Technology is needed to provide real-time assessment and evaluation of hematological parameters during prolong space flights and planetary missions. A key hematological parameter is the monitoring and measurement of emboli in the brain especially during Extra-Vehicular Activity (EVA) on planetary surfaces as well as orbital flights. A non-invasive, compact Transcranial Doppler (TCD) measurement device will provide monitoring of flight crew blood physiology during extended duration missions and deliver this data to onboard flight surgeons. To address this need, GeneXpress Informatics (GXI) and Leonid Bunegin and Dr. Claudia S. Miller of the University of Texas Health Science Center (UTHSC) at San Antonio proposes to develop a non-invasive, portable TCD sonogram based diagnostic system for real-time monitoring and detection of cerebral artery air embolisms. The detection system uses intensity audio signals and Fast Fourier Transform (FFT) analysis to detect and locate the TCD audio signals of air bubbles in the middle cerebral artery (MCA). In Phase I, GXI proposes to develop and demonstrate the non-invasive use TCD measurements for the determination of air emboli. In Phase II, GXI will proceed to a prototype development which will include construction and fabrication of a handheld field portable frequency-domain TCD measurement system.