14 February 2003
E-Bulletin Backscatter
The Future of Manned Space Flight
Thanks for your thoughts on the shuttle program. The only thing I think humans do better than our machines can currently do is satellite repair. Take the fixes to the Hubble Space Telescope. I think these would have been very difficult to execute by machine.
Michael Thwaites
Thank you for bringing that editorial (in the SAS Bulletin dated 2/7/03) to my attention. I write this a sa long-time veteran of the space program, having worked on the original Project Vanguard, and one of the original NASA employees at the Goddard Space Flight Center.
The Shuttle was a great idea at the time. It was conceived as a reusable launch vehicle, promising to be a much cheaper way to launch satellites and space probes. In its actual realization however, it became such an expensive launch vehicle that experimenters have been driven to Russian and Chinese vehicles. It also turned out to have such a horrendous vibration profile that satellites had to be extensively redesigned, in order to survive the launch.
Why is this?
Very simple. NASA decided that each shuttle launch also had to put five (or more) human beings into space with each launch. And keep them there for up to two weeks. And bring them back alive.
This turned out to be far more expensive, and difficult, than originally thought. I well remember my dismay when I realized that NASA could not even launch a 50 lb. satellite without five humans going up and returning at the same time.
The result of this is that with few exceptions (the Space Telescope being one) NASA's original mission of Science in Space has changed to Humans in Space (who may do Science if time and funding allows).
There are many other problems with the shuttle's design but they all result from the need to include live humans in each launch.
Peter D. Engels
petere@sover.net
I don't know whether or not there are good practical reasons to put man in space. But there seems to be no good practical reasons to climb MT. Everest either.
Herbert Fritzke
I have to disagree with the editorial and thoughts behind it. While it pays lip service to the idea that manned space flight is a good idea, it suggests that it should be put off into a future where it will be safe, inexpensive, and easy.
Manned space flight will never be safe, inexpensive, or easy. Manned exploration will always be dangerous, expensive, and difficult. But we explore in spite of this.
Manned space flight is not about science. It's about the spirit. It's about mankind's destiny. It's about adventure.
Robotic missions will do science. Robots will go places that are too hostile for humans. They will reveal wonders. But they are, at best, a virtual presence.
I have viewed the Vatican via the Internet. I have also visited it in person. They are not the same in any sense.
Using Mr. Krugman's logic, we could put a robotic observatory on top of Mount Everest or replace the South Pole base with an unmanned presence. It would be cheaper. It would be safer. Of those people who attempt to climb Mt. Everest, 1 on 10 die. But they keep trying.
If our ancestors had lived as Mr. Krugman advises, we would likely not exist as a race. Or in more modern times, the United States would still be clinging to the East Coast. Crossing the Appalachian mountains was dangerous, expensive, and hard.
I believe that the spirit of exploration and adventure is ingrained in western culture and probably in all of mankind. To wait until the costs, risks, and hardships of exploration are all eliminated would be to deny our basic nature.
The shuttle may not be the right engineering approach. We may be able to do better. But if we stop and wait for "perfection," it will never come.
Jim Simpson
In general, I agree with Mr Krugman, about using robots to explore space. Beyond the advantages that he has stated, there is another reason for us to develop robots. Our industrial manufacturing economy is in trouble, and has been in trouble since the mid-1950's. We are losing jobs, and we are losing entire sectors of our economy. Consumer electronics manufacturing, for example, is just about non-existent here in the USA. We need to develop and make use of industrial robots to once again become competitive in the global marketplace for manufactured goods. Our space program can give this effort a significant boost in the right direction.
With regard to the Columbia disaster, it has been a difficult and painful time for us. There are people in foreign countries, as well, who have expressed a sense of loss over this accident. Sending humans into space seems to unify our own nation, and it is fitting that we include people from other nations in this effort.
I have felt uncomfortable about the space shuttle program since the early days, with regard to safety. The heat resistant tiles that protect the shuttle from the heat of re-entry are brittle and stiff. However, the underlying metal structure must bend when it encounters the loads imposed by hyper-sonic flight in the atmosphere. So we have stiff and brittle ceramic tiles held onto a somewhat bendy airframe, with glue. This is not a happy combination of materials, and I am sure that there were engineers who felt the same way, back when the space shuttle was designed. There have been reports of missing and damaged tiles found on returned space shuttles since the earliest missions.
The decision to build a space vehicle with wings and moveable control surfaces forced the use of heat resistant tiles layered onto a metal airframe. Why did we need wings? I can only guess that someone felt it was undignified to float down under a parachute, plop into the ocean, and wait for the Navy to show up and rescue the astronauts.
When the shuttle was designed, we turned away from what we had learned building and flying cone-shaped space capsules, with heavy ablative heat shields on the bottom surface. These vehicles were small and perhaps crowded, but they were robust, fully up to the task of protecting the humans inside.
Why can't we send people into space using smaller cone-shaped space capsules, and rendezvous with larger loads carried into orbit on unmanned rockets?
Anyone who wants to see an airplane shaped space vehicle blast off into orbit, circle the earth, re-enter and land, can go to the movies.
Sincerely,
Eric T. Johnson
More on Transistors
Hi Sheldon
If Roger had actually read what I said, I said simply that the transistors on ICs were of the FET type, not the bi-polar type. I didn't say or mean to imply that FETS have replaced BJTs, or that one is inferior to the other !
Steve Taylor
Finding SAS
Hi, my name is Allan Adler. I have a PhD in mathematics and I also like to do experiments. For some time, I've been in favor of someone starting a national organization to facilitate amateur science. So I was glad to learn that you have done so. I'm interested in discussing directions for the development of the group.
There are already groups to facilitate amateur astronomy and other forms of nature watching (birdwatching, horticulture, etc.). One might also include amateur radio. But beyond that, there doesn't seem to be much.
I think the main reason for that is that these three are areas of scientific activity wherein one is least likely to injure oneself or others. If one wanted to have a chemical laboratory, it would be a different matter. One of the things I would like to see is for competent chemists to lend their expertise to guiding people in the development of amateur laboratories. I have no doubt that a lot of professional chemists started out as kids with ad hoc laboratories of their own and who somehow survived the experience. With better guidance, amateur laboratories could be developed to comply with safety standards and with applicable laws. The aptness of the amateur laboratory for a proposed experiment could also be addressed, e.g. sometimes special fume hoods are needed for certain chemicals and anyone using the lab needs to be aware of that.
Apart from helping people design their own labs, and inspecting them to make sure they remain safe and legal, the local group can have its own shared laboratory.
In the case of physics, there are a lot of classical experiments that one normally doesn't get to see performed except in advanced physics courses. These include the Franck-Hertz experiment, the Stern-Gerlach experiment, Faraday rotation, Compton Scattering and dozens of others. Leybold-Didactic, through its American representative Klinger-Educational, sells a lot of apparatus specially designed for doing these experiments. That is good but the stuff is expensive ($28,000 for a Stern-Gerlach apparatus!) and its design is proprietary. In the case of the Franck-Hertz experiment, the detailed characteristics of the gas filled tubes are not available for that reason. So while it is good that it is available, it is not what one hopes for when one encourages amateur science. I would like to see something analogous to copyleft for patents on apparatus and designs for these experiments. I would like to see the SAS develop manufacturing capability to distribute apparatus cheaply but also to allow amateurs to use its designs freely to build their own apparatus. That could also be one of the roles of local chapters. In this connection, let me also mention the book The Apparatus Drawing Project, which has a lot of shop drawings for such experiments.
Incidentally, I am not aware of any local chapters.
Books such as Strong's book Procedures in Experimental Physics (which you sell from the SAS page) contain a lot of useful information. Many people interested in science don't have room for shops or labs and can't afford equipment. One role for local chapters is to provide space and equipment under safe conditions. Schools do that also but under conditions which have many undesirable features, to wit: (1) extremely limited access to the laboratory; (2) priority is given to grades and certification over education; (3) extremely limited possibilities of developing new experiments. I think local SAS chapters should indeed serve an educational function and should guarantee that people doing a given experiment are doing so safely. But grades would play no role in this and no certification would be given.
Amateur astronomy groups often provide a great public service by presenting free public lectures on astronomy. These are often on topics of current interest. I would like to see the same thing happening with other sciences in SAS local chapters.
Many people, when they discuss educational activities, assume that such activities are for kids. What I have in mind is for adults and at a high level. That presents obvious problems, since adults have very different backgrounds and recollections of their own education. But other science groups manage to deal with that problem and I'm sure that so will SAS.
Incidentally, I notice that the SAS is selling Stan Gibilisco's book Astronomy Demystified. I don't think it is a good book and probably the SAS should be promoting something better, even if it costs more.
I haven't decided yet whether to join the SAS, although I am inclined to do so.
Sincerely,
Allan Adler
ara@zurich.ai.mit.edu
Shawn Carlson Responds:
Dear Allan,
Thank you for your well-considered letter. It's always a great day when we find a thoughtful person who believes as strongly in amateur science as we do.
We have wanted to do far more to develop the local chapters than we have been able to so far. And your thoughts on this matter parallel ours perfectly. The problem is one of management and organization. We have discovered the hard way that developing the SAS local chapters in the ways that you suggest requires the dedicated efforts of a talented full-time person at SAS to work with the various local chapters. We are now struggling to increase our annual budget to allow for such a person to be found and hired. In fact, this is a top priority! Believe me when I tell you that we understand that potential of the local chapters.
I urge you in the strongest possible terms to please join SAS and get involved. We are the premiere support organization for citizen scientists, and we are working very hard to expand our base of support so that we can do even more. We few who understand the importance of this work need to work together.
Do you live close enough to Rhode Island for a meeting? You can call me after 3:00PM at 401-823-7800.
I look forward to hearing from you again soon.
Shawn Carlson
Founder and Executive Director
Society for Amateur Science
VLF Observatory
Dear Sheldon,
Just a short note to let you know that I've been busy documenting my early work in building the VLF observatory.
For starters it has been named NCSIDO for Northern Colorado Sudden Ionospheric Disturbance Observatory. I like to assign names to bigger or more long-lived projects for the same reason that I named my children, cats, and servers - it's easier to refer to them by a short, crisp name than by some long, variable, and often changing descriptive name. So I can now speak about NCSIDO, Stephen, Mario, and Sparky, respectively.
Perhaps more importantly, the number of pages on the web site at http://xtrsystems.com/vlf/ is steadily increasing. And this situation is likely to be maintained for some time as I continue to put finger to keyboard.
At this time a single radio channel has been installed which is receiving an unnamed transmitter (wouldn't it be easier if they just named it?) operating at 25.2kHz and located in LaMoure, North Dakota. The data is displayed in real-time and from archives. Some viewers have written to me indicating they enjoy comparing to various other more official observatories and satellites.
Best regards,
Joseph A. DiVerdi, Ph.D., M.B.A.
Discontinuous Functions?
Dear Sheldon:
There seem to be a number of misconceptions in James Farr's article, "Discontinuous Functions and Their Use in Formulation of Indexes of Diversity". I get the impression that it was written hastily or not thought through critically.
I've never heard of "meanness of fit". Is this the same as Goodness of Fit, which can be tested against the Chi-square distribution? Either way the statistic he cites doesn't seem to be appropriate for this. I presume what he means is
Sum[x -E(x)]/n
where x is an individual observation and E(x) its expected value, with the difference summed over the range 1,..., n. If E(x) is not known, the average of the observations is used and the divisor is n-1. This statistic is called "Average Deviation", and is not suitable for estimating probabilities. The appropriate statistic is the Standard Deviation:
Sqrt{Sum[x-E(x)]2]/n}
Again, if the average is used as an estimate of E(x) the divisor is n-1 (one "degree of freedom" is lost in the estimation.) These days there's really no reason to use average deviations anymore since calculators are ubiquitous.
The function x = y2 + 1 is not discontinuous, i.e., it's a smooth curve (parabola) identical with x = y2, but displaced from the origin by one unit along the x-axis. An example of a discontinuous function is y = 1/x, which is undefined at x = 0.
The paragraph about circles within circles makes no sense.
About dividing a parallelogram with 30 and 60 degree angles into two isosceles triangles, this can only be done if the parallelogram is equilateral (a skewed square). Where did the two degree excess come from? Inaccurate measurement? Poor old Euclid must be spinning in his grave!
What can I say? I regret coming down so hard on James since he's one of us who really does significant research.
Norm Stanley
James Farr Responds:
Dear Norman:
I realize that some of my statistics may have been a little remote for you. I do base it on a body of good references. First, look at Zar's book on Biostatistics, which uses such complex statistical techniques as pooled Xi square analysis. Meanness of fit would be a good description of this technique and does fit in well with my description of Euclidean geometry. If you have read Euclid (in the original text) you will see that his proof of geometric functions is based soley on limits and sums.
There is nothing complicated about Euclid,except that is a very tedious,enormously long proof of simple calculus equations.
To describe the use of discontinuous functions in biology,I had to find the root reference to this form of study, that was the very early 1910 article in biometrics.
As to the parallelogram and the circle-Euclid uses both of those examples in his most fundamental proofs.
Even Einstein was found to have made a few algebraic errors in his Theory of Relativity.
James Farr
