February 8, 2010
Pandora is the idyllic blue world featured in the movie 'Avatar.'
location is a real place:
Alpha Centauri, the nearest star to our
Sun and the most likely destination for our first journey beyond the
anti-matter, the 'science fiction' fuel of choice
that could take us there. Normally, it's only created in powerful
jets that roar out of
We can now produce small
quantities in Earth-bound particle colliders.
may depend on how we see Earth at that time in the distant future.
The year is 2154. Our planet has been ruined by environmental
catastrophe. In the movie Avatar, greedy prospectors from Earth
descend on the world of an innocent hunter-gatherer people called
Their home is a lush moon far beyond our solar system called
In fact, the supposed site of this fictional solar system is one of
our most likely interstellar targets, until a better destination
Pandora orbits a fictional gas planet called Polyphemus.
Its home is a real place... Alpha Centauri... the brightest star in
the southern constellation of Centaurus.
light years away, it's part of the closest star system to
Alpha Centauri is actually two stars, A and B, one slightly
larger and more luminous than our own sun, the other slightly
The two stars orbit one other, swinging in as close as Saturn is to
our Sun... then back out to the distance of Pluto. This means that
any outer planets in this system... anything beyond, say, the orbit
of Mars... would likely have been pulled away by the companion and
flung out into space.
For this reason, Alpha Centauri was not high on planet hunters'
lists... until they began studying a star 45 light years away called
"Gamma Cephei." It has a small companion star that goes around it
every 76 years. Now, it seems... it also has at least one planet.
That world is about the size of Jupiter, and it has planet hunters
excited. Perhaps two-thirds of all the stars in our galaxy are in
so-called binary relationships. That means there could be many more
planets in our galaxy that astronomers once assumed.
At least three teams are now conducting long-term studies of Alpha
Centauri... searching for slight wobbles in the light of each
companion star that could indicate the presence of planets. If they
find a planet that passes in front of one of the stars, astronomers
will begin intensive studies to find out what it's like.
One of their most promising tools will be the
James Webb Space
Telescope, scheduled for launch in 2014 or 2015.
From a position a
million miles away from Earth, it will deploy a sun shield the size
of a tennis court, and a mirror over 21 feet wide. The largest space
telescope ever built, it will offer an extraordinary new window into
potential solar systems like Alpha Centauri.
With its infrared light detectors, this telescope will be able to
discern the chemical composition of a planet's atmosphere... and
perhaps whether it harbors a moon like Pandora.
One prominent planet hunter predicted that if a habitable world is
found at Alpha Centauri, the planning for a space mission would
Here's that star duo as seen by the Cassini
spacecraft just above the rings of Saturn.
To actually get to this pair of stairs, you have to travel as far as
the orbit of Saturn, then go another 30,000 times further. Put
another way, if the distance to Alpha Centauri is the equivalent of
New York to Chicago, then Saturn would be just... one meter away.
So far, the immense distances of space have not stopped us from
launching missions into deep space. In 1977, the
spacecraft were each sent on their way aboard Titan 3 Centaur
After a series of gravitational assists from the giant
outer planets, the spacecraft are now flying out of the solar system
at about 40,000 miles per hour.
They are moving so quickly that they could whip around the Earth in
just 45 minutes, twice as fast as the International Space Station.
Voyager I has now traveled over 110 astronomical units. That's 110
times the distance from Earth to the Sun... or about 10 billion
miles. But don't hold your breath.
If it was headed in the right direction, it would need another
73,000 years to travel the 273,000
astronomical units to Alpha
When it comes to space travel, we've yet to realize the
dream forged by rocketeers a century ago...