What’s Up in the Sky – November, 2018
Getting a Closer Look at Mercury
Of all the planets, it is not surprising that the one that has been visited and studied by spacecraft from Earth the most often is Mars. It is nearby and relatively easy to get to although it is also very difficult to land on. Its surface gravity is similar to Earth’s and its surface conditions are cold and dry, but manageable, just like in the movie, The Martian. There are currently a number of spacecraft both on the surface and in orbit studying all sorts of things about Mars, most of which are related to a search for water.
It may surprise you, however, that the planet Mercury is one of the planets visited by the fewest spacecraft – two. In 1974 and 1975, Mariner 10 flew past Mercury three times and mapped almost half the planet’s surface. In 2011, Messenger went into orbit around the planet and completed mapping 100 percent of its surface. However, its data forced astronomers to rethink their theories of how the planet formed, its geography, and its surface features.
A third mission to Mercury was launched on October 19 and is currently on its seven year journey to the planet. Named BepiColumbo, the mission is a joint venture by the European Space Agency (ESA) and the Japanese Aerospace Exploration Agency (JAXA) and includes a carrier spacecraft and two orbiters. It is named after Giuseppe “Bepi” Columbo who was an Italian mathematician and engineer in the mid twentieth century who discovered important features of Mercury’s orbit.
The spacecraft is composed of the Mercury Transfer Module (MTM), which provides electrical power during the journey from Earth, and two orbiters, ESA’s Mercury Planet Orbiter (MPO) and JAXA’s Mercury Magnetospheric Orbiter (MMO). The orbiters will separate from the MTM just before the spacecraft reaches orbit around Mercury. They will then be put in separate orbits and begin collecting scientific data.
Scientists hope the mission will help them understand not only how the planet had formed but also provide important information about the solar system’s formation. Some of the mission’s objectives include: study the planet’s geology, interior structure, composition and craters; determine the origin of Mercury’s magnetic field; investigate polar deposits; and perform a test of Einstein’s theory of general relativity.
BepiColumbo will also be the first ESA interplanetary mission to use solar-electric propulsion. Used successfully by a number of NASA and JAXA missions in the past, the system uses electricity generated by the spacecraft’s solar panels to create xenon ions that are accelerated to extreme speeds by powerful magnetic fields. The ion stream is of low mass but high velocity and must deliver thrust over a long period of time.
Along with the new generation of giant telescopes and upcoming missions to planets and asteroids, projects such as BepiColumbo will continue to give us a better understanding of what’s up in the sky.
This month in history:
Nov. 9: Carl Sagan born. – 1934
Nov. 12: Great Leonid Meteor Shower – 1833
Nov. 16: Interstellar message broadcast from Arecibo radio telescope – 1974
Nov. 19: Second lunar landing made by Apollo 12 – 1969
Nov. 27: First photograph of a meteor shower – 1885
Nov. 30: Fragment of 10-pound meteorite strikes and bruises Alabama woman, Elizabeth Hodges-1954
