Issue No. 50

Welcome to Issue #50! This week’s theme is asteroids and meteors—because they rock 🤘

The Orbital Index

Issue No. 50 | Feb 6, 2020

🚀 🌍 ☄️ 🛰

The effects of extraterrestrial impacts on life on Earth. Most people know about the Chicxulub impact that helped kill the dinosaurs (and 75% of all other plant and animal species as well), but growing evidence suggests that impacts over geologic history have shaped life on Earth in many other ways too. Recently, evidence based on an increase in the platinum and iridium content of sediment around the world (paper) has lent support for the Younger Dryas Impact Hypothesis, first suggested in 2007, which posits that an extraterrestrial impact 12,800 years ago caused a 1000 year ice age and the extinction of many large animal species along with a simultaneous decline in human populations. (Human hunting likely played a large part in megafauna extinctions as well, which is on-brand for us.) Further back, a newly confirmed impact 800,000 years ago may have cleared an expanse of jungle for human habitation. And even further back, 466 million years ago, the collision and breakup of a large asteroid in the belt between Mars and Jupiter created a dust cloud that showered the inner solar system, blocking sunlight and causing an ice age, the possible instigator of the Ordovician radiation, a rapid increase in biodiversity at the time (paper). This Ordovician meteor event remains the largest breakup in the last 3 billion years and is the source of almost a third of all the meteorites that still strike Earth today, almost half a billion years later. And finally, 4 billion years ago, the building blocks for life itself may well have been delivered to Earth on meteors and comets. (Much more controversially, it’s possible that muons from a supernova 2.6 million years ago could have wiped out large ocean animals, and that the Younger Dryas impactor could have been a supernova remnant.)

State of the asteroid union. As of 2020, our species has sent probes to 14 asteroids throughout the solar system, beginning with Galileo’s observation of Gaspra in 1991. Most have been near-Earth objects (NEOs), which can pose both an existential risk (see previous item), as well as a potential source of accessible in-space resources (here’s a fabulously detailed report, but also see the Etc. article from Casey Handmer below), including water, iron, cobalt, nickel, and platinum-group metals. For planetary defense, NASA announced the NEO Surveillance Mission last fall with the goal of launching an L1-located space telescope that observes in infrared to spot super dark NEOs as they are warmed by the sun. Recently, Hubble discovered that Eurybates—a Trojan asteroid scheduled to be visited by the upcoming 2022 Lucy mission (mission tour guide)—has a small "bonus" satellite that the mission will get to observe. Additionally, OSIRIS-REx just made its closest flyover (620 m) of its August sample gathering site on Bennu, and Hayabusa2 is currently returning to Earth to deliver bits of Ryugu this December. Other planned asteroid missions include NEA Scout (a CubeSat mission which will hitch a ride on Artemis I and then visit NEOs using a solar sail ✨⛵️), ASTER (Brazil's first planned, but perhaps unlikely, deep space mission), DART/Hera (shoot and then monitor an asteroid!), Psyche (cf. Issue 17), and China's proposed mission to Kamo'oalewa.

(Less impactful) News in brief. ESA and NASA’s Solar Orbiter is launching this Sunday—the mission will fly out of the ecliptic by slingshotting past Earth and Venus to study the Sun’s poles for the first time (see ars piece on the future of solar observation); Voyager 2 suffered a technical glitch; Rocket Lab launched some sort of small observation satellite for the NRO and again guided its booster intact through reentry into the ocean ahead of plans for mid-air capture; OneWeb plans to launch 34 satellites today on a Soyuz—they’re aiming for 648 in the final Internet service constellation; billionaire Yusaku Maezawa canceled his (we think highly misguided) personal lunar dating show due to "personal reasons" and apologized to the 27,722 women who applied; SpaceX may also want to build Starship and Super Heavy vehicles at a factory at the Port of Los Angeles—they would then be barged to Boca Chica or Florida for launch; another dramatic Starship SN1 test, this one using cryogenic liquid nitrogen filling a massive 9 m test tank, reached the 8.5 bar required for crewed flight, with approval for communications equipment for a 20km test flight requested from the FCC with a launch date NET March 16th; secretive Alameda, CA-based Astra (intro video) is planning a first orbital test on February 21—they had a failed suborbital flight test in Dec 2018; a Russian spy satellite (Kosmos 2542) is likely spying on a US spy satellite—the USA is known to observe other satellites as well through the Geosynchronous Space Situational Awareness Program (GSSAP).


Technically correct, the best kind of correct. (Although, really it would be a meteor until it hit the ground… *waits to be stomped*)

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