As we just passed Hubble’s 30th birthday, I think it is more than necessary to take a step back and look at its beginnings. How did it become one of the most important realizations of the human race? It is a marvel of engineering. Maybe more than that, it was and is one of our key ways to look at the Universe. Yes, it sounds romantic. It is.
The flawed mirror. You most probably heard of it? What is the story in brief? Just a few weeks after the telescope was launched, the first images Hubble sent were nothing of what everybody expected. There seemed to be some major flaw, which made all the pictures fuzzy.
Funny thing, I guess that happened to all of us somehow. Tell me you never made a fuzzy photo, or that you never had your camera scratched or broken. I won’t believe you. What is interesting though, is that these things happen even to the greatest engineering machines. Yes, it happened to Hubble too.
The longer story
The telescope’s mirrors had been made by a company NASA worked with, Perkin-Elmer. To this day, the people of NASA still believe that Perkin-Elmer is responsible for the inconvenience. But it’s hard to know for sure.
Of course, there have been some mistakes during the tests. It is stated that an error in one of them led to the ‘fiasco’. That is what caused Perkin-Elmer to not realize the mirror flaw.
It is called a null corrector. What’s that? In brief, it is an optical instrument used in testing large mirrors. This instrument generates some kind of “contour map”, and it is called a null corrector because if the mirrors are perfect, the numerical result of the test will be null. Some NASA tests concluded that this null corrector was a few millimeters askew, and that small mistake led to errors in the tests. Still, Daniel Schroeder, one of the designers of Hubble, says that such a mistake can be crucial and that is “very large by optical standards”. We know that. In optics, especially in this kind of optics, even small things like this can have huge consequences.
Theories (or facts)
It is hard to put the guilt on only one person or organization, especially when we are dealing with such enormous machines. A lot of evidence suggests NASA’s lack of attention to these kinds of details.
It wouldn’t be the first time. Feynman’s report on the Challenger disaster is well known. That was another step-back for NASA. It is not the first time results are made to come out in accordance with our or NASA’s (in this case) expectations.
Still, I am finding a hard time to figure it out. On the other hand, mistakes like this are very small. It is easy to get away with things like this. When thinking about what scale errors like these happen, you realize what a tough and rough job this is. Mistakes happen to everybody. Even in the case of a 1.5 billion-dollars telescope.
How NASA got out of this, big time
Of course, when this happened back in 1990, there have been a lot of people like me who hurried to put the blame on somebody. After all, it is somewhat understandable. Every American citizen contributed to the Hubble telescope, as it was a government-funded project. This gave NASA rough times, having to repair the telescope, coping with the costs, and having to talk and deal with the public. There were some dark days there.
But the people there are some of the smartest in the world. They quickly identified the problem, and came to a solution. A risky, though, and pretty expensive one, but it was worth it. And we thank NASA for dealing so well with this.
The solution, at heart, was very simple (as they many times are). First, they thought about replacing the mirror, as Kodak had a back-up mirror on the ground. But that would have been too expensive, and very, like very, hard to do. So they came up with this: if the mirror is wrong-shaped somewhere, why wouldn’t we make another piece, with the exact same error, but with an inverse effect. That would cancel the error, of course.
Now Hubble has been designed to have intervention missions in space. That was something the people at NASA expected, and prepared for. Except that it happened sooner than they planned to.
There were a total of 5 servicing missions for the Hubble telescope, the first one in 1993, and the last one in 2009. Of course, not all of them dealt with the same problem we’re discussing here. That was the first servicing mission, the one from 1993, STS-61. The mission consisted of 7 extremely well-prepared astronauts and had a length of 11 days. It established a lot of records for NASA, including the fact that it was one of the most complex missions ever.
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As a fun fact, it also made a record for EVAs (Extravehicular Activity – spacewalks in common language), having no less than 5 in 11 days. The legendary astronauts were Commander Richard Covey, Pilot Kenneth Bowersox, and Mission Specialists Kathryn C. Thornton, Claude Nicollier (of ESA), Jeffrey A. Hoffman, F. Story Musgrave, and Thomas D. Akers.
We thank you, NASA, and all the people who put their hearts in making the Hubble Telescope what it is today. Thank you, to all the astronauts, who, over the 5 missions, made Hubble better and better. Your kid is 30 now. Stay safe.