# Issue No. 116

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# The Orbital Index

Issue No. 116 | May 12, 2021

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 ¶Starship survives to hop another day. SN15 flew and landed and failed to explode for the first time (and on the 60th anniversary of the first American in space, no less). Starship SN15 ascended through low lying cloud cover, performed a nominal climb to 10 km, then belly-flopped, and finally completed a successful two-Raptor soft landing—SN10’s hard landing was due to low thrust during its single-engine touchdown. A small methane fire at the base of the vehicle was again visible after landing, possibly due to a thermal protection blanket coming loose and catching fire. But, unlike SN10, the fire did not appear to be caused by structural damage and there was no unplanned return to flight. SN15 boasted many advances over previous Starship testbeds, including improvements to flight structures, plumbing, avionics software, and its Raptor engines. SN15 will likely fly again, and SN16 is nearing completion, with the possibility of rolling out to the pad in the next week (the most optimistic tank watchers are suggesting it might also fly this month). We’ll see what comes next. When the belly flop landing was first proposed, some felt it was incredibly unlikely that SpaceX would successfully complete a landing. And so, this landing represents a significant step forward for SpaceX, opens the door for an aggressive timeline to reaching orbit with Starship, and is a major milestone in their quest to build a Mars-capable transportation system.
 ¶News in brief. Brainchild of the late Paul Allen, Stratolaunch’s Roc aircraft, the largest plane in the world by wingspan, completed its second test flight—the new owners hope to use it as a launch platform for experimental hypersonic vehicles; Blue Origin confirmed July 20th as the launch date for their first crewed suborbital flight and would like you to pay a lot of money to join them (they still have yet to announce long term pricing); Unseenlabs raised €20M for RF geolocation of ships and Firefly Aerospace raised $75M to continue development of their Alpha smallsat launch vehicle and Blue Ghost lunar lander; the Parker Solar Probe broke its own record (again) as the fastest human-made object, moving at 147 km/s as it swung through perihelion 10.4 million km above the Sun—at this speed, about .05% the speed of light, it could circle the Earth in 4.5 minutes; fragments of China’s Long March 5B core stage landed in the ocean near the Maldives—China received much criticism and ultimately got lucky that its uncontrolled reentry didn’t occur over land, as in 2020 when a Long March 5B core stage scattered debris over Côte d’Ivoire; continuing Australia’s support of its nascent launch industry, Catherine Roberts will become the country’s first Space Commander; with the confirmation of NASA Administrator Senator Bill Nelson, Steve Jurzyk has announced his retirement and has been replaced as Associate Administrator by Robert Cabana, current director of KSC—meanwhile, Vice President Harris will chair the National Space Council; and, OSIRIS-REx fired its main engines for 7 minutes and started its 2.5-year voyage back to Earth with samples from Bennu.  Stratolaunch’s Roc, the largest plane in the world by wingspan, during its second test flight.  ¶Etc.An exploration of meandering rivers that never existed. (Really, all of the portfolio pieces on his site are beautifully explained.)Use your data science skills to help identify anomalous signals (one example could be aliens) in scans of Breakthrough Listen targets and win$15k with SETI Breakthrough Listen’s Kaggle data science competition.NASA’s upcoming Psyche mission to the rusting metallic asteroid of the same name will be the first to use Hall thrusters in deep space. Hall-effect thrusters are a type of ion engine that confine an ionized propellant with a magnetic field and then accelerate it with an electric one. Psyche’s Russian-made SPT-140 xenon Hall thrusters are integrated into a Maxar-built satellite bus based on the ones used in their commercial communications satellites. The SPT-140s use up to 5 kW of solar power to produce ~0.27 N of thrust, 3X the thrust of Dawn’s ion thrusters. Related: What could volcanoes look like on a metallic world like Psyche? Enter ferrovolcanism.There are also many other types of electromagnetic thrusters. An untested new type is a plasma thruster that uses magnetic recombination rather than electric fields (paper). These thrusters would produce higher exhaust velocities than conventional plasma thrusters and have the ability to use both heavy and light elements as fuel. The challenge, as with most electric propulsion techniques, will be to find a sufficiently large power source, which in this case would probably have to be fission- or fusion-based. Related: Scott Manley has a review of far future engine technologies (using KSP, natch). How Many Decimals of Pi Do We Really Need? JPL uses 15.