# The Orbital Index

Issue No. 30 | Sep 17, 2019

🚀 🌍 🛰
 Watery exoplanet found in a habitable zone, just a quick 111 light-year trip away. For the first time, water vapor has been detected in the atmosphere of an exoplanet in a star's habitable zone. The planet, K2-18b, is likely a “temperate” mini-Neptune with water in its very thick atmosphere, with a smaller possibility of being rocky, terrestrial, and having liquid surface water. K2-18b was first identified by Kepler in 2015, imaged by Hubble in '16 and '17, and confirmed to be in the habitable zone by Spitzer in '17. It is about eight Earth masses and orbits K2-18, an active small red dwarf that likely produces a hostile high-energy radiation and low-light environment that couldn't support life as currently imagined. Two separate teams published papers on K2-18b after analyzing the publicly available Hubble data—the University College London team released open-source algorithms now available on Github. Next-generation space telescopes like JWST and ESA’s ARIEL will improve researchers' abilities to characterize exoplanet atmospheres [post is by a study author], and it seems inevitable that we’ll eventually find an Earth-sized rocky world that has large bodies of liquid water. (Related: an attractive, if somewhat dated, visualization of 500 known exoplanets.)
 A second interstellar object has been spotted. Like Oumuamua before it, C/2019 Q4 (Borisov), moving at 33 km/s relative to the Sun while still far away, appears to be on a hyperbolic trajectory with eccentricity high enough to rule out gravitational interactions in our solar system. Unlike Oumuamua, Borisov is a comet, has a visible tail, and should be observable for at least a year, with its closest solar approach in December (check out that trajectory animation!), providing plenty of observation time. The comet was spotted by amateur astronomer Gennady Borisov with a custom-built 0.65-meter telescope. If confirmed to be interstellar in nature, the object’s name will be modified to begin with 2I/.
 Manufacturing optical fiber in space. Made in Space, who recently received $74 million from NASA to demonstrate assembly of large solar panel arrays on orbit with their Archinaut mission, has announced that they will start selling ZBLAN optical fiber manufactured on the ISS next year, enabled by the ISS’s new availability for commercial use. ZBLAN fiber, an exotic heavy metal fluoride glass, has 10-100 times lower IR signal loss than silica fiber, and is considered one of the most likely materials for profitable manufacture in space due to its high value—more than$100 USD per meter of fiber—and the ability to pull thousands of meters on orbit from a 1 kg raw glass “preform” shipped up from Earth. In Earth’s gravity, ZBLAN’s components tend to crystalize non-uniformly during cooling, reducing its clarity. In microgravity, however, this effect is reduced, resulting in a material ideal for medical and military fiber lasers and high-speed communication equipment. Other companies are pursuing opportunities for material manufacturing in space as well, including more ZBLAN, protein crystals, and 3D printed human tissues. For more than you probably want to know about ZBLAN, see “Exotic Optical Fibers and Glasses: Innovative Material Processing Opportunities in Earth's Orbit” (or just read Andy Weir's novel, Artemis, for a fictional account).
 Papers.Eruptions of Io's largest volcano fluctuate on a ~500 Earth-day cycle timed with the orbits of Jupiter's other moons. Unlike stresses from Io’s rapid orbit, this slow cycle seems to couple with the motion of magma inside the planet. Phys.org has the details and a good description of how Io's resonance with other Jovian moons maintains its elliptical orbit, which in turn creates the gravitational friction that keeps its core molten. Also interesting: Jupiter's auras are likely powered by alternating current (paper). The Spaceline, a modest proposal for a space elevator from the surface of the moon to roughly geostationary lunar orbit, “achievable” with current technology… oooor, we could just build an Earth-Moon Fire Pole. Three Earth-sized planets have been found around a nearby star (paper), and one is likely in the habitable zone. Unlike K2-18b, their M dwarf is only 12 light-years away (our 20th nearest star). Neutron stars, typically pictured as balls of pure neutrons held up by degeneracy pressure, actually contain layers with mixtures of electrons, protons, and possibly exotic quark-gluon plasma. Pulsars are spinning neutron stars with very (very very) regular periods, but sometimes they "glitch" and change spin slightly as material shifts inside of them, which, according to a new paper (pdf), provides a glimpse into their internal structure, in which “a soup of super-fluid neutrons in the inner layer of the crust, moves outwards first and hits the rigid outer crust of the star causing it to spin up.”
 News in brief. Neither ISRO nor NASA’s Deep Space Network have heard back from Vikram, and NASA’s Lunar Reconnaissance Orbiter will attempt to image the lander’s resting place today; SpaceX’s Gwynne Shotwell announced that SpaceX may launch four more Starlink missions this year and 24 (!!) in 2020, each with 60+ satellites onboard, now into 72 orbital rings (up from 24); China’s massive 500-meter FAST single-dish radio telescope is now fully operational, with 4,450 individual panels and more than twice the collecting area of the Arecibo Observatory in Puerto Rico; based on a regulatory filing, SpaceX plans for the initial Mk1 Starship prototype test flight to reach an altitude of ~20 km; and, Bigelow Aerospace gave a tour of their boilerplate Mars Transporter Testing Unit, one of four potential habitation units for NASA’s Lunar Gateway.
 Etc.Extreme Life and Where to Find ItESA’s Mars lander parachute problems may be worse than we thought.Phase 2 of NASA’s Space Robotics Challenge is now open, if you’re a company whose into that sort of thing.A new material, 10 times blacker than the blackest previous material, absorbs 99.995% of incoming light, from every angle—v. good for telescopes.Major clean water regulations in the US are being rolled back, adding to the long list of environmental protections being rolled back by the Trump EPA. Related: a set of 70s pre-EPA photos.Valerie Stimac, a friend of ours, just published Dark Skies: A Practical Guide to Astrotourism with Lonely Planet—the first 100 sales get a free mission patch. “The Mars-facing side of Deimos is probably the most valuable real estate in the solar system.”
 An artist’s impression of K2-18b with its host star and K2-18c (an unconfirmed second planet) in the background.