1. Spacecraft missions: This involves sending robotic probes, satellites, and even crewed spacecraft to explore different celestial objects like planets, moons, asteroids, and comets. These missions gather data through instruments like cameras, spectrometers, radar, and other scientific tools.

2. Ground-based observations: This involves using telescopes and other instruments on Earth to observe and analyze objects in space. These tools can be optical telescopes, radio telescopes, X-ray telescopes, and more, each detecting different types of radiation from space.

Both methods have their strengths and weaknesses. Spacecraft missions offer close-up, detailed observations, but are expensive and require careful planning. Ground-based observations are more accessible and can be used to study a wider range of objects, but their resolution is limited by Earth's atmosphere.