This close-up of swirling clouds around Jupiter's Great Red Spot was taken by Voyager 1.

What do you think are the most significant events that have occurred in the past fifty years of robotic planetary exploration? Why?

"Mars Exploration Rovers -- of course! For the past eight years they have become very familiar, almost like friends -- very, very far away friends."

Since we are limiting the question to robotic exploration I have to choose the Voyager missions as the most significant event from the past 50 years.

The Voyagers are now the most distant man-made objects -- they are humanity's ambassadors. The fact that they are still working and gathering data is amazing. I was quite young back when they were launched -- I had no idea what space exploration was, how spacecraft are built or that eventually I would end up in this business.

This image is the first photograph ever taken from the surface of Mars. It was taken by the Viking 1 lander shortly after it touched down on Mars on 20 July 1976.

Secondly, I choose the Viking missions: The first explorers of the planet that has become my second home. I still remember how amazed I was seeing the images on TV.

This spectacular picture of the Martian landscape by the Viking 1 Lander shows the rock "Big Joe" and a dune field with features remarkably similar to deserts on Earth.

Third, I choose the Mars Exploration Rovers -- of course!

After traveling about 491 million km (305 million miles), Opportunity hit a science jackpot when it settled into this crater on Mars' Meridiani Planum.

For the past eight years they have become very familiar, almost like friends -- very, very far away friends. The landscapes, especially at Meridiani, are very beautiful to me.

This image from the Mars Exploration Rover Spirit's rear hazard identification camera shows the rover's hind view of the lander platform.

And finally Cassini: Not being a planetary geologist, I can only be amazed by the quality and beauty of the images returned by this mission. These are the images I had in my mind when reading science fiction novels.

While flying over the unlit side of Saturn's rings, the Cassini spacecraft captured Saturn's glow, represented in brilliant shades of electric blue, sapphire and mint green.

Giant plumes of ice were photographed in dramatic fashion by the Cassini spacecraft during a flyby of Saturn's moon Enceladus. Numerous plumes are seen rising from long tiger-stripe canyons across Enceladus' craggy surface.

The existence of oceans or lakes of liquid methane on Saturn's moon Titan was predicted more than 20 years ago. But with a dense haze preventing a closer look it was not possible to confirm their presence; that is until the Cassini flyby on 22 July 2006.

In your field of work, what are some examples of the great achievements and discoveries in planetary science and robotic exploration throughout the past 50 years?

NASA's Mars Exploration Rover Opportunity used its navigation camera for this northward view of tracks the rover left on a drive from one energy-favorable position on the northern end of a sand ripple to another. The rover team calls this strategy "hopping from lily pad to lily pad."

I could argue the many achievements of the MER vehicles -- they have returned data that will keep geologists busy for decades, and some of the images are stunning. But it is the Voyager mission that I have deep in my heart. We have sent many spacecraft to various places in our solar system, but they are the only ones that are beyond our small neighborhood.

Our neighborhood. Earth is on the left.

Other favorite images?
There are two: The first is Earth's view from Mars Reconaissance Orbiter's (MRO) High Resolution Imaging Science Experiment (HiRISE).

Besides viewing Mars, MRO's HiRISE camera can also be used to view other planets. This is an image of the Earth and the Moon.

The second is the classic "Pale Blue Dot" image of our home planet.

"Look again at that dot," Carl Sagan wrote in his book "Pale Blue Dot." "That's here. That's home. That's us. On it everyone you love, everyone you know, everyone you ever heard of, every human being who ever was, lived out their lives. The aggregate of our joy and suffering, thousands of confident religions, ideologies, and economic doctrines, every hunter and forager, every hero and coward, every creator and destroyer of civilization, every king and peasant, every young couple in love, every mother and father, hopeful child, inventor and explorer, every teacher of morals, every corrupt politician, every 'superstar,' every 'supreme leader,' every saint and sinner in the history of our species lived there -- on a mote of dust suspended in a sunbeam."

Both images show the Earth as a unique place, a single entity, not divided by countries or property lines. These images make our problems and horror stories seem quite petty.

Read More:

People:

• Paolo Bellutta's People Profile

• Voyager 1 Mission Page
• Voyager 2 Mission Page
• Viking 1 Mission Page
• Viking 2 Mission Page
• Mars Exploration Rovers Mission Page
• Cassini-Huygens Mission Page

• Mars' Planet Page

Last Updated: 8 August 2012