  Neutrinos with energies in the PeV to EeV range produce upgoing extensive air
showers when they interact underground close enough to the surface of the
Earth. We study the possibility for detection of such showers with a system of
very wide field-of-view imaging atmospheric Cherenkov telescopes, named CHANT
for CHerenkov from Astrophysical Neutrinos Telescope, pointing down to a strip
below the Earth's horizon from space. We find that CHANT provides sufficient
sensitivity for the study of the astrophysical neutrino flux in a wide energy
range, from 10 PeV to 10 EeV. A space-based CHANT system can discover and study
in detail the cosmogenic neutrino flux originating from interactions of
ultra-high-energy cosmic rays in the intergalactic medium.
