If all goes well (an often perilous assumption, as JWST so frequently reminds us), NASA's Psyche mission to the intriguing asteroid of the same name will lift off in about two years. We're now moving out of the design and planning stage into manufacturing the spacecraft hardware, this following a period of testing on the core engineering models that will deliver the spacecraft to its target in the main asteroid belt. The critical design review, a shakeout of the three science instruments and engineering subsystems, has just been passed with flying colors. Principal investigator Lindy Elkins-Tanton (Arizona State University) calls the process "one of the most intense reviews a mission goes through in its entire life cycle." True enough, as everything from telecommunications, power and propulsion must pass the test, not to mention the flight avionics and computing systems. We're a long way past the digital blueprint stage, having followed it up with prototypes and engineering models of...

Another win for amateur astronomers. Have a look at a Juno image showing the familiar Great Red Spot (upper left) and a new, bright spot just emerging in the center of the image, an oval-shaped feature that was not present in images taken not long before by astronomers in Australia. We're looking at a plume erupting into the upper layers of the atmosphere, a convective outbreak in a region known as the South Temperate Belt, a latitude where outbreaks are not uncommon. Image: Juno's view of the swath of Jupiter visible from its recent flyby. Credit: NASA/JPL-Caltech/SwRI/MSSS. Image processing by Kevin M. Gill. The Juno image, taken on June 2, 2020, is fortuitous, because it was just two days before that South African amateur Clyde Foster (who is director of the Shallow Sky section of the Astronomical Society of Southern Africa) discovered the new spot while working with a filter sensitive to wavelengths where there is strong methane absorption in Jupiter's atmosphere. Juno happened...

What we learn about Europa may resonate with other moons in the Solar System, making the study of this 'ocean world' even more valuable as we look elsewhere among the gas giants. I notice this morning that a team of researchers from the Jet Propulsion Laboratory has presented results on Europa at the Goldschmidt conference, held virtually from the 21st to 26th of this month. The work models geochemical reservoirs within Europa, analyzing the composition and properties of the core, a layer of silicates, and the ocean itself. In the absence of hard data, models will have to do, and here we learn that a plausible composition for the Europan ocean can be advanced, one that postulates the breakdown of water-bearing minerals and the release of the trapped water. Mohit Melwani Daswani is lead researcher: "We find that different minerals lose water and volatiles at different depths and temperatures. We added up these volatiles that are estimated to have been lost from the interior, and found...

38 K, which translates to -235 Celsius or -390 Fahrenheit, is cold enough to allow atmospheric nitrogen to condense as surface frost, which appears to be what is happening on Neptune's large moon Triton. This is an intriguing place, with pinkish deposits at the enormous south polar cap that are thought to contain methane ice -- the color would derive from reactions with sunlight to form a variety of pink or red compounds. Moreover, there are geyser-like plumes here that leave dark streaks over the ices, some of them active when Voyager 2 flew past. All this and Triton's odd 'cantaloupe' terrain, still mysterious, and what appear to be landscape features produced by liquid eruptions from Triton's interior. Absorbed by Triton and its mysteries for decades now, I'm all in on a Discovery Program mission concept called Trident, now under discussion at NASA (see Firming Up the Triton Flyby for my initial take on this one). It has been 31 years since Voyager's August 25, 1989 flyby. I still...

Finding out that Titan is migrating away from Saturn should cause little surprise. Our own Moon moves away from the Earth at about 38 millimeters per year (even as Earth's rotation slows ever so slightly, lengthening the day by 23 microseconds every year). Titan's gravitational pull on Saturn causes frictional processes inside the giant world that ultimately impart energy to Titan, moving it away from its host in a similar way. The surprise attendant to a new paper on this phenomenon is the size of the movement, about 100 times greater than had been expected. The paper explains the migration process like this: Tidal friction within Saturn causes its moons to migrate outwards, driving them into orbital resonances that pump their eccentricities or inclinations, which in turn leads to tidal heating of the moons. What we're wrestling with here are the processes of energy dissipation in giant planets, which determine the timescale for their moons' tidal migration. The theory advanced in...

Terraforming a world is a breathtaking task, one often thought about in relation to making Mars into a benign environment for human settlers. But there are less challenging alternatives for providing shelter to sustain a colony. As Robert Zubrin explains in the essay below, ice-covered lakes are an option that can offer needed resources while protecting colonists from radiation. The founder of the Mars Society and author of several books and numerous papers, Zubrin is the originator of the Mars Direct concept, which envisions exploration using current and near-term technologies. We've examined many of his ideas on interstellar flight, including magsail braking and the nuclear salt water rocket concept, in these pages. Now president of Pioneer Astronautics, Zubrin's latest book is The Case for Space: How the Revolution in Spaceflight Opens Up a Future of Limitless Possibility, recently published by Prometheus Books. by Robert Zubrin Abstract This paper examines the possibilities of...

Were deviations in Jupiter's magnetic field, recorded by Galileo's magnetometer during a flyby of Europa in 2000, an indication of a cryovolcanic eruption? The data on this event have been evaluated by several independent groups in Europe and the US, an indication of how much interest such a plume would generate. If, like Enceladus, Europa occasionally blows off material from below the surface, we would have the possibility of collecting water from its ocean without having to drill through kilometers of ice. Now a team of European Space Agency scientists led by Hans Huybrighs, working with colleagues at the Max Planck Institute for Solar System Research (MPS), has gone to work on the question, this time through the measurements made by Galileo's Energetic Particles Detector (EPD), an instrument with roots both at MPS and the Applied Physics Laboratory of Johns Hopkins University (APL). EPD recorded significantly fewer fast-moving protons near Europa than expected during the same...

Space exploration has been filled with its share of frustrations, the most obvious being the lack of follow-up with travel to the Moon following Apollo 17. That's been a 50-year gap and counting, but a gap of half that size is also unsettling. It was in late 1995 that the Galileo probe began orbital operations at Jupiter, and since then we've had to rely on its imagery of Europa when we needed close up views of the ocean-filled moon. While we await Europa Clipper, scheduled for 2024 launch, and Jupiter Icy Moon Explorer (JUICE), slated by ESA for a departure in 2022, we're still refining Galileo images in preparation for future flybys. One thing the newly touched up images should remind us of is that Europa Clipper is going to give us views of much larger parts of Europa's surface at high resolution, complementing but considerably extending what Galileo was able to do. The latter was a mission with its own set of frustrations, of course, as a recollection of its unusable high gain...

Given their distance from the Sun, the gas and ice giants of our Solar System should not have upper atmospheres as hot as they are. Clearly, something is happening at the planets themselves to account for the warmth, and new analysis of Cassini data, just published in Nature Astronomy, lays out the case for auroral activity at the north and south poles of Saturn as the explanation there. The paper offers the results of the most complete mapping yet made of the temperature and density of a gas giant planet's upper atmosphere. Tommi Koskinen, a co-author on the paper describing these findings is a member of Cassini's Ultraviolet Imaging Spectrograph (UVIS) team: "The results are vital to our general understanding of planetary upper atmospheres and are an important part of Cassini's legacy. They help address the question of why the uppermost part of the atmosphere is so hot while the rest of the atmosphere - due to the large distance from the Sun - is cold." Image: This false-color...

Voyager 2’s flyby of Uranus and its moons occurred on January 24, 1986, returning images that for many of us will always be associated with the outpouring of grief over the loss of Challenger, which occurred a scant four days later. But Voyager’s data were voluminous, its images striking, as we examined the ice giant and its unusual moons up close. The spacecraft closed to 81,500 kilometers of the cloud tops, examining the ring system and discovering 11 new moons. Image: The planet Uranus, in an image taken by the spacecraft Voyager 2 in 1986. The Voyager project is managed for NASA by the Jet Propulsion Laboratory. Credit: NASA/JPL-Caltech. Uranus was already known from early analysis of the Voyager data to have an odd magnetosphere, created where solar wind plasma interacts with the planet’s magnetic field. The planet spins on its side, and its magnetic field axis is tilted 60 degrees away from its spin axis, producing a magnetosphere that wobbles in ways that researchers liken to...

316 Trans-Neptunian Objects (TNOs) have turned up in a new analysis of data from the Dark Energy Survey, 139 of these being new objects that have not been previously published in the literature. With roughly 3,000 TNOs known, the catalog from this work represents a healthy 10 percent of the total, but more significantly, extends and fine-tunes our methods for tracking such objects. Trans-Neptunian Objects, of which Pluto/Charon represents the best known, orbit beyond Neptune, with Kuiper Belt Objects being a sub-category existing between 30 and 55 AU from the Sun. Here the population is thought to be in the tens of thousands when restricting the definition by size to objects at least 100 kilometers across. But to these Kuiper Belt objects we can add the population of so-called Scattered Disk Objects, which exist in eccentric and inclined orbits, the more extreme of these with semi-major axes between 150 and 250 AU (and then there's Sedna, with aphelion now estimated at more than 900...

With surface temperatures around -180° C, Titan presents problems for astrobiology, even if its seasonal rainfall, lakes and seas, and nitrogen-rich atmosphere bear similarities to Earth. Specifically, what kind of cell membrane can form and function in an environment this cold? Five years ago, researchers at Cornell used molecular simulations to screen for the possibilities, suggesting a membrane the scientists called an azotosome, which would be made out of the nitrogen, carbon and hydrogen molecules known to exist in Titan's seas. The azotosome was a useful construct because the phospholipid bilayer membranes giving rise to liposomes on Earth need an analog that can survive Titan's conditions, a methane-based membrane that can form in cryogenic temperatures. And the Cornell work suggested that azotosomes would create a similar flexibility to cell membranes found on Earth. Titan's seas of methane and ethane, then, might offer us the chance for a novel form of life to emerge....

We're learning more about the composition of Jupiter's atmosphere, and in particular, the amount of water therein, as a result of data from the Juno mission. The data come in the 1.25 to 22 GHz range from Juno's microwave radiometer (MWR), depicting the deep atmosphere in the equatorial region. Here, water (considered in terms of its component oxygen and hydrogen) makes up about 0.25 percent of the molecules in Jupiter's atmosphere, almost three times the percentage found in the Sun. All of this gets intriguing when compared to the results from Galileo. You'll recall that the Galileo probe descended into the Jovian atmosphere back in 1995, sending back spectrometer measurements of the amount of water it found down to almost 120 kilometers, where atmospheric pressure reached 320 pounds per square inch (22 bar). Unlike Juno, Galileo showed that Jupiter might be dry compared to the Sun -- there was in fact ten times less water than expected -- but it also found water content increasing...

It's not a Triton, or even a Neptune orbiter, but Trident is still an exciting mission, a Triton flyby that would take a close look at the active resurfacing going on on this remarkable moon. Trident has recently been selected by NASA's Discovery Program as one of four science investigations that will lead to one to two missions being chosen at the end of the study for development and launch in the 2020s. These are nine-month studies, and they include, speaking of young and constantly changing surfaces, the Io Volcanic Observer (IVO). The other two missions are the Venus Emissivity, Radio Science, InSAR, Topography, and Spectroscopy (VERITAS) mission, and DAVINCI+ (Deep Atmosphere Venus Investigation of Noble gases, Chemistry, and Imaging Plus). Each of these studies will receive $3 million to bring its concepts to fruition, concluding with a Concept Study Report, at which point we'll get word on the one or two that have made it to further development and flight. The NASA Discovery...

The dataflow from New Horizons has been abundant enough that we are now drilling down to atmospheric models that may explain the dwarf planet’s topography. Mention topography on Pluto and the first thing that leaps to mind is Tombaugh Regio, and a new paper in the Journal of Geophysical Research Planets actually takes us into its role in the formation of regional weather patterns on the icy orb. For at the heart of Pluto’s weather appears to be the terrain often called Pluto’s ‘heart,’ from the distinctive shape it imposes upon the landscape. Pluto’s atmosphere, 100,000 times thinner than ours, is primarily nitrogen, with but small amounts of carbon monoxide and methane. Tombaugh Regio is covered by nitrogen ice, which warms during the day, turning to vapor that condenses in Pluto’s night to once again form ice. The researchers, led by Tanguy Bertrand, an astrophysicist and planetary scientist at NASA’s Ames Research Center in California and the study’s lead author, liken the process...

3548 Eurybates is a Jupiter trojan, one of the family of objects that have moved within the Lagrange points around Jupiter for billions of years (the term is libration, meaning these asteroids actually oscillate around the Lagrange points). Consider them trapped objects, of consequence because they have so much to tell us about the early Solar System. The Lucy mission aims to visit both populations (the 'Greeks' and the 'Trojans') at Jupiter's L4 and L5 Lagrangians when it heads for Jupiter following launch in 2021. Image: During the course of its mission, Lucy will fly by six Jupiter Trojans. This time-lapsed animation shows the movements of the inner planets (Mercury, brown; Venus, white; Earth, blue; Mars, red), Jupiter (orange), and the two Trojan swarms (green) during the course of the Lucy mission. Credit: Astronomical Institute of CAS/Petr Scheirich (used with permission). Right now the focus is on Eurybates as mission planning continues, for we've just learned thanks to the...

It should be evident why getting information about the solar wind is useful for future deep space missions. Concepts like the electric sail, recently discussed in these pages, and various forms of magnetic sail using superconductors all rely on hitching a ride on this fast-moving stream of particles and magnetic fields emanating from the Sun. A key problem has been tracking the solar wind's behavior in space through changing solar cycles as we get to increasingly large distances from the Sun, but fortunately we do have a few assets at system's edge. New Horizons' Solar Wind Around Pluto (SWAP) instrument continues to return data useful not only for Solar System science but also for understanding how the outflow from the Sun could affect spacecraft in the Kuiper Belt. Of interest here are the spacecraft's measurements of 'interstellar pickup ions' in the outer heliosphere, a region through which only the two Voyagers and the two Pioneers before them have previously traveled. Pickup...

When I think about mapping new places, I remember Vincent Van Gogh, who once said "To look at the stars always makes me dream, as simply as I dream over the black dots of a map representing towns and villages. Why, I ask myself, should the shining dots of the sky not be as accessible as the black dots on the map of France?" Why not indeed? The exciting process of mapping new worlds continues to take place as we pursue our reconnaissance of the Solar System, now pushing well into the Kuiper Belt. Mapping Saturn's giant moon Titan is particularly satisfying, because as you'll recall, Voyager 1 was diverted from its original trajectory because Titan was just too interesting a target to miss. No Titan mapping then, though we did have useful scientific results, because Voyager 1 saw a world shrouded in orange smog. Cassini changed the game, of course, and now we're looking deep beneath the clouds. Image: The colorful globe of Saturn's largest moon, Titan, passes in front of the planet and...

The spectacular success of New Horizons inevitably leads to questions about what an orbiter at Pluto/Charon might accomplish. It's heartening that NASA has funded the Southwest Research Institute (SwRI) to look further into the matter, the Institute having already examined the question on its own. Now a Pluto orbiter becomes one of ten mission studies NASA is sponsoring as we look toward the next National Academy Planetary Science Decadal Survey. Beginning in 2020, the survey will outline science objectives and recommend missions over a ten year period. The NASA decision leverages all the work SwRI has put into the Pluto orbiter concept, and brings the focus to what we might accomplish with such a mission that a flyby could not. Particularly significant will be the choice of science instruments, which a spacecraft achieving global coverage will demand. And because we have a system at Pluto with five moons, we have a range of targets that can be subjected to detailed study. There is...

While I'm working on the project I discussed the other day, I'm trying to keep my hand in with the occasional article here, looking forward to when I can get back to a more regular schedule. Things are going to remain sporadic for a bit longer this month, and then again in mid-November, but I'll do my best to follow events and report in when I can. I did want to take the opportunity to use an all too brief break to get to the Enceladus news, which has been receiving attention from the space media and, to an extent, the more general outlets. We always track Enceladus news with interest given those remarkable geysers associated with its south pole, and now we return to the Cassini data pool, which should be producing robust research papers for many years. In this case, Nozair Khawaja (University of Berlin) and colleagues have tapped data from the spacecraft's Cosmic Dust Analyzer (CDA) to study the ice grains Enceladus emits into Saturn's E ring, finding nitrogen- and oxygen-bearing...