Bowman spends months to the ship alone, slowly but surely approaching Iapetus. Through his technique, he steadily notices a little black spot to the surface area of Iapetus, and later on finds it equivalent in shape to TMA-1, only much larger. The researchers on this planet name this monolith "TMA-2", https://legitcash38158.digitollblog.com/36285172/little-known-facts-about-2001-cash