Issue No. 30

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).


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.


An artist’s impression of K2-18b with its host star and K2-18c (an unconfirmed second planet) in the background.

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