Radar and Measurement Technology

Atmospheric Re-entry Measurement

SPC has been involved in atmospheric re-entry measurements for both the NASA Space Shuttle and the CNES Ariane 5 launch programs.

Working with the French Space Agency (CNES) and Novespace of Bordeaux, France, SPC has developed the latest generation of its radar systems for observing atmospheric re-entry: the airborne Re-entry Measurement System (RMS).

The system employs both a VHF wide-beam radar, and a wide field-of-view high-resolution optical video camera. By operating at 50 MHz, the VHF radar is sensitive to both re-entry ionization and the ionospheric turbulence produced by a body passing through the Earth's ionosphere. These are key signature elements for detecting and analyzing the destruction of the re-entry body.

Plane on tarmacThe airborne RMS can be deployed anywhere in the world, and is capable of measurement observations at ranges in excess of 500 km.

Since 1999, the RMS system has been used to observe the re-entry of the Ariane 5 main cryogenic stage (EPC), providing CNES with detailed data on the re-entry process. By taking advantage of multi-path signals created by the airborne RMS's unique observation geometry, SPC is able to determine the EPC altitude without the use of complex and expensive tracking hardware.

Read a detailed discussion on the success of this program, or visit our Publications list.

Background

In 1990, SPC fielded three VHF radars in Hawaii to observe the re-entry and breakup of the NASA Space Shuttle (STS-31) external fuel tank. These systems consisted of dipole and co-linear antenna arrays, 50-kW transmitters, receivers, O-scopes, and analog tape recorders.

In 1999, SPC developed a more flexible, airborne version of the VHF system to measure the re-entry of the main cryogenic stage (EPC) of the CNES/Arianespace Ariane 5 rocket. In order to achieve the mobility necessary to observe reentries over the open ocean, SPC worked with the US Army Big Crow Program Office (BCPO) to incorporate the radar on a KC-135 aircraft. This new system used the same transmitters as the STS-31 system, but employed COTS-based multifunction I/O cards and PCs to provide pulse control, real-time data processing, and digital data collection. The PC-based radar control and real-time processing systems are described here.