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Wake up, Rosetta!

The comet chaser Rosetta and the Royal Belgian Institute for Space Aeronomy

The comet chaser Rosetta has woken up from hibernation the 20th of January 2014. This was the start of the last phase of its 10-year journey to the comet 67P/Churyumov-Gerasimenko.

The Rosetta space mission of the European Space Agency (ESA) will for the first time study a comet up close during its journey around the Sun. The Royal Belgian Institute for Space Aeronomy (BISA) has helped to build the ROSINA (Rosetta Orbiter Spectrometer for Ion and Neutral Analysis) instrument on board of the satellite.


Because of their sudden appearance in the night sky, comets speak to the human imagination since time immemorial. A comet nucleus is composed of ice and dust and can be considered a "dirty snowball", a few kilometers in size.


Rosetta at comet
Image credits: ESA


As a comet approaches the Sun, it heats up. Progressively more ice from the comet nucleus will begin to evaporate. The gas and dust released in this way form the comet atmosphere. The comet tail (in fact there are two tails, the ion tail and the dust tail), which is visible from Earth, is created by the interaction of cometary gas and dust with the Sun.


Image credits: ESA


In May, Rosetta will start to orbit around the comet. The satellite will take pictures and make measurements of the comet atmosphere. The ROSINA instrument is designed specifically to determine the composition of the comet atmosphere. Ultraviolet sunlight causes all sorts of chemical reactions in the gas.


Rosetta Spacecraft
Image credits: ESA


BISA has developed a computer model that takes into account these reactions to determine the composition of the evaporating material on the comet nucleus surface based on the ROSINA measurements.

Rosetta carries a small lander named Philae, that will descend onto the comet nucleus in November. The results of the computer model can then be compared with the measurements of the lander. This will provide insights into the chemical and physical processes that occur in the comet atmosphere.

Why are astronomers so eager to examine a comet up close?

Comets are believed to be a kind of "fossils" dating back to the birth of the solar system, more than 4 billion years ago. Similar to the Rosetta stone, which allowed to decipher the hieroglyphs 200 years ago, it is hoped that the Rosetta mission will help to unravel the secrets of the origin of our solar system, and perhaps even shed light on the origin of life on Earth.

Comets might be the source of water on Earth and may possibly have brought necessary building blocks for life to Earth.


Further timing:

  • August 2014: Rosetta will arrive at 67P/Churyumov-Gerasimenko (orbit the nucleus)
  • November 2014: Probe "Philae" will land on the comet’s surface




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