Mars Floods – The Mars rover Perseverance has been studying the western delta fan, which was built up by layers of sediment dropped into Jezero Crater by a river, back when the crater was a lake, about 3.7 billion years ago. The fan contains about two dozen large boulders and hundreds of smaller stones that had to have been carried here by powerful floods, rather than gently flowing water. These rocks are believed to have been carried here from tens of miles away. Based on the position of the boulders relative to calmly layered areas, scientists believe that the violent floods occurred late in the history of the lake in Jezero. It is not known if the floods moving the boulders were caused by heavy rains or massive snow melts or some other origin. More data is needed, and is expected to be provided when the rover approaches this area more closely.
Mars Helicopter – Since the Mars helicopter Ingenuity made its first flights in May, the air pressure at its site has dropped by roughly a third. This is a normal Martian seasonal occurrence, due to the large amount of carbon dioxide that freezes out of the atmosphere into the seasonal polar caps. Helicopter controllers had initially not planned on still making flights as the Martian season changes, so the expected pressure drop wasn’t going to matter. But the helicopter mission was extended, and mission operators developed a plan to fly in the reduced pressure by spinning the rotors faster. In mid-September operators conducted a successful test to see if the rotors would spin faster. The rotor blade tips reached nearly 80 percent the Martian speed of sound. However, two further test flights attempting to lift off at higher spin did not actually lift off. Then Mars passed behind the Sun, interrupting communication with all craft on Mars. Meanwhile controllers are working on determining what went wrong.
Marsquakes – The InSight Mars lander has detected three more large marsquakes. Initially, spacecraft controllers had planned on turning off the seismometer during the planet’s period of weakest sunlight as Mars, in its highly elliptical orbit, reached its farthest from the Sun, and therefore lowest solar panel electrical generation. However, an experiment to see if controllers could clean dust off the solar panels by trickling blowing sand on them was successful, and the panels were able to generate sufficient power to leave the seismometer on. Otherwise, these latest large marsquakes would have been missed. Two of the quakes occurred in the daytime. The three quakes occurred at different distances from InSight. All previous large marsquakes had occurred at one location, the area called Cerberus Fossae.
Galaxies Without New Stars – Scientists at the University of Massachusetts, Amherst discovered six distant large galaxies that stopped forming new stars just a few billion years after the Big Bang while most other galaxies at this time were peaking in their new star production. The six galaxies were discovered in images taken by the Hubble Space Telescope to look at distant objects through gravitational lenses, in which gravity of a galaxy cluster bends light, magnifying and brightening objects behind. Follow-up observations of the six galaxies were made with ALMA, a radiotelescope array in Chile. Galaxies form new stars when there is adequate cool gas to collapse into stars. It is not known whether these six galaxies had their gas heated somehow, or expelled their gas, or had turned all their gas into stars already.
Quasar Mass – A new method to find the mass of a quasar, which is being called spectroastrometry, has been developed by researchers at the Max Planck Institute for Astronomy. It can be performed using only a spectrum of the quasar. It measures the rotational speed of gas orbiting the black hole in the quasar, and it determines the distance at which that gas is orbiting, even when that distance appears too small to resolve with existing telescopes. The mass of the black hole is then calculated from the orbital size and speed of the orbiting material. The method was tested on the quasar J2123-0050 in Aquarius. It is so distant that its light left 2.9 billion years after the Big Bang.
Neutron Star Mass – Astronomers have been puzzled as to why the average mass of neutron stars detected by LIGO, the gravitational wave detectors, is considerably higher than the average mass of neutron stars seen with light (including radio and other forms of light). In fact, the masses of neutron stars seen almost never are as large as the masses seen by LIGO. A new study from researchers at the University of California, Santa Cruz, using computer simulations of supernova explosions, appears to have solved this puzzle. When stars finish nuclear fusion of the hydrogen at their cores, it leaves a sphere of hydrogen too cool to further fuse surrounding the helium core. However, if the star is in a close orbit about a companion star, that companion gravitationally strips the hydrogen, leaving only the helium core. The new study found that when such a stripped helium core explodes as a supernova, it will leave behind either a neutron star that is more massive than usual, or a black hole that is less massive than usual. But this fully explains the puzzle only if there is some reason that these massive neutron stars created by helium core supernovas are almost never seen in light. Most visible neutrons stars are pulsars, neutron stars that spin fast and emit radio or other forms of light from their poles, so that we see a pulse every time the emitting region rotates by. The simulations in the new study showed that the massive neutron stars produced by the helium core supernovas, depending on the masses of both the companion stars, can spin slowly, and likely will not be pulsars. Puzzle solved.
Best Observed Supernova – Astronomers, led by researchers at the University of California, Santa Cruz and using the Hubble Space Telescope and several other telescopes have obtained the best picture of how a massive star explodes as a supernova when it runs out of nuclear fuel. This supernova, known as SN 2020fqv, was first spotted by the Zwicky survey using the large Schmidt camera at Palomar. It was immediately observed by Hubble, which was able to analyze the material closely surrounding the star before the explosion blew it all away, which was determined to have been expelled over the year preceding the explosion. Archived Hubble images were found that recorded the star’s behavior for decades prior to the explosion. The star was found to be in the current field of view of TESS, a planet-finding space telescope. TESS takes an image of its current field every 30 minutes, so it recorded a detailed record of the star’s brightness change both before and after the explosion. Astronomers calculated the mass of the star before exploding by three different methods, which agreed well, at 14 to 15 times the Sun’s mass. The mass of a star that explodes is important to know because stars of different mass explode differently. Astronomers are examining the behavior of the star in the decades before it exploded in hopes of being able to predict when other massive stars are going to explode. The supernova is located in the colliding Butterfly galaxies, NGC 4567 and 4568, in Virgo.
White Dwarfs – A new survey by the Isaac Newton Group of Telescopes observed every known white dwarf star within 65 light-years of Earth, using both spectra and polarization. Previous studies of white dwarfs have observed only the brighter ones, so likely produced biased views of white dwarfs. In particular, white dwarfs cool as they age, producing dimmer light, so previous observations have tended to neglect older white dwarfs. New findings about white dwarfs include: weak magnetic fields are quite common; magnetic fields at the surface of the stars are rare in young white dwarfs, but typically develop later as the star cools, and increase with age. About two thirds of the stars in this study had never been observed in spectra and polarization before.
FRB – Astronomers at the Chinese Academy of Sciences, using the giant Chinese radiotelescope dish FAST in 2019, observed the location where a fast radio burst (FRB) was first seen in 2012, and has been seen to repeat bursts since. The FAST observations saw 1,652 more bursts in 47 days. This is more bursts than all other FRBs ever observed. The cause of FRBs is still a mystery, and among the proposed causes are highly magnetic neutron stars, black holes, and cosmic strings. Periods between one millisecond and 1,000 seconds were searched for in the new observations, but no period was found. Most FRBs have never been seen to repeat, but a few repeaters are known, of which the one observed by FAST was the first discovered.
Active Asteroid – Comets have elongated orbits at random tilts compared to planet orbits and, when near the Sun, emit material that forms a head and tail. Asteroids do not give off material and tend to have more circular, less inclined orbits. Then there are about 20 objects with comet/asteroid identity crises, being termed active asteroids. A team at the Planetary Science Institute discovered another of these, called asteroid 248370. It orbits in the low-tilt, nearly circular asteroid belt beyond Mars’s orbit. But in July it was seen to be giving off gas and forming a tail when it neared its perihelion, its closest point to the Sun. The tail is particularly narrow, which implies that the material being thrown off is doing so at slow speeds. The comet-like activity was first spotted by the near-Earth object survey ATLAS, and confirmed by other telescopes. The next perihelion of this active asteroid will occur in September 2026, and astronomers plan on watching.
Another Active Asteroid – Phaethon is another one of those few active asteroids, and is the only asteroid known to supply the material for a meteor shower; all meteor showers other than the Geminids come from comets. The meteor material is expelled from comets when they come close to the Sun in their orbits, warming up and sublimating ices (water ice, dry ice, etc.) into gas, which blows dust and pebbles off into space. A new study by astronomers at Caltech using simulation of asteroid behavior as it approaches the Sun may have solved how Phaethon produces meteors without having ices to sublimate. According to the study, sodium takes the place of ices. Phaethon gets hot enough when near the Sun to boil sodium, which then blows off dust and pebbles. A lab test of a meteorite containing sodium heated to Phaethon’s highest temperature helped to confirm this.
Taurid Objects – The Taurid meteors are pieces sloughed off from Comet Encke. A few asteroids are known to orbit within that meteor stream, which has prompted some astronomers to believe that the comet and those asteroids are all broken pieces of a former larger body. The asteroids are too large to have come from Encke, so it had to be from something bigger. The breakup must have occurred about 20,000 years ago to match the current spread of objects. A new study by astronomers at the University of Antioquia found more potential debris with orbits similar to Encke, bringing the total to 88 objects. Cometary activity was found in two thirds of the newly discovered objects. This is highly supportive of the theory of a bigger object breaking up. Previous work has proposed that collisions with objects in the Taurid cloud explain various die outs and other disasters.
Binary Trans-Neptunian Objects – New Horizons, the spacecraft that flew by Pluto in 2015, took images of a few small trans-Neptunian objects in its vicinity in 2018. New analysis by researchers at Johns Hopkins University of these images shows that two objects are each binaries, that is, two objects orbiting each other. The images showed the objects as elongated though they were not quite resolved as separate objects. However the brightness and shape matched computer simulations of binary objects nearly resolved. The best match for the object dubbed 2011 JY31 was two 30 mile wide components orbiting about 120 miles apart, while that for 2014 OS393 was two 19 mile components at about 90 miles separation.
Plutonian Non-Volcano – A new analysis by researchers at the Southwest Research Institute of images of Pluto taken by the New Horizons spacecraft show that the mountains named Wright Mons and Piccard Mons are likely not cryovolcanoes, contradicting earlier reports. Examining the elevations of the parts of the mountains showed they did not fit volcano shapes. The terrain about the mountains is likely frozen cryovolcanic material, but it appears that it did not erupt from either mountain, but probably erupted from openings elsewhere. By impact crater count, the area’s age can be estimated at about one billion years. This raises the question of what heat source would exist that would drive cryovolcanic activity that late in Pluto’s history. Changing tidal pulls can be ruled out because both Pluto and its large moon Charon have one face gravitationally locked to the direction of the other body, eliminating changes in tidal forces.
White Dwarf’s Exoplanet – Astronomers at the University of Tasmania discovered a Jupiter-mass exoplanet with a Jupiter-like orbit around a white dwarf star. Because white dwarfs already passed through the giant phase, this is another piece of evidence that planets can survive the giant stage. This exoplanet was discovered using an unusual method: it showed up in a gravitational microlensing event, where a star passes in front of the exoplanet and the star’s gravity bends the light of the background object, brightening it. This is the first discovery of a planet orbiting a white dwarf that was made using microlensing. The system was confirmed in infrared by the Keck-II telescope in Hawaii. While there is plenty of evidence of rocky planet debris orbiting white dwarfs, there are few intact planets doing so. It has been proposed that planets widely orbiting white dwarfs are common, so that they were outside the reach of the stars’ giant phases, but they are just hard to detect.
Exoplanet Clouds – An international team of astronomers have detected clouds in the atmosphere of an exoplanet named WASP-127b and determined the altitude of those clouds. The work used both visible light from a ground-based telescope and infrared observations from a space telescope, since those different wavelengths penetrate different depths of the planet’s atmosphere. The measurements were made spectroscopically while the planet was passing in front of its star, allowing starlight to pass through the planet’s atmosphere. Sodium and water vapor layers were found, and clouds of unknown constitution above that. The planet is a “hot Saturn,” with a mass similar to Saturn, but orbits so close to its star that it reach over 1,900 degrees Fahrenheit. This puffs up the atmosphere to 1.3 times the size of Jupiter, making it one of the least dense planets known.
Exoplanet Auroras – Scientists at Leiden University, using the LOFAR radiotelescope array discovered radio signals from 19 red dwarf stars which may be generated by auroras associated with unseen exoplanets. Further observations planned will search for periodic behavior in the radio signals and for more evidence of the planets using optical telescopes. LOFAR operates at lower radio frequencies than other radiotelescopes. Elements of LOFAR are spread across Europe.
Lucy Launches – On October 16, the Lucy spacecraft launched to begin a 12-year mission to explore Trojan asteroids for the first time. Those asteroids share Jupiter’s orbit, occupying the gravitationally stable Lagrange points that lie ahead and behind the giant planet. They are called Trojans because they are individually named after heroes of the mythological or perhaps historic war between Greece and Troy. Two flybys of Earth are planned, in 2022 and 2024, for gravity slingshots to extend the spacecraft’s orbit out to the outer Solar System. The spacecraft sports two huge circular solar panels to power it even though it will reach the farthest distance ever from the Sun of any solar powered craft. Lucy was named after the three-million-year-old fossil of a human ancestor found in east Africa in 1974 by Donald Johanson. Astronomers hope that the mission will fill in a major gap in Solar System history like the fossil filled in pre-human history. Astronomers believe that the Trojan asteroids have been relatively undisturbed since they formed at the same time as the Solar System planets and are likely made of the same material that formed the cores of the giant planets. Lucy the fossil was named after the Beatles song “Lucy in the Sky With Diamonds.” Lucy the spacecraft does indeed have a diamond in the sky, as a component of an optical instrument. A plaque on the side of the spacecraft has inspirational quotes from Einstein, Sagan, several poet laureates, and the Beatles. On the way to the Trojans, the spacecraft will flyby a main-belt asteroid, which has fittingly been named Donaldjohanson. Seven Trojans will be visited, split among the leading and trailing Lagrange zones.
Lunar Rover Landing Site – NASA is planning to land a rover named VIPER on the Moon in 2023 to look for near-surface ice and other resources. They have now announced that a landing site has been selected: near the western edge of Nobile Crater in the south polar area. There is considerable evidence that there is ice in the Moon’s polar areas. The selected landing site has areas of permanent shadow and sunny areas. The shadow areas are most likely to have preserved ice, but the sunny areas are needed to recharge the rover’s batteries using solar panels. VIPER is part of the Artemis program to land people on the Moon.
Asteroid Mission – The University of Colorado at Boulder made an agreement to build a spacecraft for the United Arab Emirates that will flyby six asteroids, and land on a seventh, to launch in 2028. The same parties built the Hope spacecraft that is now orbiting Mars.
Space Tourists – Blue Origin launched its second New Shepard rocket with crew to suborbital space. Aboard was William Shatner, the actor who played Captain Kirk, exploring the galaxy on Star Trek television and films. At age 90, he is the oldest person to reach space. Three other space tourists were on board, including a vice president of Blue Origin.
Space Movie – Russian actress Yulia Peresild and movie producer Klim Shipenko rode to the International Space Station aboard a Soyuz rocket to film the space-location parts of a movie called “Challenge” during a 12-day stay in space. Some cosmonauts also participated. The plot involves a surgeon who operates and saves the life of a cosmonaut in space. This is the first entertainment film, as opposed to documentaries, to be shot in space.
