NASA will get its first ever close-up images of Mercury today, as the first spacecraft to do a detailed survey of the planet in 35 years powers 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. Launched in 2004, it 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 these instruments sees in the visible spectrum. For that the dual imaging system has to be turned on.

The agency will hold a press conference tomorrow at 2 p.m. to discuss the spacecraft's findings and release more images. The two scientists participating 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.

(Updates here).