Comet chaser ‘Rosetta’ will have close rendezvous with Earth next week

November 14th, 2007 - 10:20 am ICT by admin  

The latest Earth ’swing-by’ for Rosetta would take the spacecraft on the right track and would also help it save fuel later on.

Swing-bys like these make use of the gravitational attraction of planets to modify a spacecraft’s trajectory and to gain the orbital energy needed to reach the final target.

The last time Rosetta experienced Earth swing-by was on March 4 2005. Later in February this year, it made its closest approach to Mars, to use its gravity.

On November 13, Rosetta is expected to speed past at 45000 km/h relative to Earth, and would be 5301 km above the Pacific Ocean near Chile.

This will be followed by the spacecraft’s third and last swing-by, using Earth’s gravity, on November 13, 2009.

While the first swing-by was needed to slow the spacecraft down and head back towards the inner solar system, the second Earth swing by would help Rosetta gain enough energy to reach the outer Solar System through the asteroid belt, and observe asteroid Steins, one of its scientific targets in its 10-year long sojourn to the universe.

The increased energy from this Earth swing-by will also help Rosetta cross the asteroid belt for a second time, observe Lutetia (its second target asteroid) and finally rendezvous with comet 67/P Churyumov-Gerasimenko. The rendezvous will take place about 4 astronomical units or 600 million km from the Sun in 2014.

The latest Earth swing-by is considered to be critical, according to scientists at the ESA and it would be under unfavourable solar illumination and thus temperature conditions.

The criticality has led to availability of only very limited slots for the instruments to be used safely.

Despite this, a few experiments both on the orbiter and the Philae lander will be activated for calibration, scientific measurements and imaging.

Rosetta will first point to Earth to make observations of the atmosphere and the magnetosphere, including a search for shooting stars from space. It will take image of urban regions in Asia, Africa and Europe and then point to the Moon and obtain spectra of the illuminated Moon. Flying away after closest approach, Rosetta will take image of the Earth-Moon system from a distance. (ANI)

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