Wednesday, August 06, 2014

Rosetta Meets Chury. . . the Comet

By Douglas V. Gibbs

"Europe's Rosetta is now the first spacecraft in history to rendezvous with a comet, a major highlight in exploring our origins. Discoveries can start," said Jean-Jacques Dordain, the European Space Agencies's Director General, in a statement.

The chase took a little over ten years, $1.75 billion, five loops around the Sun using the planetary gravity of Mars and Earth to help with a slingshot maneuver, and a reawakening of the probe after more than a two-year hibernation - which helped conserve power.  One mistake, and the project would be a loss.  Now, the probe's speed and trajectory is in alignment with that of the comet's.

The comet, 67P/Churyumov-Gerasimenko, known as "Chury" for short, is currently 405 million kilometers from Earth, about half way between the orbits of Jupiter and Mars, and the ESA's probe is right there with it, not on the surface, but traveling with the comet as the celestial body orbits the Sun. It only took 6.4 billion kilometers of carefully calculated travelling maneuvers to get it there.

Getting there is only the beginning.

The mission hopes what will follow will be a series of historic accomplishments. In November mission controllers are shooting to reach another "never done before" accomplishment by placing a robotic lander, Philae, on the surface.

Rosetta's travel plans are different than past fly-bys we have seen space agencies perform in recent space-exploration history.  Rosetta will travel alongside the comet for more than a year, mapping and measuring how the comet changes as it is blasted by the Sun's energy.

As the journey with Chury continues, scientists expect to learn more about the composition of comets, including the water content of the comet.  Some have speculated that comets may have brought water to the Earth long ago, or perhaps even brought some of the chemicals that make up the building blocks of life.  In ancient times, comets were always an anomaly, not necessarily obeying the orderly nature of planetary orbital mechanics that Isaac Newton had determined.

The real work is now upon Rosetta.  The probe is expected to map the surface of the comet, and establish a fact-finding mission that will hopefully learn more about Chury's gravitational pull. The data will not only be analyzed so that we may learn more about comets, but also so that the engineers can find a suitable landing site for Philae and continue to make the right adjustments to keep Rosetta in the right orbit with the comet.

It is understood that as comets approach the sun, any ice melts and is turned into an ionized gas tail. The dust produces a separate, curving tail.  This phenomenon is just one of the many characteristics of a comet that Rosetta scientists hope to be able to study, and learn about, from such a never before attained close proximity.  Other studies should be able to reveal what the comet nucleus looks like now, and when it gets closer to the sun.

Chury is known as a short-period comet, reappearing every six years as its orbit brings it close to the Sun. Halley's comet has a period of about 76 years and is not due to return close enough to Earth to be visible until 2061. Some comets take thousands of years to return to the Sun.

Chury's six year cycle, for the ESA, Rosetta, and humanity, has made it a once in a lifetime experience, and a learning opportunity never achieved before in the history of life on Earth.

The project is hoped to last until December of 2015.

-- Political Pistachio Conservative News and Commentary





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