However, it formed close to the sun, and is composed of heavier material than the moon is. A major conference was held in 1976 to compare the two bodies. However, such a comparison is difficult because of the poor quality of images available of Mercury. Mercury is a difficult target for exploration. It requires a large change in velocity in order to reach and achieve orbit, largely due to the planet's high velocity and its large inclination on the ecliptic.
Heat is a problem for any spacecraft that close to the sun.
Mercury is far away, requiring a robust communications system. However, because of the close proximity of the sun, power production is less difficult. It has no atmosphere to interfere with optics. It has a very small magnetic field, resulting in no phenomena comparable to the Van Allen radiation belts. This program will be named after the Dutch astronomer Tyco Brahe because of his tireless devotion to observing and carefully cataloging the movements of the stars and planets.