable

lichen

fungus that grows symbiotically with algae

light year

the distance that light in a vacuum would travel in one year, or about 9.5 trillion kilometers (5.9 trillion miles)

lithosphere

the rocky outer crust of a body

littoral

the region along a coast or beach between high and low tides

lobate scarps

a long sinuous cliff

low Earth orbit

an orbit between 300 and 800 kilometers above Earth's surface

lunar maria

the large, dark, lava-filled impact basins on the Moon thought by early astronomers to resemble seas

Lunar Orbiter

a series of five unmanned missions in 1966 and 1967 that photographed much of the Moon at medium to high resolution from orbit

macromolecules

large molecules such as proteins or DNA containing thousands or millions of individual atoms

magnetohydrodynamic waves

a low frequency oscillation in a plasma in the presence of a magnetic field

magnetometer

an instrument used to measure the strength and direction of a magnetic field

magnetosphere

the magnetic cavity that surrounds Earth or any other planet with a magnetic field. It is formed by the interaction of the solar wind with the planet's magnetic field

majority carriers

the more abundant charge carriers in semiconductors; the less abundant are called minority carriers; for n-type semiconductors, electrons are the majority carriers

malady

a disorder or disease of the body

many-bodied problem

in celestial mechanics, the problem of finding solutions to the equations for more than two orbiting bodies

mare

dark-colored plains of solidified lava that mainly fill the large impact basins and other low-lying regions on the Moon

Mercury

the first American piloted spacecraft, which carried a single astronaut into space; six Mercury missions took place between 1961 and 1963

mesons

any of a family of subatomic particle that have masses between electrons and protons and that respond to the strong nuclear force; produced in the upper atmosphere by cosmic rays

meteor

the physical manifestation of a meteoroid interacting with Earth's atmosphere; this includes visible light and radio frequency generation, and an ionized trail from which radar signals can be reflected. Also called a "shooting star"

meteorites

any part of a meteoroid that survives passage through Earth's atmosphere

meteoroid

a piece of interplanetary material smaller than an asteroid or comet

meteorology

the study of atmospheric phenomena or weather

meteorology satellites

satellites designed to take measurements of the atmosphere for determining weather and climate change

microgravity

the condition experienced in freefall as a spacecraft orbits Earth or another body; commonly called weightlessness; only very small forces are perceived in freefall, on the order of one-millionth the force of gravity on Earth's surface

micrometeoroid flux

the total mass of micrometeoroids falling into an atmosphere or on a surface per unit of time

micrometeoroid

any meteoroid ranging in size from a speck of dust to a pebble

microwave link

a connection between two radio towers that each transmit and receive microwave (radio) signals as a method of carrying information (similar to radio communications)

minerals

crystalline arrangements of atoms and molecules of specified proportions that make up rocks

missing matter

the mass of the universe that cannot be accounted for but is necessary to produce a universe whose overall curvature is "flat"

monolithic

massive, solid, and uniform; an asteroid that is formed of one kind of material fused or melted into a single mass

multi-bandgap photovoltaic

photovoltaic cells designed to respond to several different wavelengths of electromagnetic radiation

multispectral

referring to several different parts of the electromagnetic spectrum, such as visible, infrared, and radar

muons

the decay product of the mesons produced by cosmic rays; muons are about 100 times more massive than electrons but are still considered leptons that do not respond to the strong nuclear force

near-Earth asteroids

asteroids whose orbits cross the orbit of Earth; collisions between Earth and near Earth asteroids happen a few times every million years

nebulae

clouds of interstellar gas and/or dust

neutron

a subatomic particle with no electrical charge

neutron star

the dense core of matter composed almost entirely of neutrons that remain after a supernova explosion has ended the life of a massive star

New Millennium

a NASA program to identify, develop and validate key instrument and spacecraft technologies that can lower cost and increase performance of science missions in the twenty-first century

Next Generation Space Telescope

the telescope scheduled to be launched in 2009 that will replace the Hubble Space Telescope

nuclear black holes

black holes that are in the centers of galaxies; they range in mass from a thousand to a billion times the mass of the Sun

nuclear fusion

the combining of low-mass atoms to create heavier ones; the heavier atom's mass is slightly less than the sum of the mass of its constituents, with the remaining mass converted to energy

nucleon

a proton or a neutron; one of the two particles found in a nucleus

occultations

a phenomena that occurs when one astronomical object passes in front of another

optical interferometry

a branch of optical physics that uses the wavelength of visible light to measure very small changes within the environment

optical-interferometry based

the use of two or more telescopes observing the same object at the same time at the same visible wavelength to increase angular resolution

optical radar

a method of determining the speed of moving bodies by sending a pulse of light and measuring how long it takes for the reflected light to return to the sender

orbit

the circular or elliptical path of an object around a much larger object, governed by the gravitational field of the larger object

orbital dynamics

the mathematical study of the nature of the forces governing the movement of one object in the gravitational field of another object

orbital velocity

velocity at which an object needs to travel so that its flight path matches the curve of the planet it is circling; approximately 8 kilometers (5 miles) per second for low-altitude orbit around Earth

orbiter

spacecraft that uses engines and/or aerobraking, and is captured into circling a planet indefinitely

orthogonal

composed of right angles or relating to right angles

oscillation

energy that varies between alternate extremes with a definable period

osteoporosis

the loss of bone density; can occur after extended stays in space

oxidizer

a substance mixed with fuel to provide the oxygen needed for combustion

paleolake

depression that shows geologic evidence of having contained a lake at some previous time

Paleozoic

relating to the first appearance of animal life on Earth

parabolic trajectory

trajectory followed by an object with velocity equal to escape velocity

parking orbit

placing a spacecraft temporarily into Earth orbit, with the engines shut down, until it has been checked out or is in the correct location for the main burn that sends it away from Earth

payload

any cargo launched aboard a rocket that is destined for space, including communications satellites or modules, supplies, equipment, and astronauts; does not include the vehicle used to move the cargo or the propellant that powers the vehicle

payload bay

the area in the shuttle or other spacecraft designed to carry cargo

payload fairing

structure surrounding a payload; it is designed to reduce drag

payload operations

experiments or procedures involving cargo or "payload" carried into orbit

payload specialists

scientists or engineers selected by a company or a government employer for their expertise in conducting a specific experiment or commercial venture on a space shuttle mission

perihelion

the point in an object's orbit that is closest to the Sun

period of heavy meteoroid

the earliest period in solar system history (more than 3.8 billion years ago) when the rate of meteoroid impact was very high compared to the present

perturbations

term used in orbital mechanics to refer to changes in orbits due to "perturbing" forces, such as gravity

phased array

a radar antenna design that allows rapid scanning of an area without the need to move the antenna; a computer controls the phase of each dipole in the antenna array

phased-array antennas

radar antenna designs that allow rapid scanning of an area without the need to move the antenna; a computer controls the phase of each dipole in the antenna array

photolithography

printing that uses a photographic process to create the printing plates

photometer

instrument to measure intensity of light

photosynthesis

a process performed by plants and algae whereby light is transformed into energy and sugars

photovoltaic

pertaining to the direct generation of electricity from electromagnetic radiation (light)

photovoltaic arrays

sets of solar panels grouped together in big sheets; these arrays collect light from the Sun and use it to make electricity to power the equipment and machines

photovoltaic cells

cells consisting of a thin wafer of a semiconductor material that incorporates a p-n junction, which converts incident light into electrical power; a number of photovoltaic cells connected in series makes a solar array

plagioclase

most common mineral of the light-colored lunar highlands

planetesimals

objects in the early solar system that were the size of large asteroids or small moons, large enough to begin to gravitationally influence each other

pn single junction

in a transistor or other solid state device, the boundary between the two different kinds of semiconductor material

point of presence

an access point to the Internet with a unique Internet Protocol (IP) address; Internet service providers (ISP) like AOL generally have multiple POPs on the Internet

polar orbits

orbits that carry a satellite over the poles of a planet

polarization state

degree to which a beam of electromagnetic radiation has all of the vibrations in the same plane or direction

porous

allowing the passage of a fluid or gas through holes or passages in the substance

power law energy spectrum

spectrum in which the distribution of energies appears to follow a power law

primary

the body (planet) about which a satellite orbits

primordial swamp

warm, wet conditions postulated to have occurred early in Earth's history as life was beginning to develop

procurement

the process of obtaining

progenitor star

the star that existed before a dramatic change, such as a supernova, occurred

prograde

having the same general sense of motion or rotation as the rest of the solar system, that is, counterclockwise as seen from above Earth's north pole

prominences

inactive "clouds" of solar material held above the solar surface by magnetic fields

propagate

to cause to move, to multiply, or to extend to a broader area

proton

a positively charged subatomic particle

pseudoscience

a system of theories that assumes the form of science but fails to give reproducible results under conditions of controlled experiments

pyroclastic

pertaining to clastic (broken) rock material expelled from a volcanic vent

pyrotechnics

fireworks display; the art of building fireworks

quantum foam

the notion that there is a smallest distance scale at which space itself is not a continuous medium, but breaks up into a seething foam of wormholes and tiny black holes far smaller than a proton

quantum gravity

an attempt to replace the inherently incompatible theories of quantum physics and Einstein gravity with some deeper theory that would have features of both, but be identical to neither

quantum physics

branch of physics that uses quantum mechanics to explain physical systems

quantum vacuum

consistent with the Heisenberg uncertainty principle, vacuum is not empty but is filled with zero-point energy and particle-antiparticle pairs constantly being created and then mutually annihilating each other

quasars

luminous objects that appear star-like but are highly redshifted and radiate more energy than an entire ordinary galaxy; likely powered by black holes in the centers of distant galaxies

quiescent

inactive

radar

a technique for detecting distant objects by emitting a pulse of radio-wavelength radiation and then recording echoes of the pulse off the distant objects

radar altimetry

using radar signals bounced off the surface of a planet to map its variations in elevation

radar images

images made with radar illumination instead of visible light that show differences in radar brightness of the surface material or differences in brightness associated with surface slopes

radiation belts

two wide bands of charged particles trapped in a planet's magnetic field

radio lobes

active galaxies show two regions of radio emission above and below the plane of the galaxy, and are thought to originate from powerful jets being emitted from the accretion disk surrounding the massive black hole at the center of active galaxies

radiogenic isotope techniques

use of the ratio between various isotopes produced by radioactive decay to determine age or place of origin of an object in geology, archaeology, and other areas

radioisotope

a naturally or artificially produced radioactive isotope of an element

radioisotope thermoelectric

device using solid state electronics and the heat produced by radioactive decay to generate electricity

range safety destruct systems

system of procedures and equipment designed to safely abort a mission when a spacecraft malfunctions, and destroy the rocket in such a way as to create no risk of injury or property damage

Ranger

series of spacecraft sent to the Moon to investigate lunar landing sites; designed to hard-land on the lunar surface after sending back television pictures of the lunar surface; Rangers 7, 8, and 9 (1964-1965) returned data

rarefaction

decreased pressure and density in a material caused by the passage of a sound wave

reconnaissance

a survey or preliminary exploration of a region of interest

reflex motion

the orbital motion of one body, such as a star, in reaction to the gravitational tug of a second orbiting body, such as a planet

regolith

upper few meters of a body's surface, composed of inorganic matter, such as unconsolidated rocks and fine soil

relative zero velocity

two objects having the same speed and direction of movement, usually so that spacecraft can rendezvous

relativistic time dilation

effect predicted by the theory of relativity that causes clocks on objects in strong gravitational fields or moving near the speed of light to run slower when viewed by a stationary observer

remote manipulator system

a system, such as the external Canada2 arm on the International Space Station, designed to be operated from a remote location inside the space station

remote sensing

the act of observing from orbit what may be seen or sensed below on Earth

retrograde

having the opposite general sense of motion or rotation as the rest of the solar system, clockwise as seen from above Earth's north pole

reusable launch vehicles

launch vehicles, such as the space shuttle, designed to be recovered and reused many times

reusables

launches that can be used many times before discarding

rift valley

a linear depression in the surface, several hundred to thousand kilometers long, along which part of the surface has been stretched, faulted, and dropped down along many normal faults

rille

lava channels in regions of maria, typically beginning at a volcanic vent and extending downslope into a smooth mare surface

rocket

vehicle or device that is especially designed to travel through space, and is propelled by one or more engines

"rocky" planets

nickname given to inner or solid-surface planets of the solar system, including Mercury, Venus, Mars, and Earth

rover

vehicle used to move about on a surface

rutile

a red, brown, or black mineral, primarily titanium dioxide, used as a gemstone and also a commercially important ore of titanium

satellite

any object launched by a rocket for the purpose of orbiting the Earth or another celestial body

scoria

fragments of lava resembling cinders

secondary crater

crater formed by the impact of blocks of rock blasted out of the initial crater formed by an asteroid or large meteorite

sedentary lifestyle

a lifestyle characterized by little movement or exercise

sedimentation

process of depositing sediments, which result in a thick accumulation of rock debris eroded from high areas and deposited in low areas

semiconductor

one of the groups of elements with properties intermediate between the metals and nonmetals

semimajor axis

one half of the major axis of an ellipse, equal to the average distance of a planet from the Sun

shepherding

small satellites exerting their gravitational influence to cause or maintain structure in the rings of the outer planets

shield volcanoes

volcanoes that form broad, low-relief cones, characterized by lava that flows freely

shielding

providing protection for humans and electronic equipment from cosmic rays, energetic particles from the Sun, and other radioactive materials

sine wave

a wave whose amplitude smoothly varies with time; a wave form that can be mathematically described by a sine function

smooth plains

the youngest plains on Mercury with a relatively low impact crater abundance

soft-landers

spacecraft that uses braking by engines or other techniques (e.g., parachutes, airbags) such that its landing is gentle enough that the spacecraft and its instruments are not damaged, and observations at the surface can be made

solar arrays

groups of solar cells or other solar power collectors arranged to capture energy from the Sun and use it to generate electrical power

solar corona

the thin outer atmosphere of the Sun that gradually transitions into the solar wind

solar flares

explosions on the Sun that release bursts of electromagnetic radiation, such as light, ultraviolet waves, and X rays, along with high speed protons and other particles

solar nebula

the cloud of gas and dust out of which the solar system formed

solar prominence

cool material with temperatures typical of the solar photosphere or chromosphere suspended in the corona above the visible surface layers

solar radiation

total energy of any wavelength and all charged particles emitted by the Sun

solar wind

a continuous, but varying, stream of charged particles (mostly electrons and protons) generated by the Sun; it establishes and affects the interplanetary magnetic field; it also deforms the magnetic field about Earth and sends particles streaming toward Earth at its poles

sounding rocket

a vehicle designed to fly straight up and then parachute back to Earth, usually designed to take measurements of the upper atmosphere

space station

large orbital outpost equipped to support a human crew and designed to remain in orbit for an extended period; to date, only Earth-orbiting space stations have been launched

space-time

in relativity, the four-dimensional space through which objects move and in which events happen

spacecraft bus

the primary structure and subsystems of a spacecraft

spacewalking

moving around outside a spaceship or space station, also known as extravehicular activity

special theory of relativity

the fundamental idea of Einstein's theories, which demonstrated that measurements of certain physical quantities such as mass, length, and time depended on the relative motion of the object and observer

specific power

amount of electric power generated by a solar cell per unit mass; for example watts per kilogram

spectra

representations of the brightness of objects as a function of the wavelength of the emitted radiation

spectral lines

the unique pattern of radiation at discrete wavelengths that many materials produce

spectrograph

an instrument that can permanently record a spectra

spectrographic studies

studies of the nature of matter and composition of substances by examining the light they emit

spectrometers

an instrument with a scale for measuring the wavelength of light

spherules

tiny glass spheres found in and among lunar rocks

spot beam technology

narrow, pencil-like satellite beam that focuses highly radiated energy on a limited area of Earth's surface (about 100 to 500 miles in diameter) using steerable or directed antennas

stratigraphy

the study of rock layers known as strata, especially the age and distribution of various kinds of sedimentary rocks

stratosphere

a middle portion of a planet's atmosphere above the tropopause (the highest place where convection and "weather" occurs)

subduction

the process by which one edge of a crustal plate is forced to move under another plate

sublimate

to pass directly from a solid phase to a gas phase

suborbital trajectory

the trajectory of a rocket or ballistic missile that has insufficient energy to reach orbit

subsolar point

the point on a planet that receives direct rays from the Sun

substrate

the surface, such as glass, metallic foil, or plastic sheet, on which a thin film of photovoltaic material is deposited

sunspots

dark, cooler areas on the solar surface consisting of transient, concentrated magnetic fields

supercarbonaceous

term given to P-and D-type meteorites that are richer in carbon than any other meteorites and are thought to come from the primitive asteroids in the outer part of the asteroid belt

supernova

an explosion ending the life of a massive star

supernovae ejecta

the mix of gas enriched by heavy metals that is launched into space by a supernova explosion

superstring theory

the best candidate for a "theory of everything" unifying quantum mechanics and gravity, proposes that all particles are oscillations in tiny loops of matter only 10^-35 meters long and moving in a space of ten dimensions

superstrings

supersymmetric strings are tiny, one dimensional objects that are about 10^-33cm long, in a 10-dimensional spacetime. Their different vibration modes and shapes account for the elementary particles we see in our 4-dimensional spacetime

Surveyor

a series of spacecraft designed to soft-land robotic laboratories to analyze and photograph the lunar surface; Surveyors 1, 3, and 5-7 landed between May 1966 and January 1968

synchrotron radiation

the radiation from electrons moving at almost the speed of light inside giant magnetic accelerators of particles, called synchrotrons, either on Earth or in space

synthesis

the act of combining different things so as to form new and different products or ideas

technology transfer

the acquisition by one country or firm of the capability to develop a particular technology through its interactions with the existing technological capability of another country or firm, rather than through its own research efforts

tectonism

process of deformation in a planetary surface as a result of geological forces acting on the crust; includes faulting, folding, uplift, and down-warping of the surface and crust

telescience

the act of operation and monitoring of research equipment located in space by a scientist or engineer from their offices or laboratories on Earth

terrestrial planet

a small rocky planet with high density orbiting close to the Sun; Mercury, Venus, Earth, and Mars

thermodynamically

referring to the behavior of energy

thermostabilized

designed to maintain a constant temperature

thrust fault

a fault where the block on one side of the fault plane has been thrust up and over the opposite block by horizontal compressive forces

toxicological

related to the study of the nature and effects on humans of poisons and the treatment of victims of poisoning

trajectories

paths followed through space by missiles and spacecraft moving under the influence of gravity

transonic barrier

the aerodynamic behavior of an aircraft moving near the speed of sound changes dramatically and, for early pioneers of transonic flight, dangerously, leading some to hypothesize there was a "sound barrier" where drag became infinite

transpiration

process whereby water evaporates from the surface of leaves, allowing the plant to lose heat and to draw water up through the roots

transponder

bandwidth-specific transmitter-receiver units

troctolite

rock type composed of the minerals plagioclase and olivine, crystallized from magma

tunnelborer

a mining machine designed to dig a tunnel using rotating cutting disks

Tycho event

the impact of a large meteoroid into the lunar surface as recently as 100 million years ago, leaving a distinct set of bright rays across the lunar surface including a ray through the Apollo 17 landing site

ultramafic lavas

dark, heavy lavas with a high percentage of magnesium and iron; usually found as boulders mixed in other lava rocks

ultraviolet

the portion of the electromagnetic spectrum just beyond (having shorter wavelengths than) violet

ultraviolet radiation

electromagnetic radiation with a shorter wavelength and higher energy than light

uncompressed density

the lower density a planet would have if it did not have the force of gravity compressing it

Universal time

current time in Greenwich, England, which is recognized as the standard time that Earth's time zones are based

vacuum

an environment where air and all other molecules and atoms of matter have been removed

vacuum conditions

the almost complete lack of atmosphere found on the surface of the Moon and in space

Van Allen radiation belts

two belts of high energy charged particles captured from the solar wind by Earth's magnetic field

variable star

a star whose light output varies over time

vector sum

sum of two vector quantities taking both size and direction into consideration

velocity

speed and direction of a moving object; a vector quantity

virtual-reality simulations

a simulation used in training by pilots and astronauts to safely reproduce various conditions that can occur on board a real aircraft or spacecraft

visible spectrum

the part of the electromagnetic spectrum with wavelengths between 400 nanometers and 700 nanometers; the part of the electromagnetic spectrum to which human eyes are sensitive

volatile

ices (e.g., H₂O and CO₂) that are solids inside a comet nucleus but turn into gases when heated by sunlight

volatile materials

materials that easily pass into the vapor phase when heated

wavelength

the distance from crest to crest on a wave at an instant in time

X ray

form of high-energy radiation just beyond the ultraviolet portion of the spectrum

X-ray diffraction analysis

a method to determine the three-dimensional structure of molecules