Radio Astronomers Win Spectra

General_Corto writes: "The BBC is currently running an article about the latest global allocations of EM spectrum for radio astronomy. The entire range from 75GHz to 275Ghz has been given to them alone, which should ensure that all their readings are free from earth-based interference. Apparently, "there is more energy at millimeter and sub-millimeter wavelengths washing through the Universe than there is of light or any other kind of radiation." Hopefully all those little green men out there use cellphones in that frequency range." You may also be interested in the home pages of the International Telecommunications Union and the International Astronomical Union.

Comments

Why Radio astronomers need protected wavelengths

[tjwhaynes]

IWARA - I Was A Radio Astronomer!

For all of you unadventurous souls who seem to believe that giving specific wavebands to astronomy is a waste (and yes I am aware that the article merely points out that the current astronomy wavelengths are going to remain protected) I think I ought to explain why radio astronomy can't function without this protection. Here's a little demonstration:

Put your pen on the floor - a bic biro will do. Lift it above your head. You have just used up more energy than the entire collection of radio telescopes on the surface of the earth has ever collected from the sky. The base unit of energy for most radio astronomers is the Jansky - often written Jy - which is equivalent to 10^{-26} W m^{-2}. Most of the radio objects in the sky have intensities of less than 1 Jy. A few reach up into kJy.

Now consider a mobile phone. These stick out a few watts of energy. So they are about 26 orders of magnitude more powerful than the average radio source appears in the sky.

Any terrestrial transmitter dwarfs the emissions we get from the sky by design. For communications, the radio emissions are background noise to be squashed under the signal. If we are to further our understanding of physics, and radio astronomy provides a unique testing crucible to test the theories against, we need protected bandwidth.

Cheers,

Toby Haynes

It isn't all about LGM

[HiyaPower]

One of the prime uses for radio astronomy is earth weather. Water vapor has a spectrl line at 22.235 GHz and 117 GHz (and up). Oxygen has a complex of lines around 50 GHz. By picking your frequencies carefully and being clever with your processing, you can tell the vertical temperature distribution of the atmosphere as well as water content. Also, the microwave emission quality of the ocean varies with wind speed. Again you can tell something about it. Snow pack depth is also something that you can monitor in the spectral region. Since most of the earth is covered by water, and infra-red does not penetrate cloud tops well, remote sensing by microwaves has help immensely with the ability to forcast weather in the past 20 years. All we need is for some commercial interests to blow the spectrum out of the water in order to broadcast a bazzilion channels of the latest WWF tag team.

Wrong, Wrong, Wrong

[Detritus]

Read the article:

WRC 2000 has protected for science all the frequencies between 71 and 275 gigahertz that radio astronomers currently use. They have added more than 90 GHz of spectrum to the 44 GHz already set aside for their use in this frequency range.

Radio astronomers have been given some new allocations, but not the entire 71-275 GHz frequency range. Allocating all of that range to radio astronomy would be a disaster for research, experimentation and other users of the RF spectrum.

Evolution of Life

[Digitalia]

Through the years, nature has developed two means of propagation: saturation and specification. While most fauna are specific in their intent, flora opt for the easier of the two. A dandelion does not release one seed into a SSW vector. It's species would have gone extinct long ago if it had. Instead, it releases a gross of seeds into the wind. Perhaps we need to do the same. Concentrating on radio alone will get us no where. We will go extinct before we meet an alien species. I am a proponent of sending out beacons. Launch a thousand small craft with a solar sails towards the most promising targets. On board is a cache of data on humanity, and a radio transmitter.

Continue to scan the skies with our antennas, but in a universe of so many stars, and so many planets, a proactive solution is the only one that will work.

One way glass?

[MikeFM]

Hrm.. if we have that whole range of easy to see signals blocked off so we can see any lil green men sending in that range I guess we're not sending anything out at that range. What if the lil green men decided that this was an optimal range to watch also so they aren't sending anything out either. We're each sitting behind a one-way mirror trying to see the other but evidently only seeing the blank reflection of our own window. :)