Astronomy and space news summarized by Don Lynn from NASA and other sources

The Hubble Space Telescope shut down all observations on June 13 because of a failure in its payload computer, which controls all its onboard instruments. On the ground, operators switched the telescope to use the backup payload computer, but that didn’t fix the issue. Days of troubleshooting showed that the failure had to be in another component that interfaces with the payload computer. After several trials, controllers switched to the backup command and data unit, and that fixed the problem. The failure was in the power unit within the command and data unit. Hubble was out of service for just over a month and the observations that were scheduled during that time are being rebooked for later times. Hubble has been operating for 31 years and has made 1.5 million observations. It was last serviced by astronauts in 2009, but such servicing is no longer possible since the Space Shuttles were retired.

Hubble Tension – Two of the main ways of measuring the expansion rate of the Universe, known as the Hubble Constant, have generated conflicting results, but ongoing work by researchers at the University of Chicago appear to be easing the tension. Measurements of the expansion’s effects on the Cosmic Microwave Background (CMB) settled in on a value of 67 kilometers per second per megaparsec, but techniques derived from the distances and speeds of distant Type Ia supernovas yield values around 74, a discrepancy dubbed the Hubble tension. A new paper by Wendy Freedman recalculates the Hubble Constant using the supernova method but added a new calibration. Previous research used a type of pulsing star known as a Cepheid variable to calibrate the distance to the Type Ia supernovas, but Freedman and her team have been developing a method that better calculates the distances using the brightest red giant stars. With this, they came up with a Hubble constant of 69.8, much closer to CMB results, and are continuing to refine their measurements.

Zodiacal Light – It has long been known that the Zodiacal Light, a faint wedge of light seen at dusk or dawn, is caused by sunlight reflecting off dust particles residing in a disk in the plane of the planets. It had been generally believed that this dust came from collisions in the asteroid belt. The spacecraft Juno flew through the zone of the Zodiacal Light disk twice between launch and arrival at Jupiter and recorded every time a dust particle collided with its solar panels. A new analysis of this data by researchers at the Technical University of Denmark found that very little dust was encountered in the asteroid belt, but much was found orbiting near Mars, meaning the source of Zodiacal Light dust appears to be Mars. Dust has long been observed lifting high in the Martian atmosphere during storms, but how the dust achieves enough speed to escape the planet’s gravity is still a mystery.

Ingenuity – The Mars helicopter Ingenuity made two more flights in the past month. One of these set new records for the fastest flight (11 mph) and the longest in both time (166 seconds) and distance (2050 feet). It scouted some nearby fractures and boundaries between rock layers, locations that the Perseverance rover might want to visit, as well as a huge sand trap, a spot that the rover should avoid. It was the first time that the helicopter navigation system had to deal with undulating ground beneath it.

Martian Methane – Since 2004, various spacecraft have reported conflicting observations of methane in the atmosphere of Mars, but measurements by the Curiosity rover may have solved the issue. The rover sniffed for methane at various times of day and night and found that the gas was present only at night, usually peaking near one part per billion. Previously, the best methane detections had been made at night, while the most sensitive non-detections had been made in daytime. Additionally, the Perseverance rover, located 2,300 miles away, never detected methane, while the Curiosity rover found it, so it appears to be location dependent, as well as time dependent. Scientists still don’t know what is emitting methane, or how it dissipates in mere hours.

Martian Aurora – The Hope spacecraft, sent to Mars by the United Arab Emirates, observed scattered areas of aurora in ultraviolet light over the Red Planet. The aurora does not concentrate at the magnetic poles like it does on other planets, because Mars long ago lost its planet-wide magnetic field.

Cosmic Web – Astronomers at the Leibniz Institute for Astrophysics Potsdam have found that the dust, gas and dark matter that make up the filaments connecting galaxies in the massive cosmic web, are spinning slowly about their long axes. This was measured by taking spectra of galaxies on both sides of 17,000 cosmic filaments and finding slightly more redshift on one side than on the other. The Millennium Simulation, a computer program that simulates evolving of the cosmos over time, had predicted that the filaments in the cosmic web should spin. The cosmic web is composed of huge filaments that connect clusters of galaxies.

Black Hole Jets – The Event Horizon Telescope (EHT), an international array of eight radiotelescopes most famous for producing the first image of a black hole two years ago, imaged the center of the galaxy Centaurus A, 13 million light-years away. Because of the size of the black hole in Centaurus A and its distance, the EHT could not resolve the detail of the black hole but did observe the bases of the jets thrown out from near the black hole. The jets appeared hollow with brightly glowing edges. The image has 16 times better resolution than any previous ones of Centaurus A.

Inevitable Supernova – An international team of astronomers led by scientists at the University of Warwick monitored the light variations from a star known as HD265435 and concluded that it must be tear-drop shaped, pulled by a dimmer but massive companion star. Further observations showed that the companion is a white dwarf star with about the mass of our Sun, and the pair are so close together that they orbit each other in about 100 minutes. In about 70 million years, they will spiral together, and their combined mass is enough to cause a Type Ia supernova explosion. By that time, the star will reach the end of its life and also become a white dwarf.

Unusual Supernova – Theorists have long proposed that stars about eight to ten times the mass of the Sun should, at the ends of their lives, collapse and explode as supernovas by a different mechanism than more massive stars. This has been termed an electron-capture supernova. Magnesium and neon atoms in their core capture electrons, thereby reducing the electron pressure in the core, resulting in the core collapsing into a neutron star, but exploding away the outer layers. New analysis by astronomers at the University of California Santa Barbara and the University of California, Berkeley of a supernova seen in galaxy NGC 2146 in 2018 shows that it had many properties predicted for an electron-capture supernova: before it exploded, the star was a particular type of red giant known as a super-asymptotic giant branch star; it was between eight and ten solar masses; it had shed much mass before exploding; the shed mass was abundant in helium, carbon and nitrogen, but with little oxygen; the explosion was weaker than normal; the light of the explosion lingered longer than typical; the remnant contained stable nickel but not radioactive nickel. Archived space telescope observations allowed astronomers to identify the star that later exploded, an unusual situation. Astronomers also think that the Crab Nebula, the remnant of a supernova seen in the year 1054, may also be an electron-capture supernova.

Most Massive White Dwarf – Counterintuitively, the more massive a white dwarf star is, the smaller its diameter. Astronomers at Caltech found white dwarf set the record for the largest known mass and for the smallest known diameter. It is 1.35 solar masses, and only about 1.2 times the diameter of our Moon. Most white dwarfs are roughly the diameter of the Earth, far larger than Moon-sized. The astronomers believe that this white dwarf reached this large mass when two smaller white dwarfs merged. If the two merging stars had been more massive, the result would not have remained a white dwarf, but instead would have collapsed into a neutron star. When two white dwarfs merge, they get a boost in magnetic field intensity and in spin rate. This particular white dwarf has a magnetic field nearly a billion times as strong as our Sun and spins once every seven minutes. This is near the white dwarf spin record of 5.3 minutes.

Gravitational Waves – In January gravitational wave detectors recorded two events, ten days apart, that match predictions of a black hole colliding with a neutron star. All previous gravitational wave detections have been of two like objects colliding, either two black holes or two neutrons stars, with one possible exception that is still being debated. The new detections were certainly from a black hole and neutron star, as their masses were firmly determined. Both collisions occurred somewhat under a billion light-years away. The first collision was a black hole with nine times the Sun’s mass consuming a neutron star with 1.9 solar masses. The second consisted of a black hole with six solar masses and a neutron star with 1.5 solar masses. The collisions were too far and too faint to be seen by any telescope. Collisions between these unlike objects are predicted to be commonly detected with the level of sensitivity of the gravitational wave detectors on their next observing run, scheduled for summer of 2022.

Planet Formation – A team of scientists at the Universidad de Chile used ALMA, a radiotelescope array in Chile, to study the young star named Elias 2-27. They found evidence of gravitational instabilities in the disk of material about the star, showing that instability plays a role in planet formation. The instabilities formed spirals within the disk. The gas in the disk was found to be asymmetric, which was unexpected, as well as an unexplained gap in the disk. The star is under 400 light-years away in Ophiuchus.

Venus Crustal Blocks – A new study, led by researchers at North Carolina State University, of radar images of Venus found that parts of the lowlands consist of broken blocks of the planet’s crust that moved in a manner similar to pack ice on Earth. However, they are not like Earth’s tectonic plates as they don’t flow under and subduct one another when they collide, nor do they build large mountains. There are places on Earth’s continental interiors where crustal blocks have been seen with motions that resemble these Venusian ones. The Venusian blocks are geologically very young, and their motion may have continued until the present. Scientists believe that Earth’s crust during its early history may have broken and moved like these new observations of Venus, because the Earth’s crust was thinner in the distant past.

Enceladus Methane – New analysis by researchers at the University of Arizona and the Paris Sciences et Lettres University of old Cassini spacecraft data detected methane in the geysers of Saturn’s moon Enceladus. One of the ways methane is generated on Earth is by tiny organisms feeding off material spewing out of hydrothermal vents at the bottom of oceans. Enceladus is believed to have hydrothermal vents at the bottom of its ocean, but the scientists in this analysis are not ready to conclude that life is involved in the Enceladus ocean.

Jovian Moons – An amateur astronomer named Kai Ly discovered a new moon of Jupiter, provisionally named S/2003 J 24. This is the same person who recovered some “lost” moons of Jupiter last year. The recoveries and discovery were made by searching publicly available images made by the 3.6-meter Canada-France-Hawaii telescope around 2003 by professional astronomers who discovered 23 moons of Jupiter. The amateur also used images made by other telescopes to find the object as late as 2018. There are probably still many more moons of Jupiter to be found. Some really deep images taken last year of an area near Jupiter found dozens of new objects, but didn’t follow up to determine their orbits. From this it was estimated that there are about 600 Jovian moons of at least a half mile size.

Large Comet – Astronomers at the University of Pennsylvania discovered what may be the largest known comet. It was at first given an asteroid designation, 2014 UN₂₇₁, but was declared a comet, designated C/2014 UN₂₇₁ (Bernardinelli-Bernstein), when a faint comet coma was found surrounding it. Its orbit shows it came from the Oort Cloud and will make its perihelion, its closest approach to the Sun, near Saturn’s orbit in 2031. Its orbital period is roughly five million years, and its aphelion, the farthest point from the Sun in its orbit, is about a light-year. Unfortunately, the large perihelion will likely prevent it from getting very bright as seen from Earth. It is expected to reach only magnitude +17, about the same as Pluto’s moon Charon, unless it happens to outburst. From its brightness, it is estimated to be roughly 60 miles across, though different estimates vary considerably, both smaller and larger. It was discovered in archived images from the Dark Energy Survey, which maps galaxies over a large portion of the sky using a very wide-field camera on the 4-meter Victor Blanco Telescope in Chile. When found, the comet was located around the orbit of Neptune, the farthest distance at which a comet has been discovered.

New ISS Solar Panels – Astronauts have begun replacing the solar panels on the International Space Station (ISS) in a series of spacewalks. The new panels are much more efficient in that they generate more power even though they are smaller in area. The new design delivers the panels rolled up for the astronauts to unfurl during installation, while the old design unfolded like an accordion when they were deployed. The new panels are part of the plan to increase total ISS power to support the Artemis program to return to the Moon.

New Station Module – Russia launched a module called Nauka, which translates to “science”, to the ISS. At 22 tons and 42 feet long, it is now the largest ISS module. It takes the place of the Pirs module, which was discarded into the Pacific Ocean. Nauka chiefly houses research facilities, but also adds a bedroom and toilet. It has its own oxygen and water recycling systems, and sports an external mechanical arm supplied by Europe.

Squid in Space – 128 baby bobtail squid were launched to the ISS as an experiment to determine how immune systems change during spaceflight. It is hoped that what is found will also apply to astronaut immune systems, which are known to change in space. Also 5000 tardigrades, microscope animals, were launched to understand how they adapt to extreme conditions of space.

New Lunar Missions – NASA selected three new science packages to land on the Moon around 2024: Lunar Vertex, which includes a rover, that will investigate the magnetic fields in a lunar swirl; Farside Seismic Suite, which will measure moonquakes from the Schrödinger basin, near the lunar south pole; LITMS, also landing in the Schrödinger basin, to measure heat flow from within the Moon, and electrical conductivity.

Space Tourism – Richard Branson, founder of the Virgin Galactic spaceflight company, rode along with five other crew members to the edge of space on July 11. It was the first flight with passengers of the rocket plane VSS Unity and it flew to an altitude of about 53 miles, crossing NASA’s definition of the boundary of space at 50 miles up. The crew experienced a couple minutes of weightlessness, but the plane is not capable of the speed required to reach orbit. Not to be outdone, Jeff Bezos, founder of the Blue Origin spaceflight company, on July 20 rode his rocket New Shepard to above 62 miles altitude, which is the international definition of the edge of space. Along for the ride were Bezos’s brother, an 18-year-old student from the Netherlands – now the youngest person ever to fly to space – and Mary Wallace “Wally” Funk – now the oldest person to fly to space. Wally was a member of the corps of women who trained as astronauts in the 1960s, but who never were given the opportunity to fly to space. Both companies plan to take paying passengers to space on a regular basis soon.