<P> The next easiest target is Venus . This was a target of great scientific value , since it could provide an unambiguous way to measure the size of the astronomical unit , which was needed for the nascent field of interplanetary spacecraft . In addition such technical prowess had great public relations value , and was an excellent demonstration to funding agencies . So there was considerable pressure to squeeze a scientific result from weak and noisy data , which was accomplished by heavy post-processing of the results , utilizing the expected value to tell where to look . This led to early claims ( from Lincoln Laboratory , Jodrell Bank , and Vladimir A. Kotelnikov of the USSR ) which are now known to be incorrect . All of these agreed with each other and the conventional value of AU at the time . </P>
why did scientists use radio telescopes to bounce radar pulses off of venus
to measure the size of the astronomical unit , which was needed for the nascent field of interplanetary spacecraft public relations value demonstration to funding agencies