In the summer of 2004 the English billionaire tycoon Sir Richard Branson announced plans for his vision of commercial spaceflight, Virgin Galactic. He claimed that once the idea was conceived into reality then flights from London to Sydney Australia would take around 45 minutes instead of 24 hours.
This was to be achieved by the spacecraft entering the lowest 'ring' of orbit (around 100-200 miles up*) and thus travelling at around 17,000 miles per hour, and of course giving the passengers the feeling of weightlessness as they fell around the earth.
A few years after this the claim was dialled back somewhat to say that the flights would actually be around, a still impressive 62 miles, and thus the dream of being weightless on a passenger flight was killed then and there**.
Even so, whilst the 45 minute London-Sydney claim was killed with the new parameters, it still gave hope to many that a faster, sleeker form of air travel was just around the corner. Afterall, Branson had already started an airline using the same Virgin name.
Yet here we are in the year 2018, some 14 years after the initial claims, and many, many test flights later and still no Virgin Galactic.
*Being weightless in space has nothing to do with height and rather orbital velocity, however to experience weightlessness for any length of time the higher you are the better.
**In theory a Virgin Galactic flight could turn its engines off at maximum altitude and passengers would feel weightless as the aircraft fell back towards earth.
A Question Of Thrust
You may have heard the expression, 'It's not rocket science', used when referring to something that is supposedly far easier than rocket science.
The thing is though rocket science is actually easy, the technology that utilises that science however is a another matter.
If you go outside right now and film yourself side-on throwing a tennis ball into the air at a far off target; when watching the film back you will notice that the ball creates a curve from your hand to the ground. This is called a parabola curve, and its shape is defined by the earth's gravitational pull on the ball, and the thrust applied to it by your throwing arm.
If you were able to throw the ball so hard that it reached a speed of 17,000 miles per hour, the parabola curve would turn into a circle and the ball would constantly be 'falling around' the earth. If you get to roughly 18,000 miles per hour, you hit escape velocity and your ball will no longer curve, rather it will break free of the gravitational influence of the earth and shoot off into space. This is essentially 'rocket science'.
Sounds simple, the problem is, in order to create that much thrust you either need the throwing arm of Obelix the Gaul, or several hundred tonnes of rocket fuel. Even reaching a fraction of orbital speed takes so much fuel that the thing you put it in, basically turns into a flying bomb. Seeing as you don't want to explode your passengers every time you take off, you have to devise a clever way to reach those speeds safely, and therein lies the problem.
As Chris Hadfield, the famous guitar-playing ISS astronaut says; "[Space flight is] hard. They're discovering how hard. They wanted to fly years ago and faced a lot of obstacles. [...] No aeroplane you've ever gotten into had less than thousands of flights before they took their first passenger. Because vehicles are unsafe at first. We only flew the [space] shuttle 135 times total. Every flight was a radical test flight. With really high stakes."
The latest Virgin Galactic test flight (of which there have been many) in April of 2018 managed a height of around 84,000 feet (roughly 15 miles) and a speed of around 1400 mph. These figures are very impressive for a passenger jet, those kind of speeds and altitudes are usually reserved for military fighter jets, however it is still way short of the expected 62 miles and 4500 mph.
Fuelling The Problem
The very first engines to be designed by humans ran on a process called internal combustion, whereby fuel is compressed at high pressure and ignited. The resulting controlled explosion drives pistons up and down, which in turn drive a crank shaft round and round, then via an attached rod can also turn wheels around and around.
This is the basics of an internal combustion engine, a jet engine runs on pretty much the same principles, differing in the fact that the energy from the engine is used to power a compressed fan, powered by a turbine.
Ultimately though, a rocket or jet engine is still an internal combustion device and so needs to use flammable liquid fuel. The problem is that most of the energy from the fuel is given up in heat and so is very inefficient. This means you need lots and lots of fuel to go at high speeds.
The V2 rocket ship designed by Virgin, tries to get round the problem by piggy backing on another plane White Knight II and then igniting when it is already 50,000 feet in the air. It also uses a new type of plastic based fuel, after initially trying a rubber based fuel, but even this has only managed to push it another 30,000 feet. The combined total altitude is still almost three times the height of the average passenger jet, but that just highlights how difficult it is to get up into space.
So it seems that perhaps Virgin Galactic's ambitions are ahead of the time. Because if we had some other form of propulsion that was just 20% more efficient than the current rocket fuel it uses, then perhaps we would already have space passengers and hotels on the moon.
Dreaming Big
The nature of the human race is that we have always dreamed big, and there have always been things that have been considered impossible that ultimately somebody comes along and proves everyone wrong.
I for one would like to see Branson, or even Musk or Jeff Bezos succeed in taking paying customers up into space, simply because that would be a mark of progress.
When I was a child the year 2000 seemed like it was so far away that it held the promise of a science fiction future where we would all be holidaying on the moon and regularly going into space for fun.
In 2018 that dream is still just that, a dream, but maybe, just maybe, it is that little bit closer to becoming reality.
Virgin Galactic Timeline
2004 Virgin Galactic Company formed.
2005 The Spaceship Company formed by Branson and a partner. The first and only customer is Virgin Galactic.
2008 Branson announces first flight will take place within 18 months
2010 White Knight II and SpaceShipTwo complete first (low altitude) dual flight together.
2014 Disaster strikes as test co-pilot Michael Aylsbury is killed in a crash in California's Mojave desert, with pilot Peter Siebold sustaining serious injuries
2015 VSS Enterprise launches Virgin Galactic smallsat launch vehicle
2018 April Successful test flight of SpaceShipTwo VSS Unity of 84,012 feet over Mojave desert.
WHERE DO YOU SEE THE FUTURE OF COMMERCIAL SPACE TRAVEL GOING? HOW LONG WOULD IT TAKE YOU TO GO UP THERE; OR WOULD YOU EVEN DO IT?
AS EVER, LET ME KNOW BELOW!
Sources:
Virgin Galactic 'not much of a space flight' - Guardian Chris Hadfield Interview
Watch:
VSS Unity test flight April 2018
Title Image: By NASA on Unsplash