The Messenger Satellite launched by NASA is to study Mercury.

The Messenger (Mercury Surface, Space Environment, Geochemistry, and Ranging) satellite was a space probe launched by NASA (National Aeronautics and Space Administration) with the primary objective of studying the planet Mercury. Here are some key points explaining why the correct answer is option 'A':

1. Purpose of the Messenger Satellite:
The Messenger Satellite was specifically designed to investigate and study the planet Mercury. It was the first spacecraft to orbit Mercury, allowing for detailed observations and data collection about the planet's surface, composition, magnetic field, and atmosphere.

2. Mercury's Unique Characteristics:
Mercury is the closest planet to the Sun and is known for its extreme temperature variations, ranging from scorching hot to freezing cold. It is also the smallest planet in our solar system. Due to its proximity to the Sun and its unique characteristics, Mercury presents many scientific mysteries that the Messenger Satellite aimed to unravel.

3. Objectives of the Messenger Mission:
The primary objectives of the Messenger mission were to study Mercury's geology, magnetic field, atmosphere, and surface composition. The satellite carried several scientific instruments to accomplish these objectives, including a gamma-ray and neutron spectrometer, magnetometer, and a suite of cameras and spectrometers.

4. Data Collection and Analysis:
During its mission, the Messenger Satellite collected a vast amount of data about Mercury. It mapped the planet's surface, identified various geological features, and detected the presence of water ice in permanently shadowed craters near the poles. The spacecraft also measured Mercury's magnetic field and studied its thin atmosphere.

5. Mission Duration and Findings:
The Messenger mission began with its launch on August 3, 2004, and ended on April 30, 2015, when the satellite deliberately impacted the surface of Mercury. Throughout its operational lifespan, the Messenger Satellite provided valuable insights into the geologic history, magnetic field, and composition of Mercury, significantly enhancing our understanding of the planet.

In conclusion, the Messenger Satellite was specifically launched by NASA to study the planet Mercury. It successfully accomplished its objectives and provided valuable data about the smallest and closest planet to the Sun in our solar system.