Word: doppler
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...generated by intelligent beings." The Mullard team searched in vain for slight changes in signal frequency that would indicate it came from a planet or a double star system; in orbit around a star, for example, a planetary transmitter would alternately approach and recede from the earth, producing a Doppler effect that would first increase and then decrease the frequency of its signal...
There were other, more remarkable changes in the sky. At the tremendous velocities necessary for interstellar travel, there were noticeable Doppler shifts in the frequencies of light emitted from the stars. As the spacecraft approached stars at high velocity, their light appeared to be shifted toward the blue, or higher frequency end of the spectrum. Moving rapidly away from other stars caused their light to appear more red. Stars viewed through the front window of the spacecraft generally became more blue, those through the rear window more red, as the spacecraft velocity increased...
...remedies worked. Knowing that glitches were bound to occur in the 83,000 different Surveyor components (34,000 in the Doppler and descent radar alone), scientists considered the first four craft as "engineering models," and would have been delighted if only one of them had made a successful soft landing. Thus no one was more surprised than the JPL and Hughes crews when the first Surveyor not only made a perfect landing and transmitted back thousands of pictures of the lunar surface but also proved so durable that it came back to life after each of two lunar nights, having...
...calculated. The future position data is fed back to each satellite, which in turn broadcasts the information at two-minute intervals. A ship equipped with special receivers and computers can then fix its own position by measuring the shifting frequency of the Transit's beeping signals. This Doppler shift, similar to the falling pitch of a passing train whistle, gives the distance between the satellite and the ship...
...Doptone, based on the Doppler effect, transmits a narrow beam of very-high-frequency sound into the abdomen, detects fetal life and heartbeat after the tenth week of gestation, with out harming the mother. It also pin points blockages in peripheral arteries, as a guide to surgery...