The long and winding road to Pluto: Bob McDonald

When the New Horizons space probe arrived at Pluto last July, it had been travelling for more than nine years. Meanwhile,it took me nine days on a motorcycle to drive from Victoria to Pluto Mission Control near Baltimore to see what the probe sent back to Earth.

In reality, the full journey to the outer edge of our solar system took half-a-century.

The historic first-everflyby of Pluto on July 14was 50 yearsto the day since the Mariner 4flyby of Mars (the firstflyby of another planet).Mariner 4 provided the first close-ups of the Red Planet in 1965, showing a somewhat disappointing view that looked more like the moon than a world covered in canals built by a Martian civilization.

Since that time, every planet in the solar system, along with more than 100 moons, hasbeen seen by a fleet of roboticexplorers, revealing a crazy diversity of worlds that come in different sizes, different colours, even different compositions some made of gas, others of ice. But all showthat our little planet Earth is only one of a wide variety of forms a planet can come in.

Like historic explorers

As a journalist, it has been my exquisite pleasure to be at Mission Control for most of these first-time encounters with alien worlds, an experience akin to being a passenger on the ship of an early explorer when the lookout hollers,"Land ho!"

The new lands we saw were eerily beautiful, sometimes familiar, but totally alien. When the Viking landerstouched down on Mars in 1976, they gave us the first colour images from the surface of the Red Planet, and we got it wrong.

At that time, the cameras had to be colour-balanced, but there was such a clamour from the media to get the images out quickly thatthe technicians adjusted the colours to match what they believed to be a blue sky - like our own. Later, when the camera was pointed to a colour calibration chart on the side of the lander and adjusted properly, the sky on Mars turned out to be pinkish-orange, not blue.

It was a lesson on how other planets have their own identities, even if they are similar to the Earth. We were being Earth-chauvinistic, believing that because our planet has a blue sky, all planets do. (Actually, the sky on Mars does turn blue briefly during sunsets).

The real surprise

As we explored farther from home, the alien nature of our family of planets became even more apparent. Jupiter's roiling storms, larger than the entire Earth;Saturn's magnificent rings, made of billions of snowballs the size of your fist, organized into stately ringlets as regular as the grooves on a vinyl record; sideways Uranus with thin rings as black as charcoal;and blue Neptune with almost supersonic winds in its methane clouds the fastest in the solar system.

But the real surprise, the most alien of all worlds, were the moons of the giant planets, especially those covered in ice.

Europa,a moon of Jupiter, first appeared as smooth as a billiardscue ball, with no mountains or deep valleys anywhere on its surface. On closer examination, it looked more like a cracked egg, with long rifts in the ice and patterns showing movement. The ice is floating on an ocean containing more water than all the oceans on Earth.

The act was repeated at Enceladus,a moon of Saturn with cracks so deep in its ice, geysers of water are spewing out into space from the ocean below. If we are looking for life beyond Earth, these ice-moon oceans are a good place to start.

To the delight of everyone, Pluto turned out to be an interesting world in its own way. Not only did we see ice, we saw different kinds of ice. Nitrogen, methane, carbon monoxide allfrosted out on the slightly yellow-tinted surface. Mountains as high as the Rockies rise straight out of the ice, held up by mysterious forces active within the planet.

The best is yet to come as the New Horizons robot begins its slow, year-long download of the closest pictures and data fromPluto taken bythe seven instruments on board. So stay tuned.

Endlessly fascinating

The Pluto flyby was a fitting conclusion to my virtual exploration of our solar system over the last 40 years. It was a privilege to once again be among the remarkable group of people who design, build and fly these robots across unimaginable distances, to other worlds that are endlessly fascinatingbut totally inhospitable to us. In other words, if you step outside on any other planet or moon in our cosmic backyardwithout the protection of a space suit, you will die in moments. Which is an important reason to study these planets;they put the Earth in its proper context.

Our planet would be a very different place if it was a little closer, or a little farther away from, the sun. We could be searing hot like Venus, ultra cold and frozen like Pluto, or be ravaged by violent storms with poisonous ammonia clouds like Jupiter.

Following the Pluto encounter, I straddled my motorcycle for the 6,000-kilometretrip home, a journey across beautiful landscapes under a blue sky... and I wasn't wearing a spacesuit. How fortunate we are.

Tune in toQuirks & QuarksSaturday at noon on CBC Radio One or download our podcastfor our feature interview with Alan Stern, the scientist who has led the New Horizons mission for more than 10 years.