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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First use of frangible nuts in space?

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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What is a Beam Waveguide dish and why does the Deep Space Network 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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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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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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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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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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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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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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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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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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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 ...
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What terminology is used to describe spacecraft in stationkeeping?

Forgive any inaccurate wording of this question. If a Soyuz craft which had been docked at the Zvezda module backed away from the ISS and remained at stationkeeping, would NASA, Roscosmos, or the ESA ...
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Official terminology for non osculating orbital elements

When I need to talk about an orbital element that is not osculating and that it is the true/actual element at a given instant, I use the term "actual": actual perigee, actual eccentricity, actual semi-...
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What is the proper terminology for the process of a satellite entering a planet's shadow? [closed]

What is the proper terminology for when a satellite or spaceship passes into a planet's shadow or night side? Is it crossing the terminator? Passing into eclipse (or something better)? If there is a ...
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Does NASA use any of the twilight designations?

Do the differences in civilian, nautical, and astronomical twilight have any technical relevance to NASA either on Earth or any other object in the solar system where a probe has landed? Does NASA ...
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NASA's definition of a launch vehicle

Does NASA's use of the term launch vehicle apply only to those that ascend from the Earth's surface and leave the atmosphere? If so why is the term limited that way?
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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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What is the difference between a “Suicide burn” and a “Hoverslam”?

As far as I can tell, the terms Suicide burn and Hoverslam have both been invented rather recently (with SpaceX themselves coining Hoverslam and the Kerbal Space Program community loosely credited ...
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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 ...