It can happen

Theories are nice. Having a way of explaining an event or failure, or both is a nice comfort blanket. It can give us a way of trying to look ahead. The common notion that; if it has happened once, it can happen again, is part of our mental hard wiring. We store up memories and are constantly ordering and re-ordering them in our minds. Looking for patterns.

What cuts across is a simple factual recollection of an event. Examples can be illustrative of a theory. Also, they can stand alone as evidence that anyone of us can fall foul of the unthinkable. One of my favourite events, which has the ingredients of the unthinkable happened in the 1990s. It’s about exploration and the space industry. That said, a story on this theme could be written about any part of the aerospace world.

Safety assessments are scoped to consider about anything that’s not extremely improbable. Let’s be clear that’s an approach that consciously asks people to discount some events as absurd or never going to happen, just beyond what we would ever do. The lesson is that when considering how things go wrong it’s as well to be open minded.

Let’s go back to December 1998. A spacecraft called the Mars Climate Orbiter (MCO) was intended to skim the upper atmosphere of the planet and return data to Earth. It had taken over 9 months to get to Mars. A journey like that one come with costs mounting in the tens of millions.

The spacecraft was about to go into orbit, it disappeared behind Mars but failed to re-emerge. Efforts to communicate with it were continued for a long-time but nothing came back. An investigation into the MCO’s loss concluded that it had crashed into the surface of the red planet. This was not the crux of the matter. Such projects have risks that can be unknown.

Investigation concluded that the MCO had been obliterated[1]. It was off course by 60 miles, so it plunged to destruction rather than entering orbit around Mars.

Now, I said that anyone of us can fall foul of the unthinkable. In this situation, that’s what happened. The managing organisation for spacecraft thruster data had been using imperial units. Thruster performance data was in “English” units. NASA’s navigation team had assumed the units used were metric. The trajectory modelers assumed the data was provided in metric units as per their requirements. Thus, the difference between miles and kilometres sealed the fate of the MCO.

Discovering that cause of the loss must have been excruciatingly embarrassing. One of the published recommendations; take steps to improve communication, seems modest. In addition to taking on-board all the investigations findings, my take on this event is two-fold.

  1. Think the unthinkable. Not all the time, but every so often it pays dividends and
  2. Question assumptions. Even the most cherished simple assumptions can be wrong.

These two are universally applicable.


[1] https://llis.nasa.gov/llis_lib/pdf/1009464main1_0641-mr.pdf

Avionics

Segmenting, categorising, and naming technical subjects has a long history. However, it’s not often there’s a back story to say what’s in each name. Numerous definitions exist. These are quite often an afterthought. Naming that evolves rather than can be traced to a single author.

The subject on my mind is Avionics. It’s a ubiquitous term in aircraft engineering. In fact, it’s applied much more widely than that because administrators, pilots and air traffic controllers all use it. So, let’s look at the history, etymology and usage of the word.

The word seems obvious, as to not need a definition. Bring the world of aviation and electronics together and there it is – Avionics. However, Avionics often extends beyond the world of aviation and into space. So, it may be better to say, bring the world of aeronautics and astronautics and electronics together and there it is – Avionics.

Notice that it’s electronics and not electrics that forms the definition. A loose distinction between the two might be to say that, in terms of electric current, electronics is anything below an ampere[1] and electrics is that above an ampere.

Marconi was the first to experiment with airborne radio. It was even available to pilots in the First World War. However, spark-gap radio was unloved, heavy, and awkward.

The name Avionics started being used in the 1940s. VHF radio communication between aircraft and ground stations was vital to an aircrafts’ operation. The fabrication of radio valves in high volumes and at low costs led to the use of numerous radio technologies: communications, navigation, RADAR and Radio Altimeters to name a few.

The science and technology of electronics, and the development of electronic devices has advanced faster than that of aircraft design and manufacture. Avionics engineering has been divided into numerous sub-fields as a result.

Where once an aircraft could complete safe flight and landing with a complement of defective avionic equipment that is no longer the case. It’s quite the reverse, as the current generation of both military and civil aircraft are highly depended upon the correct functioning of their avionic systems.

Often the more complex an aircraft and its operation becomes, the more complicated the avionic systems become. Aircraft flight-control systems can be of great sophistication. By contrast a VHF radio hasn’t changed much, in its basic function, for decades.

Although avionics is a common term, it doesn’t often find its way into legislation or everyday usage. There’re certainly great swathes of the population for which the word means nothing. It’s an unusual day if the six-o’clock news has a reference to this technical word. 


[1] https://www.npl.co.uk/si-units/ampere

Mars flight

I was wondering – is there air on planet Mars? It’s one thing to say is there life on Mars? We’ve been asking that big question of generations. But can we use the word “air”? There’s a thin atmosphere on Mars but can you call it air? The rover that’s there will be listening for sounds in what is 95% carbon dioxide. That kind of atmosphere on Earth would be our worst nightmare.

Let’s look at the definition of that everyday word – air.  Air is the mixture of gases which forms the Earth’s atmosphere and which we breathe.  No way could we breath on Mars.  That gas we depend on, oxygen is down to about 0.1%. Taking that basic definition then Mars does not have “air” in the common sense.

I’m going down this rabbit hole because of the references to Ingenuity, the Mars Helicopter that is being prepared for flight. This innovative flying machine has been landed on Mars and is being referred to as a helicopter.  Now, a Helicopter is a heavier-than-air aircraft supported in flight chiefly by the reactions of the air on one or more power-driven rotors on substantially vertical axes[1].

Oh dear, there’s that reference to the air as per planet Earth.  I may be being an aviation pendant, but this could be the time to revisit the definition of helicopter and change the word “air” to “atmosphere”. Afterall, if there’s a gas of sufficent density then flight is possible with the right equipment.

Ingenuity could also be known as a Rotorcraft.  It undeniably has two rotors, so it must be a craft supported in flight chiefly by the reactions of an atmosphere. Since we are entering a new era of aviation as a human built extra-terrestrial vehicle makes a controlled flight for the first time, revisiting definition could be appropriate. 

Then Airworthiness is then better expressed as Flightworthiness. Maybe, Aircraft ought to be Flightcraft. There’s a history here given that a craft that hovers is called a Hovercraft. Which is more important? What it does or what it does it in?

Whatever the nuisances of these internationally used definitions in English, the wonder of this fantastic achievement is not lost on me.  This moment only happens once. The first time the immense challenges of controlled flight on another planet are overcome we are in a new era of aviation. 

Flying in a hostile cold, thin atmosphere will be amazing. Take-off and landing several times will be astonishing.  What magnificent engineering design. Rotors spining at 2400 rpm. This robotic rotorcraft will test the feasility of flying on another world. Imagine what that will open up. From me, all the best good fortune to the team who made this possible. Lift-off and come down in one piece. Looking foward to seeing the pictures.


[1] Annex 8 to the Convention on International Civil Aviation