The Nano-Satellite Processor Unit (NANOSATPRO) is a high-performance onboard computer (OBC) that is compatible with nano-satellite platforms for advanced space missions. It is a control unit that has high fault tolerance and processing power specifications for difficult space conditions. As a target, NANOSATPRO is designed to be operational in a low earth orbit (LEO) for at least two years. NANOSATPRO has an operating system running on an FPGA (soft processor-based) and supports the most commonly used interfaces (UART, RS485, CAN, SPI, I2C, etc.) in nanosatellite platforms. With its modular design, it easily adapts to the connection constraints of the target platform. Single Event Effects (SEE) protection is provided through the use of a Fault Tolerant (FT-LEON3) processor core, Triple Modular Redundancy (TMR) in FPGA, Error Detection and Correction (EDAC) in memory units, Watchdog on software, Latch-up Current Limiter (LCL) in power units.