| Active Space Technologies | | Thermal Analysis and Simulation of instruments, satellites, and launchers. Development, calibration, and qualification of instrumentation and optoelectronics. |
| Aerospace Engineering | | Builds spacecraft buses and instruments and provides a variety of aerospace products, integrates and tests systems and handles mission control. Also designs and manufactures specialty spaceflight hardware. |
| Aerospazio Tecnologie | | Space Simulation and spacecraft. Electric rocket Propulsion. Electromagnetic compatibility Plasma diagnostics. Large Vacuum Test Research and development of electric propulsion technology Testing of electric thrusters EMI/EMC testing under vacuum |
| Alenia Spazio | | Company active telecommunications, remote sensing, orbital infrastructures and scientific satellites. |
| Andrews Space & Technology | | Aerospace company that specializes in enterprise and technology development for the emerging space markets. |
| ANSER | | Consulting and research organization. |
| Astrium Space | | A European space company owned 50% by Aerospatiale Matra and BAE Systems, and 50% by DaimlerChrysler Aerospace. |
| AstroKeys Inc. | | Develops technologies for small spacecraft; Distributes SINDA/G software; Provides On-Orbit Servicing expertise, consulting and contract services to space. |
| AUSPACE LIMITED | | Auspace Limited is an aerospace and defence engineering company serving the needs of the science, commercial and defence communities in space, airborne and ground systems. |
| Ball Aerospace & Technologies Corp. | | Provides systems engineering services, and designs and manufactures complete space systems; spacecraft; space and Earth science instruments and sensors; cryogenic subsystems; antenna systems and video products for commercial and governmental customers. |
| Bigelow Aerospace | | Goal is making habitable space stations affordable for corporate communities. |
| Broad Reach Engineering | | Spacecraft Avionics, Star Trackers, GPS Receivers, EPS, C&DH, Flight Software, EGSE, Systems Engineering, Low Mass/Power Avionics, LEO-to-GEO, Satellite Electronics, Mass Storage, Command & Telemetry Hardware |
| Callisto Space | | Small company working in Satellite Telecommunications Engineering. | |
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