Space Terminology: Abbreviations and Definitions

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ABBREVIATIONS + DEFINITIONS

 

A

Aerospike Engines
Aerospike engines are an innovative propulsion system designed to maintain efficiency throughout a rocket’s ascent by adapting to changing atmospheric pressure. Unlike traditional bell-shaped nozzles, which lose efficiency as atmospheric pressure changes during ascent, aerospike engines use a wedge-shaped or truncated spike design. This allows the surrounding air pressure to act as a virtual wall, dynamically shaping the exhaust plume for optimal thrust at varying altitudes.

Aerospike engines are particularly suited for single-stage-to-orbit (SSTO) missions, as they eliminate the need for multiple stages by adapting to atmospheric conditions. Despite their advantages, such as improved fuel efficiency and versatility, they face challenges like complex design and cooling requirements. While not yet in commercial production, aerospike engines are undergoing testing and hold promise for future space exploration.

Apollo Missions (US)

Artemis Missions

Asteroid

Astronomical Units (AU)

Aurora

B

Binary Star

Black Hole

Black Hole Cosmology
Black hole cosmology, or Schwarzschild cosmology, posits that our observable universe could be situated within a black hole in a larger parent universe. This concept was initially proposed by theoretical physicist Raj Kumar Pathria and mathematician I. J. Good.

The theory suggests that the "Schwarzschild radius" or event horizon—the boundary beyond which nothing can escape a black hole, not even light—is analogous to the horizon of the visible universe. This implies that black holes within our universe might serve as gateways to other "baby universes." These baby universes remain unobservable because they lie beyond their event horizons, trapping light and preventing information from escaping to external observers.

Polish theoretical physicist Nikodem Poplawski of the University of New Haven has been a prominent advocate for this theory. He posits that each black hole could potentially give rise to a new universe, expanding our understanding of cosmic structures and the nature of our own universe.

In general relativity, a massive object collapsing under its own gravity becomes a Schwarzschild black hole, with a singular point at its center. However, the Einstein-Cartan theory suggests this collapse forms a regular wormhole, instead of a singularity.

This theory also proposes that the Big Bang could have been a "Big Bounce," meaning the universe didn't start from a singular point but from a minimum size. It could also mean that our universe emerged from a supermassive white hole formed by a black hole in a parent universe. This idea challenges traditional cosmological theories and offers a new perspective on how our universe might have formed.

 

C

Chandrayaan Missions (ISRO)

CubeSat

 

D

Dark Big Bang

Dark Energy

Dark Matter

Dark Matter Halo

Distant Retrograde Orbit (DRO)
A Distant Retrograde Orbit (DRO) is a highly stable orbit around a moon where a spacecraft moves opposite to the moon’s direction around its planet. DROs take advantage of gravitational stability caused by the interactions with L1 and L2 Lagrange points, making them useful for long-term missions, space stations, and deep-space exploration. Think of it like swimming upstream in a river—while the moon follows its usual orbit, the spacecraft moves against the flow.

Spacecraft can stay in DRO for long periods without using much fuel. That makes them useful for deep-space missions, lunar gateways, and long-term space habitats. NASA, China, and other space agencies are exploring DROs for future missions since they provide a steady, low-energy orbit that could be key for space stations near the Moon.

 

E

Einstein-Cartan Theory
The Einstein-Cartan theory is an extension of Einstein's general theory of relativity. It incorporates the concept of "torsion," which means that, in addition to the curvature of spacetime, spacetime can also twist. This twist or torsion is linked to the intrinsic spin of matter particles.

In simpler terms, while general relativity describes how mass and energy curve spacetime, the Einstein-Cartan theory adds that the spin of particles can also influence spacetime by creating a twisting effect. This allows the theory to better describe the behavior of matter at very high densities, such as in black holes or the early universe, potentially avoiding singularities and offering new insights into the nature of the universe.

Euclid Mission
The Euclid Mission, led by the European Space Agency (ESA) with contributions from NASA, is designed to investigate the universe's accelerating expansion, attributed to the mysterious force known as dark energy. Launched in July 2023, the mission uses a space telescope to observe billions of galaxies, creating a detailed 3D map of the universe. By studying the shapes, distances, and distribution of galaxies, Euclid aims to uncover how dark energy has influenced the universe's expansion over time. This six-year mission represents a significant step in understanding the "dark universe." You can find more details here.

Einstein Ring
An Einstein Ring is a fascinating astronomical phenomenon caused by gravitational lensing, a concept rooted in Einstein's theory of general relativity. It occurs when light from a distant celestial object, such as a galaxy, passes near a massive foreground object, like another galaxy or a black hole. The immense gravitational field of the foreground object bends the light, distorting its path through spacetime. If the alignment between the observer, the foreground object, and the distant light source is nearly perfect, the bending creates a symmetrical ring-like structure around the foreground object.

Against a dark blue background, this infographic contains a paragraph of text in the top left corner, the logo of ESA in the top right corner and a succession of graphics in the bottom half of the image. The text paragraph explains the principle behind Einstein rings, and it can be read in the image caption. The graphics below it illustrate this astrophysical phenomenon, and by looking at them from left to right we can understand the process of how Einstein rings are formed. The left-most element in the bottom half of the image is a graphic representation of a galaxy, labelled ‘distant galaxy’. To the right of it, another galaxy is shown, labelled ‘Foreground galaxy acting as a magnifying lens’. The third illustration, to the right of the previous one, shows ESA’s Euclid space telescope and is labelled ‘Telescope’. The ‘distant galaxy’ and the ‘Telescope’ are connected by two lines that form an elongated diamond-shape around the ‘Foreground galaxy’. This line is labelled ‘Gravity bends the light rays of the distant galaxy’. The fourth and last illustration in the line shows a ring of light around a central disk and is labelled ‘What the telescope sees’

Credit: ESA

These rings are rare and provide valuable insights into the universe. They act as natural magnifying glasses, allowing astronomers to study distant galaxies that would otherwise be too faint to observe. Einstein Rings also help researchers investigate dark matter and test the principles of general relativity. They're not just visually stunning but scientifically significant.

 

F

Faring

Fermi Paradox

 

G

Gaganyaan Mission (ISRO)

Gravitational Lensing
Gravitational lensing is a phenomenon predicted by Einstein's general theory of relativity. It occurs when a massive object, such as a galaxy or a cluster of galaxies, creates a gravitational field that bends and magnifies the light from a more distant object behind it. Essentially, the massive object acts like a cosmic magnifying glass.

This illustration shows a distant quasar's light being altered by a massive foreground galaxy's powerful gravity, warping and magnifying the quasar's light, producing four distorted images of the quasar. (Credit: NASA, ESA, and D. Player (STScI))

There are three main types of gravitational lensing:

  1. Strong Lensing: This creates dramatic effects like Einstein rings (complete circles of light) or multiple images of the same object.

  2. Weak Lensing: This subtly distorts the shapes of background objects, helping astronomers map the distribution of dark matter.

  3. Microlensing: This occurs when a smaller object, like a star, passes in front of a distant star, temporarily magnifying its light.

Two examples of Gravitational lensing:

  1. Einstein Cross: A galaxy bends light, creating four images of a distant quasar.

  2. Abell 370: A galaxy cluster produces elongated arcs of magnified light.

Gravitational lensing is a powerful tool in astronomy. It allows scientists to study distant galaxies, detect dark matter, and even observe the universe's early stages. It's like peering into the past through nature's own telescope.

Great Filter

GTO - Geosynchronous Transfer Orbit

 

H

Heliophysics Survey

HLS - Human Landing System

Hycean planets
Hycean planets are a proposed class of exoplanets that are hydrogen-rich, ocean-covered worlds with potentially habitable conditions. The term "Hycean" is a portmanteau of "hydrogen" and "ocean," reflecting their key characteristics. They were first theorized in 2021 by astronomers at the University of Cambridge.

Key Features of Hycean Planets:

  1. Atmosphere: Dominated by hydrogen (H₂) with possible traces of water vapor, methane, and ammonia.

  2. Surface: Likely covered by a deep, global ocean beneath the thick hydrogen-rich atmosphere.

  3. Size & Mass: Larger and more massive than Earth, typically between 2-10 Earth radii, falling into the mini-Neptune category.

  4. Temperature: Can be hot or cold, but some orbit in the habitable zone where liquid water could exist.

  5. Potential for Life: Their vast oceans and organic chemistry might support microbial life, even without a rocky surface like Earth.

Why Are They Interesting?

  • More Common & Easier to Detect: Hycean planets are more abundant than Earth-like planets and have thicker atmospheres, making them easier to study with telescopes like JWST.

  • Broader Habitable Zone: They can remain habitable even farther from their stars than Earth-like planets because hydrogen atmospheres trap heat efficiently.

  • Biosignature Search: Scientists are looking for gases like dimethyl sulfide (DMS) or methane, which could indicate life in Hycean oceans.

Examples & Research:

  • K2-18b (a potential Hycean candidate) showed signs of water vapor and methane in its atmosphere.

  • JWST is studying other Hycean planet candidates for biosignatures.

Challenges:

  • Extreme pressure and lack of sunlight in deep oceans could limit life forms.

  • Some Hycean planets may be too hot or lack a stable surface ocean.

Hycean planets expand the search for life beyond Earth-like worlds, offering exciting new targets in the hunt for habitable exoplanets. 🌍🔭

 

I

IAA - Indian Astronautical Association

IAA - International Academy of Astronautics

IAF - International Astronautical Federation

ICBM - Inter-Continental Ballistic Missile (range >5500 km)

ICO - Intermediate Circular Orbit

IDIQ - Indefinite Delivery Indefinite Quantity

IMU - Inertial Measurement Unit

ISA - Iranian Space Agency

ISRO - Indian Space Research Organization

ISRU

 

J

JPL - Jet Propulsion Lab (US)

K

Kármán line

 

L

Large Magellanic Clouds

Lunar Soil Simulant

 

M

Magellanic Clouds

Magnetosphere

Mare

Megaconstellations (Satellites)

Metasurface Technologies

Millimetre Continuum

 

N

Neutron Star

NIRCam
NIRCam, or the Near Infrared Camera, is one of the primary instruments aboard the James Webb Space Telescope (JWST). It is designed to capture light in the near-infrared spectrum, ranging from 0.6 to 5 microns. This capability allows it to observe some of the earliest galaxies formed after the Big Bang, young stars in the Milky Way, and objects in the Kuiper Belt.

NIRCam also plays a critical role in aligning JWST's 18-segment primary mirror, ensuring precise imaging. Equipped with coronagraphs, it can block out bright starlight to study faint objects like exoplanets. Its advanced detectors and filters make it a versatile tool for high-resolution imaging and spectroscopy, contributing significantly to our understanding of the universe's formation and evolution.

NSSL - National Security Space Launch (US Space Force)

 

O

ORCs -

 

P

Payload

Planetary-Mass Objects
Planetary-mass objects (PMOs) are celestial bodies that have masses similar to those of planets, but they don't orbit a star like traditional planets do. Instead, they drift freely through space, unbound to any specific star. Here are some key points about PMOs:

  • Mass Range: PMOs have masses between that of typical planets and stars, often comparable to gas giants like Jupiter.

  • Formation: They can form in various ways, including the collapse of a gas cloud (similar to stars) or through violent interactions within young star clusters.

  • Types: PMOs include objects like rogue planets, which are ejected from their original star systems, and brown dwarfs, which are too small to sustain nuclear fusion like stars.

  • Observations: PMOs are difficult to detect because they don't emit much light, but advances in astronomy have enabled the discovery of several PMOs in our galaxy.

 

Primordial Black Holes

Prometheus Program (AFRL - US)

Protocluster

Protoplanetary Disc

PSLV - Polar Satellite Launch Vehicle

 

Q

Quantum Information Theory
Quantum Information Theory is a field that combines principles from quantum mechanics and information theory to understand how information can be represented, processed, and transmitted using quantum systems. Unlike classical information, which is based on bits (0s and 1s), quantum information uses quantum bits or qubits, which can exist in multiple states simultaneously due to the principle of superposition.

Key concepts in Quantum Information Theory include:

  • Quantum Entanglement: A phenomenon where particles become interconnected, allowing the state of one particle to instantly influence the state of another, regardless of distance.

  • Quantum Superposition: The ability of a quantum system to exist in multiple states at once until it is measured.

  • Quantum Measurement: The process of observing a quantum system, which collapses its superposition into a single state.

  • No-Cloning Theorem: A principle stating that it is impossible to create an identical copy of an arbitrary unknown quantum state.

Quantum Relative Entropy
Quantum relative entropy is a measure of how different two quantum states are from each other. It is an extension of classical relative entropy (or Kullback-Leibler divergence) to the quantum domain.

In simpler terms, quantum relative entropy helps quantify the distance or difference between two quantum states. This measure is crucial in various areas of quantum information theory, such as quantum communication, quantum computing, and the study of quantum entanglement. It provides a way to compare and analyze quantum states, aiding in the development of more efficient quantum algorithms and protocols.

 

R

Regolith

 

S

SAR - Synthetic Aperture Radar

SAST

Satellite Bus

SBIR

Schlieren Photography
Schlieren photography is a fascinating technique used to visualize changes in the density of transparent media, such as air or fluids, which are otherwise invisible to the naked eye. Developed in 1864 by German physicist August Toepler, this method relies on the principle of refraction—how light bends when it passes through regions of varying density.

In a Schlieren system, a light source produces parallel rays that pass through the medium being studied. Variations in density, such as shock waves or heat currents, cause the light rays to bend. These bent rays are then focused onto a knife edge or filter, which blocks some of the light, creating a contrast pattern that reveals the density changes. The result is a striking image showing the flow of air, shock waves, or other phenomena.

This technique is widely used in aerodynamics, supersonic flight studies, and even to capture the shock waves of bullets or the heat rising from a flame.

Schwarzschild cosmology
See Black Hole Cosmology

SDANet

Small Magellanic Clouds

Solar Maximum

SPACs -

Space Tug

SPACEWERX

SPADOC

Spectroscopy

SSO

SSN

STRATFI

STTR

Supernova

 

T

TacRS

TACFI

Type Ia Supernovae

 

U

 

V

 

W

White Dwarfs

 

X

 

Y

 

Z