¶A new plane of space. Earlier this week, China launched a Long March 2F carrying a classified payload from the Jiuquan Satellite Launch Center in northwest China. The LM-2F vehicle is China’s main provider for crewed and space station launches (and its launch facility got some upgrades earlier this year). This launch was rumored to be an early prototype of a reusable space plane—China has had many space plane projects, with few details publicly available—and as yet no other clear details about the craft have emerged. China did mention in 2017 that there would be a space plane test in 2020 (but stated it would utilize horizontal takeoff in addition to landing). Some are reporting that this is a new version of the Shenlong space plane first glimpsed in 2007. After orbiting the Earth for two days at ~350 km and leaving behind an unidentified object, the spacecraft landed and was referred to as a “reusable experimental spacecraft” by the state media. This craft likely joins the Shuttle, Buran, and X-37 as the fourth member of the orbital space plane family (possibly to be joined by Dream Chaser next year).
An artistic imagining of a Chinese Space plane, inspired by the 2007 Shenlong and the X-37.
¶So metal. Stellar metallicity refers to the quantity of elements in a star that aren’t hydrogen or helium. (To the dismay of chemists, astronomers call all elements above atomic number 2 “metals”.) These heavier elements are created in the star through fusion, build up until there are no longer enough light elements to fuse, and ultimately lead to the star’s demise as a slowly cooling white dwarf or a dramatic supernova that spreads these and even heavier elements across space. (“We are made of star-stuff.”) The average metallicity of stars tells us about their age and the medium from which they formed. Very low metallicity stars are likely ancient stars that formed before the stellar medium was enriched with heavier elements. Because of this, they tell the history of our universe, and there’s an ongoing effort to identify more very low metallicity stars—a recent paper adds five to the tally. Related: Neutrinos created through the CNO fusion cycle have finally been detected from the Sun (paper).
The diaphanous edge of the Cygnus supernova blast wave, travelling at 350 km/s, as caught by Hubble. This particular supernova occurred between 10,000 and 20,000 years ago and its remnant now covers an area of the sky 36 times larger than the full moon.
| ¶News in brief. Starship hopped again (video), with SN6 more smoothly flying to 150 m and landing safely powered by its single Raptor engine—SN7.1 (a 304L stainless steel test tank) starts destructive testing any time now, while SN8 and SN9 are under assembly; meanwhile, Starship’s Super Heavy booster production is just beginning and Musk recently shared some updates on its design; Northrop Grumman tested a full-scale version of the SLS’s booster after a 14-month delay (video); Canada appointed Lisa Campbell as the new president of the national space agency; China launched Gaofen-11 (02) on a Long March 4B, yet another remote sensing satellite in their growing network (and dropped the toxic booster near a school...); Hubble is experiencing some pointing errors; and, InSight’s Mole is underground.
- ISS-based research suggests that nanoparticles may improve cellular resilience to oxidative stress (which plays a part in aging, heart disease, muscular atrophy, and Parkinson's disease). This research also adds to the ‘baby-astronaut’ hypothesis of weightlessness—that astronauts' changes in tissue are similar to tissue development in-utero (paper).
- Applications for the 12-month Earth observation Copernicus Accelerator 2021 close in 2 weeks.
- The Sun is an oddly quiet star, with a median brightness variation of 0.07%, while other similar stars in Kepler data had medians of 0.36%, 5x as high. Phil Plait of Bad Astronomy digs in. Given that powerful solar flares can sterilize planets, perhaps we shouldn’t be surprised to find ourselves in a quiet solar system.
- Based on evidence of excessive UV exposure in 359 million year old fossil plants, researchers are proposing that the Devonian extinction event was caused by the ozone layer being wiped out by multiple nearby supernovae (paper). Related: Based on interstellar particles of iron-60 found in ocean sediments and arctic ice (paper), the solar system has been moving through a different ancient supernova remnant for the last 33,000 years.
- The 33 stars within 12.5 light years of our Sun. And here’s a beautiful 3D version. To go even deeper, check out Stellarium or the stellar (pun intended) Space Engine.
- The primary mirror for NASA’s Roman Space Telescope has been completed. It is polished to an average bump height of 1.2 nanometers. “If the mirror were scaled to be Earth’s size, these bumps would be just a quarter of an inch high.”
- When stars like our Sun die, they leave behind an Earth-sized hot core called a white dwarf. It will take trillions of years for those white dwarfs to finally cool into black dwarfs, which are basically inert. Except, nothing in quantum mechanics is truly inert and over enough time, quantum tunneling will allow the fusion process to continue until the star’s degeneracy pressure grows weak enough through loss of electrons that the star collapses in a supernovae-like explosion (paper). These black dwarf collapses will begin to “occur about 10^1,100 years from now [...], 10^100 is known as a googol, so 10^1,100 would be a googol googol googol googol googol googol googol googol googol googol googol years.”