科技英语新闻:NASA's Dawn spacecraft sends asteroid images back

WASHINGTON, Dec. 21 (Xinhua) -- NASA's Dawn spacecraft has sent around 10,000 pictures of the giant asteroid Vesta back to Earth for the first time since its launch in 2007, the U.S. space agency announced Wednesday.

The images were taken from an average altitude of 209 km, the closest the spacecraft can get.

From the images, scientists could see Vesta's stippled and lumpy surface in great detail, and its many small craters, grooves, and lineaments. The fine scale of the images highlights small outcrops of bright and dark material.

With these new discoveries, scientists believe that studying Vesta can help decode the early history of the solar system.

Dawn will maintain its low-altitude orbit for another 10 weeks before moving to a higher orbit for another round of photo-taking.

Launched in 2007, the 446 million U.S. dollar project aims at studying the chemical composition of Vesta's surface and probing its interior structure.

Dawn will leave Vesta in July next year and arrive at the dwarf planet Ceres in February 2015.