This program (which is quite short, only 5 days) does not aim at all at the direct observation of planets that harbor intelligent life outside our solar system and is similar to the SETI program in the US. The optical telescope that the Japanese use is quite small (2 m.), and has absolutely no capacity to discern any extrasolar terrestrial, or Earth-like planet. From what I know, even though their radio telescope is 10 m., it too is quite incapable of obtaining images of, or even detecting extrasolar terrestrial planets.
It is thought that only terrestrial planets can harbor life because bigger planets would crush life as we know it, that is why it seems that only they matter for finding intelligence.
So, instead of trying to find such planets or intelligent life on them by directly observing them, researchers use the radio telescope to capture radio (not visible light, or optical) frequencies originating from certain areas in space. Doing this, they do not construct an image. Instead, they scan the frequencies for patterns that cannot be explained by non-living processes. Having captured the data, they can scan it for data much later.
With such inadequate equipment, it seems the Japanese researchers only use the optical telescope after they spot a suspicious pattern in the data. Then they can use both the optical and the radio telescope to obtain images of the area that the patterns originated from so that they can study it in more detail. It is worth noting that while radio telescopes can be used to obtain images, they have much worse resolution in comparison with equivalent optical ones, but are used because radio data can provide valuable information.
In fact, any current Earth-based telescope, even the currently largest 10-11 m. optical telescope mirrors are incapable of discerning extrasolar terrestrial planets, because the atmosphere limits the resolution of any optical telescope. That is why even the relatively small 2.5 m. Hubble telescope, which is unfortunately going to be de-orbited soon, has a much superior resolution to even the biggest Earth telescopes. However, it still pays off to build much large telescopes on Earth than we currently have, because even though the resolution from Earth hits a limit, those very large telescopes are capable of discerning much dimmer, fainter objects. There is work underway to build optical telescopes with a single 100+ metre mirror. I've also read about techniques to compensate for the undesired effects (such as turbulence) of the atmosphere, and it is possible that one day those new very huge telescopes are going to allow the detection of extrasolar terrestrial planets right here from Earth.
To get most of the function of a large telescope (optical, radio, etc.) without building one, it is possible to use a technique called interferometry, to combine two or more telescopes separated by a certain distance, and obtain the effect of having a single telescope with a mirror area equalling not only the combined mirror area of the separate telescopes, but also considerably larger one. However, an interferometer is still an inferior substitute, so it still makes sense to build the large telescope.
Our current Holy Grail of search for extraterrestrial planets that can harbor intelligence are projects making use of an array of smaller telescopes in an interferometer configuration, using ingenious techniques called nulling or nullifying interferometry, also known under the name of interferometric coronography, to cancel out the glare of stars around which terrestrial planets may be orbiting (I remember reading how one of the caveats in it is the usage of filters in the form of a cat eye). While cancelling out glare is not an absolute requirement for the detection of Jupiter-sized planets for example, and many of them have already been successfully found in other solar systems, light from the smaller Earth-like planets is overtaken by their star(s) (or sun/s/), and that does not allow us to discern those planets. Similarly, the gravitation effects of an Earth-like planet on its surroundings is negligible and we do not seem to be able to use it as a discerning factor, either. So all in all, only such interferometers, or their large equivalent telescope, and their situation in space, seems the only thing for the foreseeable future that is going to allow us to discover Earth-like planets -- unless there is a breakthrough in Earth-based telescopes, but even if there is, it is probably going to occur after we have already found many Earth-like planets through the usage of space interferometers.
The
ESA Project Darwin is an infrared space interferometer will makes use of the nulling technique and 6 telescopes, currently slated for launch in 2014.
The NASA equivalent is the
Terrestrial Planet Finder, slated for launch in 2012-2015, with 4 telescopes (but larger than Darwin's) but still undecided (will decide this year or next) on the exact design of the telescopes to use. The page says the Terrestrial Planet Finder is going to be able to detect Earth-like planets 50 light years away.
Probably, as Bomohwkl said, aliens do not communicate with radio waves, because the latter travel at the speed of light, and the distances between stars are too great to allow for efficient communication. In the Meanwell audio interviews, of which there are excerpts on Meanwell's site, Michel Desmarquet states this is not the way to communicate and that is why the people of Mu built their pyramids -- to have instant communication at the speed of thought.
