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In the mid 1990s two space VLBI missions, VSOP (Japan) and \mbox{RADIOASTRON} (Russia), are due to be launched. Significant contributions to these missions are being provided by NASA and NRAO. Operating in conjunction with ground-based VLBI networks, such as the VLBA, these missions will be able to provide high resolution images or models of several different classes of astronomical objects, most notably the cores of AGN. \mbox{RADIOASTRON} will be in a 28-hour orbit with an apogee height of 80,000 km whereas VSOP will be in a 6-hour orbit with an apogee height of 20,000 km. The principle scientific goal of the \mbox{RADIOASTRON} mission is to search for high brightness temperatures, while VSOP will primarily focus on high resolution imaging. At the maximum observing frequency of 22 GHz, the resolution with \mbox{RADIOASTRON} will be 30 $\mu$as compared to 75 $\mu$as with VSOP. The announcements of opportunity (AOs) to propose for these missions are expected to be released in late 1993. This paper describes these missions, the US contributions, and how US scientists can propose to use these missions.
