BVEX
Balloon-borne VLBI Experiment
Stratospheric VLBI at 22 GHz
Working toward the first VLBI correlation between a balloon-borne telescope in the stratosphere and ground-based radio observatories.
Mission Overview
BVEX is a balloon-borne radio telescope designed to observe from the stratosphere, above 99% of Earth's atmosphere. Its goal is the first VLBI correlation between a balloon platform and a ground telescope.
Mission Status & Flight Data
August 2025 Launch
BVEX launched on 29 August 2025 from Timmins, Ontario, on the CNES and CSA STRATOS campaign. A leak in the balloon kept it from reaching float altitude, and the flight was terminated at 16.5 km, where pointing was not possible, so no VLBI data were taken. The backend and timing systems stayed powered through the ascent and returned housekeeping and thermal telemetry.
BVEX 2.0 Development
We are rebuilding the payload as BVEX 2.0, with changes drawn from the 2025 flight, for a 2027 reflight from Palmas, Brazil.
Mission Objectives Status
Principal Mission Goals
- Demonstrate sub-millimeter positional stability
- Achieve meter-level 3D position accuracy for VLBI correlation
- Characterize stratospheric phase stability at 22 GHz
- Generate interference fringes with ground-based telescopes
System Architecture
Interactive diagram showing the distributed computing architecture with real-time control systems operating across ground stations and balloon-borne flight computers.
Ground
Sagittarius
Ophiuchus
Click on any subsystem block to navigate to its detailed section below
System Components
The key systems that make VLBI from a balloon possible.
BCP - Sagittarius
Primary DevelopmentComplete C-based flight control software managing all subsystems on the Sagittarius flight computer, including the RFSoC spectrometer, VLBI backend, timing system, GPS, PR59, position tracking, and heater control. I developed the UDP client-server architecture enabling communication with the Ophiuchus flight computer and ground station command interface.
- Dual flight computer UDP communication protocol
- Ground station command interface with real-time telemetry
- Multi-layer safety systems with watchdog protection
RFSoC Backend System
Primary DevelopmentThe RFSoC 4x2 FPGA system implements multiple signal processing pipelines for spectroscopy and VLBI operations. I developed the complete FPGA control system, spectral analysis algorithms, and high-speed data acquisition.
- AMD-Xilinx XCZU48DR RFSoC Gen3 control
- 5 GSPS sampling with 14-bit to 2-bit requantization
- Coarse spectrometer (960 kHz bin resolution)
- Fine 120 kHz spectrometer for water line detection
- VLBI 100 GbE link for high-speed data packet capture
VLBI Data Storage
Primary DevelopmentHigh-speed data recording system handling continuous 100 Gbps data streams from the RFSoC. I developed the complete storage optimization algorithms, real-time recording system, and data integrity verification.
- 12 GB/s sustained write performance
- 16 TB storage capacity (6 hours at full rate)
- Automatic file rotation and redundant verification
Timing System
Primary DevelopmentThe timing chain that VLBI correlation depends on. I integrated the OCXO reference, the GPS receiver, and a time-interval counter (TICC) that measures the OCXO's drift against the GPS pulse-per-second, so timestamps can be corrected after the flight.
- 60 ps time-interval counter resolution
- 7×10⁻¹¹ Allan deviation at 1s
- Free-running OCXO, drift measured against GPS PPS
Housekeeping System
CollaborativeHealth monitoring across 84+ analog channels distributed through the payload, with LabJack integration and real-time telemetry. Built with Rafael Costa and Terry Yang.
- 20+ temperature sensors across all subsystems
- Real-time power monitoring (0.1A resolution)
- Environmental sensors and safety limits
Power Breakout Board (PBoB)
CollaborativeCritical power distribution system enabling remote operation of all BVEX subsystems. Developed collaboratively with Terry Yang, providing intelligent power management and monitoring with LabJack-based control and current sensing capabilities.
- 10 individually switched power channels (28V input)
- Remote power cycling capability via ground station
- Real-time current monitoring with shunt sense resistors
- Overcurrent protection and brownout detection
Position Tracking System
CollaborativeDistributed network of high-precision MEMS sensors characterizing mechanical vibrations and pointing stability. Developed in collaboration with Rafael Costa and Aarchi Shah for sub-millimeter position tracking.
- 3x ADXL355 accelerometers (±8g, 1000 Hz)
- 1x SPI single-axis gyroscope (1000 Hz)
- 1x 3-axis I2C gyroscope (1000 Hz)
- 20 μm RMS position resolution
Heater Control System
Direct ContributionDistributed heating system maintaining operational temperatures for critical components during passage through the -60°C tropopause. Developed control algorithms and integration with Rafael Costa.
- 5x Kapton heater circuits (20W each)
- PID temperature control with safety limits
- Solid-state relays with thermal protection
PR59 TEC Control System
Primary DevelopmentPrecision thermoelectric cooler (TEC) control system for pressure vessel thermal management. I developed the complete control electronics, feedback algorithms, and integration with the PBoB power system.
- Thermoelectric cooling control for pressure vessel
- Temperature feedback with ±0.1°C precision
- Integration with housekeeping telemetry
OCXO Timing Reference
Primary DevelopmentOven-controlled crystal oscillator providing the ultra-stable 10 MHz reference for VLBI operations. I designed the thermal control system, distribution amplifiers, and integration with the timing chain.
- 10 MHz ultra-stable reference (7×10⁻¹¹ Allan deviation)
- Oven temperature control (±0.01°C stability)
- Distribution to RFSoC and timing systems
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