Fri, 28. June 2013
Astro-Speaker Watch - June 2013
Guest Speaker at the Macarthur Astronomy Forum in June was Dr. Jeremy Bailey from the University of New South Wales, who discussed the exploits of Mariner 2 - the first successful space mission to visit another planet (in 1962).
Of the six principal instruments on board, the two radiometers (microwave and thermal) were the most significant.
The Mariner 2 instruments.
A radiometer is a device for measuring the radiant flux (power) of electromagnetic radiation. Generally, the term radiometer denotes an infrared radiation detector, yet it also includes detectors operating on any electromagnetic wavelength. (Wikipedia).
Black body temperature measurements at various wavelengths.
The spacecraft was launched on 27th August 1962 and despite the failure of some of its instruments along the way, it successfully flew past Venus on 14th December 1962 at a distance of 35,000 km. The radiometers determined that the high temperatures on Venus came from the surface, not the cloud cover; and this success led to the development of radiometers for many other purposes, including the detection of the Cosmic Microwave Background.
The magnetometer also determined that Venus lacks a strong magnetic field.
The Mariner 2 Spaceraft.
Since then, radiometers mounted in Earth orbiting satellites have tracked the rise in global temperatures since 1975 and have been used to improve modern long-range weather forecasting.
Weather forecasting and monitoring of global warming.
The Mariner 2 legacy is that it proved we could explore the solar system; it recognised the importance of the Greenhouse Effect; and it led to improved weather forecasting and climate monitoring techniques.
A great presentation from Dr. Bailey, about a pioneering space probe, which certainly had the attention of three MAS presidents:
Dr. Bailey answers questions, watched by current president, Chris Malikoff, sitting with two former presidents, John Rombi and Noel Sharpe.
As if the talk on its own were not interesting enough, arguably the most interesting part of the evening for many members was when Dr. Bailey took us outside afterwards and demonstrated his thermal and microwave radiometers.
By pointing his wide-field microwave radiometer at the outside sky he was able to demonstrate the existence of the Cosmic Microwave Background Radiation itself!
Now that was really cool:
2.72548±0.00057 deg K to be precise!
Dr. Bailey demonstrates a microwave radiometer outside after the meeting.
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