EXPERIMENT: CLOSE-UP OF MARS

[Music] [Music] by now this is a familiar sight a spacecraft ready for launch but this is not the story of that spacecraft it's the story of two men leaders of a team of scientists and engineers who designed and built a camera system that's inside that spacecraft their camera system has to survive the liftoff and eight months of travel 325 million miles of space send back our close-up of mars as an experiment of all the planets in the sky this is one of the most intriguing because it seems most like earth this is what it looks like when it's 35 million miles from earth and photographed through a telescope it's the planet mars that one poor region is a white area is it snow or ice or something else the dark patches vary in size and color are they vegetation of some kind that changes with the seasons scientists have been asking such questions for many years finding the answers has been difficult because mars comes relatively close to the earth only once every two years and never any closer than 35 million miles to find out more about mars scientists had to get closer to it somehow and then the national aeronautics and space administration announced they were going to send a spacecraft across 325 million miles of space toward mars it would take eight months to get there it would make only one pass a few thousand miles from the planet then leave mars to orbit permanently around the sun could photographs be taken of mars and sent back to earth it would be in camera range less than half an hour this unusual opportunity to try to photograph mars was welcomed by dr robert layton professor of physics at the california institute of technology the requirements for the photographs of mars were worked out at many meetings with scientists interested in mars and with technical experts from the jet propulsion laboratory at pasadena dr robert sharp chairman of the division of geological sciences at cal tech and a terrestrial geologist and dr bruce murray associate professor of planetary science and i collaborated on determining the scientific objective of the photographs naturally we wanted to look at as much of the planet as possible under the highest magnification possible of course there were severe limitations to what could be accomplished under the conditions of the flight plan richard sloan was the project scientist acting as liaison between the scientists and jpl and al harriman of jpl was the cognizant scientist for the camera system denton allen was the cognitive engineer responsible for building the camera after many meetings and a lot of give and take we finally agreed that we should try to get a series of black and white photographs that should begin at the limb and continue across the planet to the shadowed area the photographs should show detail at least 10 times better than any taken from earth the pictures would be taken in overlapping pairs one through a green filter the other through a red filter to increase contrast and tell something about the colors on the planet considering the altitude angle of approach possible resolution and rate of sending back data to earth we designed the system to take 22 photographs design and build a camera system that can travel eight months in the cold and vacuum of space and then take 22 close-up pictures of mars break the pictures up into tiny pieces so they can be radioed one at a time across 135 million miles back to earth the camera system to do all this can weigh no more than 11 pounds and can use only 10 watts of electricity slightly more than it takes to light a christmas tree bulb the team assigned to do this was headed by denton allen when the project was first thrown at me it was pretty scary the early stages of the discussion with the scientists became clear that a television camera was it viticon tubes had sent back some darn good shots of the earth of course from only 325 miles our project was only one of eight experiments on board we had to run the whole camera system on 10 watts not enough to light a small closet and the weight limitation 11 pounds my kid could eat that many bananas in a week we didn't worry about the 10 watts and 11 pounds in the beginning first we had to get something that would work with the camera at an estimated altitude of 10 000 miles or so from mars we needed a telescope the red and green filters could be set into a circular shutter with the predicted brightness of mars the exposure should be about one-fifth of a second then the shutter would be closed for 48 seconds the vidicon tube couldn't be pulled off the shelf we'd have to find a special tube and design circuitry to operate the camera and tube the picture information from the tube would need some juggling then conversion to computer language using a binary code for sending back to earth it didn't look too bad the tube was the scariest part the tube was the scariest part he was concerned about the tube because manufacturers tried hard not to make the kind of tube he needed let's say this is the front of a television vidicon tube now in ordinary vidicons the image is needed for a very brief time so the faster it fades away the better i'm going to turn out the lights and fire this flash onto the surface of this tube the image of my hand is stored on the surface denton allen needed a viticon tube that could hold the image for a long time while the picture information on it was scanned and changed to code he found what he thought was a tube that could do the job and began planning the camera system around it the designing of the various sub-assemblies began according to a schedule that said on june 8 8 months from now we're going to have ourselves a breadboard of this camera system with a slow scan vidicon in there that works so boy you put that date in the back of your minds and go at it because if that one isn't met by the next date down there you're in real bad shape you know you've got to have a bunch of amplifiers in there and you know darn well to run this tube you've got to have deflection circuitry this means system design and individual circuit design going on that can withstand the rigors of the space environment the same time you have to conserve power throughout because you're trying to operate the thing with 10 watts the system also converts the picture elements into the binary code that will be sent by radio back to earth of course we had to simulate that part on the ground then convert the binary code back into picture elements again and hopefully reproduce the same picture we started with here's a picture of a common object you can't recognize it because all you can see are some of the dots that make up the picture the camera system was designed to produce a picture with dots like these two hundred in a line this way and two hundred in a line this way when you can see more of the dots they become a picture of a tennis ball the pictures of mars will be made up of dots too forty thousand of them each of the dots in the picture has to be evaluated by the camera in terms of a gray scale represented by numbers black at one end with a value of 63 and white at the other with a value of zero let's say a sequence of dots in a row in the picture have these values now the numbers have to be changed to code black with a value of 63 becomes this in code that's the code that's going to be sent by radio from mars at the receiving end the code is changed into the proper number later the number is used to duplicate the original dot in this case black the camera system has to do this for every one of the 40 000 dots in each picture with these numbers the 40 000 different dots can be duplicated and arranged in their proper positions to form the completed picture on june 8th dan allen's team was supposed to have the first experimental model of the entire camera system the breadboard version ready to produce a picture in this way by this time we checked out the best slow scan tubes we had time was getting pretty short but each engineer still had a lot of last minute details to worry about his sub assembly had to be ready to work in the system then on june 8 we all got together and said all right i'll plug mine into yours and you plug yours into somebody else's and let's see if it works so we put in the vidicon aimed at a test pattern we're supposed to have a picture and after about a half hour of tweaking things up by these various sub-assemblies came together and generated for the first time a slow scan completely coded and decoded picture it was kind of climactic we were all pretty proud of ourselves there are a lot of congratulations here's to the team and all that kind of stuff it gave us a real boost at this point we're probably drawing 15 watts rather than 10 and you look at this stuff spread all over the table and you say gee 11 pounds for this whole thing the next job is a big one we've got to do it a little bit here and a little bit there refining it a piece at a time we thought we could get rid of some of the circuitry without sacrificing performance we reduced the weight an ounce at a time wherever we could and to eliminate those five extra watts we had to reduce our power consumption at every step finally we built a prototype that took beautiful pictures of a test pattern in the lab it took us about a year to work out most of the problems meanwhile we kept in close touch with dr leighton and the other scientists and engineers we wondered how it would work when it was focused on a real object in the sky lighted by the sun rather than a test chart the moon for instance after some further refinements we took it up to the mount wilson observatory and mounted on one of their telescopes when i saw the photographs that the vidicon reproduced of the moon i really got excited about what it might do with mars it looked as if we had a vidicon and a system that could do the job viticons had been checked out in the environmental tests vibration especially was a worry and it worked out okay later when we put the vidicon on the scanning platform is going to ride on we figured it was going to get a pretty rough ride the vidicon is a fragile device and there is lots and lots of gadgetry inside and sure enough our first test was catastrophic no picture at all when they asked us what happened we said we can't really tell it's just mangled the inside completely fell apart it was just a pretty sad day in about a year marina would go whether we were ready or not we went to work to try to figure out what we could do about it would the tube really get that rougher ride could the tube itself be built stronger could we mount it better to reduce the vibration to the tube one day one of the guys looked at the stuff the tube came packed in it came all the way from texas in the mail wrapped in that stuff maybe it could get to mars so over the weekend he made a structure to support the tube using this foam material it's not so hot at low frequency vibration but at high frequencies where you really begin to worry the foam was just a big cushion the tube was working beautifully all we could do was hope this was a valid test for the vibration the tube would get during liftoff because by this time we couldn't make any more design changes you're tied into so many other systems you can affect them all so this was the camera system that was going to mars at cape kennedy the instruments for the eight scientific experiments are now being installed on the mariner 4 spacecraft there's the camera system on the scanning platform you can see the telescope behind it inside is the shutter and the sticky viticon tube that gave them so much trouble even now they're not sure it will survive the vibration during liftoff in the camera system there's only one mechanical device the shutter when current flows through this solenoid it turns the shutter the exposure is one-fifth of a second through the red filter then the shutter is closed for forty eight then the green filter four fifth of a second and the shutter is closed for a longer period then the cycle starts again they'd run tests on this shutter in a vacuum chamber and found there was a limit to the number of times it would turn it was decided to replace the shutter in the camera and limited to one thousand exposures now we're down to the point where we're having to put a new solenoid in the shutter mechanism a week before launch finally the last solenoid was installed in the flight camera and put back on the spacecraft the final test is run and off she goes each guy of course thinks about his own part i was thinking about the vibration on that vidicon but there were many other guys who worried about their problems there were seven other scientific experiments on board and it takes a lot of teamwork to plan and execute a flight like this [Music] a week after launch the flight path is corrected mariner 4 is now headed for mars during the flight information about the engineering and scientific equipment on board is radioed back to the jet propulsion laboratory and displayed as numbers like this so far during the flight the numbers give engineering data about the spacecraft itself but eight weeks after liftoff a command will be sent to remove a protective cover from the camera telescope and to check out some of the elements of the camera system so everybody at the jet propulsion laboratory was standing by each one waiting to see how his part of mariner 4 was functioning there's the sheet of numbers is it was my turn the red filter and the green filter so we knew the shutter was working and the camera was not seeing any light this could be accounted for by a lot of things this is exactly what we saw when the viticon had broken up we didn't know if the viticon was okay but when the temperature control data came in it showed the temperature in the camera head had gone up that could only be caused by the viticon filament warming up the filament was one of the most delicate parts inside so i figured the rest of the stuff was okay too that gave us a pretty good feeling the real test was yet to come when mariner 4 got to mars that was a long wait five more months scientists worked out some models for us to take pictures of with the backup camera system the models were supposed to simulate what might be on mars all this time we're worrying about the solenoid that activates the shutter remember we kept changing them practically up to launch by now it had been in space about seven months then jpl got a new vacuum chamber so the guys suggested we tested in this new chamber i didn't know what i was getting into the shutter failed after about one thousand exposures it was programmed for 750 exposures on the spacecraft before it even saw mars this meant no safety margin should we change the automatic sequence because of these tests the big worry is you get any kind of a glitch in the system way out there the time you've got to correct it is essentially zero so it was decided to turn on on schedule ten hours before encounter so we turned it on at seven o'clock in the morning and we just sat there i didn't know whether the shutter was running or not if it had run and stopped i wouldn't know where it had stopped open or closed we just had to sit there until three o'clock boy that's the critical time i can just see those numbers coming up with no shutter on i'd have to disappear into the woodwork at that point of course everyone knew about that shutter the project manager dan schneiderman assistant project manager bill collier and the space flight operations director ted douglas and a lot of other guys just the probability of getting that spacecraft all the way to mars still communicating loud and clear over all that space the numbers coming in right on schedule everything else was ready to go the telemetry switched to mode three sure enough the shutter was running at this point looked real solid but can it run another two hours because we're not at the planet yet we won't be at the planet until five o'clock so we had two hours of just watching those numbers to see if that one number was alternating each time wide angle acquisition so we know the mariner is where it's supposed to be in about an hour the narrow angle sensor should pick up the planet and automatically start the camera sequencing so we watched it go through watched all the numbers show the camera had started the shutter was still working and the pictures were being recorded on tape but we couldn't see any of that picture information whatever was recorded on tape would be sent back to earth very slowly because of the great distance and the limited power available a little over eight bits of code per second it's going to take about eight hours to send each picture back to earth here's what the picture information looked like when they tested the camera system on the ground these first three numbers indicated various engineering checks and the last three numbers the actual engineering data when these numbers change to 500 that was picture information from the first line of the first picture here were the grayscale values of each one of the dots in line one this is what they're expecting to see if there's any picture information on the tape recorder 135 million miles out in space so the next morning about five o'clock we're expecting the first picture numbers to come up so we watch the numbers and all we see is black for the first six lines which is what the first six lines are supposed to be i had clued them in on this but on line seven we'd better start looking to see if things were not going to be 63s anymore and sure enough those numbers came out the director of jpl dr pickering was there so were leighton murray sloan everybody this was really exciting as soon as the guys had a bunch of numbers they would tear off the sheet from the printer run off to another room and paste it up on a board then they had guys painting these numbers with colored chalk it really got to be a big thing people all over jpl got wind of this just hundreds of people came to see this first picture of mars mariner 4 successfully carried out the scientific investigation of mars it sent back approximately 18 million scientific measurements information about the interplanetary magnetic field cosmic dust solar wind and flares and other deep space phenomena and it took 22 pictures of mars here they are what do the pictures mean to dr layton and the other scientists and engineers who initiated the experiment even this limited view we have of mars can still give us something definite to relate to earth and the moon because the most important information in the mars pictures comes from the craters which seem to be large in number if the mariner sample is representative of the martian surface the total number of craters of the sizes so far observed is more than ten thousand compared to a mere handful on earth there are many subtle features in the craters that will take some time to study in detail they seem remarkably well preserved which suggests that mars has had only a thin atmosphere for many hundreds of millions of years if the martian is truly primitive it may prove to be the best if not the only place in the solar system still preserving clues to its original development we believe that mariner photos will profoundly affect the scientific views about the origin and evolution of the planetary bodies in the solar system the photographs of mars are now available to scientists throughout the world they've achieved striking results by studying photographs that cover only one percent of the martian surface the other 99 remains a mystery to be probed through [Music] experiment [Music] [Music] you