Ultra low noise bolometers are required for space - based astronomical observations. Detection of faint sources needs wide-band continuum observation using direct detectors (bolometers) not restricted by the quantum noise of indirect heterodyne receivers. We are developing a novel concept of the normal metal hot-electron microbolometer with capacitive coupling of an absorber to the antenna by tunnel junctions. The tunnel junctions used for high frequency coupling give simultaneously perfect thermal isolation of hot electrons in the small volume of the absorber. The same tunnel junctions are used for temperature measurements and electron cooling. The latest function is especially important in presence of a real background power load. The bolometer with tunnel junctions does not have frequency limitation in THz range due to high potential barrier of the tunnel junctions in contrast to the hot-electron microbolometer with Andreev mirrors limited by the superconducting gap. A SQUID can be used as a readout system in a voltage-biased mode. The bolometer has been fabricated and tested experimentally. Theoretical estimations and preliminary experiments shows that it is possible to realize the necessary sensitivity of 10^-18 W/Hz^1/2 with antenna-coupled nanobolometers at temperature 0.1 K. Two novel concepts of Superconducting Hot-Electron Bolometer and Cascade Quasiparticle Amplifier (CQA) are discussed. The CQA is an amplifier based on strong electron cooling of normal metal traps (or superconducting traps) and utilizing a cascade principle of amplification.