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October/November 2017 | Unmanned Systems Technology 44 Insight | Unmanned space vehicles robot that can return samples to Earth. The maiden launch of the technology, known as the MX-1E, is scheduled for the end of 2017 or early 2018 on a rocket from Rocket Lab USA. The rocket has a range of payloads from the International Lunar Observatory Association, INFN National Laboratories of Frascati and the University of Maryland, Celestis Lunar Memorial Spaceflight and a rover for the XPrize. The Harvest Moon expedition in 2020 will use the more advanced MX9-3 design to provide the first commercial sample return mission, which also begins the business phase of lunar resource prospecting. The lunar samples brought back will be the only privately owned Moon materials on Earth, and will be used to benefit science as well as commercial purposes, says Moon Express. Like Moon Express, Interorbital also plans to send an autonomous system to the Moon for mining. This will be based around the autonomous Robotic Interplanetary Prospector Excavator and Retriever (Ripper). It is designed to land on the Moon or elsewhere in the Solar System, select surface samples and then excavate and retrieve them for return to Earth. Only a small quantity of lunar material, around 1.8 kg, will be brought back by the Ripper craft, and Interorbital is offering this for $7500 per gram. Fully fuelled, the lunar Ripper weighs 403 kg and will be launched on a Neptune N36M rocket, currently under development at Interorbital Systems. This has 36 propulsion modules that will place the Ripper on a lunar-direct trajectory, achieving lunar escape velocity without going into Earth orbit and then, three-and-a-half days later, allow the Ripper to land on the Moon without going into lunar orbit. The craft will spend several hours on the surface of the Moon collecting and storing samples before the return stage is triggered. This will launch the re-entry capsule on an Earth-direct trajectory until it reaches our atmosphere and re- enters via parachute, touching down in an unspecified but unpopulated area. The first stage will stay on the Moon, taking photographs and sending them back to Earth. However, with all the delays in developing the existing rocket systems, the likelihood of a Ripper launch is several years away. Another company, Deep Space Industries (DSI), is developing technologies to mine asteroids and return the minerals to Earth. It has already developed water-based propulsion units for small satellites, and is now working with the University of Tennessee under NASA’s Innovative Advanced Concepts programme to develop an aerobrake for the heavily loaded returning craft. Current braking methods use a lot of propellant to slow down a craft enough for a LEO. The NASA grant will look at how to build an aerobrake system from the regolith (or soil) collected from the mining operations using microwave sintering. The aerobrake would then act as a large heat shield that would allow the autonomous spacecraft to pass through Earth’s atmosphere, creating enough drag to slow down the payload without using propellant. “Using aerobrakes instead of propellant will expand the number of asteroids where water and other supplies can be affordably delivered to markets in Earth orbit by 30 to 100 times,” says Dr John Lewis at DSI. One asteroid, Psyche, is of particular interest to the space miners. It is one of the largest asteroids orbiting the Sun between Mars and Jupiter, it has a nickel- iron core, and it is also the name of a NASA mission to explore it. The Psyche spacecraft is targeted for launch in summer 2022, the plan being to travel to the asteroid using solar- electric (low-thrust) propulsion, arriving in 2026. The autonomous craft will spend 21 months investigating the asteroid, which measures 279 x 232 x 189 km and weighs roughly 2.72 x 10 19 kg, or nearly 30,000 trillion tonnes. A key technology advance for the project is to use laser-based comms links rather than radio, to provide ten to 100 times the bandwidth for the same mass and power consumption as radio systems. This will require much tighter control to align the near-infrared laser system with the receiver back on Earth, and the technology is being developed by the Deep Space Optical Communication The autonomous X-37B built by Boeing has spent more than two years continuously in orbit and is set to take off for a longer mission later in 2017 (Courtesy of US Air Force)