72 Insight | Space vehicles Juice measures 16.8 x 27.1 x 13.7 m and has a dry mass of 2420 kg. Within that mass are 10 scientific instruments, including a laser altimeter, a magnetometer, a spectrometer for visible and IR imaging, a sub-millimetre wave instrument, and a radio and plasma wave instrument. As of September this year, Juice had travelled 370 million km, and is expected to complete its research in 2031. Meanwhile, NASA’s Juno spacecraft is already orbiting around Jupiter, having been launched in 2011 to research the planet’s composition, magnetic field, gravitational field and polar magnetosphere. The satellite is also looking for signs of how Jupiter was first formed, including measuring its mass distribution, looking for indicators of a rocky core, studying the amount of water in the deep atmosphere, and researching its winds, which can reach speeds up to 620 kph. Juno has a cylindrical body of 4.6 m diameter and 20.1 m length. Included in its payload is a microwave radiometer with six antennas that can penetrate Jupiter’s clouds to a depth of around 550 km to measure its atmosphere for the presence of ammonia, water (and hence oxygen and hydrogen) and temperature, at various altitudes. Summary Juice and Juno are notable among exploration satellites as they are among the first to visit the outer planets without using radioisotope thermoelectric generators – essentially nuclear batteries. Their powertrains instead make use of newer solar technologies. Juno in particular features the three largest solar panel wings ever deployed on a planetary uncrewed spacecraft, setting a precedent for future innovations in interplanetary power. Amid all these advances in small satellite technologies, crewed spacecraft such as autonomous Lunar transport rovers and SpaceX’s Starship continue to be developed, with the latter making a widely televised (and uncrewed) test launch in April this year. That launch did not make its tentatively planned splashdown in the Pacific Ocean after its intended journey through the atmosphere and into orbit, instead ending prematurely in a remotely forced termination about 4 minutes after launching. However, it was still the most powerful rocket stage ever launched, and gathered invaluable data needed for launching larger spacecraft in the future. A primary cause of the failure stemmed from three of the rocket’s engines being disabled during the launch sequence, with several more failing in mid-flight. However, given the range of successful powertrain technologies available for autonomous space vehicles, missions can continue to be launched as often as possible. That can only add to our understanding of the conditions in outer space for when we follow them. October/November 2023 | Uncrewed Systems Technology NASA’s Juno spacecraft being moved to environmental testing (Courtesy of NASA, JPL-Caltech & LMSS)
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