Tracking the First U.S. Man in Orbit by Radio and Radar
1960 - 1962
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This is the ninth in a series of 12 articles entitled "First U.S. Man in Orbit." This article was written by Christopher C. Kraft Jr., Assistant Chief, Flight Operations Division, National Aeronautics and Space Administration (NASA).
Transcript
First U.S. Main in Orbit (Part 9)TRACKING THE FIRST U.S. MAN IN ORBIT BY RADIO AND RADAR
by
Christopher C. Kraft Jr.
Mr. Kraft is Assistant Chief,
Flight Operations Division,
National Aeronautics and
Space Administration
LANGLEY FIELD, Virginia--The first U.S. man in orbit flew too high for his spacecraft to be seen with the naked eye. Even powerful telescopes could not accurately follow his speedy flight.
Therefore, the U.S. relied on radio and radar to track the astronaut's global trip and thereby assure his safety.
Tracking and communications stations were established on all parts of the earth under the flight path to guide the Astronaut on his journey. He conversed with men on the ground by two-way radio. They traced the path of his spacecraft on radar scopes. Their data was used to determine the exact spacecraft position.
While the Astronaut was circling the earth, communications systems specialists and physicians on the ground listened by radio to the astronaut's voice. Automatic instruments in each station also received data by "telemetry" (measuring by radio) on the Astronaut's breathing, temperature, and pulse, for permanent records.
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Among the 90 - odd types of measurements recorded at the stations were temperature and oxygen pressure of the spacecraft cabin, pressure in the Astronauts spacesuit, battery voltages, and the Astronaut's handling of the many controls.
All this information was flashed as soon as it was received from space, via automatic communications lines, to control headquarters at Cape Canaveral, Florida. There scientists and computers quickly evaluated the data to assure that the flight was progressing as planned. They followed the Astronauts rout on a huge world map stretched above an entire wall.
If anything had gone wrong with the spacecraft or if the Astronaut's life had been endangered by the flight, personnel at the control center would have known it almost at once. They could then have taken immediate steps to attempt to correct any malfunctions.
Using their worldwide communications network, they would have informed the Astronaut and the other tracking and communications stations of any abnormal circumstances. If Necessary, the astronaut or a control station could have cut short at any time.
The face that the flight was successful is due in part to the excellent work done at the tracking stations. The close-knit bond between man and machines enabled the Astronauts to complete his journey safely.
The global instrumentation network with its split- second communications has four main functions :
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1. Tracking--to let us know the exact location of the spacecraft at all times.
2. Communications and telemetering-- to let us know in detail what is happening within the spacecraft.
3. Command Control--to enable us to control the spacecraft from the ground, under certain conditions.
4. Coordination--to enable us to communicate with the Astronaut and all ground stations, from launch until recovery.
Tracking the Astronaut began at the moment the huge Atlas rocket blasted off the launching pad at Cape Canaveral. These first few minutes were the most crucial ones of the flight.
The tracking station at Cape Canaveral and another large one at Bermuda had their complicated radar equipment aimed directly at the Atlas. They helped determine whether it was following the correct flight path.
As the Astronaut went through his checklist during blastoff, he told the ground personnel by ultra-high-frequency (UHF) radio how he and his instruments were responding.
At the same time, ground personnel examined the telemetry reports from the spacecraft.
Complex computers in both the U.S. and Bermuda calculated whether the spacecraft went into its proper orbit. Both stations would have known almost immediately if the proper orbit had not been achieved. In either case, or if there had been a spacecraft malfunction or pilot difficulty, both stations could have ordered the mission aborted, and begun a safe
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re-entry maneuver. The spacecraft would then have returned to earth earlier than had been planned.
Radar at Grand Turk and Grand Bahama islands caught the image of the spacecraft on radar scopes as it passed overhead. Next, a specially-fitted U.S. ship in the mid-Atlantic Ocean took over the communications duties for a few minutes, then passed the core to the Canary Island station.
The Astronaut radioed information to these stations and they replied.
If the spacecraft had not entered orbit correctly, it would probably have landed in the Atlantic Ocean, some distance from the Canaries. In this event, the station there would have provided re-entry and recovery data to the Astronaut and recovery ships.
Since all went well, the Astronaut next talked to the stations at Kano, Nigeria, and Zanzibar, East Africa, both of which have radio and telemetry equipment.
After the Astronaut lost contact with Zanzibar station, he conversed with the far-distant U.S. ship in the Indian Ocean. He was able to use his UHF radio as he sped over the ship, then he switched again to HF to listen for the first Australian station.
Radar at Muchea and Woomera, Australia, tracked the spacecraft across almost the entire continent. Muchea station is approximately 180 degrees, or half-way around the globe, from Cape Canaveral. Tracking data from Muchea were used to calculate the maximum observed differences between the planned and actual orbital paths.
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The Astronaut was out of contact with the surface stations for a few minutes as he started his long flight over the Pacific Ocean. He was able to try his continuous-wave (CW) radio, tapping out Morse code on a telegraph key and listening for the replies.
His next checkpoint was Canton Island in mid-Pacific where telemetry and conventional radio equipment were used again.
The Hawaii station was too far away to track the spacecraft during this orbit, but was standing by for the second orbit, as was the station in California.
As the spacecraft approached the station at Guaymas, Mexico, the astronaut knew that he would be tracked all the way across North America. As he traveled across the United States, he was picked up by stations in New Mexico, Texas and Florida.
Thus the Astronaut was in direct contact with the ground stations through approximately 90 percent of his time spent in space.
By means of the worldwide network of stations, information was sent back to Cape Canaveral in "real time," that is, at essentially the [underline] same [end underline] time that events were occurring in the spacecraft.
Because of this speed of transmittal, the computers were able to predict the path of the spacecraft. In this way, radar stations could be told moments in advance at precisely what angle to point their radar antenna, to "look" for the craft.
If anything had gone wrong with one of the means of communication between stations--radio, telephone, or teletype--the operators could have switched instantly to alternate circuits.
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The Astronaut's journey has proved the efficiency of the world-wide communications network. Now scientists can look forward to using this with similar networks during future flights around the earth, and perhaps even in flights to the moon and planets.
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This primary source comes from the Records of the National Aeronautics and Space Administration.
National Archives Identifier: 278172
Full Citation: Tracking the First U.S. Man in Orbit by Radio and Radar; 1960 - 1962; Fact Sheets and Press Releases for Mercury Atlas 6 (MA-6); Source Files on Project Mercury, 1952 - 1968; Records of the National Aeronautics and Space Administration, Record Group 255; National Archives at Fort Worth, Fort Worth, TX. [Online Version, https://docsteach.org/documents/document/first-man-in-orbit, May 7, 2024]Rights: Public Domain, Free of Known Copyright Restrictions. Learn more on our privacy and legal page.