Live from the Hubble Space Telescope
UPDATE # 7
PART 1: Clyde Tombaugh is showered with your greetings
PART 2: The Hubble will soon capture YOUR data!
PART 3: Ordering instructions for international locales
PART 4: Introducing a new activity: Student Stumpers
PART 5: Star Census: the return of an old favorite
PART 6: Taking pictures with rain buckets
PART 7: Writing new software for the next Hubble servicing mission
February 23, 1996
Inquiring minds want to know!!
The Dr. Tombaugh 90th Birthday Celebration Event, a featured activity for Live From the Hubble Space Telescope participants during the month of January, can be declared a *grand success!* The success, of course, is due to the many classrooms and individuals across the country and the globe who shared both their admiration and their wishes for a happy birthday with Dr. Tombaugh (Pluto's discoverer). Hundreds of creative hand-made birthday cards, poems, acrostics, special graphical images, T-shirts, and audio, email and fax greetings contributed to the event. Much of the student produced art work is now available at our Kids' Corner web pages, with more added weekly.
The birthday presentation was made in conjunction with Planet Advocate Marc Buie's Pluto Symposium held at New Mexico State University campus in Las Cruces, New Mexico on Friday, February 23rd. Following Marc's hour long presentation, a special ceremony was held honoring Dr. Tombaugh. Children from area elementary schools and Dr. Tombaugh's own great-grandchildren shared in a special program led by Marc Buie and Reta Beebe, Planet Advocate for Jupiter. The children and hosts shared our special Passport to Knowledge presentation package with Dr. Tombaugh, who was very gratified. He shared words of thanks to all who extended their greetings.
Marc and Reta will be sharing a detailed Tombaugh Event field journal in the upcoming weeks which will give you a close-up view of this special celebration. Of course, we have wonderful photographs which we plan to share with you both online at our web site (look in the Featured Events area) and via our upcoming television program on March 14th. Our thanks to each and every student and adult who sent greetings for Dr. Tombaugh.
Thanks also to Marc and Reta for their vital role in the planning and the celebration itself.
Stay tuned for the latest information about our own Passport to Knowledge observations of Neptune and Pluto. They are scheduled to take place over the next week and will mark a historic first with the HST dedicated to K-12 research. These are YOUR observations, with the celestial targets chosen by students who took part in The Great Planet Debate. The data from these observations will be seen for the first time ever on our upcoming live television broadcast on March 14.
Also you should know that on February 28 and 29, Planet Advocate Reta Beebe was busy with observations of Jupiter. She has promised that the results of her observations will be shortly made available to us.
We have received many inquiries from the far reaches of the globe regarding ordering the Teacher's Kit. If you are located in Canada, the cost of the Kit is $15.00 US. All other international locales are $20.00. For ALL international sites, it is essential that the currency be drawn in US currency (not on international funds). One possible suggestion is to send American Express travelerŐs checks made out to Passport to Knowledge-LHST. Checks from non-US banks cost an additional $7; if you must use this method, please be sure to include the extra fee for processing.
Send the ordering information-- name, mailing address, school name, grade level/age, number of students impacted by use of materials, phone numbers) to:
Passport to Knowledge-LHST
Do you want to get mail from other kids around the world who are participating in Live from Hubble Space Telescope? Here's how:
We challenge your kids to make riddles for other kids to solve. Students should create a question about this project that they think will be difficult but fun to answer. Pose that question (we'll put it online in the Kids' Corner of the Web), and others will email their responses directly back. You get to decide if they're right. Then, we'd love to see the results if you'd like to share.
An example question might be: Why are we not planning a landing on Neptune any time soon?
That's a pretty easy question and we know you can do better than that!
If you are interested, send your Student Stumpers to Linda at
The Star Census is back! This activity has students study the night sky, discuss their first-hand observations locally and share results with a national audience. For more information, Web us at http://quest.arc.nasa.gov/hst/events/starsearch.html (see Featured Events) or send an email message to email@example.com
February 22, 1996
I said in my biography statement that when astronomers come back from observing at a telescope, I am given a tape which contains all of the data from their observing run. This tape is just about the same size and shape as a cassette tape for a stereo, and it stores information digitally. This means that all the data is stored as a series of numbers (1's and 0's). The computer then "reassembles" the data from the 1's and 0's into a picture of exactly what the astronomer saw through the telescope.
A lot of people ask me exactly how a picture is taken through a telescope, and that's a good question. It used to be that the only way to take a picture through a telescope was with a camera. These pictures would usually be exposed on glass plates, but would be more or less like the photos you take with a "normal" camera. But the problem with using photographs is that they're not very efficient. For everyday purposes, like taking pictures of you and your friends, photographs work great. However, taking pictures of stars is a lot more difficult because there's so little light coming into the telescope--photographs just couldn't capture enough light!
Not too long ago, the CCD was invented. CCD stands for "charge coupled device." A CCD is MUCH more efficient than photographic plates, and therefore it's perfect to use when taking pictures of stars! So how does it work? A CCD is a lot like a whole bunch of rain buckets arranged in rows. It's usually square in shape, and just like rain buckets capture each individual raindrop, a CCD captures each photon of light. (You can think of a photon as the smallest possible particle of light/energy.) If you have a square array of rain buckets, each bucket would record how much rain fell at each location, right? Well, in a CCD, each miniature "bucket" records how many photons hit each point. The computer then converts all of the information about how many photons hit at each point into a picture.
But CCDs aren't perfect, and the first thing I have to do when I get a new set of data is to get rid of the "signatures" of the CCD itself. These "signatures" are a series of flaws in the image as a result of the CCD itself. Astronomers understand very well where these flaws come from, as well as how to get rid of them. In fact, huge computer programs have been written so that all I have to do is feed the data into the correct programs...and the computer does most of the work! That's what I'm doing right now! It usually takes several hours to run a night's worth of data through these computer programs--a lot of what astronomers do today just wouldn't be possible without computers!
Well, I've got to go to class now... I'll be sure to explain more about
CCDs and how I work with the data next time. Have a good week!
February 24, 1996
I actually am making up a couple of hours I missed early in the week when Mary (my wife) had to see a doctor about our baby. (She's due around the first of May.) Since I went with Mary to the doctor, she came to work with me today, and is doing some paperwork (she's a lawyer) while I work on my computer programs.
I'm working on getting six very large programs ready for the next Servicing Mission, which is scheduled for about this time next year. The programs are all part of the Data Archive and Distribution System, or DADS. DADS is where we keep the Hubble Data Archive, which has all the pictures and spectra taken from HST, plus information used to get those pictures and spectra.
For example, we have data about the "health" of the telescope, like the telescope's temperature, where it was pointed, and how much power the solar panels were generating, and lots of other things. We also have the schedules used to plan the observations, and comments made by the Operations Astronomers about the quality of the data.
We keep all this data on big optical disks, which are sort of like oversize CD-ROMs, except we can write on them. Once. Each optical disk holds about ten times as much data as a CD-ROM. All the optical disks are stored in big jukeboxes. Each jukebox has 131 disks, and we currently have three jukeboxes, with a fourth about to be installed. That's more storage capacity than 5000 CD-ROMs, and it is already more than three-quarters full!
During the Servicing Mission the astronauts will install a new solid state data recorder and two new instruments: STIS and NICMOS. Currently the telescope uses mechanical tape recorders. The new recorder will store about ten times the amount of data, and we won't have to wait for the tape to rewind. The new instruments can take many more, shorter exposures, and can give us much more data. The instrument scientists are telling us to expect seven to ten times as much data as we get today!
The result is that we expect to get a lot more information, and the new instruments will give us data in new formats. So we have to make our programs work much faster, and handle the new data formats.
There are only a few ways to improve the performance of a computer system. One is to use a faster processor. For example, the newer Pentium systems are faster than the old 386 systems. Another way is to parallel processing, so that the computer can do more than one thing at a time, or several computers can work on the same problem.
For example, if you are making 100 paper airplanes all by yourself, you might only turn out two planes a minute. You would need nearly an hour to make all 100. If you get four friends to make planes with you, the five of you can turn out ten planes a minute, and be done in ten minutes. That's parallel processing!
We're doing both. We're going from a computer invented in 1990 (old by computer standards) to a brand new system that is much faster. We're also setting things up so we can work on many things in parallel.
Each program I'm working on contains several "modules" -- smaller programs that are invoked from the main program. For example, the program that puts information about observations in a database has about thirty modules. Each module has two or three hundred lines of instructions! So this one program has over six thousand lines!
We wouldn't be able to figure out what a single six thousand line program did (or why it didn't work) so we break it up into these smaller modules, which are like building blocks, and let each module do just one thing. For example, one module just figures out the day on which an observation was taken. Another checks to see if we already have information about an observation in the database. Another figures out which instrument (camera or spectrograph) was used to take the observation. The main program just calls each smaller module to do a little piece of the work. That makes it easier to get each part of the program right, and makes it easier to add new instruments, or change the information we put in the database.
The program I'm working on today doesn't need a lot of changes. Of the thirty or so modules, only three or four need to be changed, and I'll probably have to add a couple of new ones. Then I'll test the modules I changed and the new ones by themselves, and then test the program as a while, and finally test it with the rest of the system.
Even these six big programs are a fairly small part of the DADS system. In addition to Ingest (the part I'm working on) there's an even bigger set of programs to ship the data to astronomers around the world. And the biggest programs control the jukeboxes and optical disk drives. Overall, there are between two and three million lines of instructions in DADS, so the 6000 line program I'm working on today is less than one percent of the system.
But in the next couple of hours (before Mary decides it's time for a late lunch) I'm going to try and get my one percent working.