What was it that left such an interesting infrared signature in Jupiter's atmosphere on July 19, 2009? The images below, made with a wide variety of instruments, show what appears to be the debris of an object that collided with the planet. The event was first noted by amateur astronomer Anthony Wesley in Australia, who tipped off an international team of scientists that went on to combine data from three infrared telescopes to study the impact, looking at atmospheric temperatures and the chemical signatures of the debris. The conclusion: The object was most likely an asteroid. Image (click to enlarge): Eight different looks at the aftermath of a body -- probably an asteroid -- hitting Jupiter on July 19, 2009. Amateur astronomer Anthony Wesley was the first to capture an image of the impact, with a visible-light camera attached to his telescope in Australia. A NASA Hubble Space Telescope image was obtained in visible light. Infrared images were obtained by NASA's Infrared Telescope...

After yesterday's meditation on the Voyager spacecraft and their significance in the larger canvas of space exploration, it's worth recalling that we have just celebrated Voyager 2's encounter with Uranus -- this month marks the 25th anniversary of the event. If your memories of the encounter are fuzzy, you might recall the other major news driver that January, the explosion of the Space Shuttle Challenger, which drove Uranus results off the front page. The national psyche was riveted by Challenger, and understandably so, but what a shame to see analysis of the Voyager flyby all but lost in the coverage of an event so much closer to home. Voyager 2's closest approach took place on January 24, 1986. I remember it because I was getting ready for a weekend flight training session in Frederick, Maryland and hoping I wouldn't miss the subsequent release of Voyager imagery and data. In those days, the small company I was flying for did clinics for the Aircraft Owners and Pilots...

Another comet looms, but first, some sail news. If everything went well, NanoSail-D opened its sail at 0255 UTC this morning, and indeed @NanoSailD in a tweet not long after the supposed deployment time said the satellite had sent data confirming the sail was open. We're now waiting for ground-based tracking to confirm the fact, so patience is in order. Meanwhile, reports from hams tracking the satellite's beacon on 437.270 MHz are still welcome and should be sent to the NanoSail-D2 Mission Dashboard. Henk Hamoen (PA3GUO) in the Netherlands put together the video below showing his tracking of NanoSail-D. The sail should be visible once deployed -- check Heavens Above for visible pass predictions (thanks to @MarkGStacey for the tip). Later: This from an MSFC news release: Friday, Jan. 21 at 10 a.m. EST, engineers at NASA's Marshall Space Flight Center in Huntsville, Ala., confirmed that the NanoSail-D nanosatellite deployed its 100-square-foot polymer sail in low-Earth orbit and is...

The near-Earth asteroid 1999 AT10 is telling us a greal deal about an object much further away, the main belt asteroid Vesta. And that, in turn, is giving us new information about planet formation more than 4.5 billion years ago, when our Solar System was forming. The recently published paper, which precedes the August arrival of the Dawn spacecraft at Vesta, draws on infrared studies of 1999 TA10 by researchers from the Max Planck Institute for Solar System Research and the University of North Dakota, using the Infrared Telescope Facility on Mauna Kea. The recent research compares the infrared radiation from the near-Earth asteroid to the spectral signature of Vesta. The latter, 525 kilometers in diameter, is quite an interesting object. It’s associated with a type of meteorite called HEDs -- Howardite-Eucrite-Diogenite -- which are thought to have originated in Vesta’s crust, traveling to Earth as the result of a huge impact that has left a crater on the asteroid’s southern...

I just have time this morning to get off one more post before Christmas, although it's a close call. I've got family coming over at mid-day for the first of two holiday gatherings and, because I'm an inveterate baker, I have sourdough bread to attend to. Sourdough (or as my guru Peter Reinhart likes to call it, 'wild yeast bread') appeals to me because of its slow rhythms, multiple builds and lengthy rise times, and I've enjoyed cultivating local yeasts for both a white and rye starter that I use constantly. Sometimes breadmaking is a wonderful change of pace from keyboarding -- you put the mind in neutral for a while and start kneading a mass of dough, a wonderfully Zen-like experience. The story I wrote this morning is below, but let me take this chance to wish all of you a happy holiday! Centauri Dreams relies on a reader base that has been active and engaged from the start, and I've found my thoughts on interstellar issues challenged, shaped and stimulated by our continuing...

Yesterday's post discussed interesting terrain on remote moons, Rhea and Europa among them. But while we can piece together much useful information about a moon's surface and its history from orbit, some of the most provocative places in the Solar System may well require investigation on the ground. In the case of Europa, that means robotic equipment, but the issue is stark, as Damhnait Gleeson (JPL) recently told Wired.com. "What we can see from orbit is such a simple picture compared to the surface," Gleeson said in a story on Europa analogues on Earth. "From orbit it's just ice and sulfur. We really have to go deeper to understand the system." That's just what Gleeson and colleagues have been doing with data and samples gathered at the Borup Fjord Pass on Ellesmere Island, a remote and all but inaccessible place in the Canadian High Arctic. Gleeson, who as a graduate student worked under Europa specialist Bob Pappalardo (JPL), spent time at the pass in 2006, taking samples of the...

Cassini continues to wow us with holiday imagery, not the least of which is this view from the Enceladus encounter on the 20th, with not only the plumes from Enceladus clearly visible but the adjacent image of Mimas stealing the show (credit: NASA/JPL/Space Science Institute). It's raw imagery, still unprocessed, but it gets across the wonder of the occasion. Cassini's next encounter is with Rhea, a flyby at 76 kilometers scheduled for January 11, but it's two earlier Rhea flybys (from November of 2009 and March of 2010) that caught my eye this morning. Remember that Cassini's mission has been extended until 2017, offering us the opportunity to enhance considerably our view of the features on various moons. In fact, the recent images of Rhea have already helped us produce a cartographic atlas of the moon that includes names approved by the International Astronomical Union. The 2009 flyby allowed scientists to create a 3-D image of terrain on Rhea's trailing hemisphere at higher...

Interesting chemistry on the surface of Saturn's moon Rhea seems a natural conclusion following the announcement of the discovery of oxygen in its evanescent atmosphere. And what a difference from Saturn's largest moon, Titan, whose atmosphere is not only thick, but packed with nitrogen and methane, with little trace of carbon dioxide or oxygen. Rhea's tenuous exosphere, which includes carbon dioxide, is so thin that its density of oxygen is about five trillion times lower than that of Earth's atmosphere. Even so, interesting things may happen on an icy surface in this scenario. I'm diverted as I write this -- pardon the digression, but this does come back to Rhea -- because I'm thinking about German friends who are fans of the wonderful 1960's television show Raumpatrouille (Space Patrol), which followed the adventures of the spaceship Orion some years before Star Trek ever appeared on German screens. First broadcast in 1966, Space Patrol went on to achieve true cult status in West...

Keep an eye on the EPOXI site at the University of Maryland. New images from the Hartley 2 comet encounter are coming in, some of them truly breathtaking, as is the one at left. The jets clearly visible in the image can be linked with distinct areas on the surface of the comet, the first time we've ever seen a comet with this degree of clarity. Image by image, the tiny comet is yielding its secrets. We now learn that spectral analysis of the material coming from the cometary jets shows it to be primarily carbon dioxide, along with dust and ice particles. Image: This enhanced image, one of the closest taken of comet Hartley 2 by NASA's EPOXI mission, shows jets and where they originate from the surface. There are jets outgassing from the sunward side, the night side, and along the terminator -- the line between the two sides. The image was taken by EPOXI's Medium-Resolution Instrument on Nov. 4, 2010. The sun is to the right. Credit: NASA/JPL-Caltech/UMD. Jessica Sunshine (University...

The Hartley 2 flyby was an outstanding event, and the only thing I regret about my recent travels was that I was unable to follow the action as the images first streamed in. By now, sights like the one at left have made their way all over the Net, so I won't dwell on them other than to say that if you haven't seen the short video clip of the EPOXI flyby, you should definitely give it a look. You're getting the view from a spacecraft that closed to 700 kilometers or so of the surface, during an encounter taking place at a speed of 12.3 kilometers per second. Image: Comet Hartley 2 can be seen in glorious detail in this image from NASA's EPOXI mission. It was taken as the spacecraft flew by around 6:59 a.m. PDT (9:59 a.m. EDT), from a distance of about 700 kilometers (435 miles). Jets can be seen streaming out of the nucleus. Image credit: NASA/JPL-Caltech/UMD. I'll go along with EPOXI principal investigator Michael A'Hearn's description of the comet's "stark, majestic beauty."...

With NASA's EPOXI mission closing on comet Hartley 2 at 12.5 kilometers per second, be aware that live coverage of the close encounter will begin at 1330 UTC (0930 EDT) on Nov. 4 from mission control at the Jet Propulsion Laboratory. NASA TV streaming video will be available, and you should also be able to watch the action on a JPL Ustream channel. Finally, NASA's Eyes on the Solar System Web tool, a 3-D environment for Solar System exploration, is available for viewing a real-time animation of the cometary flyby on your PC. EPOXI is a great instance of re-purposing a spacecraft to extract maximum value. This is the Deep Impact vehicle that gave us such a spectacular view of the impactor smash-up on comet Tempel 1 back in the summer of 2005. Under the name EPOXI, the mission has pressed ahead with two separate objectives, the first being EPOCh, or Extrasolar Planet Observation and Characterization, which has involved a number of nearby stars known to have transiting exoplanets. The...

It's staggering how much our view of the Solar System has changed over the past few decades. The system I grew up with seemed a stable place. The planets were in well-defined orbits out to Pluto and, even if it were always possible another might be found, it surely couldn't pose any great surprise in that great emptiness that was the outer system. But today we routinely track trans-Neptunian objects with diameters over 500 kilometers -- about 50 of these have now been found, and some 122 TNOs at least 300 kilometers in diameter. We know about well over a thousand objects in that ring of early system debris called the Kuiper Belt. It's an increasingly messy place, this outer Solar System, and it has its own terminology. We have centaurs and plutinos, resonance objects, cubewanos, scattered disk objects (SDOs), Neptune trojans, damocloids, apollos and, perhaps, inner Oort cloud objects. Nope, this isn't the Solar System I grew up with, and every new discovery adds to the enchantment....

Here's an interesting bit of news from the New Horizons team. Remember that the spacecraft, having made its pass by the Pluto/Charon system in 2015, will be moving ever deeper into the Kuiper Belt. It's been the hope of mission planners that a close study of one or more objects there might be possible. Now astronomer Scott Sheppard (Carnegie Institution of Washington) has announced that he has detected the first asteroid in Neptune's trailing Trojan zone (the planet's L5 point), an area New Horizons will fly through before arriving at the Pluto/Charon binary. 2008 LC18 is not itself in range for a New Horizons flyby, but mission principal investigator Alan Stern notes its significance in a recent report on the mission's Web site: " ...its discovery shows that additional and potentially closer Neptune Trojans that New Horizons might be able to study could be discovered in the next three years." And that gives us an interesting mission extension for New Horizons, to take advantage of...

Voyager's controllers thought so much of Titan that when Voyager 1 approached Saturn and the choice arose between sending it on to the outer planets or taking a sharp jog off the ecliptic to view the enigmatic moon, they chose the latter. We all know the result: Titan remained as mysterious as ever, its surface shrouded in orange haze. But you can see why they needed that look. Here was a moon that was large enough to be a planet, with a thick atmosphere and all kinds of speculation about what was on its surface. No wonder Titan was the most tempting of targets, and one of huge scientific value. These days we routinely get Cassini imagery from Titan flybys, and the place has gained definition. I remember once asking Geoffrey Landis, having read his superb 2000 novel Crossing Mars, whether Mars had become more or less an everyday place to him, like Cleveland (he lives there, working at NASA GRC). And it was true: After you study and survey and write novels about a place, it does...

The outer Solar System has always been something of an obsession for me, to the point where as a kid, I used to haunt the libraries looking for books on planetary science. Absurdly, I had the notion that even though little was known about places like Triton and Pluto, I might just stumble upon the one book that had details known to no one else. So I would work my way through the shelf, finding the odd speculation here, the small insight there, but it wouldn't be until Voyager's 1989 Neptune flyby that some of these places began to take on actual shape for all of us. All the Myriad Ways And then there was Larry Niven's 'Wait It Out,' a short story from the Known Space universe that was originally published in 1968, in a wonderful collection called All the Myriad Ways. Here a team of astronauts on the surface of Pluto is marooned and the narrator, after his comrade has died, removes his helmet, freezing to death so quickly that his brain becomes a superconductor, so that a strange form...

IBEX, the Interstellar Boundary Explorer, was never designed to visit the regions it studies. Indeed, the spacecraft, launched in October of 2008, is in Earth orbit and a highly elliptical one at that, with an apogee of 322,000 kilometers and a perigee of 16,000 kilometers. But from that vantage IBEX is able to study and map the boundary between the heliosphere and true interstellar space. It does this by detecting energetic neutral atoms of hydrogen (ENAs) produced at the heliosheath, helping us understand the effects of the solar wind as it collides with interstellar materials. The encounter between solar wind and the interstellar medium causes ENAs to be scattered in all directions from the heliosheath -- those that pass near the Earth are what IBEX detects, and the spacecraft scans overlapping strips of sky to build up a 360-degree map. It was last October, a year after launch, that we learned from the first IBEX map that the interstellar boundary was a more lively place than...

It's hard to believe it's been over six years since the launch of the European Space Agency's Rosetta mission, now well enroute to comet 67P/Churyumov-Gerasimenko, a ten year journey that will be completed in 2014. Upon reaching the comet, Rosetta will begin an extended encounter that includes an orbiter that will circle Churyumov-Gerasimenko for thirteen months as it moves toward the Sun, and a small lander that will investigate surface conditions. We learned more about the mission in today's sessions of the European Planetary Science Congress, now being held in Rome. Jeremie Lasue (Los Alamos National Laboratory) presented the latest Rosetta findings at the conference, drawing on computer models that predict the behavior of the comet's nucleus over the course of the spacecraft's operations. Landing on a comet is tricky business, because dust, ice and frozen carbon dioxide and carbon monoxide will be active as the comet's tail begins to form. What Lasue and colleagues have done is...

Imagine being Jean-Pierre Lebreton. The man behind the Huygens probe, Lebreton and the ESA team behind him hold the record for the most distant landfall in history, the 2005 descent onto the surface of Titan. I have no idea what dreams this man might have had in his childhood, but one of mine was descending through Titan’s thick atmosphere to see its never before glimpsed surface. Huygens pulled off the feat with astonishing ease, descending slowly and steadily while snapping panoramic views of the enigmatic moon. Doubtless Lebreton has much to share about all this at this year’s European Planetary Science Congress, now being held in Rome. EPSC is the major meeting in Europe for planetary scientists, and it’s no surprise that Titan appears prominently in the news from the conference. Cassini’s Visual and Infrared Mapping Spectrometer instrument (VIMS) has been keeping an eye on Titan’s cloud cover since the orbiter first took up its vigil around Saturn, and 2000 VIMS images have now...

I was fortunate enough to meet Joel Poncy (Thales Alenia Space, France) at last year's deep space conference in Aosta, where he gave the audience the lowdown on an extraordinary mission concept, an orbiter of the Kuiper Belt object Haumea. Haumea is a tricky target, lacking an atmosphere that would allow aerobraking and pushing all our limits on propulsion and power generation. But Poncy's team worked out a design using either electric or magneto-plasma technologies, assuming a gravity assist to shorten the journey for arrival around 2035. In a later lunch conversation, Poncy talked to me about the benefit of probing the Kuiper Belt, and the collateral advances that such a mission would bring in terms of developing the orbiters, landers and deep-drilling capabilities we'll need to explore planetary moons like Europa or Ganymede. Sometimes you choose targets, in other words, not only for their immediate payoff, but because they become part of the process of developing next generation...