Issue No. 151

The Orbital Index

Issue No. 151 | Jan 12, 2022

🚀 🌍 🛰

The Nancy Grace Roman Space Telescope. Now that the JWST is deployed and could have a lifespan of 20 years  🎉 🥳, let’s talk about NASA’s next, next telescope. The wide-field infrared Nancy Grace Roman Space Telescope (née WFIRST) is scheduled to launch in 2025. Like JWST, it will also orbit at the Sun-Earth L2 point. The NGRST has two instruments: the Wide Field Instrument, a 300-megapixel camera with a Hubble-class 2.4 m aperture, but 100x the field of view, and the Coronagraph Instrument, for imaging and spectroscopy of nearby exoplanets. It is predicted to find 100,000 transiting exoplanets via both transit detection and microlensing. Microlensing occurs when, from our perspective, a star passes in front of a more distant star, and light from the further star is distorted by the gravity of the closer star and any exoplanets—the spatial and temporal difference in distortion due to the additional mass of one or more exoplanets is a telltale sign of their presence. Of the 4,884 exoplanets discovered so far, only 120 were found through microlensing. Through this technique, NGRST should be able to detect planets smaller than Earth—possibly approaching the size of moons like Ganymede—as well as stellar-mass black holes and rogue planets that are wandering the galaxy after having been ejected from their host stars. There is a proposal for a follow-on mission called the Starshade Rendezvous Probe (paper) which would add a 26 m starshade that would precisely position itself far in front of the telescope and allow direct imaging of nearby Earth-like exoplanets. The petal-shaped starshade would fly 20,000 to 40,000 km ahead of the telescope while maintaining a positional accuracy of only 1 meter, precisely blocking a star’s light but not the glow of its exoplanets. No big deal. This add-on mission would serve as a test ahead of even larger starshade companions to future observatories such as those called for by last year’s decadal survey.

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Some recent (mostly sci-fi) reading. We wanted to take a moment and look back at some of the books we enjoyed over the past year(ish). 

  • Rendezvous with Rama. Arthur C. Clarke's 1973 telling of the exploration of an interstellar visitor (an alien ‘Oumuamua/O’Neill cylinder) holds up incredibly well after almost 50 years. The inexorable progression of interstellar velocities lends weight and realism.
  • Project Hail Mary. Andy Weir’s third novel perhaps even rivals The Martian. Hard sci-fi to its core (albeit more fantastical than The Martian), sporting a science teacher hero, the story moves along at an engrossing clip and only suffers from challenges being too easily overcome by science and engineering, and from relying on the old crutch of amnesia to unfold the backstory progressively. We’d say more, but we don’t want to spoil the plot.
  • Seveneves. Another “What would humanity do if it was staring in the face of imminent extinction?” book, Stephenson’s very near future mostly relies on extant technology, with one or two hopeful technologies like nuclear propulsion and robots that actually work. A true Stephenson novel, it often gets lost in the details of orbital mechanics and other physics which slows down the plot development, but that’s also what makes it good.
  • The Lattice Trilogy. What would people do if they could watch everything, everywhere in the past and present? Eric Hanberg writes a compelling trilogy about the fight for privacy in a world where it has become an almost imaginary concept.
  • Honorable Mentions: The Bobiverse series (just delightfully fun and nerdy wish fulfillment sci-fi), The Three-Body Problem (an immensely interesting sci-fi take on life in a three-body system’s unpredictable progression, and also a viewpoint from within China, one rarely experienced by westerners), Electrify (not sci-fi — Saul Griffith’s optimistic guide to combating climate change by electrifying everything), and on a more personal note, The Grand Human Empire series (about a sci-fi smuggler/grudging hero) and The Galactic Cold War series (sci-fi secret agents) from Ben’s friends John Wilker and Dan Moren (respectively).

News in brief. GOES-16 (and surprised residents) detected a nondestructive half-ton meteor airburst near Pittsburgh on the first day of 2022 SpaceX launched 49 more Starlink satellites China’s Tiangong station tested its 10-meter robotic arm by repositioning the docked Tianzhou 2 cargo craft to a new docking port Dr. Katherine Calvin has been named NASA's new Chief Scientist and Senior Climate Advisor Some pebbles are (hopefully only temporarily) obstructing Perseverance’s sampling system ESA’s Sentinel-1B is having power management issues, threatening to decrease the availability of its powerful SAR—without 1B, the revisit interval would go from 6 to 12 days The faulty engine controller on one of the RS-25 engines being used by Artemis I’s SLS has been successfully replaced—launch is now probably April (or later) IXPE has been commissioned and will start science observations shortly LauncherOne is scheduled to launch eight small US government test satellites and two SatRevolution EO sats tomorrow Transporter 3 is also scheduled for tomorrow to send yet another plethora of smallsats to SSO.



A year-long keogram from Dutch astronomer Cees Bassa. Keograms were developed for studying aurorae—this image is a composite of the pixels of the meridian line from 2.1 million all-sky images taken every 15 seconds by a Raspberry Pi and shows the progression of day length (blue/black), moon phases (silvery diagonal stripes), cloud cover (gold at night), and higher solar declination (shiny highlight on the right side of the image). Cees’ thread gives more detail. 🧵

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