In 2007, NASA launched the Dawn mission to explore Ceres and then Vesta in the asteroid belt.
Dawn won’t arrive at Ceres until 2015, but when it does it will have the opportunity to examine a proto-planet, a planetary body in its infancy.
The asteroid belt, which is located between Mars and Jupiter, is thought to be the remains of the initial disc that formed the planets within our solar system billions of years ago.
Ordinarily, these asteroids would have slowly accumulated into a planet like Mars, Earth or Venus, but the thinking is that Jupiter’s gravitational presence has kept this from happening by drawing off most of the mass, and this gives us a glimpse into the remote past, the opportunity to understand more about how our own planet once formed.
Perhaps the most remarkable aspect of this mission, though, is the use of an ion propulsion engine.
Hold a single sheet of printer paper in your hand and feel the minuscule sense of weight pressing down on your fingertips. It’s hard to imagine how an engine producing this little force against a spacecraft could ever be considered viable, but the ion engine is not only viable, it has set the speed record for interplanetary spacecraft.
Ion engines may sound like some exotic, futuristic alternative to the chemical rockets we’re so familiar with, but the concept was first experimented with in 1916, during the First World War. On Earth, ion engines are little more than a novelty. In space, where they can operate without wind resistance, they are the undisputed champions of travel, but you have to be patient.
Like a bank account earning interest over fifty years, the law of compounding effects allows the ion engine to slowly but surely continue gathering momentum to reach astonishing speeds.
It took Dawn four days to accelerate to 60 miles per hour, but over several years, that constant steady push, never more than the weight of paper in your hand, has resulted in an accumulated acceleration of 9,600mph. The craft’s total change in velocity since it left Earth is over 38,000 miles per hour, and, what’s more, it’s done this using less fuel than you find in most semi-trucks. Dawn uses xenon, not diesel, but it’s only carrying roughly 115 gallons (937 pounds to be precise).
So think about the Dawn mission the next time you see a semi driving by or pick up some paper from the printer. Small efficient engines can go a long way.