NASA's Dawn spacecraft entered its first science orbit around asteroid Ceres on Thursday as scheduled, the U.S. agency said Friday.

Following a delay in communicating a command sequence, the spacecraft briefly entered into safe mode and awaited further instructions, which were sent by mission controllers.

As of early Friday, Dawn returned to normal operating mode and the mission team continues to prepare for science data collection.

Beginning on Thursday, Dawn will spend approximately three weeks in a nearly circular orbit. During its first science orbit, Dawn is expected to acquire more than 2,500 images of Ceres. On May 9, Dawn will begin to make its way to lower orbits to improve the view and provide higher-resolution observations.

Since arriving at Ceres on 6 March, Dawn has been manoeuvering into the 13,500 km-high orbit using its ion engine and became the first spacecraft to orbit a dwarf planet, and the first to orbit two extraterrestrial targets.

After spending more than a month on the dark side of Ceres, Dawn spacecraft has captured new images of two bright spots on the surface of the dwarf planet, which have fascinated scientists for months.

"The approach imaging campaign has completed successfully by giving us a preliminary, tantalizing view of the world Dawn is about to start exploring in detail. It has allowed us to start asking some new and intriguing questions," said Marc Rayman, Dawn's mission director and chief engineer.

The spacecraft, which was launched in 2007, previously explored the Vesta for more than a year, from 2011 to 2012, delivering new insights and thousands of images from that distant world. Ceres and Vesta are the two most massive residents of the solar system's main asteroid belt between Mars and Jupiter.

Ceres, with an average diameter of 950 km, is the largest object in the main asteroid belt between Mars and Jupiter. By comparison, Vesta has an average diameter of 525 km, and is the second most massive body in the belt.

Ceres is of great interest to astronomers and scientists, who believe that the small dwarf planet may also be a large water reservoir in the inner solar system aside from the Earth. However, scientists are unsure how much of that water is actually liquid.

The spacecraft will continue its investigations until at least June 2016.
Source: XINHUA