Hot topic: Artist's impression of the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (Messenger) spacecraft in orbit at Mercury. Messenger launched in 2004, and will begin a year-long orbital study of Mercury in 2011. Though the Sun is up to 11 times brighter at Mercury than we see on Earth and surface temperatures can reach 450 °C, the probe's instruments will operate at room temperature behind a sunshade of heat-resistant ceramic fabric.
Credit: NASA
WASHINGTON: Scientists are eagerly awaiting new images and data today, when a NASA spacecraft flies past Mercury in the first visit to the mysterious planet since 1975.
They expect to harvest some 1,200 images and other data from instruments aboard the MESSENGER spacecraft that could shake up the study of the Solar System, said officials.
"I think we're in for some big surprises," NASA scientist Faith Vilas said in a teleconference with reporters.
MESSENGER will measure the mineral and chemical composition of Mercury's surface, study its atmosphere and magnetosphere and collect data about the magnetic tail that sweeps behind it.
"Raw scientific exploration"
"This is raw scientific exploration and the suspense is building by the day," added Alan Stern, associate administrator for NASA's science Mission directorate.
The probe will swoop as low as 200 km above Mercury's cratered, rocky surface, and will use the planet's gravitational pull – in this flyover and two others planned this year and next – to position itself to enter the planet's orbit. MESSENGER is scheduled to fly over Mercury again in October 2008 and September 2009, then return for a final sweep in 2011 when it will enter Mercury's orbit for a year-long study of the planet.
The spacecraft has already flown once past Earth and twice past Venus since its August 2004 launch. It will have travelled 7.8 billion kilometres when it completes its six-and-a-half-year odyssey.
The historic flyby will be the first since the Mariner 10's March 1975 visit, when that spacecraft conducted three flights over the planet closest to the Sun. Mariner surveyed only one hemisphere of Mercury, using weaker observational tools.
