Space Electronics
FPGAs span the extremes of space engineering
© NASA
Ken O'Neill looks at how non-volatile FPGA technologies are meeting the needs of an increasingly diverse space industry
O
nce the sole preserve of the military, an increasing number of organisations are discovering the appeal of space. Even schools are finding they can develop and operate a significant piece of an orbiting satellite.
The UK Space Agency is backing the launch of the country's first picosatellite, marking a milestone in the development of the country’s space policy: opening up the satellite market to a much wider user base that extends from commercial organisations to schools and colleges. The picosatellite has taken just a couple of years to move from concept to near launch-readiness. That is much faster than
18 September 2012
most satellite projects but it is a reflection of the diversity of requirements that now exists in the market. Speed and flexibility are the
cornerstones of development in picosatellites. Even the shape of the UK's first official 'cubesat' is a testament to an approach that is all about using commercially available technology. The original concept for the cubesat came initially from Stanford University, with researchers there working with colleagues at Cal Poly to develop the hardware concepts.
Cubesats have a standard footprint: a 10cm square. This makes it possible to put
Components in Electronics
an enclosure around a stack of PC/104 embedded computer and peripheral boards. Originally, the concept was for a cube-shaped satellite, hence the name. But the first launch needed a bigger chassis. So the researchers formalised a hardware design based on 1U, 2U and 3U shapes, measuring up to 30cm tall. The systems are packed into a Poly-PicoSatellite Orbital Deployer (P-POD) that is then mounted in the nose cone of the launch vehicle. Once the launcher has reached its target height, the doors open on each of the P- PODs and springs force the cubesats out. The standardisation makes it much easier to book a launch as the user simply has to find a launcher that will carry at least one P-POD. As a result, cubesat users do not have to plan for a specific launch and have the flexibility to miss a particular launch window if their hardware is not ready - they can simply book for a later slot. This is in stark contrast to the critical timing needed for conventional satellite launches.
The flexibility of launching and the use of low-cost standard hardware makes the loss of an individual satellite much easier to bear. If a cubesat fails, it is relatively straightforward to replicate its hardware and book the next available launch. If a large commercial satellite fails, the costs are far greater.
Failures and problems A 1996 review conducted by NASA of 100 failures and problems on its spacecraft found one-third were caused by ionising radiation leading to single event upsets (SEUs) - state changes in logic or memory - or permanent degradations in performance.
The danger to electronics from ionising radiation is due to the way high-energy particles lose energy when they hit dense matter. They ionise the medium through which they pass, leaving behind a wake of electron-hole pairs. These electron-hole pairs can change the state of a memory
www.cieonline.co.uk
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