Saturday, February 24, 2007

Rosetta over Mars

Rosetta Swing-by 250 km over Martian surface
The Rosetta swing-by of Mars is the second of four gravity assist manoeuvres that are required to place Rosetta on course for its final destination.

Timeline: Mars swingby at 36 000 km per hour
The closest approach of the swing-by will take place at 01:54 UT, 25 February 2007, when the spacecraft will pass 250 km above the surface of Mars.

Rosetta's NAVCAM captured the black & white image of Mars at 19:32 CET from a distance of 237 477 km.

In the upper left it is possible to identify the Elysium Mons region centred at approximately 147° East. Mars' equator runs horizontally approximately across the middle of the image.

Just northeast of the 'double finger' feature, visible in the lower half of the disk, is Aeolis Mensae mountain, located at 140° East.

The small double feature visible in the upper-right quadrant is the Cerberus Fossae ridge.

Spectacular view approaching Mars Animations from ESA
Beautiful new images of Mars - OSIRIS UPDATE 25/02/07
Stunning view of Rosetta skimming past Mars - 25/02/07
Rosetta successfully swings-by Mars – next target: Earth
A gravitational slingshot is the use of the gravity of a planet to alter the path and speed of an interplanetary spacecraft. It is a commonly used manoeuvre for visiting the outer planets, which would otherwise be prohibitively expensive, if not impossible, to reach with current technologies. It is also known as a "gravity assist".

A slingshot manoeuvre around a planet changes a spacecraft's velocity relative to the Sun, even though it preserves the spacecraft's speed relative to the planet.

Consider a spacecraft on a trajectory that will take it close to a planet.

As the spacecraft approaches the planet, the planet's gravity will pull on the spacecraft, speeding it up. After passing the planet, the gravity will continue pulling on the spacecraft, slowing it down. The net effect on the speed is zero, although the direction may have changed in the process. (Image Cassini trajectory)

New Engine Helps Satellites Blast Off With Less Fuel
The Georgia Tech engine operates with an efficient ion propulsion system. Xenon (a noble gas) atoms are injected into the discharge chamber. The atoms are ionized, (electrons are stripped from their outer shell), which forms xenon ions.

The light electrons are constrained by the magnetic field while the heavy ions are accelerated out into space by an electric field, propelling the satellite to high speeds.

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