In this task, you will be presented with a passage and have to answer a question based on your understanding of the events inferred from the passage. Try to find the best answer that is most likely to fill in "_". Note that the URLs in the text have been replaced with [Link].
Q: The Dawn spacecraft has captured amazing new images of the mystery bright spots on the dwarf planet Ceres, which continue to baffle scientists. In particular, the images show the brightest spot and its companion standing out against the darker surroundings. But experts are still at a loss to explain the composition and source of the bright spots. Scroll down for video Nasa scientists in California have revealed new images of the dwarf planet Ceres. They reveal new views of the two brightest spots in a crater (shown). However, scientists are still not able to explain what they are. Dawn will begin its first science orbit around Ceres on 23 AprilNasa scientists in California reveal new images of dwarf planet CeresThey show new views of the two brightest spots in a craterHowever, scientists are still not able to explain what they areDawn will begin its first science orbit around Ceres on 23 April 
 Question:‘The approach imaging campaign has completed successfully by giving us a preliminary, tantalising view of the world _ is about to start exploring in detail.
A: 
Dawn