Radio Astronomy

It is surprising that many people, radio astronomy not be heard for ET phone home. SETI (the Search for Extraterrestrial Intelligence), a relatively small part of radio astronomy. It seems that the public perception of radio astronomy conjures up images of astronomers in tight jeans wear headphones to see some weak signal buried in the galactic noise. If we have a brief reality check, we find that radio astronomy is similar to optical astronomy telescopes in this (instruments that detect, image and enlarge) are used to observe the cosmos.

The difference is that while optical telescopes present images that are familiar in composition (ie the images on frequencies that we can see directly). Radio telescopes to observe the cosmos much lower frequencies. Most of us have seen the spectacular images acquired by the Hubble Space Telescope. To be sure these images not only give us an insight into the wonders of the universe, but move us in spirit by a sense of awe. Unfortunately, the primary sensory cells input device for us humans (eyes) is very limited "bandwidth" (the range of electromagnetic frequencies, or "colors" to which it is sensitive), and although the images move us, they do not give up their secrets easily . As a result, much of what happens in the universe is hidden from our view.

To put it simply, every color is a different frequency, and most of the color, with the range of the cosmos is painted is invisible to our eyes. It only makes sense, our sensitivity, the instrumentation, on the other frequencies of the electromagnetic spectrum. The radio telescope is one of those instruments. It allows us to monitor and the image of the universe at frequencies below our visual capabilities, which shows much of what is going on in the universe. Because certain frequencies pass easily through annoying dust and gas clouds, we can now study until now blocked objects from our point of view. Also, because certain gases, molecules and materials in the universe either emit or absorb light to radio frequencies, these structures can be viewed by the radio telescope. This feature not only allows the viewer to the image of these objects, but also allows the observers to collect much more information such as composition, speed, temperature and mass.

The range of frequencies, the spectrum is immense, so that the diversity and the types of instruments that make up radio telescopes is diverse in terms of design, size and configuration. Lower frequency (10 MHz - 100 MHz (wavelengths of 30 meters to 3 meters)) instruments are usually arrays of antennas similar to "TV antennas or are stationary reflectors of gigantic proportions with moveable nodes some are over 30 Meters high and 500 meters wide. At higher frequencies (100 MHz to 1 GHz (wavelengths of 3 meters to 30 cm)) very large parabolic or spherical reflectors used as the large ball "Dish" in Arecibo, Puerto Rico. For frequencies of (1 GHz to 10 GHz (wavelength of 30 cm to 30 mm)) medium to large parabolic reflectors used 5 to 90 meters in diameter.

These reflectors are fully articulated and can observe any object simply by pointing the reflector. For frequencies above 10 GHz (wavelengths of 30 mm to .3 mm) high precision necessary parabolic reflectors are typically 3 to 20 meters in diameter. The reflectors are more like mirrors and are thermally stable and supported by complex structures, as the surface curvature is held to demanding standards. The surface of these tolerances reflectors are held to plus or minus one hundredth of a millimeter radio telescopes in the millimeter to Sub-millimeter wavelength range. Each type of instrument opens a new set of "Colors" for the astronomers can the universe.

Optical telescopes and gives these clear images because the wavelength of visible light is so small in relation to the diameter of the focus device (mirror or lens). Radio waves with wavelengths of enormous comparison: Do not focus on the clean "images" rather they tend to deal with each other, since the focus device (reflector) is tiny compared to the wavelength. For the construction of a 10 mm wavelength radio telescope with imaging capabilities of a small 4-inch optical telescope will have a reflector, about 2 km (over 6000 meters) in diameter, clearly this enormous size is impractical. It may at first sight that radio astronomy would be doomed to low detail rather boring observations and data collection tasks. The fact that light and radio waves tend to each other is a technique known as interferometry. Simply put, this allows two or more antennas brought to justice far apart or in arrays (such as the VLA "Very Large Array in New Mexico) to function as if they were a large antenna (Aperture Synthesis). The interference between the signals from each of the receiving antennas, if timing corrections are introduced, allows for image reconstruction with Fourier transformations. We can look at the resolution of a 2 km antenna, by using multiple antennas 2 km apart and correlation of data. With this technique, it is possible to obtain milliarcsecond resolution. A milliarcsecond is about the equivalent of seeing one quarter in New York from Los Angeles!

With the advent of DSP (Digital Signal Processing), faster and smaller computers, and the introduction of super implementation of amplifiers radio astronomy has made progress to a fraction neck pace. New arrays of antennas are currently being developed and built. Some contain more than a thousand individual antennas all in harmony, what resolutions, the rival optical telescopes. Other arrays cover a hectare and a process extends over a square kilometre as "Phased Array type imaging capabilities never seen before. The future of radio astronomy looks brighter than ever before.