# The Orbital Index

Issue No. 36 | Oct 29, 2019

🚀 🌍 🛰
 ¶Highlights from the 70th International Astronautical Congress. A few items of note from last week’s IAC:ESA is asking their 22 member states for funding to continue development of their reusable, methane-fueled Prometheus rocket engine for future Ariane vehicles. The agency is targeting an eventual cost of €1 million each, about 10% of the cost of the current Vulcain engines.Rocket Lab announced plans to deliver hosted payloads of up to 30kg to lunar orbit with their Photon upper-stage/satellite-bus. Made In Space plans to send a plastics recycler to the ISS for use with their 3D printer that’s already there.Responding to NASA’s CFP, Blue Origin announced plans to collaborate with three small companies—Lockheed Martin, Northrop Grumman, and Draper—on a crewed lunar lander for 2024.ConsenSys Space, the result of the “blockchain company” ConsenSys acquiring Planetary Resources last year, announced a beta version of TruSat, an attempt to improve space situational awareness with an app for hobbyists to report satellite positions. (While interesting, we suspect it would be better to use the money to build automated telescopes.)According to SpaceX’s COO Gwynne Shotwell, Starlink could start providing commercial broadband services next year, necessitating 6+ launches of 60 satellites each. On the 15th, SpaceX asked the ITU for spectrum for 30,000 more satellites, and on the 21st, Musk tweeted, apparently via Starlink. Interestingly, since light travels faster in a vacuum than in glass, satellite links could provide better latency than terrestrial fiber for distances greater than ~3,000 km. Shotwell also suggested a Starship timeline of a first orbital flight in 2020, a lunar landing in 2022, human cislunar orbit in 2023 (related: great visualization of lunar halo orbits), and a crewed lunar landing in 2024.
 ¶SABRE hits a cool Mach 5. The Synergistic Air-Breathing Rocket Engine (SABRE), which we covered way back in Issue #4, hit a major milestone last week. Its pre-cooler, called HTX, was successfully tested with inlet air at temperatures exceeding 1000° C. The pre-cooler diverts intake air through a heat exchanger made up of 50 km (yes, km) of tubing with just 30 μm thick walls. HTX can transfer 1 GW/m3 from the hot intake air to cryogenic hydrogen, dropping its temperature to -150° C in just 1/20th of a second. The cooled air is then compressed, combined with the hydrogen, and fed into SABRE’s combustion chamber. Testing was conducted in Colorado by feeding super hot exhaust from an F-4’s turbojet engine into HTX. When flying, SABRE will use atmospheric intake air at up to Mach 5.14 and 28.5 km in altitude, or ~20% of the altitude and speed required to reach orbit. Altogether, this allows for a peak Isp of ~3,600 seconds at sea level. Compare this to a max of ~450 s for traditional engines and 800 s for nuclear rockets, which we do not recommend using at sea level. Vacuum performance will be a fairly standard ~460 s. This allows for an SSTO spaceplane design—we’re curious to see what type of engine bell is chosen to perform both at sea-level and in vacuum (although we hear Aerospikes are great for SSTO). Up next for SABRE: wind tunnel testing of the compression chamber in Germany.
 ¶News in brief. NASA’s 2021 Lucy mission to study Jupiter’s Trojan asteroids completed Critical Design Review; a NASA report calls for modernization of Planetary Protection practices [full pdf] that haven’t changed significantly since the early days of space exploration; Virgin Galactic (SPCE) became the first publicly traded space tourism company—it’ll be interesting to see how many people are willing to pay $250,000 for a 90 min flight with 5 min of weightlessness and whether an eventual “low” cost of ~$60,000/seat will increase the size of the market significantly; so far so good for James Webb sun-shield tests; Japan is planning to join the Artemis program; the eROSITA X-ray telescope that launched in July has seen first light; and, the X-37B military space plane landed after a record 780 days in orbit (we still don’t really know what its been doing up there).
 ¶Etc. “OMG space is full of radiation and why I’m not worried.” An excellent article about radiation exposure in space with comparisons to historical and present exposures on Earth. “The highest [radiation level of a] known inhabited place is a community built around a hot spring in Ramsar, Iran. The spring’s waters are thought to promote healing, and are loaded with radon, a radioactive gas. One house has a total background level of 200 mS/year, equivalent to the unshielded exposure on Mars. [...] not only do people in Ramsar live apparently long and normal lives, there is no local increased rate of cancer attributable to radiation exposure!” The Deep Space Catalog V1.0. The first attempt at a coordinated catalog of deep-space artificial objects for situational awareness.People are not always aware of all the technology transfer that happens due to space exploration. Here are six advanced manufacturing technologies that NASA has developed over the past several years.“How many small launch vehicles are being developed? Too many to track!”Quantum superposition and interference, as with the classic double-slit experiment, demonstrated in molecules of 2,000 atoms (paper), remaining in superposition for > 7 ms. Meanwhile, Google and NASA published their rumored Quantum supremacy results (paper).Optimal control of a lunar lander.Spectrographic evidence of elements from consumed rocky worlds was found when observing 6 white dwarf stars (what is left after a Sun-like star exhausts its hydrogen), suggesting that rocky terrestrial planets may be quite common (paper).“This fused quartz sphere was manufactured for use in a gyroscope in the Gravity Probe B experiment. It is one of the most accurate spheres ever manufactured, deviating from a perfect sphere by no more than 40 atoms of thick­ness. Only neutron stars are thought to be smoother.” 🔮😍The Chicxulub asteroid that wiped out the dinosaurs also strongly acidified the world’s oceans (paper) resulting in an underwater mass extinction. This is relevant today as we acidify the oceans again to potentially similar levels (and results).We finally have proof that neutron star collisions are a source of the Universe’s heavy elements (paper). Video about the ridiculous program to develop SLAM in the 1950s⁠—the nuclear-powered ramjet cruise missile that could stay aloft for 180,000 km while covering everything below it with radioactive exhaust from its unshielded reactor core. Fortunately, the US decided not to build one. Unfortunately, Russia is. NASA is building its first electric airplane, the X-57 Maxwell.An absolutely lovely interactive article about the Earth, Sun, and their relationship.
 HTX, SABRE’s pre-cooler test system containing 50 km of tubing.