Astronomy and space news summarized by Don Lynn from NASA and other sources
InSight – All solar panels sent to the surface of Mars eventually collect enough dust to seriously degrade the power generated. Sometimes a passing windstorm or dust devil will clean some of the dust off, restoring power. Unfortunately, nature has not cleaned the solar panels on the InSight lander, and spacecraft controllers are planning to turn off its instruments, including the seismograph, during the Martian season of least available sunlight, leaving only heaters and other necessary equipment turned on. They would like to delay this science stoppage as long as possible, so in labs here on Earth spacecraft engineers tried everything they could think of to clean InSight’s solar panels. What worked best was dribbling coarse-grained sand onto the solar panels on a windy day. The blowing sand scrapes off some of the dust. Spacecraft controllers tried this on the real InSight on Mars, and it worked. Solar panel power is up by 30 watt-hours per Martian day, and the instruments can be left on a while longer.
Ingenuity – The Mars helicopter Ingenuity made the first two flights of its extended mission, its sixth and seventh flights overall. Flight six encountered a glitch in its navigation system, but flew the rest of the planned flight while wobbling, and landed gently about 16 feet from the planned site. Craft controllers fixed the error and flight seven went without any problems. The issue was that a timing problem lost one of the images taken of the ground under the helicopter, which it uses to navigate. After the image was lost, the helicopter control software thought that it was at the location of the latest image at an incorrect time. However, stability software in the copter kept it flying regardless. The landing software does not use the navigation images in the same manner, so landing happened perfectly. Controllers plan to fly Ingenuity about every two weeks, testing new capabilities, for a few more months.
Martian Clouds are fairly rare, but do occur more often during the coldest part of the Martian year. Scientists at the Space Science Institute working with the Curiosity rover made a special effort to image the clouds this season. They captured wispy clouds, filled with ice crystals, some of them showing iridescent color. The first clouds of the season were found to be at higher altitude than the later ones. Typical clouds are up to 37 miles high and are water ice. The early clouds are higher than that and likely carbon dioxide ice (dry ice). Some of these clouds qualify as noctilucent clouds, as they are lighted much of the nighttime due to their altitude.
Solar Discoveries – A team of astronomers at the University of Hawaii who have taken spectroscopic measurements of the Sun’s corona during more than a decade of total solar eclipses has announced some new discoveries. The temperature of the corona does not change much with the 11-year cycle of sunspots and other activity on the Sun. Both the slow and fast portions of the solar wind appear to originate from corona material at about the same temperature. Probably that speed depends on magnetic fields, not temperature. Coronal mass ejections and dynamic solar wind appear to originate in hot sheaths around prominences. The team used not only their observations, but also ones made by ACE, a solar space telescope.
Juno – NASA’s Juno spacecraft has completed its primary mission of studying Jupiter and is beginning its extended mission, which includes flybys of some of Jupiter’s moons. The first of these, a pass by Ganymede, occurred June 7. The Jovian moons have not been seen close-up since the Galileo mission about 20 years ago. Juno’s flybys will afford an opportunity to see if anything has changed during the intervening years. Ganymede is the largest moon in our Solar System, even larger than the planet Mercury.
Resonant Planets’ Future – About 13 years ago, a system of four exoplanets was found orbiting the star HR 8799 in resonance with each other, such that the lengths of the years of the planets were in the ratios 1:2:4:8. Astronomers wondered how long this system would remain stable, so recently researchers at the University of Warwick and University of Exeter ran a computer simulation of these planets. They found that the planets should remain in their same orbits until their star swells into a red giant in about three billion years. At that time their orbits will become chaotic, with many possible outcomes, including ejecting some planets out of the system and sizes of the orbits changing or exchanging. The system now has a dust disk inside the planets’ orbits and another disk outside. These disks will be greatly disturbed when the planets go chaotic, with much disk material thrown into the star.
Exoplanet Ideal For Atmospheric Observations – A team of astronomers at NASA’s Jet Propulsion Laboratory and the University of New Mexico discovered an exoplanet whose properties make it an excellent candidate for studying its atmosphere. It is somewhat smaller than Neptune, and about the same density, so is likely an ice giant with a deep hydrogen-helium atmosphere. The planet orbits its red dwarf star every 24 Earth days, has a fairly high orbital velocity and a temperature only a bit hotter than Earth. It is only 90 light-years away, and crucially it transits its star. Every one of these features makes it easier to get spectra of the planet’s atmosphere. The planet was discovered in data from the TESS planet-finding space telescope and is known as TOI-1231 b. Observations with the Hubble Space Telescope are already scheduled, and it is hoped to observe the planet with the James Webb Space Telescope when it is operational.
FRBs – The Hubble Space Telescope took images of several locations where radiotelescopes had detected Fast Radio Bursts (FRBs) and found that five of these bursts originated in the outer arms of distant spiral galaxies. The new observations were made in ultraviolet and infrared light and analyzed by a team at the University of California, Santa Cruz. All the five galaxies are so distant that the light took about half the age of the Universe to reach us. There are several theories as to what causes FRBs, and these new observations are most consistent with the theory that they’re emitted by magnetars, extremely magnetic neutron stars.
More FRBs – How do astronomers find FRBs if they last only milliseconds? Radiotelescopes rarely are pointed just the correct location when an FRB occurs. The answer is the CHIME radiotelescope, operated by an international collaboration. It consists of four large, half-cylindrical antennas anchored to the ground in Canada. It detects radio from all directions above ground. A supercomputer sorts out from what direction each radio signal came by analyzing the timing at which each signal reached the various parts of the antenna. CHIME has detected 535 FRBs in its first year of operation. Only 18 of those have emitted more than one FRB from the same location in the sky, what astronomers refer to as repeaters. All the others have failed to repeat during CHIME operation so far. The repeaters and one-timers were found to have slightly different frequency and timing characteristics. This implies there are likely two different mechanisms producing FRBs. From the rate at which CHIME is finding FRBs, scientists estimate that there are about 800 FRBs per day in the visible Universe.
White Dwarf Core Density – The core density of a white dwarf at the time of its explosion as a Type Ia has been measured for the first time by researchers at the Kavli Institute for the Physics and Mathematics of the Universe. They measured the ratios of isotopes of titanium and chromium, through the X-ray spectrum in the cloud of debris left after the explosion. Computer simulations of Type Ia supernovas show that those isotope ratios are quite sensitive to the density of the core of the white dwarf before it explodes. The density of this particular white dwarf was found to be about three times higher than is typical for a white dwarf. The supernova remnant is known as 3C 397, a radio source designation, since it was first discovered by radio astronomy. Researchers want to better understand how Type Ia supernovas work, as they are used as “standard candles” to determine distances to distant galaxies.
Cosmic Web – There have been only a few detections of the cosmic web, the thin gas filaments that connect galaxies. This web is difficult to detect, and in fact all such detections have been in distant locations. A new study by astronomers at Penn State mapped the dark matter more locally and found that it shows much the same cosmic web structure that distant ordinary matter exhibits. This was expected, because simulations of the Universe developing show the cosmic web forming as dark matter, followed by ordinary matter falling in. The team trained a computer program to recognize dark matter about ordinary matter, using areas where previous work had shown dark matter exists, then the trained program was fed a comprehensive map of all the relatively nearby galaxies, and that produced the dark matter map.
Venus Missions – NASA announced the next two missions in its Discovery series, a class of relatively inexpensive spacecraft. Both will fly to Venus. One craft, named DAVINCI+, will orbit that planet to study its atmosphere, and drop a probe into the atmosphere. The other probe, named VERITAS, will map the planet’s surface from orbit using infrared and radar, with particular attention to its geology. NASA hasn’t sent a spacecraft to Venus since Magellan, whose mission ended in 1994. The European Space Agency is also planning a Venus probe, named EnVision, equipped with capabilities to observe the atmosphere, surface, and underground. Unfortunately there was not enough NASA money in this round of mission selection for two other highly regarded proposals: a spacecraft to Jupiter’s moon Io and a mission to Neptune’s moon Triton. Maybe next time. Two previously approved Discovery missions are under construction for launch this year: Lucy to explore Trojan asteroids, which share Jupiter’s orbit; and Psyche to explore the asteroid Psyche.
New Space Telescope – NASA announced that work is beginning on designing an infrared space telescope to find and track potentially hazardous asteroids and comets. Its name is NEO Surveyor, and it will observe from beyond the Moon’s orbit. Even dark objects, and many asteroids are dark, show up well in infrared. Also a fairly accurate size can be calculated from infrared data, but not from visible light data, when the object is too small to resolve, as is the case with most near-Earth objects. The goal is to complete within about a decade the task begun in 2010 of finding most of the potentially hazardous objects over about 460 ft across, since those could cause serious damage if they collide with Earth. The University of Arizona will lead the project.
Tiangong Crew – The Chinese space agency sent a crew of three to their recently-launched Tiangong space station. Their stay is planned to be about three months, which will be by far the longest mission for Chinese astronauts. This is the first Chinese space mission with crew in about five years.
SLS – The first SLS rocket had its solid rocket boosters bolted to the main stage. Its launch on a flight without crew around the Moon is expected late this year or early next. The SLS is NASA’s most powerful rocket, to exceed the Saturn V of the Apollo era.
JWST – The latest estimate is that NASA’s James Webb Space Telescope (JWST) will likely be launching in November this year, rather than October, because though the telescope is on schedule, the rocket is not. An Ariane 5 rocket will launch JWST, and two recent Ariane 5 launches have had anomalous performance at the time of shedding the fairing (payload cover), and JWST engineers wish to have analyses of these problems finished and closely watch the performance of the next two Ariane 5 launches, which are scheduled for June and August, before committing to the JWST launch.
