William Atkins
Friday, 04 July 2008 19:35
Science -
Space
Page 1 of 3
The NASA spacecraft MESSENGER flew by Mercury on January 14, 2008. It reported back to scientists on Earth some information they did not know about its volcanic history and the source of its magnetic field.
NASA reported these discoveries from the planet Mercury on Friday, July 3, 2008, based on the mapping by MESSENGER of about 30% of the planet.
For over thirty years, since the NASA Mariner 10 mission, astronomers really did not know how the smooth plains on Mercury were formed.
Some scientists thought they were created by materials ejected out of large meteorite impacts bombarding the planet from outer space. Others thought the smooth plains were formed from inside the planet by lava erupting from giant volcanoes.
Astronomers also did not know much about the magnetic field of Mercury. They knew it had an active magnetic field, like on Earth, but these astronomers did not know its source. The core of Mercury was previously identified as consisting of a large iron-rich inner core and a molten outer core. However, it was unknown if that core produced the magnetic field on Mercury.
In addition, some of surface details on Mercury indicated that the planet had been slightly larger in its past than what it is now. Such contraction of the planet was a mystery to scientists, too.
Before MESSENGER, only one other spacecraft has gotten close to the planet--the robotic Mariner 10 spacecraft, which mapped about 45% of the planet between 1974 and 1975. It fly by the planet on March 29, 1974, September 21, 1974, and March 16, 1975.
Launched on November 3, 1973, the
Mariner 10 mission was to measure Mercury’s and Venus’ atmospheres, surfaces, and other characteristics. Most of the other observations of Mercury were made with ground-based telescopes and other instruments.
The scientists had theories about these and other unknowns of the planet, but no facts to collaborate those hunches.
What did the scientists learn from the first flyby of Mercury by MESSENGER? Please read on.
