NASA vs. CSA

Nearly everyone on planet Earth has heard of the organization called NASA.  They may not know that NASA stands for National Aeronautics and Space Administration, but they do know that it runs the world’s most successful space program.  Though founded in 1958, NASA was immortalized in 1969, when it sent a man to the surface of the moon.  The event was the landmark of the twentieth century, and cemented the United States as the world leader in space exploration. 

The economic benefits that the United States reaped from its lunar landing cannot be overstated.  Leaders in aerospace are leaders in technology, and leaders in technology are economic superpowers.  If the American energy and auto industries matched the level of excellence of NASA, the United States would be technologically untouchable.

I would bet that the vast majority of Canadians haven’t a clue what CSA is.  The Canadian Space Agency is the Canadian equivalent of NASA, but the two organizations are hardly equivalent.  CSA is a fine organization.  They participate in the expensive practice of space exploration on a meagre budget; it is however the level of funding of national space organizations that determines the extent to which they may participate.

Here is an order of magnitude scale for the kind of aerospace related activity you can afford for a given amount of American dollars in 2011:

$100,000,000,000                 Manned interplanetary mission

$10,000,000,000                   Manned lunar mission

$1,000,000,000                     Unmanned rocket for satellite placement

$100,000,000                        Complete communications satellite or a 747 airplane

$10,000,000                         Space payload (eg, Satellite Antenna)

$1,000,000                           Basic helicopter

$100,000                              Half a tank of gas for a 747 airplane

$10,000                               One foot wide meteorite (collector’s item)

$1,000                                 Typical coach plane ticket with return

$100                                    Nike sneakers to jump as high as you can

$10                                      Movie ticket for Apollo 13

$1                                        Paper airplane

Breaking the Sound Barrier

The expression “sound barrier” refers to the speed of sound in a given medium.  In the field of aerospace, which studies motion through air and space, the medium in question is air.  Space is a vacuum, which is no medium at all.  Sound can only travel if there is a medium to carry its information from one neighbouring molecule to the next.  As such, sound does not travel outside our atmosphere, contrary to what silly movies like “Armageddon” would lead one to believe.

What is the speed of sound in air?  It is dependent on two factors associated with the air itself: its density and its bulk elasticity.  For standard atmospheric conditions, the speed of sound in air is about 340 m/s.

When an object travels through the air below this speed, its motion is said to be subsonic.  The term Mach number (M) refers to the ratio of a vehicle’s speed to the speed of sound of the medium it travels through.  A typical commercial airplane may travel around 170 m/s, or M = 0.5.  Jets travelling beyond 340 m/s are supersonic.  When an aeronautical engineer hears about Mach 4, he or she thinks of supersonic air travel, and not a Gillette razor. 

What is Aerospace?

To kick off “Aerospace Month” on the Engineer’s Pulse, let us first examine what the term aerospace refers to.  As the word indicates, aerospace studies the motion of objects through both air (in the Earth’s atmosphere) and space (outside the Earth’s atmosphere). 

The field of study can therefore be broken down into two principal areas: aeronautical (within the atmosphere) and astronautical (within space).  Examples of aeronautical navigation include aircrafts (aviation), helicopters, and even hot-air balloons.  Astronautical navigation is limited to spacecrafts and satellites.

There is no real line in the sand, where the atmosphere becomes space; there is just a very gradual transition between the two extreme states.  Near the surface of the Earth, the medium known as air is a reasonably dense gas, with roughly 1 atm of pressure (101.3 kPa); this figure depicts how tight the molecules of the matter are packed together.  In space, at about 300 km altitude, we begin to see the other extreme, where molecules like Oxygen may travel a kilometre before colliding with another molecule.