Friday, April 30, 2010

Cosmic Calculations

We spend a lot more money exploring outer space than we spend exploring our oceans. What we learn about the cosmos may be fascinating, but it has little impact on our lives. By contrast, human life depends on healthy oceans. And we know so little about the oceans, which may be why we overfish, pollute and upset the balance of life, creating massive dead zones.

The public at large lets this happen. One reason is that people have a hard time thinking rationally about the universe, because the scale is so enormous. So instead, they think about it romantically. Even scientists in the space industry say things like, “It is mankind’s destiny to travel to the stars.”

Well, I’ve been working my calculator, and I’d like to ground this concept a little bit.

The nearest star is 4 light years (nearly six trillion miles) away. That means that it would take a beam of light, which travels at 67 million miles per hour, four years to reach the nearest star.

NASA photo

We all know that no spacecraft can travel that fast. The fastest velocities on record were achieved by accelerating a craft around the sun – about 150,000 miles per hour. That speed would get us to the nearest star in about 1,800 years.

But let’s say that at some future time, we develop a spacecraft that can propel a manned crew at the speed of 1,000,000 miles per hour. Traveling at that ungodly speed, a crew could go from Earth to the moon in about 15 minutes. Or from Earth to Mars in about a day. Now we’re talking!

Hopefully no space matter would hit our ship, because at that speed even an asteroid as tiny as a grain of sand would create an explosive impact. But let’s assume that somehow a safe journey is assured. At that amazing speed it would take our brave crew over 267 years to arrive at the nearest star.

Correction. The crew would have died of old age a couple centuries before that. The great-great-great-great grandchildren of the original crew would be in charge of the craft as it arrived at the nearest star. And for what? To do what?

But let’s not get into that.

Because back on Earth, a lot would have changed. Quite possibly human culture would no longer care about the purpose of the now-ancient mission. In the worst case, humans would have spoiled the oceans and atmosphere, killing themselves off along with most other species.

In the best case, reason and vision would have prevailed, and civilization would have flourished. So imagine that one hundred years after launch, a second space craft began a journey to the same star at a much higher speed, say 5 million miles per hour. The newer craft would catch up with the first one half-way to the star—rendering the original mission a pointless one.

Today, nations around the globe fret about diminishing resources. So what should our priorities be? Humankind may be destined to explore and learn, but which frontier should be the higher priority? Our planet, or outer space?


Patrick @ said...

Denny, good that you've set the perspectives right. I don't thing that a bit wishful thinking and sci-fi romance isn't good - and yes even our everyday life will get affected by the new technology achieved. Maybe we get next generation microwave ovens.

But as mankind we definitely need to focus - and our oceans will always have a much deeper impact on our lives and our destiny - so true.

I've heard from scientist, that the oh so feared deep asteroid impact that Hollywood made movies off, could only be detected with a slight chance and maybe some minutes upfront the impact.
So what's the use then.

But I am pretty sure that before we get hit by a deadly asteroid, we will be able to destroy one of the biggest resources of life on earth.

Thanks for this great article.

Sean said...

Actually getting a rocket ship to travel near c (the speed of light) is not a difficult problem; with constant acceleration, you'd come up to speed fairly quickly.

But so what? That only gets you to the nearest star. Let's assume there's life out there, okay? In our galaxy there are over 200,000,000,000 stars in an area 100,000 light years across.

It may be safe to assume that most of these stars are near the galactic core and probably uninhabitable due to a greater chance of catastrophic collisions.

But to even explore stars within 10,000 light years of us... "locally" in our area of the galactic rim.... well say it's 10,000 years for a probe we send to get there, and 10,000 years for a signal to get back, that's 20,000 years! Our whole civilization will have either died or evolved into something weird by then.

Now let's say about 1% of the galaxy is in our local area (things are less dense in the galactic rim). So there's only about 2,000,000,000 stars to explore in the next 20,000 years. That's a LOT of interstellar probes. Even if we could get the cost down to a million dollars (through mass production), you're still looking at over two quadrillion dollars. Current NASA budget is about one millionth of that.

So you can see how futile it is to explore the galaxy, even at the speed of light.

Scott Allison said...

Great post! Getting our priorities right is so important. This is where leadership plays such a pivotal role. Thanks for sharing these thought-provoking ideas.