How have spacecraft allowed scientists to study the surfaces of Mars and Venus?

Spacecraft have enabled scientists to study the surfaces of Mars and Venus through a combination of flybys, orbital mapping, and direct lander missions.123

Studying Mars

Exploration of Mars has utilized various robotic technologies to analyze its geology, atmosphere, and potential for life:
* Orbiters: Spacecraft like Mariner 9, Mars Global Surveyor, and Mars Reconnaissance Orbiter have systematically mapped surface topography, mineralogy, and gravity fields using high-resolution cameras, spectrometers, and radar.1
* Landers and Rovers: Missions such as Viking 1 and 2, Spirit, Opportunity, Curiosity, and Perseverance have performed on-site research, including soil analysis, rock grinding, and drilling to search for signs of past water and microbial life.12

Studying Venus

Because Venus is permanently shrouded in thick clouds, scientists rely heavily on radar technology:
* Radar Mapping: The Magellan spacecraft used synthetic aperture radar to penetrate the clouds, creating high-resolution maps of 98 percent of the planet's surface.43
* Surface Landers: The Soviet Venera program successfully landed probes on the surface, providing the first direct images and data on the composition of the rocky, volcanic landscape.35