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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56
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7answers
47k views

Who coined the phrase 'Rapid Unscheduled Disassembly'?

Usually simply abbreviated as a RUD, and also sometimes expanded as Rapid Unplanned Disassembly, and being a way of understating that a rocket exploded. I saw it attributed recently to Elon Musk, ...
46
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2answers
9k views

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 ...
43
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2answers
28k views

What is the difference between Cape Canaveral and Kennedy Space Center?

Cape Canaveral and Kennedy Space Center are both at pretty much the same location in Florida. I do not understand why they are referenced separately in media. How much are they separate entities? Is ...
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1answer
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What is a “suicide burn”?

The term suicide burn occasionally comes up in answers and comments, usually without any real explanation or definition. What is meant by the term "suicide burn"?
36
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5answers
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Does the moon have a name?

Is there any scientific name for "The Moon", Earth's satellite, when talking about it apart from, but in context of, other moons? Google simply states that Earth's only natural satellite is simply ...
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3answers
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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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5answers
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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 ...
25
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4answers
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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 ...
25
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3answers
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What is the difference between docking and berthing on the ISS?

People often talk about docking and berthing. They both seem to be connecting a spacecraft to the ISS, yet seem to be very different. Why?
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3answers
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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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4answers
1k views

Karman line analog on other celestial bodies

Is there a common definition of where the space begins on other planets (and other celestial bodies)? An equivalent of the Karman line. How far one should go from the martian surface to get to the ...
22
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4answers
3k views

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" ...
22
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7answers
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What are these orientations called in orbit?

Let's say a spacecraft is in an orbit like this one: If the red arrows point to prograde and retrograde, and the blue arrows point to normal and antinormal, what do the green arrows point to? In ...
21
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2answers
7k views

When did the term “Space” first come into use?

When did "Space" become the accepted terminology for the area beyond the Earth's atmosphere? What, if anything, was it called before it became known as "Space"?
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4answers
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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, ...
20
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5answers
80k views

How far do you have to be from Earth to be “in space”?

According to a recent news article a group of USC students are attempting to launch a rocket "in to space" with a planned height of 62 miles. Making them "the first group of students to successfully ...
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2answers
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Can it be said that Venus is covered by an ocean rather than atmosphere?

At Venusian temperatures and pressures, CO2 becomes supercritical. This means it behaves as a dense liquid yet has no clear upper bound and continuously becomes gas with height. Can we thus say that ...
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2answers
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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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4answers
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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 ...
17
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2answers
2k views

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 ...
16
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6answers
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Is the air “sucked out” or “blown out” into space when the hatch opens?

In a somewhat famous Star Trek: The Next Generation quote Data corrects Riker on the 'correct term' for a scenario where a hatch on a space capsule breaks open and all the crew are killed. Riker: &...
16
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2answers
2k views

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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4answers
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Did NASA ever use astronomical symbols for planets?

In 19th century texts on astronomy, the planets are often represented by symbols: ☿ for Mercury, ♀ for Venus, etc.. Did NASA ever use these symbols, or were they already obsolete by then? If they ...
16
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1answer
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What does “in the bucket” mean?

I've heard this expression a couple of times before. It seems related to the engines, but I can't find any information on it, except in the context of testing them. Here's two videos where it occurs: ...
15
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2answers
5k views

Why do they say “go” and “no go”

I'm sure we're all familiar with the go/no go standard phrasing for reporting whether something is OK or not. Having a standard phrasing clearly makes comprehension easier and more reliable, ...
15
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1answer
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What is a “Sailboat Island of Stability”?

The New Horizon's team, in response to an announcement of a press conference from the Hubble team, posted some speculations as to what the press conference might be about. On the list includes "Small ...
15
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1answer
15k views

Who really coined the phrase “Light the Candle!” to commence with a rocket launch?

This NASA's image of a Mercury-Redstone rocket Freedom 7 carrying Alan Shepard, the first American in space, is titled Light the Candle:        Light the Candle (Image ...
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8answers
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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 ...
14
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2answers
2k views

What is the “specific impulse”?

One of the most important values when talking about rocket engines is the so-called specific impulse. I have read the Wikipedia article but still have trouble understanding what it really is and what ...
14
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2answers
1k views

How do apsides of celestial bodies get their names?

If you look at this site, it shows some of our common bodies' apsidal names, as shown below: Objects Periapsis Apoapsis Galaxy Perigalacticon Apogalacticon Black hole Perimélasma ...
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1answer
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Nuances of the terms (mean / osculating / Keplerian / orbital) elements

I've been assuming that osculating, Keplerian, and orbital elements are all synonyms, with mean orbital elements just being these averaged over some time. However occasional comments make me suspect ...
13
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2answers
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What is feathering?

I heard that Virgin Galactic's SpaceShipTwo just tested something called “feathering”. What is it? How come I didn't hear about the shuttle doing this, it is unique to Virgin Galactic's ship?
13
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1answer
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Did NASA use metric units for the Mercury missions?

Did NASA use metric or English units for Project Mercury? For example, did they measure delta-v in meters/second or in feet/second?
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3answers
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Origin of term “Block I”, “Block II”, etc

In NASA spacecraft development, subsequent versions of a design are referred to as "Block 1", "Block 2", etc. What is the origin of this naming convention? Why not just call them "Version 1", "...
12
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1answer
1k views

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" ...
12
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1answer
961 views

Why does NASA use the position title “Pilot”' for crew members who are not in charge of piloting the spacecraft?

Why does NASA use the position title "Pilot"' for crew members who are not in charge of piloting the spacecraft? For example famously Buzz Aldrin's position was Lunar Module Pilot but his spacecraft ...
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3answers
2k views

What distinguishes a sounding rocket from a suborbital flight?

What are the differences between a sounding rocket and a suborbital flight? Sounding rockets have long been used for science purposes. Some of them have trajectories elliptic enough to do ...
11
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2answers
2k views

What is a reference mission?

I've seen the term "reference mission" used in connection with proposed missions to the Moon, Mars, etc.. What exactly is "reference" about a "reference" mission, as opposed to a proposal, plan, or ...
11
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1answer
1k views

What's the name of this maneuver for unlimited delta-v?

Let's say you have magical unlimited delta-v, but very low thrust-to-weight ratio. You could travel by accelerating constantly for half the trip, then braking for the other half, until your arrival. ...
11
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2answers
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Is there a term to refer to a planet and its accompanying moons as a whole collection?

I am trying to find out of there is a term that can be used when referring to both a planet and any accompanying moons (if present) as a whole collection. For example if you were to refer to Mars and ...
11
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1answer
846 views

What is the difference between a “space-oriented” and an “Earth-oriented” satellite?

From the NASA TIROS page on TIROS-1: The craft was spin-stabilized and space-oriented (not Earth-oriented). Therefore, the cameras were only operated while they were pointing at the Earth when that ...
10
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1answer
2k views

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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4answers
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What term can we use to describe a planet's or dwarf planet's nearest distance to Earth?

Is there a single term that completes this sentence: "at its _____, Pluto is about 27AU from Earth." peri- something...?
10
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2answers
248 views

Is “medihelion” a word?

"Medihelion" is what I call the two points on a solar elliptical orbit where distance from the sun is the same as the ellipse's semi-major axis. These two points also correspond to the end-points of ...
10
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1answer
769 views

Is this really the logo of the North Korean space program?

Reading about the North Korean space program, and its recent launch of the Kwangmyŏngsŏng-4 satellite, I stumbled upon this logo: It is referenced in quite a few news stories, like here or here, or ...
9
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1answer
1k views

Why do the Russians call the Soyuz launcher the same name as the Soyuz capsule?

It is sometimes confusing that the Russians call the booster rocket Soyuz, and the payload Soyuz. Is there a reason for this naming model? Reading Anatloy Zak's book he notes several proposed ...
9
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1answer
442 views

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 "...
9
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1answer
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What was the procedure to stop the descent engine on the Apollo 11 LEM?

What was the correct procedure to stop the descent engine on the Apollo 11 LEM? When the LEM had a contact light on Apollo 11, there was some terminology spoken that I'm assuming is important (and ...
9
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1answer
834 views

How were the Space Shuttle missions named?

For example, why was the 19th Shuttle mission named STS-51F instead of something more obvious like STS-19? Side note: One reason I'm asking is because in the DVD commentary of Apollo 13, Tom Hanks or ...
9
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1answer
1k views

Pitch and yaw axes of rocket systems such as Apollo

Broadly speaking, most rocket systems appear to have at least 3 or 4 fold radial symmetry about their long axis (if you don't consider internals or smaller features not obvious from a distance). A ...