Monthly Archives: December 2014

Rosetta – Philae and the Comet

Rosetta_NAVCAM_comet_67P_20140919_mosaic_625A news that caught my attention recently was about the spacecraft Rosetta, and that it had landed a module, Philae, on a comet.

I thought it was special because-
As compared to planets which seem stable and calm, a comet in my mind is a racing ball of fire.
Also a planet is this large thing, and a comet is small.

So am I implying that landing a vessel on a planet is common, but its special if on a comet ?

Of course there is no basis for my idle perceptions.
Landing sites on the Moon and Mars are pin-pointed in advance, and well achieived too. A planet is this huge hurtling, spininng massive sphere – subject to great forces, and creator of its own.
Exploratory vessels have their trajectories defined for years in advance. Satellites have their orbits planned, monitored and corrected. Its all very amazing and hi-tech.

Am I implying now that a comet landing is also no great deal ? :)

I guess I still find the idea of a comet landing very fascinating, almost unreal.
Here a some more stunning facts:

  • The Rosetta spacecraft was launched in 2004 – 10 years ago.
  • The comet, 67P/Churyumov-Gerasimenko, is a big rock, about 4 kms in it longest dimension.
  • On its way to comet 67P, Rosetta passed through the main asteroid belt, and made the first European close encounter with several of these primitive objects.
  • Rosetta was the first spacecraft to fly close to Jupiter’s orbit using solar cells as its main power source.

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Acharya Sir Jagadish Chandra Bose

Archarya Sir Jagadish Chandra Bose is one of the leading luminaries of Indian Science.

Incidences from the life of this extrememly talented individual highlight his exemplary value J_C_Bosesystem, his humility and his grit and determination. For example, when he was faced with discrimation he declined his salary and continued to work for 3 years, his research conducted in trying circumstances with meagre resources, or his disinclination of filing patents for his inventions.

However in this small article we only aim to highlight 2 of his inspiring efforts.

 

Radio research and wireless signalling – including use of semi-conductor

Sir Bose’s research in microwave waves allowed him to generate waves in the millimetre level (about 5 mm wavelength).

The first remarkable aspect of Bose’s follow up microwave research was that he reduced the waves to the millimetre level (about 5 mm wavelength). He realised the disadvantages of long waves for studying their light-like properties.

During a demonstration at Town Hall of Kolkata in the 1890s, Bose ignited gunpowder and rang a bell at a distance using millimetre range wavelength microwaves.
He used waveguides, horn antennas, dielectric lenses, various polarisers and even semiconductors at frequencies as high as 60 GHz. Which is quite mind-boggling, given the time and circumstances.
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