Antenna petals from Russia's RadioAstron spaceborne radio telescope were tested in the 3m-diameter HBF3 thermal-vacuum chamber in the ESTEC Test Centre. RadioAstron's 10m-diameter dish will operate in conjunction with ground-based radio telescopes to perform high-resolution Very Long Baseline Interferometry radio mapping of active galaxies, black holes neutron stars and other exotic objects. [Image Date: 1998/09] [98.09.008-012]