Getting to Pluto

Everyone's become just a bit more enamored with he planet of the underworld lately, thanks to NASA's successful New Horizons space probe. But while you've probably already seen plenty of pictures (and spoofs) online, did you realize just how amazing it is that New Horizons traveled about three billion miles in nine and half years?

Speedy Science As I explained in a previous blog post, distances in space are huge. Remember how Bill Nye had to run to the other side of the soccer stadium ("almost out of the building") to get to Pluto? The Apollo 11 spacecraft that landed on the moon (July 20, 1969, 46 years ago last week) took nine days reach its destination, traveling at an initial speed of 24,200 miles an hour (see NASA's online mission log for more details). Had New Horizons traveled at that speed, it would have taken approximately 5,165 years to accomplish its little mission.

That's a giant leap forward in space travel. As this Gizmodo article explains, part of the New Horizons speed was due to its limited size (making it extremely efficient), while another major boost came from exploiting a force of nature we all take for granted: gravity.

After liftoff, New Horizons received additional velocity boost from Earth’s orbital motion around the sun, which is approximately 18.6 miles per second tangential to the orbital path. Altogether, then, the spacecraft barreled into the solar system with a heliocentric (sun-relative) speed of nearly 100 thousand miles per hour....

Thanks to its quick start, New Horizons made the 500 million mile journey to Jupiter in just over a year, faster than any of the seven previous Jupiter-bound missions. But the sun’s gravitational pull is relentless, and by the time New Horizons reached Jupiter in early 2007, it had slowed to (a mere!) 43,000 miles per hour. Jupiter would help New Horizons regain what it had lost.

As it neared the gas giant, New Horizons began to speed up once more, reeled in by Jupiter’s prodigious gravity, which also acted to bend the spacecraft’s trajectory. On February 28th, 2007, the tiny probe made its closest approach to the gas giant and then flung itself away, snagging a bit of Jupiter’s momentum in a move that rocket scientists call a ‘gravity assist.’ Essentially, as New Horizons was dragged into Jupiter’s gravitational field, it gained kinetic energy amounting to nearly 9,000 miles per hour worth of speed, increasing its velocity to over 52,000 miles per hour.

To balance the books, Jupiter lost as much kinetic energy as New Horizons gained, causing it to fall a little closer to the sun. A year on Jupiter today is slightly shorter than it was before—all because humans wanted to get a good look at Pluto.

Here's a NASA video that illustrates the path New Horizons took and explains the thought process that went into designing the route.

Takeaways The good news is that we're getting much, much better at making efficient, speedy space-faring vessels. While anything that carries people will have to be less efficient than a probe, the major advances New Horizons demonstrates in speed give me hope for the proposed (and long delayed) Mars landing.

On that same note, I hope that these advances in vehicle efficiency (especially as relates to an eventual craft manned by onboard human operators) represents a new way we can see some NASA/private sector synergy. Too often the public and their elected governments forget that many of the technological advances NASA pioneers are able to transfer over to the world of private citizens. Energy efficient vehicles are something everyone should be able to see the value of, whether they transport us to another town or planet.

The gravitational effects of New Horizons journey are also intriguing to me from a fictional standpoint. We've now altered the course of the largest planet in our solar system. Fortunately, no one lives on Jupiter (yet). But what if there was a populated world that went off kilter due to similar travel need? Would that world experience climate change? Would such an outcome lead to war?

Perhaps most importantly, though, it is now conceivably possible to travel to Mordor.

I look forward to finding out more about what this underworld has to offer.