NASA AUDIO

3,2,1... And we have liftoff of the Delta rocket carrying Gravity Probe B - testing for truth and the physics of our universe.

NARRATION

On April 20, 2004, a small spacecraft set out on a giant quest ... to answer one of the fundamental unanswered questions of our universe. At stake is the reputation of the 20th century's great genius ... Albert Einstein ... and also of this man. His entire career rides on this rocket.

DR JONICA NEWBY

Well, I'm here at mission control for Gravity Probe B, a program that's taken 43 years, and very soon, we're going to know the answer - was Einstein right?

NARRATION

This is the story of two great men - tested to the limits. Gravity Probe B Principal Investigator, Francis Everitt has had his ingenuity and tenacity stretched to breaking point over the last 40 years - and he's about to find out if his life's work will literally explode in front of him.

DR FRANCIS EVERITT

I've often been asked how I was feeling, and the answer is I was too busy to feel anything.

NARRATION

The other man - well Einstein may be gone, but his theories live on at the heart of modern physics ... some never tested ... until now. And this is the craft that carries the burden of their legacies.

BRAD PARKINSON

You look at it and you say oh my goodness look, it's a marvel of engineering, it's a marvel of physics and science.

NARRATION

On board Gravity probe B are some of the most delicate and intricate devices ever crafted by human kind. If just one of them fails over the next 11 months, we may never know the truth about gravity.

DR FRANCIS EVERITT

Gravity is the first force in nature that anybody really, in some sense, namely Newton understood and of all the forces of nature it's the probably the one we least understand to the day.

BRAD PARKINSON

See Newton was right, almost, and it was only when we pushed the limits that we discovered no, no, he's not quite right.

NARRATION

In 1915, Albert Einstein unleashed a revolutionary new understanding of the universe's great force. This was his theory of general relativity.

DR FRANCIS EVERITT

Einstein realised you have to treat gravity not as a force but as a field. It means that things don't interact directly, it isn't that you have two objects which pull on each other, but each of them modifies the space around them in some way.

NARRATION

No longer was gravity Newton's simple attraction between two bodies ... gravity was the curvature of spacetime itself. Einstein saw a universe where mass warps spacetime around it ... and black holes suck spacetime into a vortex.

DR JONICA NEWBY

One of the consequences of Einstein's understanding of gravity is a phenomenon known as Frame Dragging. Complicated name - simple idea. It suggests that as a massive celestial object like a planet rotates, it drags bits of spacetime with it

BRAD PARKINSON

I mean, drags space and time with it, what on earth does that mean? It means there's a coupling and that a nearby object somehow gets dragged. But it's not a force, it's not a force, it's a rotation of the local coordinate frame and this is a really weird notion.

NARRATION

But it was just a theory. While Einstein has since been proven right on most things, his theory about the nature of gravity has had surprisingly little experimental proof. When Dr Francis Everitt took on that mission back 1964, he was just 30. He had no idea he'd give his life to it.

DR FRANCIS EVERITT

It's still amazing how little testing Einstein's had. I, with the ignorance and simplicity of youth, thought I'd like a bigger challenge, and, I certainly got it. In the end, I think just sort of the sheer challenge of are we going to be able to pull this off became itself a driving force.

NARRATION

So what took so long?

BRAD PARKINSON

Concept very simple. Execution, real hard - real hard.

NARRATION

The concept did sound simple enough. They'd place a telescope - and a spinning gyroscope - in orbit above the earth. The telescope would lock on to a distant reference point - a guide star. Over the course of a year, they would see if there was a slight change in the angle of the gyroscope.

With this simple setup, they could test two key Einstein effects - and his theory on gravity with it. First is called the geodetic effect. This the amount by which the earth is curving its spacetime. More important was to test the infinitely smaller, never measured frame-dragging effect - the amount the earth is dragging its spacetime. The trouble was, the technology to measure such a tiny deviation wasn't humanly possible.

BRAD PARKINSON

So it's measuring something, an angle as seen from forty miles that is more like that.

DR FRANCIS EVERITT

The kind of gyroscope you need is one million, no ten million times more accurate than the most accurate inertial navigation gyroscopes.

NARRATION

And that meant they had to invent an entirely new form of gyroscope. This is where that mind-numbing engineering challenge was taken on - the machine shop at Stanford University, California. Everitt was here ... year after year ... as his team struggled ... and failed ... to make the heart of the gyroscope they needed ... a sphere so perfect, it didn't exist on earth. After 10 long frustrating years, they finally they hit the right formula, a quartz sphere coated in an element called niobium.

DR JONICA NEWBY

This is it - this is the gyroscope, the most perfect round object on earth. It's even listed in the Guiness book of records that way. Put it this way - if you were to blow this up to the size of the earth, the tallest mountain would be just 2.4 metres high.

NARRATION

Like all gyroscopes, once set spinning simple momentum maintains its orientation. But unlike our earthbound gyroscopes these have virtually no bumps, no touching parts, no disturbing friction of any kind. Even its axis of spin will be detected without touch through the magic of superconductivity.

Chilled to almost absolute zero, the gyroscopes niobium coating becomes a superconductor ... emitting a magnetic field ... which can be measured. Free from all external influences, its spin axis becomes an inviolable pointer, deviating only if there are changes in the very coordinates of local spacetime. They'd created the impossible. But they still had to house the gyroscopes - four in total. There was a spacecraft to build.

BRAD PARKINSON

The challenges of the space craft are pretty extreme. Space craft had to actually chase one of the gyro's and by that we mean, one of the gyro's separated by perhaps a third the width of a human hair, spinning at ten thousand RPM, if it touches, the experiment is over. We had to use little puffs of gas and have the whole satellite chase this gyro and if the satellite got a little to this side of that gap, we had to get a little gas and puff it back. And if we made a mistake, it would be fatal.

NARRATION

But it was the non technical challenges that really pushed Everitt's perseverance to the limits - and beyond.

DR FRANCIS EVERITT

I actually was doing some work at home and I received a phone call from home, ah, from a man high up in NASA, who said, are you sitting down? And I assured him I was sitting down and he said, well they've just cancelled your program ... and I can't tell you what to do about it.

NARRATION

Seven times they were cancelled - 7 times they had to make the long trek to Congress to claw the program back. And as the decades ticked by, their goal seemed to warp and recede like spacetime itself.

BRAD PARKINSON

We had some dark days. We had some things that broke. We had some things that didn't seem to work right. We had a fire, burned our whole lab. The glue that held it together, was Francis. He kept us going somehow.

NARRATION

But on a clear day in 2004, Everitt's superhuman tenacity pays off. The elegant gravity probe B is heading for the launchpad. It's taken 43 years, hundreds of scientists and more than 70 PhD's to get to this point. Now, the team's precious gyroscopes - so lovingly made in the most protected conditions - are about to be flung into the harshest environment imaginable: space.

BRAD PARKINSON

Everyone was holding their breath, you know.

DR FRANCIS EVERITT

Things do terribly happen sometimes.

BRAD PARKINSON

It was awesome when they finally said, "we've got it in orbit" and we could watch, they had a camera and you could watch the last booster falling away. We thought: "My golly, it's up there, it's up there". It was a pretty emotional moment.

NARRATION

Gravity Probe B unfurls its sails ... locks onto the guide star which will maintain its perfect alignment ... and begins to orbit the earth. Now, the nail-biting wait for data collection - will a lifetime of planning pay off ... or fail at the last hurdle as so many space missions have done.

If Everitt's patience was tested over the last 40 years, it's nothing to the months, then years passing now. In 2007, they are able to make an announcement -the geodetic effect has been confirmed - that part of Einstein's theory has stood up. But the vital frame-dragging question has a problem - the gyroscope results just won't line up. Now, in 2009, they're ready to go public.

DR JONICA NEWBY

Welcome and thank you for talking to the ABC. Can I ask first - what took you so long?

DR FRANCIS EVERITT

Well, when you're making gyroscopes that are ten million times better than any gyros that have ever been before you might expect somewhere right down at the bottom of that there would be the odd little thing that you hadn't totally predicted. So it's been a long saga.

DR JONICA NEWBY

So, million dollar question, was Einstein right about gravity?

BARRY MULLFELDER

So if Einstein were wrong and there were no such thing as general relativity then the drift in the north south and east west directions would be identically zero rather than the values that we clearly see.

DR FRANCIS EVERITT

So, we can indeed say that when the earth spins it drags spacetime with it.

DR JONICA NEWBY

That must be a good feeling?

DR FRANCIS EVERITT

It's a good feeling. Partly a sigh of relief and partly that we've done an experiment people thought was impossible.

NARRATION

90 years after Einstein first revealed his thoughts on gravity, the test is in -his legacy stands. Final measurements are being tidied up, and Gravity Probe B will soon enter the textbooks. But perhaps the biggest legacy is the many minds - and technologies - that were inspired by this grand quest to prove the impossible possible - which is what it took to confirm one of the most astounding ideas ever conceived by one human mind.