The Russian Academy of Sciences and Federal Space Agency, together with the participation of many international organizations, worked toward the launch of the RadioAstron orbiting space observatory with its onboard 10-m reflector radio telescope from the Baikonur cosmodrome on July 18, 2011. Together with some of the largest ground-based radio telescopes and a set of stations for tracking, collecting, and reducing the data obtained, this space radio telescope forms a multi-antenna groundspace radio interferometer with extremely long baselines, making it possible for the first time to study various objects in the Universe with angular resolutions a million times better than is possible with the human eye. The project is targeted at systematic studies of compact radio-emitting sources and their dynamics. Objects to be studied include supermassive black holes, accretion disks, and relativistic jets in active galactic nuclei, stellar-mass black holes, neutron stars and hypothetical quark stars, regions of formation of stars and planetary systems in our and other galaxies, interplanetary and interstellar plasma, and the gravitational field of the Earth. The results of ground-based and inflight tests of the space radio telescope carried out in both autonomous and ground-space interferometric regimes are reported. The derived characteristics are in agreement with the main requirements of the project. The astrophysical science program has begun.

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A new mechanism of nonlinear absorption of intense femtosecond laser radiation in air in the intensity range I = 10(11)-10(12) W/cm(2) when the ionization is not important yet is experimentally observed and investigated. This absorption is much greater than for nanosecond pulses. A model of the nonlinear absorption based on the rotational excitation of molecules by linearly polarized ultrashort pulses through the interaction of an induced dipole moment with an electric field is developed. The observed nonlinear absorption of intense femtosecond laser radiation can play an important role in the process of propagation of such radiation in the atmosphere.

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The vibrational-translational relaxation time of the ν3 state of ozone was deduced from the phase shift of the photoacoustic detector signal relative to the amplitude-modulated radiation of the CO2 laser used for excitation of O3. A special photoacoustic cell with a third electrode is used to eliminate an instrumentation phase shift caused by inertia of the microphone membrane. A three-level kinetic model of O3 is presented and used to fit the experimental and calculated phase shifts to determine the vibrational relaxation rate coefficients for pure O3 and binary mixtures of O3 with O2, N2, and noble gases He, Ne, Ar, Kr, and Xe. These results are presented and compared with experimental data obtained for O3, O3–O2, and O3–N2 by fluorescence and double resonance techniques. Experimental data for ν3 state relaxation in binary mixtures with all noble atoms have been obtained for the first time. These new results are compared with the simplest model of interaction. Thus we obtain a very good agreement for the decrease of constants with the increase of the colliding partner mass.

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