Questions tagged [terminology]

Questions regarding words and abbreviations used in the fields of spaceflight and space exploration, and their meaning when used in those contexts.

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2k views

What is an "octet" in the context of NASA's LunaNET Interoperability Standard? ("internet on the Moon")

The PDF Draft LunaNet Interoperability Specification, LN-IS Baseline V001 September 2, 2021 (found at https://esc.gsfc.nasa.gov/projects/TEMPO?tab=lunanet) has found its way to the popular press. 4.2 ...
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What are the differences (if any) between the techniques of range-rate and delay-doppler measurements?

This answer to How does an onboard atomic clock help interplanetary navigation? says: Range-Rate is the two-way measurement of signals broadcast from one location on Earth, received and retransmitted ...
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How old is the use of "L minus" to denote the number of days before launch?

In the SpaceX Inspiration4 Launch broadcast at about T-01:31:05 (91 minutes before launch) the term "L minus five" is used. While "T-minus" is a ...
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what is revisit rate

I want to understand what the revisit rate is. If the payload is required to make the revisit rate of 5 hours. The orbit is LEO (altitude less than 2000 kms). What does this mean? Revisit time - the ...
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Which Falcon-9 launches were of a Falcon-9R rocket?

I have heard about Falcon 9 1.1 and Falcon 9 FT, but what is a Falcon 9R? If I understand correctly R = "reusable" which seems to apply to a lot of them. Are the Falcon 9 FT rockets launched ...
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What is the difference between these various spacecraft pyrotechnics?

The following terms have been used in various Space Exploration StackExchange questions and answers. What are the differences (if any) between these various terms? detonating cord detonating fuse (...
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Can "engine" and "motor" be used interchangeably in spaceflight? Are there any cases where they can't be?

Typing "rocket motor" into google returns a page full of links mostly about rocket engines. It seems that The Google has AI-synonymized them. Question: Can "engine" and "motor&...
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Term disambiguation: acceleration with/without gravity

I'm ashamed to ask this. But a free-falling accelerometer in a gravitational field will read a nice round zero. And if that accelerometer is given some thrust, it will read the acceleration produced ...
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Nomenclature of Interstellar Objects and Stars [closed]

I tried searching the answer to this on Google for hours and visited the IAU website as well, but it didn't really clarify my doubt. I was reading about Black Widow Pulsar, which is an "eclipsing ...
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What are all the kinds of electric propulsion that don't qualify as ion propulsion in standard spaceflight lingo?

Comments on the meta question We have both electric-propulsion and ion-thruster tags, are they distinct? What would be good usage guidance for electric-propulsion? indicate that the term "...
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What is the correct term for decorations on a spacecraft?

Many spacecraft have been decorated or embellished with logos, slogans, names of people or research groups, or small stowaway items. Does NASA have a term for this practice?
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Can we compare high microgravity to low microgravity? Can we say "what it's like to be in a significant amount of microgravity"?

In this answer to What do ISS astronauts do while the ISS gets reboosted? I wrote They strap everything down first, then make videos about what it's like to be in a significant amount of microgravity ...
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First instance of a frangible nut in space? Which space-nut was first successfully "franged"?

Wikipedia's Frangible nut begins: Not to be confused with Explosive bolt. The frangible nut is a component used in many industries, but most commonly by NASA[citation needed], to sever mechanical ...
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What is "mission design"? What do mission designers do (if such a designation exists)?

The question in meta Is the mission-design tag description wrong? Should the trajectory-design tag be somehow nixed? needs some attention, so I thought I'd turn to our "panel of experts" ...
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Are there now established classes of solar-electric powered spacecraft?

The NASA.gov press release NASA Awards Contract to Launch Initial Elements for Lunar Outpost says: NASA has selected Space Exploration Technologies (SpaceX) of Hawthorne, California, to provide ...
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1answer
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What is a Beam Waveguide dish and why do deep space communications stations use them?

NASA Spaceflight.com's Deep Space Network upgrades and new antennas increase vital communication capabilities says: NASA’s Deep Space Network, commonly referred to as the DSN, has welcomed a new dish,...
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What is range angle?

In several papers on powered explicit guidance, I've come across the term "range angle." I'm familiar with inclination and azimuth angles, but range angle is new to me. A quick search gave ...
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315 views

Guidance vs. Navigation vs. Estimation

I'm still confused over what exactly falls under the scope of Navigation, Guidance, and Estimation systems. Say I have a bunch of IMUs and use them to determine my position and orientation and my ...
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1answer
111 views

What is the purpose of eccentric, parabolic and hyperbolic anomaly?

I am currently reading David Vallado's 'Fundamental of Astrodynamics and Applications' and I have this doubt on the 2nd chapter named 'Kepler's Equation and Kepler's Problems'. Although I understand ...
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How big is an orbit of "X by Y miles"?

While reading the NASA overview of Apollo 11, says: Apollo 11 launched from Cape Kennedy on July 16, 1969, carrying Commander Neil Armstrong, Command Module Pilot Michael Collins and Lunar Module ...
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Is there an acronym for secondary engine startup? SESU?

We have acronyms for main engine cutoff (MECO) and secondary engine cutoff (SECO). Do we have an acronym for secondary engine startup---SESU maybe?
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Is there an established name for the regions "above" or "below" the ecliptic plane in our Solar System?

In our Solar system, all of the planets orbit the Sun along a plane known as the ecliptic. If we extend the ecliptic plane into a sphere of the same radius centred around our Sun, is there any ...
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Does it count as orbital flight if one reentered the atmosphere due to its drag after about 1 revolution?

Imagine a spacecraft entered an orbit around the Earth whose perigee is low enough into the atmosphere so that it reenters and lands after a revolution, without having to perform a reentry burn. While ...
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Apsis suffix for object orbiting an exoplanet

Is there already an agreed upon apsis suffix for an object orbiting an exoplanet? I don't think it's super likely that there is, as I don't think any moons have been discovered (or at least not at a ...
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Is the Ceres-1 the first Chinese rocket that was given an official Romanized name?

The news feed in the The Pod Bay links to NASA Spacelfight's 2020-11-08 news item Introducing China’s new commercial rocket, Ceres-1. China’s latest commercial rocket, the Ceres-1 (Gushenxing-1) ...
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Are ECI and ECEF both frames and/or coordinate systems? Is there a difference?

I don't know really know the difference between a frame and a coordinate system. I'd proposed ECEF and ECI tags, do we need them? Frames seems to be the standard in meta but there is concern so any ...
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2answers
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During an Apollo mission, were separations after dropping the S-II considered as staging events?

I would like to clarify what is a staging event. Maybe there is no definite definition. First I though it was easy as the Nasa definition is clear. Then I though of the stage-and-a-half Atlas SLV-3, ...
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What do the RD numbers of Russian rocket engines mean?

Most Russian rocket engines have a name on the form of for example RD-107 (РД-107). But apart from different engines having different numbers, how is the number chosen? All RD-2xx engines appears to ...
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What is the official etymology of the term "service" module?

Are there any reputable sources about how the word "service" was chosen for the Apollo service module? (This is a question about how the term was chosen, not about what the term means. ...
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1answer
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IMLEO orbit height

Initial Mass in Low Earth Orbit is a well defined cost metric for space missions [1]. However, this is somewhat subjective since it depends on the orbit height. My guess is that there is a ...
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What is the name of the area on Earth which can be observed from a satellite?

The following image shows Earth and the trajectory of the ISS. A green line indicates which part of the earth can be observed from the ISS simultaneously. What is the name of this line or this area?
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French terminology for the space industry

I am interested to know if there is some consolidated resource for matching space and satellite terminology between English and French. Examples of words to translate include: Orbital Elements, Space ...
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What is a "fee area" exactly and why is it named that way?

On the map of Stennis Space Center, from the early 1960s when it was still named "Mississippi Test Facility"/"Mississippi Test Operations", part of the area is labeled "Fee ...
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Is there a canonical definition of the term "block" as used in "Falcon 9 block 5"?

I gather this has a meaning related to "version". However, I have seen this term used for military and commercial aircraft and other products (generally connected to government or aerospace)...
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1answer
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Connection between Vanguard spacecraft, Vanguard rocket, and Project Vanguard?

I think I created the vanguard tag for Why would low pump inlet pressure result in such a spectacular explosion? (Vanguard TV3) and now I'm not sure of the connection between the Vanguard spacecraft, ...
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Was "Apollo" an acronym for "America’s Program for Orbiting Lunar and Landing Operations"?

I came across this paper which, on page 9, says the following: The guidance or “shooting” algorithm is based on the Linear Peturbation Theory (Battin) developed for the America’s Program for Orbiting ...
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1answer
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Difference between collecting satellite data and tracking its position

When people talk about "tracking" a satellite, do they generally mean receiving data / communication from it, or do they mean determining its position. When an organisation sends a satellite ...
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Why does NASA now call its rovers "robotic scientists?"

NASA's 2020 July 13 press release about the Mars 2020 mission calls its rover Perseverance a "robotic scientist." Is this press release, or at least this mission, the first usage of this ...
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What is the equivalent of Curiosity's "MSL" in the context of Perseverance? What's the official name of the mission? Are the distinctions similar?

Answers to Where does MSL end and Curiosity begin? explain the difference. There was much fanfare for the naming contest for the Perseverance rover, but I don't know what the mission is called. ...
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What is the difference between "body drag", "frictional drag" and "pressure drag" for astronaut or aerobot atmospheric locomotion in microgravity?

Complaints below my answer to Would a higher air pressure on the ISS or elsewhere make it easier to “swim” in microgravity? about my spherical-cow estimate of how fast an astronaut can accelerate by &...
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Do scientist who study martian geology typically use the term areology?

In the book Red Mars by Kim Stanley Robinson, I came across the word "areology". Is this word often used in scientific publications, or is it a term limited to the scope of science-fiction, ...
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What is "TFR" in the context of operating a marine radar on top of a "water tower" at a launch site?

This answer to What is this propellor-like object on top of the SpaceX Hopper? includes the following: FCC filing: Space Exploration Technologies Corp. 0459-EX-CN-2020: ...d) List any natural ...
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How does time work on other planets?

I’m a game developer making a space-based game. I want to implement a system where the time is different depending on the planet. I think this would work like time zones, but to be honest, I’m not ...
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Is there a term that references the time delay between two objects communicating in space, especially at great distances?

When communicating at distance in space (such as Earth communicating to a craft orbiting Mars), the communication experiences a time delay. My research indicates this delay maybe called "One-Way Light ...
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Who called the Lagrangian points as "Libration" points and and why was the terminology "Libration" used?

I am curious about the naming and why were the equilibrium solutions of the CR3BP called as Libration points? Who called them that and what is the history behind it?
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Why do Russian rocket engineers call C₂H₈N₂ "heptyl"?

Unsymmetrical dimethlyhydrazine or "UDMH" is a propellant which has been used by Russian, American, European, Chinese, and Indian rockets. Russian rocket engineers nickname it "heptyl". Why was this ...
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1answer
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Is "liftoff mass" = "ignition mass"?

The answer to How much propellant is used up until liftoff? makes me wonder whether the terms "ignition mass" and "liftoff mass" have widely accepted precise meanings. Does anybody have an ...
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Does the elliptical orbit have many periapsis points?

If I have the position and velocity vectors of a satellite in an elliptical orbit for one point in time, then I can know its position in its orbit at any other time, and with that I can calculate the ...
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1answer
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Is there an alternate term to "fired" for the Reaction Control System?

Do the astronauts use any word, other than "fired" when referring to the use of the Reaction Control System for attitude control or translation?
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What is the story behind specific impulse being expressed in seconds?

I've heard a couple of explanations but none of them quite make sense. One was that the German rocket engineers used metric and the American rocket engineers used the English system and seconds were ...