Five Things Voyager Gave Us

Voyager 2

1977 and The Sex Pistols dominated the Queen's Jubilee, and Morecambe and Wise ruled Christmas.

Meanwhile NASA launched two remarkable space probes, Voyager 1 and Voyager 2.

I can chart most of my life by the journey of these two spaceships.

Jupiter and red spot

When they blasted off I was in Primary School. As they flew past Jupiter I was in Juniors. As they passed Saturn it was the summer holidays before I started Secondary School. Voyager 2 passed Uranus whilst I was getting ready for my O Levels and by the time it reached Neptune I had been bitten by the astronomy bug and was studying for a Degree in Astrophysics.

By the time they cease transmitting I'll be pushing sixty and wondering when I'll be able to retire.

But apart from providing a measure of my life, what else did this mission give us?

1. The Grand Tour

Saturn

The Voyager missions were made possible by the solving of the Three Body Problem.

Newton had figured out the Law of Gravity in the seventeenth century, but when you have a spaceship flying under the influence of two gravitational fields, such as the sun and a planet, the maths is far too tricky to do with a pen and paper.

Uranus

However in 1965 mathematician Michael Minovitch figured out a way of using a computer to make an accurate guess. He needed a pretty big computer, and was allowed to use the IBM 7090, which weighed in at 275 tons and had a memory of 32 K.

This was actually very impressive for the early sixties and allowed Minovitch to solve a problem that had defied solution for nearly three hundred years. He was able to plot a variety of possible routes to the outer planets, and amongst them was a particularly smart way of getting to Neptune by hitching a lift off Uranus, Saturn and Jupiter. The Planetary Grand Tour.

It was a once in a lifetime opportunity. Voyager had to fly by 1979 at the latest as the next time such an opportunity would come along would be 2152.

2. Extra Terrestrial Volcanoes

Volcanos on Io

Picking the best of the Voyager pictures is tricky.

For pure artistic merit nothing beats the rings of Saturn. For colour and complexity it has to be Jupiter. For enigmatic beauty it has to be Uranus.

Then there are the moons with their wonderful Shakespearean and mythological names; Ganymede, titan, Miranda and the rest. All intriguing little worlds in their own right, especially Europa and Callisto which hint at having internal oceans.

But for the Wow! factor its Io gets the prize.

On March 9 1979 astronomer Linda Morabito saw something strange on a Voyager1 photo of the Jupiter moon. A strange lump was growing out of the side, which turned out to be a 170 mile high volcanic cloud.

Suddenly these were not dead world's any more.

3. The Message to the Stars

The Golden Record

The Voyager mission was to bring the planets back to earth, but it also took a bit of us out in to space.

The famous Golden Record may never be found, but it will most likely outlast our civilisation.

When we are no more, laid low by Climate Change, Nuclear War or all uploaded onto computers, a record - literally - of what we were in the late seventies will still be drifting through interstellar space.

There was a bit of concern in the 1980s when it was feared we might have accidentally sent to voice of a Nazi into outer space, but it turned out UN head Kurt Waldheim didn't actually do anything too bad.

What I really like about this is that far in the future, when MP3s are considered as old fashioned as stone clubs, there will still be a good old fashioned record out there, complete with stylus, so that if ET takes a fancy he can listen to Chuck Berry as God intended.

4. The Pale Blue Dot

The Solar Family Portrait

In the end only Voyager 2 made the full Grand Tour. For Voyager 1 the team had to decide between Pluto and Saturn's enigmatic moon Titan.

They went for Titan and found, to their disappointment, that the atmosphere was opaque and they saw nothing. It was a bit embarrassing, but if they'd gone to Pluto they'd have found that by the time they got there it was no longer a planet.

The Pale Blue Dot

Voyager 1 was now heading up, out of the Solar System. In due course it will become the first object made by people to leave the sun's protective heliosphere and enter Inter Stellar space. But there wouldn't be much to photograph on the way.

However its cameras were turned back on for one last picture, a shot of the whole solar family taken from 4 billion miles away.

The outer planets look pretty spectacular, but nearer the sun, barely noticeable next to the glare of the sun, is a pale blue dot.

Us.

It is a deeply humbling photo, as moving in its own way as the famous Apollo 17 Blue Marble photo.

Here is our planet. Tiny, fragile, almost utterly inconsequential in the universe, but possibly the only planet in the galaxy capable of making something as complex as Voyager.

5. Carl Sagan

Carl Sagan

The man who gave the Pale Blue Dot its name was Carl Sagan.

Sagan had worked for NASA from the beginning, but it was Voyager that gave him a world stage.

He was the face of Voyager, bringing his enthusiasm for the mission to the public via the press conferences and live TV broadcasts. This would be the first time most of us would hear his message of progress and scientific humanism.

In due course his books and TV series would turn may people onto science and astronomy, including me.

Just as the Golden Record was designed to make us feel like one planet, Sagan had a vision space exploration ultimately teaching us as much about ourselves as the universe.

As the two Voyagers head out into the depths of space, I hope they are emissionaries of the sort of species that will survive and thrive in the way Sagan hoped, and not the last will and testament of one that didn't.