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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When is a rocket a rocket?

A comment was offered in this question, how technically soft landing works without air on the moon?, asking "what do you mean by 'rocket'." This brought to mind the question of what is a rocket. Does ...
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What (the heck) are “space-fixed coordinates” as described in Apollo mission trajectory analyses?

@Ludo's answer to If I wanted to reconstruct an entire Apollo mission's crewed spacecraft trajectories, what are the key sources of historical data I'd look for? shows the table and its source shown ...
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What do these Apollo era terms mean?

@Ludo's answer to If I wanted to reconstruct an entire Apollo mission's crewed spacecraft trajectories, what are the key sources of historical data I'd look for? links to Apollo Mission 11, ...
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Name for geostationary orbit around another planet

A geostationary orbit is a circular orbit in Earth's equatorial plane whose rotation period matches that of the Earth. The "geo" in "geostationary" means Earth, so is there another term to designate ...
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Definition of a trans-Earth injection

Should every "propulsion maneuver used to set a spacecraft on a trajectory which will intersect the Earth's Sphere of influence" be called a trans-Earth injection? Regardless where the spacecraft ...
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Orbital vocabulary confusion! How can the tangential velocity of an elliptical Kepler orbit not be tangent to the orbit?

I'm now officially confused about the usage of "tangential" when breaking down orbital velocity components. It started with edits and comments on this answer to Orbital speed is (vector) sum of ...
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What is the Azimuth plane and how did it originate?

Background: As I understand it, "up" and "down" navigation aboard the ISS are referred to as Nadir and Zenith with down (towards Earth) being Nadir ...
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Term used to identify the blue bars/rails in the ISS?

The interior of the ISS is filled with blue bars used by astronauts to secure their feet and remain in one place. Does NASA have a term for these?
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What is the difference between an engine skirt and an engine nozzle?

I have seen "engine skirt" and "engine nozzle" both used for the bell-shaped end of a rocket engine. Is there a difference?
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Are there any “Third Order” acronyms used in space exploration?

On a recent episode of the Planetary Radio podcast, the topic of Third-Order Acronyms was brought up. At NASA, there are many Second-order acronyms like SAFER - Simplified Aid For EVA Rescue, where ...
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What exactly is an F-mission?

This @CometInterceptor tweet shows the mission's insignia. The complete wording on the patch is as follows: COMET INTERCEPTOR F-mission Question: What exactly is an F-mission? See also: ...
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Is “Space Shuttle” written as a proper noun in the spaceflight industry?

Writing the question Was a real Space Shuttle ever used as a really big simulator? (and several others) I capitalize Space Shuttle because as far as I know, that's the actual name of NASA's spacecraft,...
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What is and what isn't ullage in rocket science?

This comment and others below this answer address ullage. "Ullage" basically just means "the portion of the tank that isn't filled with liquid". The extended rocket-science implications of ullage ...
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Why do space operations use “nominal” to mean “working correctly”?

In common parlance, "nominal" means "in name only", "small (amount or quantity)" or "stated, but not necessarily reflective of reality". So, the general sense is that "nominal" means something that ...
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Usage of “weight-to-thrust” instead of “thrust-to-weight”

Section 4.1.5 of the Apollo Program Summary Report states The major design criteria for the Saturn I were: a. Minimum vehicle lift-off weight to thrust ratio I've usually seen the reverse ...
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Gravitational keyhole for spacecraft flyby?

Is there a term for the area near a planet a spacecraft must pass through for a gravitational-assist flyby, or does 'gravitational keyhole' apply to gravitational assists as well as for asteroids?
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Did NASA distinguish between the space shuttle cockpit and flight deck?

NASA used both terms on their website, Cockpit and Flight Deck. One answer on Aviation SE Cockpit vs Flight Deck?says there is a difference between the two. Did NASA use the terms interchangeably, ...
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What is the distinction between detaching, jettisoning, and dumping?

What is the difference between the terms detach, jettison, and dump? Related Aviation.SE question: https://aviation.stackexchange.com/q/22903 Examples of using the term "detach": Why was the ...
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How often did launch vehicles have a “Stage 0”, and what does it mean exactly?

While trying to do some reading for the question Need help understanding staging shown in infographic of Titan launch of Hexagon satellites I ran across the Wikipedia article for Titan III. This ...
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Is the term 'lead head' used by astronauts?

In an article on the Space.com website, the author states "Very few astronauts have what's called the 'lead head'--immune from space adaptation syndrome or space sickness." I couldn't find any other ...
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GLOM of a launch vehicle

What do you mean by GLOM of a launch vehicle? When I googled about it, it says it is a type of mass but I am unclear about it.
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List of words and abbreviations like A-OK and MAG

Is there a list of casual, non-technical words, phrases, abbreviations and the like that have developed in any of the space agencies around the world?
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Is there a term for the activity of weightless astronauts hanging out on walls or ceilings?

Weightless astronauts often sit, stand, walk, or sleep on (or near) surfaces that (with gravity) we would normally call walls or ceilings. I reference such a phenomenon in my comment here: I would ...
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Why “strap-on” boosters, and how do other people say it?

This came up for me in the context of translating something into German. Everybody throws around terms like "strap-on boosters", although they aren't actually held on by straps. It's not even meant ...
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Did NASA have a term for the “sky” during the Apollo missions

Did NASA have a distinct word to describe what the Apollo astronauts saw when they looked at out at the stars, when traveling between the Earth and the Moon? Sky does not seem right, as that word ...
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Is GEO redundant (Geo- and Earth)? Would we call a Lunasychronous Lunar orbit LLO?

I think the title of the question Is it possible to establish a synchronous lunar orbit without using Lagrange points? is absolutely clear; it's an orbit around the Moon that is synchronous to the ...
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When was the first strap-on booster used in spaceflight?

The first use of the term "strap-on" in Google Ngram viewer is in 1930 and presumably that wasn't about a booster being attached to a rocket for additional thrust at lift-off. When was a strap-on ...
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Terminology dispute: is an orbital flight still a ballistic flight?

We have a terminology dispute with a colleague: could a flight by elliptical orbit trajectory be called a ballistic flight as well or limits of the later is a parabolic trajectory of a suborbital ...
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What is SpaceX's “rocket canister”?

The CNBC News item SpaceX, Boeing design risks threaten new delays for US space program says: Just ahead of the first scheduled un-manned test flight slated for March 2 under NASA's multibillion-...
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Opportunity's last tau was 10.8; what does that mean and how is tau defined and measured?

@ahiijny added a direct link to the Sol 5110-5114 MER B Downlink Report. These are the final days that signals were received from Opportunity. The message "Tau Value is NOT a Typographical Error" ...
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Can “space weather” refer to deep space environments or only to Earth's (or another planet's) upper atmosphere?

@OscarLanzi's interesting answer and my comment there led me to read Wikipedia's article Space weather. The article exclusively seems to only talk about effects in Earth's upper atmosphere; the only ...
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What do you call the Apollo LEM plus CM (Command Module) when they are connected?

In the question How far away can spacecraft be seen with an optical telescope? I used ...Apollo 14 CM & LEM and the Saturn IV B..." for lack of better words. Unlike some people I (don't) ...
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Is it appropriate to use the term “geology” for Martian studies?

Jargons like geology, geophysics, geothermal has its origin in and has strong connections with Earth. Other jargons like the closet point and farthest point of an orbit to a heavenly body get ...
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What's the difference between zenith and radial?

When it comes to orbital mechanics, are zenith and radial the same? Or to put it another way, are nadir and anti-radial the same?
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Why did the S-IV-B refer to “jettison”ing its ullage?

This is based on a recent question about S-IV-B ullage motor shutoff timing, specifically something found in the Technical Information Summary AS-501, page 15: Ullage Jettison ~ 532. But why "...
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Name for point in a satellite's orbit around a planet when the satellite is furthest from the sun

When a satellite is orbiting a planet (which itself is orbiting the sun) there are periodic points when the satellite is closest to and farthest from the sun, once where it is interposed between the ...
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What's the planetary exploration word for “impact parameter” (distance of closest approach if gravity were “turned off”)?

In particle scattering there's a term called "impact parameter", which is the minimum distance a particle would pass a second particle at rest, if the attractive or repulsive force were ignored or "...
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what is the relevance of ion cyclotron and ion collision frequency ratio

On earth, the ion cyclotron and ion collision frequency ratio is 1 at roughly 118 km, and this is used as one of the definitions of the limit to space. What are ion cyclotron frequency and ion ...
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Is Dawn's upcoming low periapsis orbit for XMO7 “resonant”?

The Spaceflight Insider article Dawn will enter lowest ever orbit around Ceres says: In his Dawn Journal blog, mission director and chief engineer Marc Rayman discussed the challenges of bringing ...
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What is BECO? (Gemini) Same as MECO?

This answer links to this answer which shows the acceleration g-force envelopes experienced by early astronauts, reaching as high as almost 7.5g! Both show BECO, which is what I might call MECO or ...
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Are any “strap-on” boosters held in place by actual straps?

Have there been any strap-on boosters that are attached to the main body of a rocket with actual straps (like bands of metal or something similar), as the name implies? If not, what's the origin of ...
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What is a pickup ion?

I've been reading several publications about Titan's atmosphere and chemistry, and the term "pickup ion" kept appearing here and there (see this publication for example). I looked it up and found the ...
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What is the correct term for the exterior of a rocket or space launch system?

Would you call it the casing, cladding, exterior structure, hull, shell...?
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Why are there so many apisidal names

If we look at orbital mechanics, we can find great tables like these, demonstrating the name of the periapsis and apoapsis around various celestial bodies: Objects Periapsis Apoapsis ...
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How does one refer to the “port port” on the ISS?

Saying "port port" is clumsy. Should I refer to it as the port berthing mechanism? Is there specific terminology for what I'm referring to or are there a few options? Also, I'm specifically ...
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Injection versus insertion

I've noticed that maneuvers to leave a body's sphere of influence on the way to another body are invariably referred to as injection maneuvers, for instance, translunar injection, while maneuvers to ...
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Terminology for CubeSat telecommunications

I'm looking at a brochure for the Iris V2 Deep Space Transponder by JPL. At the end of the brochure there is some data on suggested antennas. For each antenna the bps at approximately 1 AU is shown ...
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Why do delta-v and delta-v both use the same term?

As noted in this Wikipedia article, delta-v, used in spacecraft flight dynamics, is a measure of the impulse that is needed to perform a maneuver. However, in general physics (a much longer standing ...
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Why is Jupiter called a “Gas Giant”?

Jupiter's enormous gravity would turn its atmosphere first into a liquid from a certain depth, and then into a solid further towards its centre. So Jupiter has a solid core, above which is a liquid ...
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What precisely is downrange distance - how is it defined mathematically?

Wikipedia: Downrange is the horizontal distance traveled by a spacecraft, or the spacecraft's horizontal distance from the launch site. Spacecraft don't travel horizontally. I don't even know how ...