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A $30 million Google-backed competition to land a spacecraft on the moon may be about to be scooped. China’s Chang’e 3 probe successfully put itself into lunar orbit on Friday in preparation for an attempted touchdown around Dec. 14.

The way we currently reach other worlds with our present technology — or any remote location in the Universe — involves three distinct stages:The initial launch, which overcomes the Earth’s gravitational binding energy and starts our spacecraft off with a reasonably large (on the order of a few km/s) velocity relative to the Earth’s motion around the Sun.On-board course corrections, where very small amounts of thrust accelerate the spacecraft to its optimal trajectory.And gravity assists, where we use the gravitational properties of other planets in orbit around the Sun to change our spacecraft’s velocity, either increasing or decreasing its speed with every encounter.It’s through the combination of these three actions that we can reach any location — if we’re patient and we plan properly — with only our current rocket technology.

The initial launch is a very hard part right now. It takes a tremendous amount of resources to overcome the Earth’s gravitational pull, to accelerate a significant amount of mass to the Earth’s escape velocity, and to raise it all the way up through the Earth’s atmosphere.

BANGALORE: India's Mars Orbiter Mission (MOM) will look to have a date with the Siding Spring comet, which will pass very close to the Red Planet on October 19, Isro chairman K Radhakrishnan said on Thursday.

Asked how Nasa could do reprogramming on its MAVEN spacecraft to study the comet, Radhakrishnan said: "MAVEN reached there before us and has completed the orbit around the Red Planet. I have received mails about what they are going to do, and we know what we should. But MOM has to ascertain its position. It will be known in 2-3 days."

"We hope to witness two atmospheres colliding," explains David Brain of the University of Colorado's Laboratory for Atmospheric and Space Physics (LASP).  "This is a once in a lifetime event!"

Everyone knows that planets have atmospheres.  Lesser known is that comets do, too.  The atmosphere of a comet, called its "coma," is made of gas and dust that spew out of the sun-warmed nucleus.  The atmosphere of a typical comet is wider than Jupiter.

The timing could scarcely be better.  Just last year, NASA launched a spacecraft named MAVEN to study the upper atmosphere of Mars, and it will be arriving in Sept. 2014 barely a month before the comet. MAVEN is on a mission to solve a longstanding mystery: What happened to the atmosphere of Mars?  Billions of years ago, Mars had a substantial atmosphere that blanketed the planet, keeping Mars warm and sustaining liquid water on its surface. Today, only a wispy shroud of CO2 remains, and the planet below is colder and dryer than any desert on Earth. Theories for this planetary catastrophe center on erosion of the atmosphere by solar wind.