Issue 40 Unmanned Systems Technology October/November 2021 ANYbotics ANYmal D l AI systems focus l Aquatic Drones Phoenix 5 l Space vehicles insight l Sky Eye Rapier X-25 l FlyingBasket FB3 l GCS focus l AUVSI Xponential 2021

54 Insight | Space vehicles therefore a smaller landing zone, often splashing down into the ocean, incurring far higher recovery infrastructure costs. This form of re-entry means the uncrewed craft and its thermal protection system can be reused 15 times, potentially more. As it can land safely on commercially certified runways it can be trusted to ferry sensitive cargo back to Earth, such as scientific test machinery or samples that could be damaged during a rocket-based return. As well as being able to dock with the ISS, the Dream Chaser can be equipped with sensors or mechanical payloads for other LEO missions, such as remote sensing, satellite servicing, orbital scientific research or manufacturing or, again, removing space junk. More recently, Sierra Nevada Corporation completed a 2-year mission with its Demonstration and Science Experiments (DSX) craft, the largest unmanned system ever launched into orbit. It was launched in June 2019, and carried 13 scientific research payloads for studying the radiation environment of medium-Earth orbit (MEO) as well as the effects of its very low frequency radio waves on man-made waves, spacecraft electronics, hull materials and more. The DSX was a 600 kg craft, powered by two 30 Ah lithium-ion batteries that were recharged by a single, fixed, three- panel solar array made from triple- junction GaAs cells. Its structure consisted of a 180 kg avionics bus containing the comms, power, thermal management, navigation and data systems that were mounted to a 240 kg connector ring interface. It also featured a 180 kg payload module, opposite the avionics bus, carrying the research payloads. From these experiments, the US Department of Defense will derive lessons on how to design spacecraft that can survive the space ‘weather’ of MEO. From this orbital level, satellites can provide the Earth with persistent space-based high-speed satellite comms, less expensive GPS navigation, and mapping and reconnaissance services, among other commercial and civil operations. Asteroids It should not be forgotten that not all threats to the Earth and its space missions are man-made. Improvements in astronomy sensors and techniques are raising awareness of the number of asteroids continually passing through the Solar System, particularly those that could hit the planet. There are no real solutions in place yet to prevent these impacts. Given the catastrophic nature of this type of event though, NASA is working on one such solution, which is currently under development as the Double Asteroid Redirection Test (DART) mission. DART will be the first demonstration of the kinetic impactor technique for changing the motion of an asteroid. It involves sending one or more large, high-speed unmanned spacecraft in the way of an asteroid approaching the Earth. It is hoped the resulting collision would then deflect the asteroid and redirect it away from the Earth’s orbital path. The mission will target the binary near- Earth asteroid Didymos, which consists of a 780 m-wide main asteroid and a 160 m-wide ‘moonlet’. DART will aim to autonomously steer itself into the moonlet at roughly 6.6 kph. Its approach will be informed using a sensor called DRACO (Didymos Reconnaissance & Asteroid Camera for OpNav), which is based on the LORRI (LOng-Range Reconnaissance Imager) instrument that was developed for the New Horizons mission and was used to photograph the surface and satellites of Pluto in 2015. October/November 2021 | Unmanned Systems Technology Sierra Nevada’s Dream Chaser spaceplane is expected to be reuseable for 15 or more missions, such as uncrewed cargo deliveries to the ISS (NASA photo courtesy of Sierra Nevada Corporation) The DART mission will use the kinetic impactor technique to change the motion of asteroids and will target the binary near-Earth Didymos body