The space cryogenic submillimeter telescope based on hot-electron microbolometers(Project Submillimetron)

Extremely sensitive detectors are necessary for deep full-sky survey of distant extragalactic sources in the submillimeter-wave region by the cryogenically cooled telescope at the International Space Station (project Submillimetron). Detection of faint sources needs wide-band continuum observation using direct detectors (bolometers) not restricted by the quantum noise of indirect heterodyne receivers. Theoretical considerations and experiments made with laboratory samples of detectors shows that it is possible to realize the necessary sensitivity of 10 -18 - 10 -19 W/Hz 1/2 with antenna-coupled microbolometers at temperature £ 0.1 K. Two types of bolometers are chosen as the most promising ones: normal metal hot-electron bolometer (NHEB ) with Andreev mirrors for thermal insulation between absorber and antenna, and NHEB-CC with tunnel junctions for thermal isolation and capacitive coupling of antenna to the absorber. Additional advantages of using such detectors as the base of the project are: high spatial resolution (no undersampling of horn-antenna bolometers), the possibility to operate on wide range of background loads, and direct possibility of polarization measurements.