Portable Gas Analyser Tests Satellite Launch System

Europe's leading space technology company Astrium, has employed a sophisticated portable FTIR gas analyser as part of a test programme for satellite launch systems. The analyser, a 'Gasmet DX4030', was supplied by instrumentation specialist Quantitech (UK).

Astrium Propulsion Test & Launch Services Manager, Greg Richardson, says: "Many of the satellites that we design, build and launch are worth millions of Euros, so our test methods have to be extremely rigorous.

"The DX4030 was chosen because of its ability to provide highly accurate results for almost any gas. However, its intuitive software, compact size and portability were significant considerations because we use the technology at a number of our locations around the world."

One of the tests that are performed on the propulsion systems is to check the integrity of the chambers that contain rocket fuel. To achieve this, the tanks are filled with a simulant (often isopropyl alcohol and demineralised water) and exposed to launch simulation conditions - pressure, heat, vibration etc. The simulant is then removed and the DX4030 is used to check for contamination or leaks.

The DX4030 was first utilised in the testing of the LISA Pathfinder; a project for which Astrium was selected by the European Space Agency to build and launch a spacecraft that will be packed with radical instrumentation and technology to pave the way for LISA (Laser Interferometer Space Antenna), the world's first space-based gravity wave detector which will open a new window on the Universe by measuring gravitational waves generated by exotic objects such as collapsing binary star systems and massive black holes. In doing so, this project will be able to test a phenomenon predicted by Einstein’s General Theory of Relativity in 1916.

The analyser has also been used in testing the Gaia satellite which will conduct a census of a thousand million stars in our Galaxy, monitoring each of its target stars about 70 times over a five-year period. Gaia will precisely chart their positions, distances, movements, and changes in brightness. It is expected to discover hundreds of thousands of new celestial objects, such as extra-solar planets and failed stars called brown dwarfs. Gaia should also observe hundreds of thousands of asteroids within our own solar system.

The DX4030 employs FTIR gas detection technology to obtain infrared spectra by first collecting an ‘interferogram’ of a sample signal with an interferometer, which measures all infrared frequencies simultaneously to produce a spectrum. This means that data is collected for the required parameters in addition to spectra for almost all others.

Sample identification is possible because chemical functional groups absorb light at specific frequencies. As a result, the DX4030 can measure any gas, with the exception of noble (or inert) gases, homonuclear diatomic gases (e.g., N2, Cl2, H2, F2, etc) and H2S (detection limit too high).

Commenting on the work at Astrium, Quantitech's Dr Andrew Hobson said: "This has to be one of the more unusual applications for the DX4030. It is more commonly used for chemical spill, security and forensic investigations, and for occupational health, anaesthetic gas monitoring and research. The same technology is also employed to monitor industrial processes and gaseous emissions. However, Astrium's work clearly demonstrates the flexibility of the device and we are delighted to have been involved."