Approaching problems from new directions can be unusually productive, something I always think of in terms of Mason Peck's ideas on using Jupiter as a vast accelerator to drive a stream of micro-spacecraft (Sprites) on an interstellar mission. Now Peck, working with Robert Shepherd (both are at Cornell University) is proposing a new kind of rover, one ideally suited for Europa. The idea, up for consideration at the NASA Innovative Advanced Concepts (NIAC) program, is once again to exploit a natural phenomenon in place of a more conventional technology. What Peck and Shepherd have in mind is the use of 'soft robotics' -- autonomous machines made of low-stiffness polymers or other such material -- to exploit local energy beneath Europa's ice. We're at the edge of a new field here, with soft robotics advocates using principles imported from more conventional rigid robot designs to work with pliable materials in a wide range of applications, some of which tie in with the growth in 3D...

Have a look at the latest imagery from the New Horizons spacecraft to get an idea of how center of mass -- barycenter -- works in astronomy. When two objects orbit each other, the barycenter is the point where they are in balance. A planet orbiting a star may look as if it orbits without influencing the much larger object, but in actuality both bodies orbit around a point that is offset from the center of the larger body. A good thing, too, because this is one of the ways we can spot exoplanets, by the observed 'wobble' in the stars they orbit. The phenomenon is really evident in what the New Horizons team describes as the 'Pluto-Charon dance.' Here we have a case where the two objects are close enough in size -- unlike planet and star, or the Moon and the Earth -- so that the barycenter actually falls outside both of them. The time-lapse frames in the movie below show Pluto and Charon orbiting a barycenter above Pluto's surface, where Pluto and Charon's gravity effectively cancel...

Watching Ceres gradually take on focus and definition is going to be one of the great pleasures of February. The latest imagery comes from February 4, with the spacecraft having closed to about 145,000 kilometers. Here we're looking at a resolution of 14 kilometers per pixel, the best to date, but only a foretaste of what's to come. For perspective, keep in mind that while Ceres is the largest object in the main asteroid belt, its diameter is a scant 950 kilometers. Is there an ocean under this surface? Image credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA/PSI. Meanwhile, a good deal further out in the system, a small vial of Clyde Tombaugh's ashes continues its remarkable trek, with new imagery from New Horizons, the spacecraft carrying it, being released on the same day the Ceres images were taken, February 4, which happens to be Tombaugh's birthday. Born in 1906, Tombaugh's long life ended in 1997, and he has stayed very much in the thoughts of New Horizons principal investigator Alan...

With the 2016 budget cycle beginning, it's heartening to see that Europa factors in as a target amidst a White House budget request for NASA of $18.5 billion, higher than any such request in the last four years, and half a billion dollars more than the agency received in the 2015 budget. This follows Congress' NASA budget increase of last year. Casey Dreier, who follows space policy issues for The Planetary Society, cites what he calls a 'new commitment to Europa', as seen in a request for $30 million to start the mission planning process. Dreier adds: At its most basic level, it means that NASA can pursue the development process to create a mission to explore Europa. That's new, and that's important. Europa has moved from "mission concept" to "mission," with details to figure out, plans to draw, teams to assemble, and hardware to build (eventually). It's a step that Congress could not force NASA to take (NASA being an executive branch agency and all) no matter how much money it gave...

Mark January 26 on your calendar. It’s the day when the Dawn spacecraft will take images of Ceres that should exceed the resolution of the Hubble Space Telescope. We’re moving into that new world discovery phase that is so reminiscent of the Voyager images, which kept re-writing our textbooks on the outer Solar System. 2015 will be a good year for such, with Dawn being captured by Ceres gravity on March 6, and New Horizons slated for a July flyby of Pluto/Charon. In both cases, we will be seeing surfaces features never before observed. What we have so far from Dawn can’t match earlier Hubble imagery, the best of which is about ten years old, but it’s about three times better than the calibration images taken by the spacecraft in early December. At this point, Dawn is making a series of images to be used for navigation purposes during the approach to the dwarf planet. We have sixteen months of close study of Ceres to look forward to as the excitement builds. “Already,” says Andreas...

Having just looked at the unusual ‘warped’ disk of HD 142527, I’m inclined to be skeptical when people make too many assumptions about where planets can form. Is our Solar System solely a matter of eight planets and a Kuiper Belt full of debris, with a vast cometary cloud encircling the whole? Or might there be other small planets well beyond the orbit of Neptune, planets much larger than dwarfs like Pluto but not so large that we have been able to detect them? Certainly Carlos de la Fuente Marcos and Raúl de la Fuente Marcos (Complutense University of Madrid), working with Sverre J. Aarseth (University of Cambridge) think evidence exists for this proposition. The scientists are interested in how large objects can affect the trajectories of small ones, and in particular what a comet named 96P/Machholz 1 can reveal about how such interactions work. They’re focused on the Kozai mechanism, which explains how the larger object causes a quantified libration in the smaller object’s orbit,...

How objects in the sky get named is always interesting to me. You may recall that the discovery of Uranus prompted some interesting naming activity. John Flamsteed, the English astronomer who was the first Astronomer Royal, observed the planet in 1690 and catalogued it as 34 Tauri, thinking it a star, as did French astronomer Pierre Lemonnier when he observed it in the mid-18th Century. William Herschel, seeing Uranus in 1781, thought at first that it was a comet, and reported it as such to the Royal Society. By 1783, thanks to the work of the Russian astronomer Anders Lexell and Berlin-based Johann Elert Bode, Herschel came to agree that the new object was indeed a planet. Herschel, asked by then Astronomer Royal Nevil Maskelyne to name the new world, declared it to be Georgium Sidus, the 'Georgian Planet,' a name honoring King George III. The unpopular name soon met with alternative suggestions, including Herschel, Neptune and (Bode's own idea) Uranus. Image: Sir William Herschel...

Speaking of spacecraft that do remarkable things, as we did yesterday in looking at the ingenious methods being used to lengthen the Messenger mission, I might also mention what is happening with Dawn. When the probe enters orbit around Ceres -- now considered a 'dwarf planet' rather than an asteroid -- in 2015, it will mark the first time the same spacecraft has ever orbited two targets in the Solar System. Dawn's Vesta visit lasted for 14 months in 2011-2012. We have the supple ion propulsion system of Dawn to thank for the dual nature of the mission. In the Dawn version of the technology, xenon gas is bombarded by an electron beam. The resulting xenon ions are accelerated through charged metal grids out of the thruster. JPL's Marc Rayman, chief engineer and mission director for the mission, explained thruster design in one of the earliest of his Dawn Journal entries: Because it is electrically charged, the xenon ion can feel the effect of an electrical field, which is simply a...

A new study of data from the Cassini Saturn orbiter has turned up useful information about, of all places, Europa. Cassini's 2001 flyby of Jupiter en route to Saturn produced the Europa data that were recently analyzed by members of the probe's ultraviolet imaging spectrograph (UVIS) team. We learn something striking: Most of the plasma around Europa is not coming from internal activity being vented through geysers, but from volcanoes on Jupiter's moon Io. Europa actually contributes 40 times less oxygen to its surrounding environment than previously thought. These findings cast one Europa mission possibility in a new light. In 2013, researchers using the Hubble Space Telescope reported signs of plume activity, which immediately called the example of Enceladus to mind. If Europa were venting materials from an internal ocean, a possible mission scenario would be to fly a probe through the plume, just as the Cassini team has done with its probe at Enceladus. The latter also has strong...

Where did the water in Earth's oceans come from? It's an open question, but new data from the Rosetta mission, in particular its ROSINA instrument (Rosetta Orbiter Spectrometer for Ion and Neutral Analysis) indicate that terrestrial water probably did not come from comets like 67P/Churyumov-Gerasimenko, around which Rosetta has been orbiting since August. There is little doubt that water reached Earth through bombardment from small bodies early in the planet's history, but the Rosetta findings sharpen the question of where these objects came from. Image: This composite is a mosaic comprising four individual NAVCAM images taken from 19 miles (31 kilometers) from the center of comet 67P/Churyumov-Gerasimenko on Nov. 20, 2014. The image resolution is 10 feet (3 meters) per pixel. Credit: ESA. At work here is analysis of the ratio between hydrogen and deuterium, a heavy form of hydrogen with one proton and one neutron in the nucleus (common hydrogen lacks the neutron). This D/H ratio on...

No spacecraft has ever traveled further to reach its primary target than New Horizons, now inbound to Pluto/Charon. From 4.6 billion kilometers from Earth (four hours, 26 minutes light travel time), the spacecraft has sent confirmation that its much anticipated wake-up call from ground controllers was a success. Since December 6, New Horizons has been in active mode, a state whose significance principal investigator Alan Stern explains: "This is a watershed event that signals the end of New Horizons crossing of a vast ocean of space to the very frontier of our solar system, and the beginning of the mission's primary objective: the exploration of Pluto and its many moons in 2015." Image: Pluto and Charon, in imagery taken by New Horizons in July of 2014. Covering almost one full rotation of Charon around Pluto, the 12 images that make up the movie were taken with the spacecraft's best telescopic camera - the Long Range Reconnaissance Imager (LORRI) - at distances ranging from about...

Apropos of yesterday's post questioning what missions would follow up the current wave of planetary exploration, the Jet Propulsion Laboratory has released a new view of NASA's intriguing moon Europa. The image, shown below, looks familiar because it was published in 2001, though at lower-resolution and with considerable color enhancement. The new mosaic gives us the largest portion of the moon's surface at the highest resolution, and without the color enhancement, so that it approximates what the human eye would see. The mosaic of images that go into this view was put together in the late 1990s using imagery from the Galileo spacecraft, which again makes me thankful for Galileo, a mission that succeeded despite all its high-gain antenna problems, and anxious for renewed data from this moon. The original data for the mosaic were acquired by the Galileo Solid-State Imaging experiment on two different orbits through the system of Jovian moons, the first in 1995, the second in 1998....

The welcome news that the Hubble Space Telescope has found three potential Kuiper Belt targets for New Horizons means that our hopes for an extended mission may be fulfilled. Pluto/Charon is an exciting target, but how much better to use the spacecraft to visit a Kuiper Belt object as well, a member of that vast ring of debris circling our Solar System. We've been to asteroids, of course, but KBOs are a different thing altogether, objects that have never been heated by the Sun, and thus give us a sample of the earliest days of the Solar System. This was not an easy survey to complete, although when it began with the help of ground-based instruments -- the 8.2-metre Subaru Telescope in Hawaii and the 6.5-metre Magellan Telescopes in Chile -- a number of KBOs were identified. The problem was that none could be reached given the fuel available for course correction. Remember the observing conditions researchers had to deal with. Pluto is now in the direction of the constellation...

I like what Radwan Tajeddine (Cornell University) has to say about recent work on Saturn's moon Mimas. The lead author of a paper on the subject in Science, Tajeddine compares recent Cassini observations of the moon to a child shaking a wrapped gift, trying to figure out what the package conceals. 'Shaking' Mimas in a similar way through analysis of the Cassini data has revealed what might be a sub-surface ocean, or an unusually-shaped core preserved since the moon's formation. At work here is a technique called stereo photogrammetry, in which astronomers measure the moon's libration around its polar axis. Libration is an oscillation or 'wobble' that can be studied by looking at Cassini imagery -- taken by its Imaging Science Subsystem at different times and angles -- and analyzing the images with the help of a computer model that involves hundreds of reference points on the surface. The amount of Mimas' libration points to interesting things in the interior, but just what we still...

Curiosities like the unusual feature in Ligeia Mare we discussed yesterday emphasize how important it is to have a long-term platform from which to study a planetary surface. If we are looking at something related to seasonal change on Titan, we have to remember that each season there lasts about seven Earth years. Winter turned to spring in 2009 in the northern hemisphere and as we approach summer there, we're seeing rapid activity. Studying these changes over time is essential if we're to understand meteorology on the only moon in the Solar System with a dense atmosphere. Alex Tolley mentioned in a comment to yesterday's post that he wasn't sure we should rule out evaporation as the explanation for what might be an emerging area of sea floor. The argument against that is that the shoreline of Ligeia Mare seems stable throughout this period, but we have a lot to learn about Ligeia Mare and the other Titan seas, and as Alex notes, it's possible that we're seeing erosion at work on a...

Interesting doings on Titan. I would guess that the odd feature that has cropped up in Ligeia Mare, a large ethane/methane sea in Titan's northern hemisphere -- has something to do with seasonal change, and that's one possibility this JPL news release explores. After all, summer is coming to the northern hemisphere, and studying what happens during the course of a full seasonal cycle is one of Cassini's more intriguing duties. Have a look at the image: Image: These three images, created from Cassini Synthetic Aperture Radar (SAR) data, show the appearance and evolution of a mysterious feature in Ligeia Mare, one of the largest hydrocarbon seas on Saturn's moon Titan. The dark areas represent the sea, which is thought to be composed of mostly methane and ethane. Most of the bright areas represent land surface above or just beneath the water line. The mysterious bright feature appears off the coast below center in the middle and right images. Credit: NASA/JPL-Caltech/ASI/Cornell. We're...

Since we don't yet have flight-ready systems for getting to the outer Solar System much faster than New Horizons, we might as well enjoy one of the benefits of long flight times. Look at it this way: For the next ten months, we can look forward to sharper and sharper images and an ever increasing flow of data about Pluto/Charon and associated moons. It's going to be a fascinating story that unfolds gradually, culminating in the July flyby next year, and then, of course, we can hope for further exploration of a Kuiper Belt object. So New Horizons, launched in 2006, is going to be with us for a while, and it has already given us a brief look at asteroid 132524 APL and a shakeout of its science instruments during a gravitational assist maneuver at Jupiter. Now we're getting down to much finer-grained imagery from Pluto. The first image distinguishing Pluto and Charon was returned in July of 2013. The latest imagery using the spacecraft's Long Range Reconnaissance Imager (LORRI) shows...

Hard to believe that it's been ten years for Cassini, but it was all the way back in January of 2005 that the Huygens probe landed on Titan, an event that will be forever bright in my memory. Although the fourth space probe to visit Saturn, Cassini became in 2004 the first to orbit the ringed planet, and since then, the mission has explored Titan's hydrocarbon lakes, probed the geyser activity on Enceladus, tracked the mammoth hurricane at Saturn's north pole, and firmed up the possibility of subsurface oceans on both Titan and Enceladus. I mentioned the Galileo probe last week, its work at Europa and its fiery plunge into Jupiter's atmosphere to conclude the mission. Cassini has a similar fate in store after finishing its Northern Solstice Mission, which will explore the region between the rings and the planet. As discussed at the recent European Planetary Science Congress in Cascais, Portugal, the spacecraft's final orbit will occur in September of 2017, taking Cassini to a mere...

It was the Galileo mission, which ended in 2003 when the probe descended into the depths of Jupiter's atmosphere, that brought us the first solid evidence of an ocean beneath the ice of Europa. Galileo made multiple flybys of the Jovian moon, the first spacecraft to do so, with the closest pass being a scant 180 kilometers on October 15, 2001. As you would imagine, the radiation environment near Europa is hazardous, which is why the flybys were reserved for Galileo's extended mission. We've been mining the Galileo data on Europa ever since. You may remember that Galileo was unable to open its high-gain antenna on the way to Jupiter, so we had to rely on the ingenuity of mission controllers to get the maximum performance out of the low-gain antenna. That 70 percent of the mission's science goals were still met, and that we are making new discoveries with the Galileo data today, still amazes me. Now we have new work on Europa that flags the evidence for plate tectonics on the distant...

I'm glad to see Ralph McNutt quoted in a recent news release from the Johns Hopkins Applied Physics Laboratory. McNutt has been working on interstellar concepts for a long time, including the Innovative Interstellar Explorer mission that could become a follow-up to New Horizons. But he's in the news in late August because of Voyager, and in particular Voyager 2, which made its flyby of Neptune on August 25, 1989, some 25 years ago. McNutt recalls those days, when he was a member of the Voyager plasma-analysis team: "The feeling 25 years ago was that this was really cool, because we're going to see Neptune and Triton up-close for the first time. The same is happening for New Horizons. Even this summer, when we're still a year out and our cameras can only spot Pluto and its largest moon as dots, we know we're in for something incredible ahead." I can only envy someone who was up close with the Voyager outer planet flybys and is now a key player on New Horizons, for which McNutt leads...