¶Weighing neutrinos. Neutrinos are elusive, weakly interacting particles that are produced in vast numbers by nuclear reactions. Every second, roughly 100 billion solar neutrinos pass through the tip of your finger, even at night, when they must pass through the Earth to reach you. Neutrino detectors are used to understand the sun, study the most powerful cosmic ray accelerators, and have been proposed for imaging the inside of the Earth and searching for illegal nuclear reactors. In the 1990s, physicists discovered that neutrinos oscillate between three types, or "flavors", and therefore that they must have mass. (Basically: if they oscillate, they're experiencing time, and if they experience time, they cannot move at the speed of light and this must be because they have mass. QED.) Since neutrinos have mass, a stream of neutrinos will tend to “drag a little bit of matter” along with them, resulting in a “fuzzing” of the distribution of galaxies and affecting the development of large-scale galactic structure (paper). A new study (paper) used observations of this effect on 1.1 million galaxies to theorize an upper bound on the mass of the lightest neutrino flavor at 0.086 electron volts (eV) — that’s 6 million times lighter than the mass of an electron. Soon, the Dark Energy Spectroscopic Instrument (DESI) will observe 10x as many galaxies and be able to improve these bounds. (Another recent paper found an upper limit of 1 eV using the beta decay of tritium.) Understanding neutrinos may answer a fundamental question about our existence: why is there any matter in the Universe at all? Cosmology predicts that the Big Bang should have created exactly the same amount of matter and antimatter, resulting in mutual annihilation, but our existence suggests otherwise. It’s suspected that a small difference in the behavior of neutrinos and antineutrinos during their oscillations may have resulted in a tiny bit more matter being created, which we’re pretty thankful for. |
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¶NASA released a 2020 hype reel. The 3-minute video has many fun shots ranging from live footage to beautiful renderings. In it, the agency hypes Artemis 1 and SLS, but noticeably only commits to a “green run” test firing and not an actual launch, further cementing the idea that Artemis 1 won’t launch in 2020. More interesting was the significant portion of the reel spent focused on preparations for crewed deep space exploration—ISS missions, space-based biomedical research, and ISRU missions to both the Moon (VIPER, a water finding rover) and Mars (Mars 2020 includes an oxygen production experiment). Finally, CubeSat missions took a visible position near the end with cameos by both CPOD (performing a rendezvous and connection maneuver) and an unnamed water-powered cubesat (perhaps OCSD or the Artemis 1-launched Cislunar Explorers). |
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¶TESS found its first Earth-sized exoplanet in a habitable zone. The planet, TOI 700 d, as it is lovingly referred to, is approximately100 light-years away by NASA's Transiting Exoplanet Survey Satellite (TESS) using the transit method and was confirmed by the Spitzer Space Telescope. The planet is 20% larger than Earth, likely tidally locked, and receives ~86% of the stellar energy (‘insolation’) that our planet does. (For comparison, Mars receives only 43%, while Venus gets 191% that of Earth.) Initially, the host star was incorrectly categorized as a larger star, leading to its exoplanets being assumed to be proportionally larger as well—the error was eventually found by a team that included a high school student, and TOI 700 was reclassified as a smaller, dimmer M-class star leading to the discovery (video). This planet joins a small handful of Earth-size exoplanets found habitable zones by other missions. |
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¶News in brief. India is planning to attempt another Moon landing in 2021 with Chandrayaan 3, consisting of a lander and rover; NASA lost contact with the very successful Asteria CubeSat (it lasted 2 years past its primary mission); the Parker Solar Probe completed its second gravitational breaking flyby of Venus on Dec. 26 and will make its fourth close solar approach on January 29—which should give you a sense of its blistering speed; SpaceX successfully launched, landed the booster, and deployed Starlink-3 (but is still struggling to consistently catch fairings) including one satellite with an experimental antireflective coating to reduce its impact on astronomy—with these 60 additional Starlink satellites, SpaceX is now the world’s largest commercial satellite constellation operator; and, it was recently revealed that an unnamed NASA astronaut on the ISS developed a blood clot and was successfully treated in space—blood clots are more likely in space because blood can pool or flow in reverse (paper). |
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