NASA has released the first ever close-up images of Mercury, as the first spacecraft to do a detailed survey of the planet in 35 years powered up its cameras.

MESSENGER - for MErcury Surface, Space ENvironment, GEochemistry, and Ranging - is the first spacecraft to visit the planet since the Mariner mission in 1974. At 5:20 a.m. Eastern Time it picked up the very first images from Mercury orbit.

Over the next six hours, MESSENGER took an additional 363 pictures before sending some of the data to Earth. The MESSENGER team is looking over the data, which is still being received. Tomorrow, March 30, at 2 p.m. Eastern, NASA will hold a press conference tomorrow at 2 p.m. to discuss the spacecraft's findings and release more images.

The two scientists participating in tomorrow's press conference will be Sean Solomon, MESSENGER principal investigator, of the Carnegie Institution of Washington, and Eric Finnegan, MESSENGER mission systems engineer, of the Johns Hopkins University Applied Physics Laboratory.

Launched in 2004, MESSENGER reached orbit around Mercury on March 17. Since then it has been testing systems and turning on other science instruments. On March 23 MESSENGER powered up six of them: its energetic particle and plasma spectrometer, magnetometer, Mercury atmospheric and surface composition spectrometer, mercury laser altimeter, neutron spectrometer and x-ray spectrometer.

But none of those instruments sees in the visible spectrum. For that the dual imaging system had to be turned on.

The first image shows the rayed crater Debussy, which dominates the center of the image. A smaller one, called Matabei, with dark rays, is visible to the west of Debussy. The bottom half of the image is an area of the south pole that no spacecraft has ever seen before.

MESSENGER will be taking 75,000 images as it completes its year-long mission, which gets fully underway on April 4.