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45 the MS-09 to the ISS. Variations in signal strength from the different transmitters allowed the docking computers to determine relative position, attitude and rate of approach. Electrical power on the MS-09 is supplied via two solar arrays and battery packs. A KTDU-80 integrated propulsion system from KB KhimMash uses an S5.80 as its main engine to provide up to 300 kgf of thrust, NIIMash DPO-B thrusters for docking and undocking, and DPO-M thrusters from the same company for attitude control. Two tanks of fuel (dinitrogen tetroxide and unsymmetrical dimethylhydrazine), two tanks of water and two of oxygen are installed on board, some of the remaining contents of which are transferred to the ISS by means of connecting lines in the docking ring or manually by crew. At a future date, the craft will use some remaining fuel to detach and deorbit the Pirs docking section of the station, which will be replaced by the Nauka multipurpose laboratory module, after which both structures will be allowed to burn up in the Earth’s atmosphere. On the American side of the station, the summer of this year saw SpaceX achieve its 15th commercial resupply services mission to the ISS with a 3000 kg unmanned Dragon spacecraft (which is being tested for manned operations) that was launched using a Falcon 9 rocket, also from SpaceX. The shipment carried about 2700 kg of nutritional and scientific provisions, including an AI robot called Cimon designed by DLR, the German space agency, to assist astronaut Alexander Gerst with experiments. Orbital commerce Japan’s PD Aerospace is developing a series of unmanned commercial spaceplanes to begin testing by 2019, in anticipation of a manned flight in 2023. The smallest of the planned craft, the PDAS-X04, will be 5 m long and carry a 50 kg payload. It is designed largely for rapid observation of high-impact concerns such as potentially damaging weather formations or large-scale disaster zones, from a height of 10 km. A second craft, the PDAS-X07, will be 12 m long and carry a 100 kg payload limit to a maximum altitude of 110 km, for surveys and experiments under microgravity conditions. Lastly, the PDAS-X08, which has an as yet undetermined length, is planned to carry as much as 6000 kg of payload, also up to 110 km. That will enable it to deploy systems aimed at working with asteroids, the ISS and orbital satellites. Central to the success of PD Aerospace’s vehicles is the development of a patented pulse detonation engine, which can switch between rocket and jet modes to conduct a single-stage flight into orbit. That has allowed the designers to do away with a complex and heavy combination of boosters, rockets and fuel tanks to have to fly into space. The engine incorporates an air intake port, a combustion chamber and tailpipe arranged in a continuous, single-flow path. As well as drawing air in, the conical air inlet section also houses a fuel tank and injects fuel into the combustion chamber. The fuel and air are combined, ignited and consumed in this chamber, then expelled from the tailpipe to provide the kinetic energy for thrust – in jet mode. The rocket mode is designed for use at altitudes at which the air density is insufficient to enable fuel combustion for the resulting jet-mode thrust. At this stage the engine uses a servo-actuated pore closure mechanism to seal the intake, and an oxidiser tank begins injecting oxygen into the combustion chamber. That, combined with the fuel tank’s input, enables the intermittent pulse detonations for propulsion. Elsewhere in the industry, other propulsion systems are being produced for other kinds of spacecraft in different parts of the Earth’s orbit. For example, French start-up ThrustMe is developing a new electric propulsion solution principally for small satellites, although it can be scaled up for larger orbital craft to reduce the overall production cost of commercial orbital systems. ThrustMe’s system operates in a similar way to typical ion thrusters, but with a few key differences. Most ion thrusters rely on a neutraliser to supply electrons into the positive ion beam that is generated to provide thrust, in order to prevent beam stalling and charging of the spacecraft. That can be an expensive component, however, as well as challenging to scale down for Space systems | Insight Unmanned Systems Technology | October/November 2018 Team Hakuto’s rover is to be combined with iSpace’s lander to conduct cost-effective surveys of the Moon (Courtesy of iSpace)