platforms (100 kg) to give a noble compromise between increased power delivery and attributed cost  (development and recurring). Static deployable arrays vary from the more complex tracking arrays in as much as the array is deployed from the body of the craft once and to a fixed position which does not change throughout life. This means that the sun angle is improved over the traditional fixed bodymounted panels, but not as optimized as a tracking array which actively follows the sun. The cost and complexity of a tracking array was not deemed necessary for SST-100 platforms since the needed power could be achieved via the simpler static-deployable arrays (Figure 2).  SSTL operates uniquely compared to traditional space companies as it makes extensive use of  commercial off the shelf (COTS), which gives the benefit that technology is typically advanced ahead of space-rated hardware. SSTL’s matrix structure and use of COTS components both allow for rapid development schedules with the manufacture and test of Qualification Models (QM) taking place early in the project cycle. SSTL invests a focused effort and duration on design and analysis, and spends significant time on thorough test campaigns in order to gain confidence in module developments and fix problems quickly along the way. In this way, SSTL can build and test Flight Models ready for satellite  integration quickly from ‘blank-sheet’ design specifications. The deployable static solar arrays and  attributed mechanisms demonstrate this approach to spacecraft engineering. EXACTVIEW-1 / DMC-UK2B  baseline platform, with single deployable solar arrayDMC-CFESAT platform with 4  identical deployable solar arraysEXACTVIEW-1 HDRM static panel  and deployable panel subassembly on sidewall deployment jig Figure 2. SSTL-100 platforms wi th deployable solar panels Deployable Static Solar Arrays Overview Existing SSTL platforms utilize static deployable arrays, with each deployable array having 2 springdriven hinges, damping interface brackets, and a HDRM. The complete system (hinges, brackets and HDRM) is termed the Hold Down Release System (HDRS). The original HDRS philosophy was to form a  generic set of units that could cope with a variety of panel sizes and launch loads to keep future platform  non-recurring engineering costs low. The HDRM unit constrains the array against the panel craft during  launch, and once actuated, releases the panel. During launch, the HDRM therefore limits the movement of the panel both laterally and axially and thus share the loads with the hinges to prevent their bearings being overloaded. The HDRM incorporates push-off springs to physically release the array from the craft,  however, full array deployment is only possible because of the hinges. Once released, the sprung-hinges  drive the panel through deployment and a sprung latch locks into position to prevent over travel and recoil  upon reaching full deployment.  SSTL has utilized the HDRS successfully on several SSTL-100 platform missions, as captured in Figure  3. Other requirements of the platform types mean that the panel size and position of the HDRM has  varied across the missions. Depending upon the position of the HDRM, size of panel, and launcher choice, some platforms also incorporate array snubbers to further control panel displacements during launch.  422