1：Experimental Design and Method Selection:

The experiment involves designing and developing a balloon-borne VLBI station with a Cassegrain antenna, dual circular K-band receivers, frequency standard clock, VLBI data recorders, and attitude control systems. The methodology includes using VLBI techniques to form baselines with ground stations, simulating uv-coverage, and conducting ground-based tests for validation.

2：Sample Selection and Data Sources:

The primary target is the artificial signal from the geostationary satellite IPSTAR (THAICOM-4) at 19.6-20.2 GHz, with secondary targets including astronomical objects like 3C 454.3 or 3C 84. Ground-based VLBI stations include Mizusawa 10m, Takahagi 32m, Kashima 34m, Usuda 10m, and Osaka Prefecture University 1.8m telescope.

3：6-2 GHz, with secondary targets including astronomical objects like 3C 3 or 3C Ground-based VLBI stations include Mizusawa 10m, Takahagi 32m, Kashima 34m, Usuda 10m, and Osaka Prefecture University 8m telescope. List of Experimental Equipment and Materials:

3. List of Experimental Equipment and Materials: Equipment includes a 1.5m diameter antenna, LNAs (e.g., Weinreb's LNA, MITEQ LNA), OCXO frequency standard, VLBI samplers (ADS3000+, K5/VSSP32), pressurized vessels (PVS, PVM, PVL), GPS receivers, gyroscopes, accelerometers, reaction wheels, and lithium-ion batteries. Materials include aluminum for mirrors and structures, polystyrene foam for insulation, and iron powder for ballast.

4：5m diameter antenna, LNAs (e.g., Weinreb's LNA, MITEQ LNA), OCXO frequency standard, VLBI samplers (ADS3000+, K5/VSSP32), pressurized vessels (PVS, PVM, PVL), GPS receivers, gyroscopes, accelerometers, reaction wheels, and lithium-ion batteries. Materials include aluminum for mirrors and structures, polystyrene foam for insulation, and iron powder for ballast. Experimental Procedures and Operational Workflow:

4. Experimental Procedures and Operational Workflow: The balloon is launched from Taiki Aerospace Research Field, ascends to 26 km altitude, and drifts for observations. Procedures include pointing calibration using raster scans, data recording at up to 8.192 Gbps, and post-flight correlation processing. Attitude control is managed via reaction wheels and elevation actuators.

5：192 Gbps, and post-flight correlation processing. Attitude control is managed via reaction wheels and elevation actuators. Data Analysis Methods:

5. Data Analysis Methods: Data analysis involves fringe search and fitting processes after observation, using correlation techniques to handle phase stability issues. Power detection and spectrometry software are used for single-telescope observations, and simulations (e.g., with ARIS) assess uv-coverage improvements.