The MESSENGER (MErcury Surface, Space ENvironment, GEochemistry and Ranging) space- craft recently completed an orbital survey of the planet Mercury, con- cluding a decade-long phase of the project. MESSENGER is now on an extended mission set to last until March 2013.
The results have been long-await- ed by UCSB Professor Emeritus of Physics Stanton Peale, one of the MESSENGER research team’s founding members who initial- ly proposed a method of studying Mercury’s core in 1976. The radar studies proved consistent with a molten core and the MESSENGER craft, which returned tens of thou- sands of images, has now confirmed Peale’s theory with closer examina- tion.
Physics Department Chair Omer Blaes said Peale is one of the world’s leading scientists in planetary dynamics.
Professor Stanton Peale, one of the founding members of the mission, looks forward to future developments in his research. He has devoted much of his life’s work to studying Mercury.
“He’s studied Mercury all his life,” Blaes said. “MESSENGER arriving at Mercury is the culmina- tion of an entire career devoted to understanding the dynamics of that particular planet.”
MESSENGER is a state of the art spacecraft equipped with a variety of instruments including a laser altimeter, which maps topography using laser pulse; a magnetometer, which measures the planet’s magnetic field; a device for measuring the planet’s gravitational field and various spectrometers for studying everything from the surface composition to the atmosphere.
According to Peale, MESSENGER was launched in 2004 and spent most of the past seven and a half years reaching its destination.
“The reason for that is, you can’t send a spacecraft directly to Mercury because it arrives at too high a speed,” Peale said.
To slow down the craft enough for it to enter Mercury’s orbit, its flight path was directed around
several other planets, allowing their gravitational pull to reduce its velocity. It took one flyby of Earth, two of Venus and three of Mercury before MESSENGER was able to begin its study.
In addition to determining that Mercury has a mol- ten core, MESSENGER mapped much of the planet’s northern hemisphere and found it has a tail of debris like most comets, kicked off its surface by powerful solar radiation.
However, Peale said there is one research goal they have yet to accomplish.
“The holy grail which hasn’t been watched yet is … [that] radar from the Earth has detected white areas near the North and South Poles,” Peale said. “The characteristics of the backscatter of the radar are consistent with there being water ice.”
Peale said the bright areas that could represent water are permanently shadowed, allowing for ice to remain frozen by the extreme cold for millions of years, but the team can’t identify the substance without a clearer picture.
“If the neutron spectrometer could get a good view of these craters, it could tell,” Peale said.
Unfortunately, it is not certain that the craft will drift over the craters, and there is not enough fuel left for the team to adjust the orbit. So, as Peale said, “We’re stuck with what we get.”