Final answer:
Radar observations are more effective than optical cameras for studying Venus's surface due to the thick clouds that block visible light but allow radar to penetrate. The Magellan spacecraft's radar mapping provided a high-resolution view of the surface, revealing geological features larger than a football field and showing the planet's roughness. Optical observations, on the other hand, cannot reveal the planet's surface features because of the reflective clouds.
Step-by-step explanation:
Radar observations of Venus provide more data about the surface structure than a flyby with close-up optical cameras due to Venus's dense cloud cover, which is impenetrable by visible light. The thick clouds reflect about 70% of sunlight, making optical observations of the planet's surface virtually impossible. However, radar can penetrate this cloud layer, allowing us to map and analyze the surface. The Magellan spacecraft used powerful imaging radar to achieve this, producing images with an impressive resolution of 100 meters. This means that any geological feature on Venus larger than a football field could be observed.
Furthermore, Venus's surface conditions differ markedly from Earth's, with no water or ice and low wind speeds, allowing its surface to retain complex features. These conditions make radar mapping particularly beneficial, revealing the history of Venus's geological activity. The high-resolution radar images not only provide an insight into the topography but also indicate surface roughness—bright features suggest rough terrain, and darker regions are smoother. The data gathered by the radar mapping is so detailed that each 100 minutes of Magellan's data transmission could fill volumes of encyclopedias if translated into text.