On the 25-year anniversary of the launch of the Hubble Space Telescope, Space.com talked with science writer Robert Zimmerman, author of "The Universe in a Mirror: The Saga of the Hubble Space Telescope and the Visionaries Who Built it" (Princeton University Press, 2008)

Zimmerman's book chronicles the multidecade struggle to get Hubble into space, the people who fought to keep it alive (often at the expense of their own careers and personal lives), and the incredible science it has produced. You can read an excerpt of "Universe in a Mirror" here.

The concept that eventually became the Hubble Space Telescope — a large optical telescope that would orbit above the Earth's atmosphere — was first proposed in the late 1940s by astronomer Lyman Spitzer. Known throughout much of its development as the Large Space Telescope, the Hubble Space Telescope was the first optical telescope to operate above the Earth's atmosphere. While this atmosphere allows humans to breathe and helps protect the planet from harmful radiation, it also blurs the light from distant objects. With the subtraction of this blurring effect, Hubble saw the universe in a way no one could have imagined. [The Hubble Space Telescope at 25: A Photo Anniversary]

Space.com: I think a good way to start this interview is the way you start your book: In the preface, you say that the Hubble telescope is the "grandest instrument that humans have ever sent into space." So can you give me a short explanation of why this thing is so incredible?

Robert Zimmerman: When I was a kid in the 50s and 60s, I was into astronomy and space because that was the beginning of the space age. And it was obvious to me even as a kid, and it was obvious to every astronomer, that the human race was essentially blind to the heavens.

If you look at pictures of the planets taken by the best telescopes on the earth prior to Hubble, they're always fuzzy and out of focus. It's as if astronomers — this is not technically accurate — but it's as if astronomers were nearsighted, like I am, and were not allowed to put glasses on. And this was the whole human race!

When we started the space program, it was, to my mind, instantaneously: "Hey, we've got to get an optical telescope into space above the atmosphere." And then [I] proceeded to watch how it didn't happen for many, many, many decades. It took a long time to get that to take place. And when [Hubble] got launched, it was like suddenly the human race was able to put its glasses on for the first time, and get our first glimpse at what the universe really looks like. And in that sense, [Hubble] is unique [out] of almost every instrument we've put up.

Space.com: In your book, you talk about the huge cast of people who are involved with the long legacy of Hubble. I want to talk about at least one of those people, and Lyman Spitzer (the namesake of the Spitzer Space Telescope) seems like a great person to focus on. What was his role in the history of the Hubble telescope, what kind of person was he and why do you think he took on that role?

Zimmerman: Lyman Spitzer was an astrophysicist [and] astronomer. During and just after World War II, he left astronomy for a while and he helped develop some of the sonar that was used during the war to detect submarines.

After the war, though, he went back to astronomy and was doing this work, and the RAND project was just getting started. [Ed note: the Research ANd Development project, or RAND, was organized by the U.S. Air Force to investigate the benefits of rockets and orbiting satellites.] And they asked him to write an essay on what value astronomy would have with putting a satellite into orbit. This was in 1948, well ahead of Sputnik.

And Spitzer, who was somewhat of a visionary, came up with a paper in which he not only proposed putting a 10-inch optical telescope into orbit, so we could see things sharply for the first time, but he proposed putting a 300-inch telescope into orbit that would be 50 percent larger than the Hale telescope, which was then the biggest in the world. The Hale telescope weighs, by the way, a million tons. And this is a decade before Sputnik, which weighed, what, 70 lbs.?

So Spitzer was really ahead of his time in that, and he spent most of the 1950s pushing this idea for an optical telescope and he couldn't get anyone to go along with him. Most astronomers were skeptical; they thought the cost was too much. They'd rather build something on the ground that was less expensive. They just didn't think it was cost-effective and worthwhile to do.

Spitzer pushed hard for decades to get this done because he thought that with this telescope, as he said, we will "uncover new phenomena not yet imagined." And he understood that.

Spitzer, if you met him, kind of would have immediately made you think of a monkish bookworm. But what was interesting about him was that one of his hobbies was rock climbing. So even though he might have looked like a bookworm, he was out there doing lead climbs on some peaks that had never been climbed before. So he was very much into exploration, pushing the unknown, not just in astronomy but in his own personal life. And he understood the value of that and understood why the human race needs that. We're into curiosity; we have to go where we've never been before. [Gallery: The Infrared Universe Seen by Spitzer Telescope]

Space.com: And even though he was the founder of this idea and one big reason that it came to fruition, he wasn't part of the final team when it launched, was he?

Zimmerman: What happened was, he was head of the Astrophysics Department at Princeton University. And he was very comfortable in that, doing the research he liked. So when Hubble was finally financed in the 1970s, he was offered the position of project scientist. And he turned it down at the time, because this was now decades [after he proposed Hubble], and he was very settled, with family and work in Princeton. And he figured he would be principle investigator anyway for the camera on Hubble. So he turned that position down.

As it turned out, his proposal for the camera was turned down in the end. And so when Hubble was launched, Lyman Spitzer was not involved in the telescope in any official capacity at all. In many ways he was like Moses — never crossed into the Promised Land.

In the end he said it wasn't so bad because eventually he became a member of advisory committees — major astronomy advisory committees— that helped determine long-term planning for Hubble. And so he was involved nonetheless. But he was not where he thought he would be — running the camera and taking those first pictures. He did not get that position.

Space.com: It's also interesting that he was both a visionary but was also smart enough with the politics and was able to navigate that and help push Hubble through to completion over all those years.

Zimmerman: There's more to it than that, too. Spitzer was extremely smart about how to design the Large Space Telescope/Hubble. When they were putting the first design studies together in the 1960s, he was intimately involved in that. And he was one of the key players who said, "This thing should be built in conjunction with the space shuttle to be repairable and maintainable by astronauts." It's less so now, but for decades astronomers were very hostile to the manned space program. They thought it was stealing money from unmanned astronomy projects that they could do. But Spitzer was smarter — he knew that if you tie it to the manned program, you're more likely to get it funded, because it'll be exciting and that'll get the public interested. And secondly, they'd be able to keep it a state-of-the-art instrument. No matter how old it gets, you can upgrade it. And of course in that visionary sense he was right. [How the Hubble Space Telescope Works (Infographic)]

Space.com: So that's a mostly happy story about someone deeply involved with Hubble, but let's talk about Robert O'Dell, whose story was not quite as happy. In your book, O'Dell is quoted as saying (in 1985), "I somewhat look at myself as a casualty of the space telescope." What was his role with Hubble?

Zimmerman: Well, in the sense that Lyman Spitzer was a Moses because he didn't get to the Promised Land — because he wasn't the PI of the camera — Bob O'Dell had it worse.

Bob O'Dell was the guy who did accept the position as the project scientist for the Space Telescope when construction began in the 1970s. At the time, he was a very young and very successful astronomer. He was [chairman] of the astronomy department at the University of Chicago. He got that position very, very young. And he had been using major telescopes like the Hale telescope to do real scientific research. And he got offered this job as a project scientist for Hubble, where he'd have to move down to Huntsville, Alabama, which was not an astronomy hotbed. And he'd basically have to abandon his science research to become manager of the project. And he made that decision, in his words, because how could he not be participating in such a project? On a telescope that will be above the atmosphere and will see things that had never been seen before.

And so he accepted that position and then spent years doing bureaucratic lobbying and fighting to keep it funded and get it built. He had to make enemies because he had to fire people when they weren't doing the job right. He really was a key player in making sure the telescope got built.

And when it was all said and done, after years of doing this, when he left in disgust, I think, finally or at least in exhaustion, he found his reputation as a scientist was gone. He couldn't get a good academic position as an astronomer from any major university anymore. He was seen as a manager. And so his research capability as an astronomer was lost.

[Ed note: According to Zimmerman's book, O'Dell stated that living in a small town in Alabama also put a strain on his marriage, which ended in divorce.]

He managed to recover somewhat. He was able to get research time on Hubble in later years, specifically studying the Orion nebula and its shape and makeup, and the proplyds, which he named. But yes, he himself lost out.

When the telescope first went up, neither Spitzer nor O'Dell were going to be guaranteed any observing time on Hubble. What the other astronomers who did have guaranteed time did was, they all sacrificed a small percentage of their time, compiled it together and gave Bob O'Dell a share. So that he would have a chance to use the telescope without having to compete against everybody else. And O'Dell instantly called up Spitzer and said I'll split that time with you. So they both could do it.

Without O'Dell, though, the telescope would not have been built. There's no doubt about that.

I want to emphasize the fact that these two guys epitomize what happened to a lot of other people. I could tell stories about one guy who got a divorce and damaged his career, who was one of the engineers who pushed for Hubble for years — never was part of Hubble. His company that he worked for ended up losing the bids. I could talk about others. This was not an unusual thing that happened to these guys. Many people sacrificed a lot to get the telescope built and then never were there for the payoff when it was finally in orbit. [NASA's 10 Greatest Science Missions]

Space.com: Shortly after Hubble was launched, astronomers realized there was a flaw in the mirror — a very, very tiny flaw in how it was ground that made the pictures out of focus. The first manned repair mission was able to fix it, but what went wrong with the mirror to begin with?

Zimmerman: I get this question all the time. People always want to know.

The telescope, when it was finally budgeted, was budgeted under the traditional Washington way of doing things: a buy-in. Whereby, they say it's only going to cost "X" when everyone knows it's going to cost three times that. But they get it started that way and then later on, Congress is kind of forced to give them more money. But before Congress doles out the additional cash, getting the project underway is very hard. Everyone is struggling because they don't really have the cash they need.

And the company building the mirror for Hubble, Perkin-Elmer, was behind schedule and short of staff to do the job. And they were struggling to do it.

And they were using a new device for measuring the shape of the mirror called a "reflective null corrector," that they had used before and proven that it could work and work very accurately. But this was, once again, the biggest mirror that was ever going to be ground with such a device.

And there was a certain cultural imperative: "We have got to get this mirror finished within budget or close to it so that we don't get abandoned."

Because NASA had also hired Kodak, a competing company of much greater fame, to build a comparable test mirror. But that was a backup. And Perkin-Elmer's management did not want that backup flown because it would do their company enormous harm to have the press announcements: "Perkin-Elmer mirror replaced with Kodak mirror." And so they pushed hard.

And for that reason, I think among many other reasons, human reasons, human flaws, an unwillingness to look at the elephant in the room, they didn't look at their measuring data with the kind of cold-blooded eye that an engineer must always use. They kind of accepted what they were getting. Even though other data was saying there's something wrong with your null corrector's information. Other data suggested the mirror wasn't being ground correctly. But the null corrector was saying it was. And so they went with that.

As it turned out, when they were prepping the null corrector and putting it together — it's a variety of mirrors that were installed 30 feet up in the air in the roof of the room where the telescope would be rolled in to be measured. So it's up there, it's on a scaffolding, it's hard to reach. They install it and then remove the scaffolding.

Well, in the installation process, the technicians who were doing this — these were not the optical scientists, these were just technicians — they were trying to position the mirror and they found they couldn't get the mirror position in exactly the right spot that it was supposed to be in by turning the screws, by adjusting it like you would with any focus ring. And so they decided, "Well let's get some extra washers and we'll just kind of move it out a little bit and then we can adjust it in the proper position." And they did that. And the result of that was that they were grinding the mirror perfectly but to the wrong prescription, so that when Hubble was launched, it had a perfectly ground mirror, but to the wrong prescription. So therefore it could not focus as it was intended to focus.

The fortunate thing is that because it was ground perfectly to the wrong prescription, you essentially — this is a metaphor, but — you essentially can give it glasses and produce a sharp image. And because it was designed to be maintained and repaired by astronauts, it was possible to bring up instruments to correct the problem or to bring up a camera that had been corrected for the problem and they would work with that primary mirror and the images would be sharp. [Truth Behind the Photos: What the Hubble Space Telescope Really Sees]

Space.com: Thankfully Hubble was saved and went on to produce many amazing science discoveries. Do you have a favorite science result that came out of Hubble that you want to talk about or a result that you think is really important to mention?

Zimmerman: It's like trying to ask someone what's their favorite movie!

There are two things that Hubble has done that I think are not only very cool but are representative of what it represents.

One is a theme throughout the book and that's Eta Carinae. [Prior to Hubble], Eta Carinae was a typical stellar kind of object, a nebular object — it was a star with some kind of nebula around it, and it was interesting and mysterious and was probably the result of an eruption in the 1800s. But to look at it sharply was impossible. And to try to figure out what we were looking at was impossible.

And Hubble takes one snapshot — its first image before [the flaw in the mirror was fixed] and it clarifies things enormously. But then those first images after the repair were astonishing. And it's very obvious you're looking at a star that's exploding. And why, how, what, and where now become the real questions. We can now see things. And Hubble has followed Eta Carinae since then and it’s a fundamental example of what Hubble can do, because it's so obviously clear once you see these images, while before it was so obtuse from just ground-based telescopes.

And it's also spectacular! It's beautiful and spectacular to look at, so it immediately makes sense to everybody. I mean a star exploding! So this is one of the things that's an example of how Hubble's images are understandable to any human being when you look at them.

And the second significant discovery of Hubble is actually a relatively boring image: It's an image of lots and lots of tiny galaxies a far distance away. It's the Hubble deep field — the various Hubble deep-field images. The astronomers would point Hubble at a tiny spot in the sky — and this spot might be the equivalent of a speck of sand you see from six feet away — and they do the equivalent of a superlong exposure, so they can see as deep [into space] as possible. And they're looking at a blank spot that normally doesn't show anything in it at all, and with the first deep field they found 3,000 galaxies in it. And then in Hubble's last, ultradeep field, which was an even deeper image at a different spot in the sky, they found 10,000 galaxies in it, all from the early universe.

Essentially when Hubble took those images, Hubble was looking as far as [the] human eye can possibly see. [Hubble Telescope at 25: The Trials and Triumphs of a Space Icon]

Space.com: You call Hubble the telescope that was "repeatedly sentenced to death," and yet it has repeatedly been saved. Can you talk specifically about the time after the Columbia disaster, how Hubble was almost abandoned and who saved it?

Zimmerman: In the 1950s, Spitzer couldn't get anyone to even accept the concept. In the 1960s he and others couldn't get anyone to fund it. In the 1970s it almost got canceled because of the funding difficulties. In the 1980s it almost got canceled because of the construction difficulties. In the 1990s it goes up out of focus and somehow it's fixed.

In the 2000s, the Columbia accident happens, which interferes with the last shuttle [Hubble] repair mission. And the head of NASA at the time, Sean O'Keefe, he was very deeply affected by the loss of the Columbia astronauts. He had been waiting on the runway with their families for the space shuttle to land. And instead of greeting astronauts, he had to tell families that their loved ones were gone. And so it was very clear after that accident that he really did not want to be involved in approving any further manned launches.

And he was using the advice, actually, of a lot of astronomers. The decadal survey by astronomers in the early 2000s had recommended that Hubble receive no more maintenance in space, and that the focus should go to the infrared James Webb telescope as the next generation. Hubble is optical, James Webb is infrared. Astronomers themselves were saying in the early 2000s that Hubble isn't as important as an infrared telescope.

So O'Keefe said, well, if the astronomers think that, and I don’t really want to send men up there [and] take the risk of fixing this, let's just not do it.

In the end, O'Keefe resigns. He's replaced by Mike Griffin. And in his hearings before the Senate to be approved, Griffin said right off the bat that he's going to look at this more closely and he very quickly soon thereafter announced that there would be a [crewed] shuttle repair mission. And they did do it.

And they not only replaced Hubble's 1993 camera that had saved the telescope, they put a new camera in, they repaired another camera, they repaired another instrument and they did other repairs, and when they left the telescope was a state-of-the-art instrument with no instruments in it from its original launch. It was completely upgraded with the potential to last another five years. Well, we're now six years later and it's still rollin' along.

Mike Griffin is not the only hero there. I could talk about a lot of other people who lobbied. By that point, the astronomy community recognized the value of Hubble and were 100 percent behind it. It still produces the most science of any instrument that NASA has launched, by far. By far.

In fact, they recognized the value of human maintenance in space and they have added a grapple hook to the James Webb telescope, knowing that even though it's going to be a million miles from Earth and we don't have the capability to get to it and repair it with humans initially, this will give them the opportunity maybe in the future [to repair it]. And they recognize the value of that now, very strongly. [Photos: NASA's Hubble Space Telescope Servicing Missions]

Space.com: What do you see for the future of Hubble?

Zimmerman: Hubble's in an orbit where, especially because the sun hasn't been tremendously active, the atmosphere hasn't had very much of an effect on it, it probably has an orbit that's not going to decay for at least another decade, maybe two decades. It's a very stable orbit. The equipment's working just great. It seems the equipment is aging less than they expected, so things could be going for a while. Of course things can fail at any time.

But down the road they have money reserved for building an unmanned robot ship that would attach to Hubble — the last maintenance mission put on a docking port just for this purpose — it would attach to Hubble, and de-orbit it safely. Because it's large enough that it won't burn up in the atmosphere, they've got to bring it down controlled so it doesn't land on someone's head. That's an international treaty requirement.

That's what they say they're going to do, but what I think — and I'll go to the bank with this — is that when the time comes that we finally have to do something about Hubble, if it's still working, they're going to, instead of dropping it into ocean, they'll probably raise its orbit and they'll figure out how to fix it robotically or by humans decades down the road, because we'll have more capabilities by that time. I do not see us deorbiting and destroying that mirror and that technology that's up there. It's too valuable.

It would be like if someone said, "OK, the Hale 200-inch telescope is kind of obsolete now, so let's bulldoze it." Of course they don't do that. You find a way to do the science it can do that's valuable. And we're going to do the same thing with Hubble, I'm sure of it.

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Follow Calla Cofield @callacofield . Follow us @Spacedotcom , Facebook and Google+ . Original article on Space.com.

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