  The Shanghai Astronomical Observatory (SHAO) of the Chinese Academy of
Sciences (CAS) is studying a space VLBI (Very Long Baseline Interferometer)
program. The ultimate objective of the program is to image the immediate
vicinity of the supermassive black holes (SMBHs) in the hearts of galaxies with
a space-based VLBI array working at sub-millimeter wavelengths and to gain
ultrahigh angular resolution. To achieve this ambitious goal, the mission plan
is divided into three stages. The first phase of the program is called Space
Millimeter-wavelength VLBI Array (SMVA) consisting of two satellites, each
carrying a 10-m diameter radio telescope into elliptical orbits with an apogee
height of 60000 km and a perigee height of 1200 km. The VLBI telescopes in
space will work at three frequency bands, 43, 22 and 8 GHz. The 43- and 22-GHz
bands will be equipped with cryogenic receivers. The space telescopes,
observing together with ground-based radio telescopes, enable the highest
angular resolution of 20 micro-arcsecond ($\mu$as) at 43 GHz. The SMVA is
expected to conduct a broad range of high-resolution observational research,
e.g. imaging the shadow (dark region) of the supermassive black hole in the
heart of the galaxy M87 for the first time, studying the kinematics of water
megamasers surrounding the SMBHs, and exploring the power source of active
galactic nuclei. Pre-research funding has been granted by the CAS in October
2012, to support scientific and technical feasibility studies. These studies
also include the manufacturing of a prototype of the deployable 10-m
space-based telescope and a 22-GHz receiver. Here we report on the latest
progress of the SMVA project.
