The advantage of radio astronomy appears when the light is stopped by the presence of clouds of dust that hide certain regions of the sky. This material allows radio-frequency radiation and longer wavelength. But depending on the spectrum studied, part of the radiation is scattered or absorbed by the material. The celestial bodies also produce disruptive thermal radiation, not to mention the interstellar emissions (the young stars), the black body radiation at 2.7 K. not to mention the industrial activity of the “global village” and especially the satellites.
As we see below, all these “parasites” that we will come back to about SETI reduce our astronomical windows. In the best cases, by making use of interferometric bases and computer correction algorithms (DSP), radio astronomy makes it possible to probe the universe with a higher resolution than optical instruments. However, it is surpassed by the X-ray detectors of space observatories.
The future of radioastronomy is in space. If interferometric optical astronomy is still in its infancy on Mount Paranal in Chile, this is already routine for radio waves.
As mentioned, following the first successful trials of the US-Japan VSOP project whose goal was to test the space-to-Earth interferometry technique, the next step will be the installation in orbit of one or more radio telescopes. For example, NASA’s Advanced Radio Interferometry between Space and Earth (ARISE) project is a VLBI interferometer using orbital and terrestrial radio telescopes. Its resolution should reach 0.01 mas or 10 microseconds of arc, 50 times higher than the best resolution of Chilean VLTs! If it is born, it will benefit from an inflatable parabolic antenna 25 m in diameter and will weigh only 1700 kg. Proposed in 1998, ARISE has not yet found funding.