Space Progress Launching And Tracking The Space Craft

Press, Volume C, Issue 29508, 9 May 1961, Page 18

Space Progress Launching And Tracking The Space Craft

[Specially written for “The Press" by COLIN S. L. KEAY, Physic* Department, University of Canterbury)

The safe return from “space I of Gagarin and Shepard has Jed to a good deal of speculation concerning the cost of their brief journeys. Major i Gagarin had scarcely set his feet on the ground before someone rushed into print with an estimate that the trip cost the Russians considerably more than £l3sm—an expensive fide indeed, if the sum is correct. Again, someone has estimated that the 15j-minute flight by Commander Shepard cost America 400 m dollars: that would be about Im dollars a mile. Each of these figures is grossly misleading for a | variety of reasons. It is fair enough to include the cost I of the rocket and other expended components together with the preparation and running costs of the ■ whole operation, say, £lom at the most. But to add in a sizeable fraction of the capital expenditure is quite unreasonable. The costly apparatus needed for launching and tracking will be used again many times now that manned space flight has been ■proved possible. Also, much of the expensive supporting equipment is used for other space and defence programmes: so much so that it is almost impossible to separate the expenditures, lit is sufficient to remark that the amount of money spent i on the scientific exploration ■ of space promises to bring ultimate returns far exceeding the outlay. Launching Apparatus A fascinating array of support equipment is needed every time a space rocket is fired. Most people nowadays would recognise the huge service stands that surround each rocket when it is being made ready for firing. Each type of rocket has its own type of stand and associated servicing facilities, so obviously it pays to keep the number of different types of rocket to a minimum. The National Aeronautics and Space Administration plans to reduce from 10 to five the different types of rocket it employs. One of these, the huge Saturn, will be testflown for the first time later this year. The service stand for it is now ready and is shown in the illustration at the bottom of this column. It is 310 ft high—2B storeys—and contains 2800 tons of steel. Half as tall again as the Christchurch Cathedral, it ranks as the world’s largest structure on wheels. The conical concrete building is the blockhouse which shelters, under 20ft of solid concrete, the engineers and technicians who fire the rocket. No-one, apart from those in the blockhouse 150 yards from the firing pad. is allowed closer than a mile away from the rocket, otherwise they would risk permanent deafness from the roar of the motors. The space pilots Gagarin and Shepard, who sat right on top of their rockets, were carefully protected from the tremendous noise and vibration of the firing. One of the costliest but least impressive items comprising the launch complex is the firing pad itself. More than Elm dollars’ worth of concrete is necessary in the firing pad for a large rocket. The concrete has to withstand the incredibly fierce heat and blast of the rocket exhaust. The flaming exhaust gases are channelled away by means of special ducts lined with nozzles which spray thousands of gallons of cooling water into the inferno of flame. In fact, the dense billowing white clouds that can be seen surrounding most rockets at take-off are mainly steam produced from the cooling water. Tracking Stations When a rocket lifts a satellite up off the launch-pad and sends it into space the satellite’s working life begins. From the moment it leaves the pad the rocket has to be tracked and its course continually corrected for the satellite to have any chance achieving a satisfactory orbit. Once the satellite is in orbit the flood of transmitted data, telemetry it is called, has to be received and recorded. The tracking must also con-

tinue in order to know where in space the satellite is to be found at any time. The Americans have set up more than 20 tracking and telemetry stations scattered around the world. Some are linked into special networks for certain tasks. The SPAN Space Navigation Network, for example, consists of four stations Cape Canaveral.

Hawaii, Singapore and Jodrell Bank. The tracking data from these stations feed into an IBM 709 computer which calculates the speed of a space probe—maybe Im miles out —to within a few inches a second. Another important network has been set up for the Project Mercury orbital flights. These will enable America's firs* orbiting astronaut to maintain voice communication with the ground from any part of his orbit. Each tracking station costs several million dollars to establish. Usually a large rotatable parabolic antenna' is needed, such as the one shown in the inset. This “dish” is 60ft in diameter, and is located on San Nicholas Island, off the coast of California. The electronic equipment housed in buildings a short distance from the antenna is very comnlicated and highly exnensive To take an examnle, the transmitted information from a modern satellite is fed into one or more 40 000dollar tape recorders. These are capable of putting the whole of the Bible on tane in less than 10 minutes. The tape shoots through them at sft a second (newer versions at 10ft a second) recording on 14 tracks simultaneously A single contract let recently by NASA was for a quarter of a million dollars* worth of tane. A home rernrd"r could not phv through this trmrh in a lifetime Finally.' the American National Space Surveillance Network. "Snacetrack.” should be mentioned. It keeps watch on all satellites in orbit around the earth. Data from radar tracking stations feed into computers which calculate whether every object appearing above the horizon is a harmless satellite or an intercontinental missile bringing destruction. Operating around the clock, this network has assigned Snacetrack code-num-bers to every object in orbit near our planet.

By the end of last year Spacetrack had assigned code-numbers to nearly 70 man-made orbiting objects, including burn*-out final stage rockets and other bric-a-brac. The Russians are the worst offenders: in launching Sputnik IV they shot nine bits and pieces into orbit, where some remain. Reader’s Questions Questions should be sent to the address at the top of this column or to Space Progress Column. C/o. “The Press.” How did the Russians decelerate their spaceship in order to prevent it from disintegrating when entering the earth’s atmosphere?—G.A.L. Getting a large space capsule back safely without being incinerated as it slows down in the upper atmo-

sphere is quite an art. The heat generated by friction is enough to vaporise the vehicle many times over, so the secret lies in getting rid of the heat quickly before it ; can penetrate to the spacef man. American Project Mer- : cury capsules are designed i with a blunt end which creates a large shock-wave in the surrounding air (shock-waves cause the sonic bang whenever a jet flies at ; supersonic speed). This shock-wave absorbs up to 98 per cent, of the energy which would Otherwise ap- : pear as heat and carries it i away from the vehicle. The remaining energy is released as heat, raising the tempera- ; ture of the outer layers of the heat shield to nearly 4000 degrees Fahrenheit for a few minutes —not long enough for the heat to penetrate inside. The Russians probably employ similar techniques. Do men have to diet before going into space or do they have a good feed?— W.M. The prime consideration in space flight is keeping the weight to an absolute minimum. Heavy meals before the flight are avoided if possible. Commander Shepard ate special light-weight highenergy foods during the two days before his flight. I don't know what Major Gagarin had—possibly a light vodka was in order. Apart from weight considerations there is probably no reason why normal food would be banned before a space flight. Of course it would be foolish to eat foods that could induce spacesickness.