Radar was first developed in Britain, but American engineers experimented with radar before the U.S. entered the war. MIT, the top technical university in the country, opened the Radiation Laboratory to research applications for radar early in the 1940's. Back in England, the British military was using radar to catch Nazi planes sneaking across the channel, and they needed help building radio tubes that generated the strong microwave signals. MIT suggested that the British meet with Percy Spencer from Raytheon, a company founded by an MIT professor, Vannever Bush. Raytheon agreed to supply the radar tubes to Britain and Raytheon began a long history in the defense industry.

Engineers at Raytheon, including Vannevar Bush, worked hard developing radar systems for the war effort. Processing the complex radar signals from radar proved very difficult, taking thousands of calculations. Bush worked on the difficult mathematical problem of radar antenna profiles and designed an analog computer to assist with the calculations. However, digital computers would prove more effective.

Another field of research sparked by radar began with an experiment code-named Project Diana conducted right after the war in 1947 by the U.S. Army Signal Corp. Army technicians bounced radar signals off the moon and detected the reflected signal a few seconds later (Diana was the Roman goddess of the Moon). It was the first communication using a satellite, and it demonstrated the practicality of satellite communications.

However, the U.S. wasn't the first one to get an artificial satellite in orbit. That prize went to the Russians ten years later.

The Cold War Heats Up