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Nobel physicist focuses on Hubble’s heir

NASA astrophysicist John Mather is still accepting accolades for his Nobel Prize in physics, but his main focus is on the James Webb Space Telescope, the designated heir to the Hubble Space Telescope. 

SEATTLE - The two buttons on NASA senior astrophysicist John Mather's lapel say it all.

One is a tiny gold medallion that you would hardly notice — until Mather points out that it's a miniature of the Nobel Prize he won last year, for his work on interpreting the rippled fingerprint left behind by cosmic creation. The other is a gaudy campaign button, emblazoned with the words "ASK ME ABOUT JWST."

That's a reference to the James Webb Space Telescope, NASA's designated heir to the Hubble Space Telescope — and Mather's scientific baby.

Mather won a share of the Nobel Prize in physics for his work with the Cosmic Background Explorer satellite, or COBE, which detected subtle temperature variations in the full-sky cosmic microwave background radiation. Those observations led to the conclusion that those variations reflected ripples in density that gave rise to the first generation of stars and galaxies.

He's still accepting accolades for that research, which dates back more than a decade. But because he's the senior project scientist for the James Webb Space Telescope, based at NASA's Goddard Space Flight Center in Maryland, he's putting at least as much emphasis on preparations for the $3.5 billion observatory's scheduled launch in 2013.

"I've been involved in this since the very first day of this project, and so I had a strong influence on both the telescope design and on the instrument package selection," Mather, 60, told Monday during the winter meeting of the American Astronomical Society in Seattle.

The Webb telescope is designed to look farther into the cosmic past than Hubble, using a suite of cameras optimized for infrared wavelengths. The telescope's mirror is seven times larger than Hubble's — so large that it has to be folded up for its launch on a European Ariane 5 rocket. The instruments have to be kept so cold that a shade the size of a tennis court will shield it from the sun's rays. And it's due to travel so far away — 1 million miles from Earth — that it will take at least two months to get there.

At that distance, the Webb telescope can hover around a gravitational balance point known as L2, providing a steady vantage point for observations. But it will also be beyond any hope of servicing by astronauts, a la Hubble. Instead, the telescope's optics are designed so that they can be adjusted by remote control, thus avoiding the problem that marred Hubble's first years in orbit.

The Webb telescope is slated for an operating life of five years — but that could be extended, just as the nearly 17-year-old Hubble's life has been repeatedly extended.

Will the findings from Webb bring future Nobel Prizes for Mather and his colleagues?

"That's a good question," he said. "I'd like to imagine that the JWST will open up such a wonderful new area of science that someone will find a Nobel Prize-winning discovery in there, but I don't know what it is. This is more of an exploration than a test of a particular theory. When you build a general-purpose tool, people will use it in ways you can never guess. That's what we're counting on."

Here are more questions and answers taken from Monday's interview with Mather: How does all this work coming up fit with the work that you did with COBE, and that you won the Nobel Prize for? Is it completely different, or is it all of a piece?

Mather: Well, it's related, and it's also different. When I changed subjects from the work that I did on COBE and went into this area, I had to learn all new technology and meet a lot of new people. But in the end, it's very closely connected scientifically. Because the big bang, which we saw and measured with the COBE satellite, gives us the initial conditions. We saw with COBE that the early universe is not quite uniform. It's full of little hot and cold spots which are now thought to be density variations in the primordial material. The dense regions are thought to be the places where galaxies and clusters of galaxies would form, and the less dense regions are places which would empty out.

So everything that we have now and our own existence is presumed to be due to these initial conditions. Now, with the James Webb Space Telescope, we have the opportunity to make that connection and see the formation of the first things from the primordial seeds that were observed with COBE. In the end it's a very closely connected thing, but a very different technology to do it.

Did you have a role in determining which instruments would help you address that question, and did you have the whole idea of connecting to the results of the big bang in mind?

Yes, I've been involved in this since the very first day of this project, and so I had a strong influence on both the telescope design and on the instrument package selection. But nature actually tells us what we should build. It tells us where the opportunities are, and what would pay off the best in new discoveries. So that's what we have really organized it for. We're building infrared equipment because that's what we haven't seen before, and because nature has put information we want to find out at those wavelengths.

Why is infrared so important?

The distant universe is running away from us as fast as you can imagine, at speeds that are close to the speed of light. The result of that on what we see is that the wavelengths of light that we can get are much longer than what they were when they started out. The visible and ultraviolet light that was produced by hot stars comes to us as infrared. This is what's called the redshift effect. We may see light with a wavelength 10 or 20 times as long as what it was when it started out. That's the impetus for this strange and interesting new design that we have.

What are you doing this for?

We have four major themes we think people will use this telescope to think about. One is, how did the first stars and galaxies form after the big bang? The big bang was supposed to be 13.7 billion years ago and it gave us hydrogen and helium to build the universe. And now, as you see, we've got carbon, nitrogen, oxygen and all the things that we're made out of. When did that all change? Probably the answer is that the first stars and galaxies were different from the ones we see today. They had giant stars that exploded and liberated the chemical elements that were created by nuclear reactions inside. So the life that we have is possible because of this first generation of stars. That's what we think. I'd like to see it.

Closer to home, people know that they want to see how stars and planets are actually made nearby. So that's again something that you need infrared telescopes to see. You know those beautiful pictures like "the Pillars of Creation"? Those are clouds of dust that obscure our view. We can't see the stars being born inside. But infrared light will penetrate through those clouds and you can see the actual formation of stars and planets.

Even closer to home, we hope to learn about our solar system and how it is that the conditions for life became possible here on the earth. We do that by examining the outer solar system and little bits that are left from the formation our our solar system — which is quite recent, you know, it's only 4.5 billion years ago instead of 13.7 billion.

Could the Webb telescope be used in any way to look for life outside our solar system?

We certainly hope to look for life outside the solar system, in a couple of ways. One is, we already know some planets around other stars go in front of those stars or behind those stars. We can't actually see separate images of those planets yet, but we can tell something about the light that came from the planet.

When it's blocked by the star, and you can see the difference, you can tell how much light did come from the planet. And when it goes in front of the star, it blocks some of the starlight, and you can also tell something about the planet from that. So we have hopes of detecting the chemical composition of atmospheres of planets around other stars by this method.

We also are pretty sure there's a planet that could be detected directly, around a star called Fomalhaut. It's got a big cloud of dust around it which is organized in a ring.  This ring is probably due to the gravitational force of a planet that's also orbiting that same star. So we think we know more or less where to look for that planet, and that it should be big enough to see directly. But it's more like Jupiter than like Earth. So we'll be getting some clues about the possibilities for life elsewhere from all of this.

This doesn't launch until 2013. I'm wondering what it's like to commit to a design, then see advances in technology come along that you'd want. Can you incorporate new technology into this project?

Right now we are committing to the design technologies that we have now. We have just finished the 10 main inventions that we had to make. Since those are now complete, we're ready to go on to the next stage of finishing the engineering and building the telescope. So we do indeed have to commit to the particular situation right now in order to go forward. And yes, better things will be invented, but those will be for the next mission to use.

When people see that there's a new space telescope coming up, they may ask why we can't just keep the Hubble telescope going forever. Why not just put new instruments on that? Or they may hear that there's already an infrared telescope called Spitzer. Why build another infrared space telescope? Could you explain how all these telescopes fit together?

Well, to begin with, we are servicing the Hubble Space Telescope one more time, and putting in a marvelous new instrument package that will make it 10 or 100 times more powerful than it is today, and which is already far more powerful than when it was launched. So we've been very successful in putting new instruments with new technology into the Hubble. But we're not that far from perfection on the Hubble instrument package, so it seems that the best expenditure of effort now is to open up a new territory in the infrared. It demands a bigger telescope, new instrument technologies, new kinds of detectors.

The Spitzer Space Telescope also has done marvelous things. It's shown quite clearly that the infrared radiation that it measures comes from very distant things in the early universe. It's also shown us that we can see into the hearts of places where stars and planets are being made. They've even been able to see planets going around other stars. They've proven how important the infrared is.

But our new telescope will be huge by comparison. Spitzer has an aperture diameter of about 3 feet. The new telescope has an aperture which is about 20 feet. So it collects a vast amount more light and will give us much sharper images of things we are looking for.

When people look at the design of the Webb Space Telescope, they realize it's not anything like what the Hubble looks like.

Yes, the telescope uses completely new methods for getting a big telescope into space, because the telescope that we need for this purpose is larger than the rocket that we have to launch it with. So it has to be folded up, and this is a first for us, that a giant telescope deploys after launch and becomes adjusted to perfection afterward.

You know, we had a lot of trouble with the Hubble mirror a long time ago, and we learned how to adjust it — but we couldn't adjust it without sending up new equipment, which we did during servicing.

This new telescope is designed from the beginning to be adjusted after launch. All these 18 little hexagons of beryllium will be adjusted in position and radius of curvature so they focus as though they were pieces of a single perfect mirror to begin with.

So the situation with Hubble, where astronauts needed to put in some corrective equipment, is taken care of in the design of this telescope?

That's right. We plan to prove it on the ground, but this should be capable of withstanding the launch and becoming a perfect telescope in space.

There's a lot of discussion about where the money is going at NASA, and you hear space scientists grumbling about how much money is going into the manned space program. Could you talk about the cost of the Webb telescope and where it fits in the budgetary priorities?

The cost of the telescope is about the same as the cost of the Hubble Space Telescope was, just to get it into orbit. The Hubble has certainly proved its worth to science, and I expect that the JWST will as well. Costs did go up, which is not really a surprise in this business. About a year and a half ago, we saw that we needed more money. Fortunately, NASA was able to get that money and put it into this program.

It's also true that quite a lot of other programs at NASA have also risen in price. The manned program has had this tremendous jolt from the loss of the Columbia, which we're still recovering from. We still need to complete the space station and go ahead with finishing our international commitment to that. We have immense ambitions and modest budgets, by comparison with what we had in those glorious days when we were going to the moon for the first time. So we are learning how to do a vast amount more with less money than we had been. And I think quite successfully.

The new James Webb Space Telescope is far more powerful than the Hubble can be because it uses these new technologies: the folding up of the mirror and the longer-wavelength detectors that we couldn't have done 10 or 20 years ago. Because we've invested in these new technologies, the overall result is far more powerful for a similar budget.

How did you feel when NASA Administrator Mike Griffin decided to go ahead with the Hubble servicing mission? Does that have an impact on Webb operations?

I thought it was absolutely the right thing to do. Astronomers generally conclude that, because the Hubble telescope will be so much more powerful than it is today even, with the new equipment that will be in it. So we all love that idea.

The current estimate is that it will still be running about until the time that the JWST goes up. We don't know how long a piece of equipment will last, but it's expected to last until 2013. That's when JWST goes up. I think it's lovely. multimedia producer Jim Seida contributed to this report.