NASA / Final Image Messenger sent on April 30, 2015
The NASA Messenger mission was a big success. The spacecraft crashed 11 days ago into planet Mercury after its four year mission. Now researchers found from Messenger’s data that Mercury has a Magnetic Field that is almost 4 billion years old.
Originally planned to orbit Mercury for one year, the Messenger mission exceeded NASA’s exceptions. The spacecraft’s mission latest for over four years acquiring extensive datasets with its seven scientific instruments and radio science investigation.
On April 30, 2015, Messenger succumbed to the pull of solar gravity and impacted Mercury’s surface. The image above is the last one acquired and transmitted back to Earth by the mission. The image is located within the floor of the 93-kilometer-diameter crater Jokai. The spacecraft struck the planet just north of Shakespeare basin.
Scientists are still busy analyzing the data Messenger gathered. A study led by Catherine Johnson, a University of British Columbia planetary scientist, revealed that Mercury has an ancient magnetic field. The researches used data obtained by MESSENGER in the fall of 2014 and early 2015 when the probe flew very close to the planet’s surface, at altitudes as low as 15km.
It was known for a while that Mercury has a magnetic field similar to Earth’s, but it is much weaker. The motion of liquid iron deep inside Mercury’s core generates the field.
Mercury is the only other planet besides Earth in the inner solar system with such a magnetic field. There is evidence that Mars once had a magnetic field but it disappeared at some point more than 3 billion years ago.
When Messenger flew close to the planet, its magnetometer collected data on the magnetism of rocks in Mercury’s surface. Those tiny signals revealed that Mercury’s magnetic field is very ancient, at least 3.7 to 3.9 billion years old. The planet itself formed around the same time as Earth, just over 4.5 billion years ago.
“If we didn’t have these recent observations, we would never have known how Mercury’s magnetic field evolved over time,” said Johnson, also a scientist at the Planetary Science Institute. “It’s just been waiting to tell us its story.”