Deployable booms have been used since the very first spacecraft was put in orbit. Indeed launcher fairings constraints demand the foldability of elongated structures.
Deployable booms form the building blocks of many large space apertures, from solar sails to large antenna reflectors to large structures assembled in orbit (like the ISS). In addition they represent an alternative to the concept of “formation flying” (e.g. Darwin, or ESA's XEUS studies).
And indeed, for the International X-Ray Observatory mission study, an innovative application of the deployable boom concept has been conceived.
The International X-ray Observatory (IXO) is a Large-class mission candidate within ESA Cosmic Vision 2015-2025 program, being studied in a cooperative way by ESA, NASA and JAXA. Its main feature of interest for this website is its need to extend the telescope structure from about eight meters, as configured inside the launcher fairing, up to (at least) 20 meters (to achieve required operational focal length).
A unique extension system, based on three articulated arms, provided with motorised hinges and end of deployment locking system, has been conceived and preliminary designed during an ESA CDF study (ref. CDF Study Report IXO Telescope - ESA Concurrent Design Facility - CDF-86(A) April 2009, credits for the idea and preliminary design to Mr Lucio Scolamiero (ESA TEC-MSM).
This innovative deployment architecture has been considered during the above-mentioned CDF study, providing superior advantages compared to more conventional telescopic or deployable truss masts.
This architecture has also been selected, with slightly different detailed designs, by the two European industrial consortia, led by EADS Astrium (UK) and Thales Alenia Space(F), performing the ESA IXO assessment studies.
Another interesting feature of the presented deployment architecture consists of the possibility of increasing the focal length to more than 30 m (which would be highly desirable for the scientific community), by duplicating in a kind of 'double stack' concept. Deployment would be operated in a sequential fashion with an intermediate structural ring to facilitate stowed configuration and decouple the two deployment sequences both functionally and structurally.
Double stack configuration for extended focal length (up to 30m).
It is important to note that the building blocks of such a deployable system would be long thin-walled CFRP booms and motorised hinges, which are well known components for a number of different applications. Indeed at ESA the pre-qualification of long articulated/motorised CFRP booms has already been performed (in the frame of a large reflector development activity:
J. Santiago-Prowald , “Large Deployable Antenna Mechanical Concepts”, CalTech Large Space Apertures Worksop, Pasadena (USA), 10-11 Nov 2008).
The main outcomes of the articulated boom developments are shown here - below:
Left: Motorised hinge coupled to portion of deployable CFRP boom - Credit: RUAG (CH).
Right: Multiple boom Hold Down Release Mechanism - Credit: MAGNA (A)
In order to provide mathematical models to Guidance Navigation and Control (GNC) specialists (TEC-ECN) in ESA, the IXO multibody model has been slightly modified. First of all, system sensors (accelerometers, gyros,…), actuators (reaction wheels, thrusters,…) and additional output (lateral displacement of the instrument modules with regard to the service one, focal length,… ) have been included.
Last update: 7 May 2014