NASA’s Dawn spacecraft approaches dwarf planet Ceres

NASA’s Dawn spacecraft is currently 400,000 miles from the largest object in the asteroid belt between Mars and Jupiter and approaching at 450 miles per hour. When the spacecraft arrives, it will provide our first good look at the object.

The Dawn spacecraft launched in 2007 on a mission to explore the two largest objects in the asteroid belt. Dawn spent 14 months orbiting the first of these, the protoplanet Vesta, in 2011 and 2012. When it goes into orbit around Ceres in March, 2015 it will mark the first time that a spacecraft has ever orbited two targets.

The Texas sized dwarf planet Ceres has an average diameter of 590 miles. It was discovered by by Giuseppe Piazzi in January of 1801 and was originally believed to be a planet. However, despite the fact that people have known about Ceres for a long time, not very much is known about it.

“Ceres is almost a complete mystery to us. Ceres, unlike Vesta, has no meteorites linked to it to help reveal its secrets. All we can predict with confidence is that we will be surprised,” said Christopher Russell, principal investigator for the Dawn mission, based at the University of California, Los Angeles in a statement.

One thing researchers know is that Vesta and Ceres are very different objects. Researchers believe that Ceres formed much later than Vesta. In the early solar system, radioactive material was more abundant, which made things considerably warmer. As a result Vesta has very little water, while Ceres may have subsurface oceans.

In January of 2014 water vapor emissions were detected coming from Ceres. This came as something of a surprise because objects in the asteroid belt generally do not emit vapor. That type of phenomenon is usually reserved for comets which warm and cool as they travel through space.

Currently Ceres is believed to have a rocky core and a icy mantle made of frozen water and hydrated minerals. Currently researchers believe that the area between the core and the mantle to be liquid water. That is one of the answers that NASA hopes Dawn will provide.

The Dawn spacecraft carries three scientific instruments, a visible and infrared mapping spectrometer, a gamma ray and neutron spectrometer and a visible camera. Additionally the crafts navigation data provides information on the gravity field of the objects it approaches. That gravitational data provides researchers with information on the internal structures of the objects.

By using the same, exact instruments to read both asteroid belt objects, NASA hopes to obtain detailed information about the objects as well as the differences between them.

Dawn uses an ion propulsion engine in which an electrical charge applied to xenon gas and charged metal grids is used to accelerate xenon particles through the thruster. As the particles exit they push down the thruster, accelerating the spacecraft. Using this system, Dawn has shattered the record with 5 years of accumulated thrust time since 2007.

“Orbiting both Vesta and Ceres would be truly impossible with conventional propulsion. Thanks to ion propulsion, we’re about to make history as the first spaceship ever to orbit two unexplored alien worlds,” said Marc Rayman, Dawn’s chief engineer and mission director, based at NASA’s Jet Propulsion Laboratory in Pasadena, California.