Browse the glossary using this index

Special | A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z | ALL


Falcon 9

(Last edited: Wednesday, 30 August 2023, 5:47 PM)

Source : SpaceX (2016, January 16). Falcon 9 vertical at Vandenberg Air Force Base. wikimedia commons.

Source : SpaceX (2016, January 16). Falcon 9 vertical at Vandenberg Air Force Base. wikimedia commons.


Falcon 9 is the world's first orbital class reusable rocket, created and manufactured by SpaceX. It is a reusable, two-stage rocket capable of transporting both people and payloads into Earth's orbit and beyond. Reusability allows to reuse the most expensive parts of the rocket, which diminishes the cost of space access. The standard parameters of the rocket are:

Height - 70 m / 229.6 ft

Diameter - 3.7 m / 12 ft

Mass - 549,054 kg / 1,207,920 lb

The engine used in production of Falcon 9 is the Merlin, which uses grade kerosene (RP-1) and liquid oxygen as rocket propellants in a gas-generator power cycle. The Merlin engine was originally designed for recovery and reuse.

Falcon 9 has already been used in numerous missions or tests (Crew-1 Mission, Crew-2 Mission, Crew-3 Mission, DART Mission) and is planned to be launched in the next ones (for example Polaris Dawn in the last quarter of 2022). 

Sample Sentence(s):

"This rocket is the Falcon 9 that successfully reached orbit after 9 minutes and 38 seconds on its maiden test flight."
"It was suggested to be launched with a Falcon 9 rocket."

  • French: Falcon 9
  •  German: Falcon 9
  •  Polish: Falcon 9 
  •  Swedish: Falcon 9

Links to Videos/Articles:

Fluid shift in the human body

(Last edited: Saturday, 30 September 2023, 8:08 PM)
Image Source: S, M. (2023, June 01). Illustration of fluid distribution. self. self-made

Image Source: S, M. (2023, June 01). Illustration of fluid distribution. self. self-made

The fluid shift in the body is an adaption to the reduced gravitation force in space. This results in a shift of the body fluids from the lower body to the upper body.

Detailed Definition:

When a human body is placed on the earth surface, it has a hydrostatic (gravitational) blood pressure gradient and every body region has a different arterial pressure.

In the reduced gravity of space, the hydrostatic pressure in the arteries and veins is altered to a homogeneous arterial pressure in all regions (which is the original arterial pressure of the hearth), which results in the shifted fluid distribution through the body.

The human body reduces the volume of the total fluid and after the space resident, the fluid is shifted because of the returned gravity force.

This phenomenon can cause several issues like cardiac arrhytmia, muscular athropy and visual problems (because the globe is flattened, the blood flow is changed slightly and the diamteter of the optical nerve can increase).

fluid - Latin fluidus ("fluid, flowing, moist")
shift - Proto-Germanic skiftan (" to divide, change, seperate")

Sample sentence(s):

A medical effect of a space flight may be a fluid shift.

Nasa is studying the effect of the fluid shift and how it affects changes in vision.



déplacement du fluide




Przemieszczenie płynów w ludzkim organizmie



Links to Videos/Articles:


(Last edited: Friday, 28 April 2023, 6:09 PM)

Image Source:

Short Definition:

A frequency (f) is a physical variable which measures how often a event is repeated in a defined period of time.  

The SI-unit is Hertz (hz) or s^-1.  

A common scenario in which the frequency is used, is in a wave, in which it can be calculated by measuring the Period T (the time it takes to complete one cycle) and using the equation: f = 1/T 

Detailed Definition:
Another equation by which the frequency can be calculated, is the following with \( \lambda = \) wavelength and v= phase velocity (if the wave is detected in a vacuum, the following applies: v=c)
\( f = v/ \lambda \).

There exist two special types of frequency, the angular frequency and the spatial frequency, which will be explained in the following:
The angular frequency (ω) describes how fast a vibration / wave is occurring by measuring the overstepped phase angle of the vibration / wave in a defined time period. This frequency can be calculated in the already introduced frequency f by using the following equation:
\( \omega = 2 \pi f = 2 \pi /T \).

The spatial frequency (ξ) measures how often sinusoidal components (components of a sinusoidal wave) of a structure repeat per unit of distance, which can be calculated by using the following equation:
\( \xi = 1/ \lambda = f/v \).

frequency - Latin frequentia (" an assembling in great numbers, a crowding; crowd, multitude, thong")

Sample Sentence(s):
The frequency can be identified by calculating the inverse of the period T.
The frequency is a variable which can characterize a wave.

French: Fréquence

German: Frequenz

Polish: Częstotliwość

Swedish: Frekvens

Links to Videos/Articles: