Issue No. 62

The Orbital Index

Issue No. 62 | Apr 28, 2020

🚀 🌍 🛰

More interesting NIAC concepts. Continuing from last week, here are more of our favorite NASA Innovative Advanced Concepts (NIAC) concept studies that were just funded:

There are more interesting ideas, including magnets to improve aerocapture heat shields, Pulsed Plasma Rockets, hopping probes, both Martian fuel and lunar water ISRU, magneto-inductive communication using SQUIDs on Europa, robots to search Enceladus’s vents for life, a flexible and reconfigurable Venus probe, astronaut-following support robots, in-space drug production, solar sails for catching up to interstellar objects, self-assembling kilometer-sized orbital antenna arrays, heat shields for rovers, and antimatter propulsion. 😅

The Lunar Crater Radio Telescope and its crater lined with a 1km-diameter wire-mesh radio antenna.

The New Horizons Parallax Program. Now at 46 AU, well past Pluto and Arrokoth, New Horizons is heading toward the edge of our solar system at about 14 km/s, and the mission team is looking for new ways to use the spacecraft. Last week, through the New Horizons Parallax Program, they photographed two of our nearest stars, Proxima Centauri and Wolf 359, to compare their positions relative to those observed from Earth. “New Horizons is 2.89 light-hours closer to Proxima Centauri than Earth, but 3.74 light-hours farther from Wolf 359 than Earth.” This record-setting stellar parallax observation gives backyard astronomers (with 6-inch or larger telescopes) a chance to do their own parallax measurements and calculate the distance to these stars. While this effort is mostly for public relations, it is also the “first demonstration of using stars for interstellar navigation of a spacecraft”. Related: Proxima Centauri, the closest star to our Sun, is 1.3 parsecs away. A parsec, at 3.26 light-years, is the distance at which an object has a parallax of one arcsecond (or 1/3600 of a degree), and is normally measured by comparing images of the object taken when the Earth is on opposite sides of the Sun (that is, unless you have a soon-to-be-interstellar spacecraft that’s sitting around twiddling its proverbial thumbs).

The Golden Records of Voyager. This week a reader passed along an enjoyable episode of Stuff You Should Know that digs into the gold-plated records on Voyager 1 & 2 which are currently flying through interstellar space at about 10 km/s. Particularly interesting were the method for communicating the location of our solar system using 14 pulsars, a method from the 70s for encoding images as 4-second still video shots and then turning them into an audio signal (ed. This is a must click in our opinion, a 1978 article from Modern Electronics on Voyager’s records… you might just want to read the entire issue) including a key to ensure that the correct aspect ratio is used, and the music of the spheres—a guess at the sounds our system’s celestial bodies might make, originally imagined by Kepler. You can interactively explore the contents of the records at Related: a personal account of decoding the image data on the records from 2017. The real records are going to be lonely for a while, but perhaps something will decode them in 42,000 years when Voyager 2 comes within 0.6 parsecs of Ross 248, or in 303,000 years when Voyager 1 flys past TYC 3135-52-1 at 0.3 parsecs.👽

The cover for the golden records launched on Voyager 1 & 2.

News in brief. Starship SN4 passed pressure testing at cryogenic temperatures, crossing a difficult hurdle and setting up static fire and hop tests (longer flights will have to wait for SN5 & 6 due to the lack of flaps and canards on SN4); Iran launched their fifth satellite, Noor, and the Revolutionary Guard’s first, revealing an unknown rocket system and launch site; NASA JPL engineers designed a ventilator; Cheops observed its first exoplanet, a known exoplanet about 30% larger than Jupiter, but orbiting closer to its star than Mercury is to the Sun, and obtained planet size measurements with 5x better accuracy than those available from the surface of the Earth; SpaceX launched 60 more Starlink satellites to bring their constellation to 412, with internet services starting as soon as 3-6mo—meanwhile, Musk discussed apparent magnitude mitigation strategies with scienctists as part of Astro 2020 (next launch will include a ‘VisorSat’); with its 84th launch, the Falcon 9 became the active American rocket with the most launches, surpassing ULA’s Atlas V; the center of gravity of Perseverance was carefully measured, then 6.27 kg were added to the rover's 1,025 kg chassis to bring it within 0.025 mm of its intended location, which will keep the launch and cruise vehicles balanced; and, ‘Al Amal’ (translated ‘Hope’), the UAE Mars rover, arrived at its launch site in Japan.
The USGS released a complete geologic map of the Moon. Seen here are orthographic projections from the Unified Geologic Map of the Moon which uses topography based on the laser altimeter aboard the Lunar Reconnaissance Orbiter. (Thereʼs also a 712 MB pdf— we didn’t link it directly in order to prevent complete web browser annihilation).

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