Ever since the dawn of the Space Age, humans have been building
robotic spacecraft alongside human space flight. In fact, the first spacecraft - the Soviet Sputnik 1, was of course, a robotic machine.


While human space flight can achieve a tremendous amount -- for example, astronauts travelled far further on the moon in a few days than the Mars Rovers have travelled in 5 years, it is simply impractical to travel anywhere further than the moon given the state of propulsion technology at the beginning of the 21st century.

So, we have to use Robots as our eyes and ears to the planets, moons and beyond.

This being said, what we have learned through the use of robotic spacecraft has opened our eyes to the Solar System and the Universe in ways we could not imagine 50 years ago.

We used to think there were nine planets and about 20 moons (Earth - 1, Mars - 2, Jupiter about 10, Saturn about 10, Uranus 4, Neptune, about 4).

Now we know that Jupiter, Saturn, Uranus and Neptune have at least 60 moons apiece.

We have relegated Pluto to the status of minor planet. Why? Because -- keep your socks on -- we have discovered a slew of minor planets, many larger than Pluto. How many? So far -- about 168,000. And we're still counting.

The images we have seen of the moons of different planets show that there are moons with thin layers of ice covering warm(ish) water. There are moons that have seas of methane and ethane. That most moons are different from each other. One or two moons are larger than the planet Mercury.

We have learned that the moons of Saturn are the source of material that make up Saturn's rings.

We have sent probes to every planet in our Solar System, and three, to the very edge of the Solar System, and two are still functioning -- after 30 years.

Today, we have spacecraft orbiting planets, we have landed on Asteroids, gathered material from comets, and have fleets of robots investigating the sun, and the Earth.

And we are just getting started.

For a full list of US missions, you can go
here and for European missions, here

In the following pages, I'll share highlights of some robotic missions.