Even in it’s last gasp, the NASA Messenger spacecraft has provided astronomers with a wealth of useful information on the planet Mercury. NASA mission controllers took the exploratory probe in for a close flyby (within 15 km) of the surface of the Mercury last week before the craft crash landed on the super-hot surface of the planet closest to the Sun.
According to data from a new study published in the journal Science earlier this week, astronomers have gained new insights into Mercury’s relatively strong magnetic field, and into the source of the magnetic field: the liquid dynamo in the outer core of the planet.
More on NASA Messenger spacecraft mission
The NASA Messenger spacecraft was the first ever to orbit Mercury, and has been sending back a great deal of valuable data over the last four years until it crashed onto the surface of the planet just last week.
Until recently, the closest the spacecraft came in its orbit above Mercury’s surface was about 200 kilometers (120 miles). However, over the last month of the mission, the probe swooped to within 15 kilometers, or less than 10 miles, of the surface of the dense planet, offering an unprecedented close-up view.
With the aid of a magnetometer on long boom to minimize interference from the spacecraft, Messenger measured the strength and direction of the planetary magnetic field at two locations, including Suisei Planitia, a basin named after the Japanese word for Mercury
The data showed suggest that the surface of Mercury locked in its magnetic field characteristics when the molten rock solidified somewhere around 3.7 billion to 3.9 billion years ago. However, this is the “lower bound on the average age of magnetization,: meaning the planet’s magnetic field is at least 3.7 billion to 3.9 billion years old.
The research team notes that if this timeline is accurate, it raises a number of questions regarding the evolution of Mercury’s core.
Statement from study lead author
“One of the puzzles these observations leave open is: How would you have driven that early dynamo?” study lead author Catherine Johnson, a geophysicist at the University of British Columbia in Vancouver, Canada, points out.
Johnson also noted that the Earth also has a liquid outer core that produces its magnetic field (close to 100 times stronger than Mercury’s), so figuring out exactly what is going on to with Mercury’s magnetic field could help us understand the history of Earth’s magnetic field..
“These kinds of things are interesting problems for Earth too,” Johnson commented.