Back from the Dead

I was reading about SETI and UFOs and such last night on Wikipedia. Specifically I read about "Active SETI" and the idea of sending messages out for other civilisations to find. It got me thinking about radio astronomy in general. Radio Astronomy is not just about looking for ET. Most commonly it is used to examine the radio spectrum given off by stars and other extra solar objects.

There are many terrestrial based radio telescopes currently in use. Some have exclusion zones where no man made radio transmissions are aloud to be produced. This means that if you happen to live near the telescope you cannot use a cordless phone, bluetooth, cell phone, wifi, or many of the other wireless technologies now available to consumers. However, this exclusion zone is important since many of these signals or weak and require highly sensitive receiving equipment. This equipment can easily be overwhelmed by local noise. Unfortunately for Radio Astronomers Earth is now a very noisy planet RF wise. Wireless Technology is a staple of 21st century life. Almost Everyone in the Industrialised World owns some sort of device that acts as a deliberate transmitter. Most modern communications would be near impossible without wireless linking of some sort. These wireless advances have helped civilisation progress to its modern form and life would be very much different without them. But an unfortunate consequence is that it also makes our planet a noisy one.

This leaves two solutions for Radio Astronomy, either remove the noise or move somewhere that doesn't have noise. For obvious reasons removing the noise is unacceptable. But finding suitable terrestrial locations free of artificial radio signals is getting increasingly difficult. I feel that there should be a radio telescope constructed in space. As a side benefit to escaping interference, stellar signals would not be refracted, or otherwise affected by the atmosphere. For this there are a few options:

1. Build an orbital telescope

The idea is to build a telescope similar to the Hubble but instead of being optical it is a radio telescope. The design would be a lot more simple than Hubble since in basics it would just be a fancy communications satellite, with a receiving antenna pointing away from Earth. From Orbit the telescope would escape much or the RF noise present on the surface. Since the receiving antenna would be pointing away from the planet it would not be in an optimum position to receiving interference from space bound terrestrial signals. The main body of the telescope could be construction to provide further shielding. This option is relativity cheap and routine. Depending on the orbit astronomers should have access to a large variety of objects to observe. As has been demonstrated by Hubble repair and upgrades to this telescope are also possible.

2. Build a Lunar telescope

The construction of a telescope on the "dark side" of the moon is another appealing option. An object on the far side of the moon should be shielded from man-made signals by the moon itself. Since the moon has no atmosphere there is also no chance of atmospheric interference. Another advantage is the size of a telescope, or an array of them is less limited. While currently manned missions to build and repair such a facility are difficult, there are several manned missions to the moon planned in the near future. Regardless robotics has progress (thanks in part to other space exploration programs) to a point where a robot, or remote controlled device could be sent to do this. Since the moon orbits the Earth once a month, astronomers still have vast choices available. There are two major problems to a Lunar telescope. First off since the moon is blocking signals from Earth, it will also block transmission to Earth, meaning that data collected by thee telescope would be difficult to send to Earth for analysis. This could be overcome either by an relay satellite in orbit of the moon, or by some sort of network to send the data to the near side, where it could be transmitted to Earth. Either option would be expensive to initially setup but once built could be used for further Lunar projects. The second problem is powering the telescope. Since it is on the far side on the moon it is also on the "dark side" so there is no way for solar energy to be used directly. Options include a nuclear reaction, which would be an excellent choice, except sending the fuel to the moon is highly dangerous. Another one I can think of is building a solar array on the near side and using a transmission line to send the power to the telescope. The solar array and power line could be constructed along side the communications beacon and data network.

3. Construction on other bodies in our solar system.
The advantage are similar to those listed above. There is the additional benefit of alternate points of view, which would also help optical telescopes. However, a system on the Martian surface would be susceptible to atmospheric interference and damage from dust storms. Realistically given the cost I do not see this option being used in this century.

Personally I like the Lunar option but given the initial cost of setup I do not see it being used in the near future. It could however, be implemented within this century, if a Lunar colony is constructed then option 2 is certainly possible. Option one is the most probable in the near future. The relative cost of launching such a telescope is fairly inexpensive next to other space and terrestrial projects. With many organisations launching commercial satellites on a routine basis I can easily foresee either a government, or private radio telescope satellite being done. In fact as the amount of RF noise on the Terran Surface continues to increase, this option may be necessary in order to continue radio astronomy at all.