| During last half a century, space science has revolutionised astronomy by opening up several hitherto inaccessible windows in the electromagnetic (EM) spectrum. Each new spectral window has produced unexpected major discoveries, and made it possible to understand comprehensively the new physical processes in celestial sources by observing their emissions in the entire spectrum.
Sky radio emission below 10 MHz is inaccessible from the Earth's surface due to the absorption and scattering in the Earth’s ionosphere. To explore this region of the electromagnetic spectrum, a space-based radio telescope would be required. The far side of the Moon is shielded from the Earth's radio interferences and offers a very large and stable platform for a radio observatory. In the very first lunar missions, a very low frequency radio interferometer can be implemented with a lander and a rover to get a degree-level angular resolution.
I will present my design and study on a Moon-based radio interferometer. I will show even with two antennas reasonable sky images can be obtained after few lunar days. In the design, an active tripole antenna has been developed as the prototype antenna for the future lunar mission. I will discuss the estimation of directions of arrival (DOA) of different radio sources with a tripole antenna. To verify the performance, the tripole antenna was installed in LOFAR core station CS011 to do the sky observations; I will introduce some observation results, showing its performance and ability of DOA estimation. AS finding the origin of cosmic ray is one of the potential scientific objects, I will discuss the detection of cosmic ray with the lunar radio interferometer.