Posted to News on 1st May 2013, 20:08
Ensuring satellite reliability with vibration testing
RAL Space provides world-leading space research and technology development for customers around the world. They offer space test and ground-based facilities where they design and build instruments, analyse and process data. They also operate ground-station facilities, and lead conceptual studies for future missions.
Working with space and ground-based groups around the world, they are now the largest space science department in Europe, and have been involved in over 150 missions in recent years, including the groundbreaking SOHO and STEREO solar missions, the Earth Remote-Sensing missions ERS-1, ERS-2 and ENVISAT, and solar system missions such as the Rosetta cometary lander, the Cassini/Huygens mission to Saturn and its moon Titan, and continuing work on MIRI (Mid-Infrared Instrument) for the James Webb Space Telescope (JWST).
The JWST is due to be launched in 2018 as the scientific successor to the venerable Hubble Space Telescope. The JWST's 10-year mission is to find and study the first luminous objects, the assembly of galaxies, the birth of stars, the birth of planetary systems, and the origins of life.
JWST might appear serene, but that fragile mass of technology must endure being stowed as the 6-tonne payload of a launch vehicle. The satellite and its components (such as MIRI) must endure the noise and subsequent vibration of the ~145dB interaction between the rocket engines and launch-pad environment, the jarring transonic climb phase, pyroshock as stages separate, turbulent boundary layer excitation and more.
In 2010, RAL Space decided to replace their existing LDS V954 Vibration System with a more powerful and flexible one to meet its increased testing needs. Their older V954 had served them well, but with increasing payload masses and more severe tests required, RAL Space needed to improve their capabilities.
This new system provides the increased capacity necessary for future test programmes, and is based on the LDS V8 electro-dynamic shaker, with the ability to operate in horizontal or vertical orientation. An integral slip table measuring 1200mm × 1200mm is coupled to the shaker as necessary, allowing large objects to be mounted securely. The slip table has nine high-pressure hydrostatic bearings arranged on a 3 × 3 matrix. This configuration provides for maximum overturning restraint for devices under test with a high centre of gravity. They also have an additional interchangeable 750mm × 750mm slip plate for high acceleration testing.
The amplifier - a 56kVA class "D' switching amplifier - is forced-air cooled and incorporates an integral DC field power supply which is required for the shaker field coils. The shaker is also forced-air cooled and relies on a fixed blower device to pass air through the shaker for efficient cooling during operation.
The full RAL Space article is available to read on Brel & Kjr's website at www.bksv.com
