Scientists were able to study the characteristics of the moon through direct missions, robotic missions, lunar samples analysis and remote observations over decades. Astronauts contributed through direct exploration and data collection during the Apollo and other lunar missions. Here's how scientists and astronauts obtained these insights:

1. Apollo missions: Neil Armstrong and Buzz Aldrin of the Apollo 11 mission in 1969, achieved the historic feat of walking on the Moon. Apollo astronauts collected lunar samples which were later examined for composition and properties in laboratories on Earth. Experiments were conducted during these missions to study the lunar environment.

2. Remote observation Satellites, telescopes and other instruments placed in orbit around the Moon or operated from Earth have allowed for continuous observation of the Moon. These observations helped map the Moon's surface and study its topography, temperature variations and other features.

3. Unmanned Lunar probes: Robotic spacecraft such as the Lunar Reconnaissance Orbiter (LRO) and the Lunar Crater Observation and Sensing Satellite (LCROSS) explored the Moon without humans. These missions collected valuable data about the surface composition, gravitational field and searched for the potential presence of water ice in polar regions.

4. International collaboration Various space agencies from different countries have collaborated on lunar missions, sharing their expertise and resources. These partnerships allowed for more advanced spacecraft and technologies, such as the Chang'e missions by China and the Chandrayaan missions by India.

By combining direct observations, remote sensing, sample analysis, and collaborative efforts, scientists and astronauts have been able to gain a greater understanding of the Moon's composition, geology age, surface conditions, and overall characteristics.