Sunday, April 19, 2015

The glaringly obvious problem with space travel

We seem to be in the middle of a space travel renaissance at the moment. Numerous companies are working on all sorts of rockets, satellites and other space vehicles. Astronomers are discovering new exoplanets light years away all the time - and the desire to colonise new worlds, especially places like Mars, is stronger now more than ever.

It seems the planets and stars that we see in the heavens are almost within reach, but there are so so many obstacles in our way preventing our species from expanding out into the starry night.

Space is relentlessly, unashamedly hostile to human life. Not only that, the distance between planets is mind-boggingly huge. It's going to take decades just to put humans on Mars - but getting there is the easy part. Trying to live on a cold, radiation-soaked, low gravity rock devoid of a decent atmosphere is more akin to suicide than anything else.

In the midst of all these challenges, there's one thing that appears to be amiss from all of the chatter about space travel. It's blindingly obvious to me, but I've not come across it and it's something that I reckon is one of the biggest hurdles there is.

You see, although space is mostly a dark, empty void it's actually still got stuff floating around in it - albeit very very very spread out. There are planets and stars, of course, but then you've got dwarf planets, planetoids, asteroids and comets. Small chunks of ice, rock and dust are out there too in all sorts of shapes and sizes. From the size of a small car down to microscopic specs - they're just spinning lazily around in the black soup happily minding their own business.

Which, I think, is a problem for us wannabe spacefarers.

At the moment, our spacecraft are just hunks of metal welded together. Granted, the walls of these vehicles are probably a few feet thick, but should they collide with a piece of space debris bigger than a tennis ball they might as well be made of tin foil – especially if that piece of junk is travelling at any kind of speed. The Sandra Bullock movie 'Gravity' illustrates the danger of mid-space collisions pretty well in all its terrible zero-G destructiveness. Various space stations and satellites have experienced small-scale damage over the years and NASA has previously researched the effects of meteoroid and space debris damage on spacecraft with its LDEF (Long Duration Exposure Facility). It's one of the many hazards associated with space exploration and, as we venture further and further away from home, will become more of an issue.

Colliding with something in a geo-stationary orbit is one thing. Hitting an obstacle while travelling at 17 metres per second is another. Voyager 1 is the first man-made object to enter interstellar space and is going that fast. It doesn't have much time to do an emergency stop, that's for sure. Obviously, Voyager 1 has been sent on a course that minimizes any chance of hitting something but surely eventually one day it will hit something. Maybe not for thousands or million of years, but it will no doubt one day be smashed to smithereens on some lonely moon out there in the cosmos (either that or gracefully fall into the fiery furnace of some distant star).

And that's the thing - yes, the chances of colliding with another object far out into deep space are pretty small, but we don't know what's out there in the quiet regions of space. Our telescopes wouldn't detect tiny fragments of rock left over from some ancient cosmic incident, and hitting one of those fragments at 17 metres per second is pretty much going to tear a hole in your ship that's going to be difficult to repair.

What's worse, though, is that any spacecraft headed for the nearest star systems will most likely be travelling much faster than that. Even at ten percent the speed of light, it would take about forty years to reach Proxima Centauri, but travelling at that speed is incredible: 30 million metres per second. Yes, that's right. Ten per cent the speed of light is a mere - ahem - 1,764,705 times faster than Voyager 1's current velocity. Imagine hitting a grain of sand at that speed! I don't know the physics, but surely it's going to do some damage? Maybe small particles would simply vaporise and be of little danger, but I'm not entirely convinced.

How could we possibly chart a course into deep space that avoids a collision with not just large asteroids but the tiniest speck of matter?

Now, making a short hop to the closest star system is challenging enough, but were we to develop some kind of faster than light engine (as featured in most sci-fi shows or movies) where we wanted to travel further afield, then we would be going at insane speeds, like 1.5 billion metres per second. Again, hitting something miniscule that fast is going to cause problems. Hitting anything sizeable could simply mean adios amigos.

I guess the interstellar void between stars is pretty unlikely to have anything in it. Presumably anything floating around in space is naturally drawn to any source of gravity so stars have done the job of hoovering up any bits and pieces that could potentially cause problems. But - you never know what might be out there. Should we ever get to a 'Star Trek' level of sophistication when it comes to space travel, there's also the very slight (but still possible) chance of smashing into another one of our craft if we're not too careful.

My feeling is that the only way to traverse these brain-achingly vast distances is to make use of worm holes, bypassing the need to do any travelling as such and simply 'hop' from one place to another. How we achieve that exactly is anyone's guess and probably will be beyond our capability for centuries.

Interestingly, a recent scan of the stars concluded that there are - as far as we can tell - no alien galactic empires anywhere. Assuming that a galaxy-conquering race would emit certain heat emissions, no traces were found in around 100,000 potential candidates. It's not conclusive proof that intelligent alien life doesn't exist out there in the cosmos but it's a strong indication that even intelligent life may struggle to get very far.

So, either we are very alone in the universe - or it's practically impossible to travel great distances among the stars.

Which is a real shame, because who wouldn't want to fly around in the Millennium Falcon like Han Solo? I know I would...

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