Complex sentence: The DRB proposed a site between five and six hundred miles from the Churchill Rocket Research Range, which was already being used for extensive aurora research with their rocketry program, allowing the radars to directly measure the effects of aurora on radar by tracking the rocket launches.
Split into simpler sentences: The DRB proposed a site between five and six hundred miles from the Churchill Rocket Research Range, which was already being used for extensive aurora research with their rocketry program. Such a location would allow the radars to directly measure the effects of aurora on radar by tracking the rocket launches.