Starfinder; No. 2; Pictures From Numbers

<v Maggie Linton>Hi, and welcome to another edition of Starfinder. <v Maggie Linton>I'm Maggie Linton. Have you ever done one of these paint by number pictures? <v Maggie Linton>You know the kind, where all the spaces in the picture with a number five inside <v Maggie Linton>get dabbed with the number five blue paint. <v Maggie Linton>Well, in today's show, you'll find out what this amateur technique <v Maggie Linton>has in common with the way we take and make photos from space. <v Maggie Linton>You'll also meet David Soderblom, Chief of the Research Support Division, <v Maggie Linton>who helps to interpret these photos. <v Maggie Linton>But first, we're going to speak with Eric Chaisson at the Space Telescope <v Maggie Linton>Science Institute and dip into the latest news from the HST <v Maggie Linton>data stream. <v Eric Chaisson>Today, I'd like to show you the very first picture that was telemitted to the Earth <v Eric Chaisson>by Hubble. As you know, it's not necessarily a very exciting <v Eric Chaisson>region that we first imaged because it was chosen by engineers <v Eric Chaisson>as a test region, to test the telescope's pointing, to test its focus, <v Eric Chaisson>and to do a variety of other early engineering checks.

<v Eric Chaisson>The region is called NGC3532. <v Eric Chaisson>It's simply the 3532nd object in a catalog <v Eric Chaisson>that astronomers call the New General Catalog, NGC. <v Eric Chaisson>The region is a cluster of stars--seen from the Southern Hemisphere only, can't <v Eric Chaisson>see it from the Northern Hemisphere-- which is about, oh, about 1300 <v Eric Chaisson>light years away. It has a moderate age of about 2 to 3 billion <v Eric Chaisson>years. And it's a, again, a rich cluster of stars. <v Eric Chaisson>And we were going to focus with a wide field planetary camera on one small portion <v Eric Chaisson>of that cluster. It was a very exciting time. <v Eric Chaisson>No question about it. It was more, all the more exciting because we took the image--I <v Eric Chaisson>remember exactly--twelve minutes past eleven and fourteen minutes past <v Eric Chaisson>eleven. There were two such images we first took. <v Eric Chaisson>But we didn't have a real time contact. <v Eric Chaisson>By real time I mean, we couldn't get the data to the earth immediately through the <v Eric Chaisson>tedious communications satellites, some 22,000 miles above the earth.

<v Eric Chaisson>The data was stored onboard Hubble on a rather ordinary tape recorder, <v Eric Chaisson>and then about three hours later were transmitted to the earth. <v Eric Chaisson>Now, I want to show you now those images that caused a great deal of excitement on the <v Eric Chaisson>ground when we first saw them. <v Eric Chaisson>One of the images we saw, in fact the first image we saw, really, and looked at <v Eric Chaisson>carefully, is shown on this particular monitor behind me. <v Eric Chaisson>This is the Hubble Space Telescope view in the frame at the right of a small portion <v Eric Chaisson>of the region NGC3532. <v Eric Chaisson>And by contrast, this is the same set of stars as seen from the ground. <v Eric Chaisson>Not any old ground location, one of the best viewing sites <v Eric Chaisson>on the surface of the earth, in South America. <v Eric Chaisson>And you can see already, in the very first image, that we are resolving <v Eric Chaisson>stars, especially these two stars at the top of the frame, with <v Eric Chaisson>Hubble, better than that, ground-based telescope can resolve those stars. <v Eric Chaisson>And also, if you look at the second image that came down--a shorter

<v Eric Chaisson>exposure--that image enabled us to see those two stars, <v Eric Chaisson>which were at the top of the previous frame, even more clearly now, with Hubble, <v Eric Chaisson>than we were able to, in fact, to see those two stars from the ground. <v Eric Chaisson>So this was exciting. And it was telling. <v Eric Chaisson>Because the very first image with Hubble, first light, showed <v Eric Chaisson>the objects resolve a little bit better than anything we can typically do on the ground. <v Maggie Linton>Putting a camera into space is a big enough challenge. <v Maggie Linton>But then how do we get the pictures back? <v Maggie Linton>The answer is right in front of your eyes. <v Maggie Linton>We'll explain today on Science Links. <v Maggie Linton>Let's make a video. Put the tape into the VCR. <v Maggie Linton>And there you are, just as you were seconds before.

<v Maggie Linton>But get closer to the screen. <v Maggie Linton>You're not exactly as you were. <v Maggie Linton>You've been broken into thousands of tiny blocks of color that make up an image <v Maggie Linton>that looks like you. This image is a facsimile or a lookalike of you. <v Maggie Linton>These minute video puzzle pieces are electronic impulses called <v Maggie Linton>picture elements or pixels. <v Maggie Linton>Pixels make up the images on your computer screen, too. <v Maggie Linton>Breaking a picture into many tiny elements, then reconstructing it, is not <v Maggie Linton>a brand new idea. <v Maggie Linton>Your computer at school makes a picture from tiny elements of color, too. <v Maggie Linton>But these computer pixels are digital, which means they're actually pictures <v Maggie Linton>made from numbers. They don't seem to look like anything when you're too close to them. <v Maggie Linton>But back up, and you can see that the pieces make a complete picture. <v Maggie Linton>The pictures that the Hubble Space Telescope is sending are pictures from numbers, too. <v Maggie Linton>Let's look at how the HST sends us pictures from its orbit,

<v Maggie Linton>380 miles above the Earth. <v Maggie Linton>Here's a picture from the HST. <v Maggie Linton>This image entered one of the HST's cameras looking just like this. <v Maggie Linton>The camera changed it from a single image into a <v Maggie Linton>640,000 electronic pixels. <v Maggie Linton>The CCD, or charge coupled device, inside the camera <v Maggie Linton>actually changes the light of the image into electronic pixels. <v Maggie Linton>Each pixel was scanned by the computer to determine how bright or dark it <v Maggie Linton>was. Then it was given a code number. <v Maggie Linton>The lowest number is zero. That's the darkest, black. <v Maggie Linton>The highest number a pixel gets is 255. <v Maggie Linton>That's pure white. Everything in between is a shade of gray. <v Maggie Linton>Two hundred fifty six, zero counts as a number, is not just a random <v Maggie Linton>number. That's how many different elements can be stored in the counting unit <v Maggie Linton>of a computer system called a byte.

<v Maggie Linton>In this case, it's the number of different shades between white and black <v Maggie Linton>that can be stored in one byte. <v Maggie Linton>To capture a color image like this one, the cameras on the HST <v Maggie Linton>must do a little more work. <v Maggie Linton>They take three black and white frames of the same image and pass the light through <v Maggie Linton>blue, green and red filters. <v Maggie Linton>When the image has been converted into pixels and coded with the right number of values, <v Maggie Linton>it's sent back to earth by a process called telemetry, sending information <v Maggie Linton>by radio signals. <v Maggie Linton>Telemetry has been used to send images back from space since the first satellites were <v Maggie Linton>launched in the 1960s. <v Maggie Linton>Close up views of Mars, moon craters, and planetary rings have come <v Maggie Linton>back to us by telemetry. <v Maggie Linton>The millions of digital electronic pulses that now make up the images leave <v Maggie Linton>the HST on a path of radio waves headed for the Space Telescope <v Maggie Linton>Science Institute in Baltimore.

<v Maggie Linton>But it's not exactly a straight shot. <v Maggie Linton>First, they head farther into space, about 22,000 miles, <v Maggie Linton>to a satellite in the tracking and data relay system. <v Maggie Linton>From there, they are sent down to earth to a receiver at White Sands, New Mexico. <v Maggie Linton>They're on earth, but not for long, because, again, they're bounced back to a domestic <v Maggie Linton>satellite 22,000 miles up, which then relays them <v Maggie Linton>down to Goddard Space Flight Center in Greenbelt, Maryland. <v Maggie Linton>And finally, the last leg of the trip, to the Space Telescope Science Institute, <v Maggie Linton>30 miles away. <v Maggie Linton>We're here at the Space Telescope Science Institute, where computers put the HST <v Maggie Linton>images back together. Right now, we still have a bunch of coded <v Maggie Linton>electronic signals stored in these computers. <v Maggie Linton>How do we finally get to see what the HST has already seen? <v Maggie Linton>We reverse the process. <v Maggie Linton>We convert electronic impulses into an image. <v Maggie Linton>The Science Institute's computers can tell from the number of values coded on each pixel

<v Maggie Linton>just how light or dark it should be and where it's located in the picture. <v Maggie Linton>Here we see computers put pieces of the HST picture back together <v Maggie Linton>into a facsimile of its original image. <v Maggie Linton>The image can then be displayed on a computer screen, printed out <v Maggie Linton>as a glossy photograph, or made into a slide. <v Maggie Linton>For color images, the Science Institute's computers direct the HST <v Maggie Linton>to send pixels back through colored filters. <v Maggie Linton>These three images are sent separately to the Science Institute, where they are blended <v Maggie Linton>back into their original colors. <v Maggie Linton>What starts out as a reflection of the cosmos in the HST's cameras comes <v Maggie Linton>back to Earth in radio waves as digital electronic pulses. <v Maggie Linton>At the Space Telescope Science Institute, computers and scientists <v Maggie Linton>reconstruct those pulses into images that will make up one of the greatest scrapbooks <v Maggie Linton>of our time.

<v Maggie Linton>David Soderblom is Chief of the Research Support Division with the Space <v Maggie Linton>Telescope Science Institute, and he considers his division the bucket <v Maggie Linton>at the end of the pipeline. By receiving and then analyzing the data piped <v Maggie Linton>back to Earth from HST, people like David can provide the latest information <v Maggie Linton>to astronomers. We asked David to analyze his job as one <v Maggie Linton>of the people behind HST. <v David Soderblom>One of the things I recall from childhood--must have been ten or twelve years old--and <v David Soderblom>this was back when we sent one of the first probes to Mars, sent back pictures, <v David Soderblom>and it was just marvelous, awe-inspiring that you <v David Soderblom>could send this little ball of machinery off to <v David Soderblom>another planet and get back a picture at all. <v David Soderblom>My deepest interest in astronomy started at the college level. <v David Soderblom>I was an undergraduate at Berkeley and they have an astronomy major.

<v David Soderblom>And from Berkeley I went to University of California, Santa Cruz, <v David Soderblom>where Lick Observatory is headquartered, and got a PhD. <v David Soderblom>I got involved there with building a instrument for the <v David Soderblom>120-inch telescope on Mt. <v David Soderblom>Hamilton, which was very interesting. <v David Soderblom>Had the aspects of both the scientific work and building real hardware, <v David Soderblom>tangible things you can get your hands on. <v David Soderblom>And only recently came seriously into space astronomy. <v David Soderblom>This division of which I'm part has elements that <v David Soderblom>provide the software, the computer programs that are used for reducing <v David Soderblom>and analyzing the data from space telescopes. <v David Soderblom>We provide the computers here that people work with to do that. <v David Soderblom>We provide the data itself that's stored in computers and made available. <v David Soderblom>And then we have a staff of people to help astronomers put all that <v David Soderblom>together. <v David Soderblom>The astronomer comes to visit.

<v David Soderblom>They sit down at the computer. <v David Soderblom>They have either gotten the data physically on a reel of tape or have access <v David Soderblom>to it directly here. And then pull up <v David Soderblom>an image, for example, on the computer and start to work on it. <v David Soderblom>Early on, I expect practically everyone who observes the space telescope <v David Soderblom>to come here for two reasons. One is that we can provide certain kinds of data, <v David Soderblom>the calibration data that they would have a difficult time getting home. <v David Soderblom>And second, they will also have access easily to expertise--the <v David Soderblom>people who are knowledgeable in the instruments, the software. <v David Soderblom>The fact that this vastly complex beast space <v David Soderblom>telescope has been put into orbit is phenomenal. <v Maggie Linton>Pictures from numbers. The idea doesn't seem so complicated anymore, does <v Maggie Linton>it? On our next show, we'll find out why stars twinkle, and Eric <v Maggie Linton>Chaisson will unveil the latest surprise from the HST.

<v Maggie Linton>Our special guest will be Bruce Gillespie, a matchmaker who arranges <v Maggie Linton>dates for astronomers with the HST. <v Maggie Linton>I'm Maggie Linton. See you next time on Starfinder. <v Announcer>Starfinder has been made possible in part by grants from the United States <v Announcer>Department of Education. <v Announcer>And the Martin Marietta Corporation, dedicated to helping unlock the <v Announcer>mysteries of the universe.

<v Announcer>Martin Marietta is masterminding tomorrow's technologies.