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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.

The sun has "flipped upside down", with its north and south poles reversed to reach the midpoint of Solar Cycle 24, Nasa has said. Now, the magnetic fields will once again started moving in opposite directions to begin the completion of the 22 year long process which will culminate in the poles switching once again."A reversal of the sun's magnetic field is, literally, a big event," said Nasa’s Dr. Tony Phillips."The domain of the sun's magnetic influence (also known as the 'heliosphere') extends billions of kilometers beyond Pluto. Changes to the field's polarity ripple all the way out to the Voyager probes, on the doorstep of interstellar space."

The researchers suspect they've reached a region of the solar-interstellar boundary that nobody had predicted. In this area, the magnetic field lines of the Sun link up with those of the interstellar field. Scientists are calling this linkage a "highway" for particles to travel along. It lets solar wind particles escape more readily, causing the drop in their intensity. And it opens the door for low-energy cosmic rays to slip in to our Solar System, which is why Voyager 1 is seeing so many of them. According the researchers at the press conference that announced these results, most steady-state models of the Solar System failed to predict anything like this. A few models did have a feature like this, but it was only a transient one that appeared at certain times of the solar cycle.

"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.