Planet News Archives

September 15, 2009December 24, 2015 by Nancy Atkinson

Spot Discovered on Haumea Rich With Organics and Minerals

Light curve of Haumea in two wavelenths.

A dark red area discovered on dwarf planet Haumea appears to be richer in minerals and organic compounds than the surrounding icy surface. Since Haumea is so small and far away, it shows up in telescopes as just a point of light, but the spot was discovered by measuring changes in brightness as it rotates. Small but persistent differences indicate that the dark spot is slightly redder in visible light and slightly bluer at infrared wavelengths.

The spot could be from a recent impact, so scientists aren’t sure if the materials come from Haumea or the impactor. The dwarf planet is thought to be a rocky body covered in ice.

“Our very first measurements of Haumea told us there was a spot on the surface” said Dr. Pedro Lacerda, from Queen?s University in Belfast. “The two brightness maxima and the two minima of the light curve are not exactly equal, as would be expected from a uniform surface. This indicates the presence of a dark spot on the otherwise bright surface. But Haumea’s light curve has told us more and it was only when we got the infrared data that were we able to begin to understand what the spot might be.”

Possible interpretations of the changes in the light curve are that the spot is richer in minerals and organic compounds, or that it contains a higher fraction of crystalline ice.
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Haumea orbits the Sun beyond Neptune, in a region known as the Kuiper belt. It is the fourth largest known Kuiper belt object (KBO) after Eris, Pluto and Makemake. These large KBOs, together with main-belt asteroid Ceres, are known as dwarf planets. One of the most surprising characteristics of Haumea is its very fast rotation, with one day lasting only 3.9 Earth hours. No other large object in the solar system spins as fast as Haumea. The rapid spin deforms Haumea into an elongated ellipsoid, 2,000 km by 1,600 km by 1,000 km, whose shape balances gravitational and rotational accelerations. It is believed that Haumea was spun up by a massive impact more than a billion years ago.

Because of its rotation and elongated shape, Haumea brightens and dims periodically as it reflects more and less sunlight. The extent of this variation tells us how elongated Haumea is, and the time between each brightening and dimming is a measure of the rotation period. The precise Haumea shape and spin period imply that it has a density 2.5 times that of water. Since we know from spectroscopic observations that Haumea is covered in water ice, this high density implies Haumea must have a rocky interior, in contrast with its bright icy surface.

New observations of this spot are planned for early 2010 using the ESO Very Large Telescope. “Now we will get detailed spectroscopy of the spot to hopefully identify its chemical composition and solve the puzzle of its origin” said Lacerda.

Source: Europlanet

August 21, 2008December 24, 2015 by Nancy Atkinson

Real Hitchhiker’s Guide to the Solar System on the Way

A NASA image of asteroid Eros (left) and Robert Gaskell's shape model of the asteroid (right). Credit: PSI

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Thinking about trekking across Titan or meandering around Mercury? Along with your backpack and towel, you’ll also want to pack one of Robert Gaskell’s maps. Gaskell, a senior scientist at the Planetary Science Institute, is working on creating real hitchhiking guides to the various bodies in our solar system. He’s been equated to the final frontier what Lewis and Clark were to the American West – the guy producing the most accurate and detailed maps available. And thanks to current space missions sending back loads of data, Gaskell is beginning to work on creating precise maps of Mercury, the asteroid Eros, and eight moons of Saturn including Enceladus. Gaskell has created sophisticated software that combines hundreds of spacecraft images of varying resolution to create the maps. He’s been developing the software for nearly 25 years, and if you want to map a planet, moon, or asteroid, he’s the guy to ask.

Gaskell uses a method called stereo-photo-clinometry, or SPC. Just as stereo-phonic means sound from different directions, stereo-photo means light from different directions, and clinometry means that slopes, or inclines, are being measured. So SPC means finding slopes from the way the surface looks under different illuminations, and once we know the slopes we can find the heights.

Four computers in Gaskell’s office grind out mapping data nearly 24/7. But despite his quarter century of mapping work, Gaskell says he’s just getting started. “There are thousands of objects in the solar system, and so far, I’ve barely scratched the surface, if you’ll pardon the expression,” he said.

Gaskell has won an NASA Exceptional Achievement medal for his detailed maps of the asteroid Itokawa.

His newest project will create highly accurate maps of the entire surface of Mercury based on images sent back by NASA’s MESSENGER spacecraft. MESSENGER flew by Mercury in January and will fly by again in October before going into orbit of Mercury in 2011.

Currently Gaskell is combining images from the January flyby with those taken by Mariner 10, which visited Mercury in 1973, to produce initial maps. But the sun angle for the Mariner 10 photos was the same for three flybys and so far there is only one flyby for MESSENGER.

“It won’t be until we get overlapping data from different sun directions that it will really start making a lot of sense,” Gaskell said. “It does give a reasonable solution now, but I don’t completely trust it.”

Gaskell’s maps not only give scientists useful information about a body’s surface, they also can be used for navigating spacecraft, calibrating spacecraft instruments, and gaining information about the geology, internal structure and past history of an object.

In addition to Mercury, Gaskell is mapping eight of Saturn’s moons, including Enceladus, a frigid world punctuated by icy geysers. In October, NASA may use those maps as navigational tools to plot – and possibly adjust – the Cassini spacecraft’s trajectory as it flies past Enceladus.

Once Gaskell’s computers produce maps covering an entire body, they yield a very accurate image of the object’s shape. The moons of Saturn, for instance, have changed orbits during their history and gravitationally interact with one another. Once their shape became fixed, it recorded the tidal stresses at the time they froze, which gives scientists a way of determining the orbital history of the system.

For Io, Jupiter’s highly volcanic moon, mapping its shape provides planetary geologists with part of the data they need to determine what processes may be going on inside its fluid core, which is being heavily torqued by the giant planet’s intense gravitational field.

Describing himself as an evangelical stereo-photo-clinometrist, he is sharing his work with others and recruiting more researchers into the long-term effort to map the solar system. Some of those are at the Jet Propulsion Laboratory, The University of Arizona, the Johns Hopkins Applied Physics Laboratory, and USGS.

With so many planets, moons and asteroids to explore and map, “It’s like being in a big candy shop,” Gaskell said.

Source: Planetary Science Institute

April 3, 2008December 24, 2015 by Ian O'Neill

Rocks Roll on Mars Too: New Images From HiRISE

The High Resolution Imaging Science Experiment (HiRISE) on board NASA’s Mars Reconnaissance Orbiter (MRO) has done it again. When the instrument caught a Mars avalanche in action in March, we were able to witness a fairly common terrestrial event on a different planet. The impact was huge; we were all fascinated by the slide of rock and ice for weeks. Now looking on the very small-scale, HiRISE has picked up a seemingly mundane terrestrial occurrence: a rock rolling down a hill. But this rock rolled down a crater side on Mars, leaving a track in the Martian regolith big enough to be spotted by the MRO…

These new pictures were observed by the HiRISE instrument onboard the MRO currently orbiting the Red Planet. Since its orbital insertion in 2006, the orbiter, a multi-purpose satellite, has returned some of the highest resolution images ever seen of the surface of Mars. Back in March, the HiRISE instrument took pictures of an escarpment in the north polar region of the planet. Along this scarp, HiRISE captured four separate avalanches occurring hundreds of kilometres apart. Never before had such a geologically dynamic event been captured by a Mars orbiter.

And now for the lowly rock. Looking at these new HiRISE images (taken on March 6th), it appears that rocks roll on Mars too. It’s not that we didn’t already know this, but this is the first time we’ve been able to resolve recently disturbed surface debris after it has rolled some distance down a slope on Mars (objects measuring ~167 cm across are resolved). What is really special are the very clear tracks from the rolling rocks imprinted in the regolith. In one example (pictured top) a large boulder (about 4 meters in diameter) had rolled down the crater side, picked up speed, hit a mini crater, skipped and bounced down the slope until coming to a stop. Taking a rough estimate, the rock in the image possibly rolled for a few hundred meters. These images were taken around the southern branch of Shalbatana Vallis, where it links with Chryse Planitia.

It is thought that the boulders were disturbed in some way, breaking them loose from the crater edge (possibly a meteorite impact or other tremor) as there are several tracks in the regolith pointing in two directions. It also seems possible that they might be the ejecta from another meteorite impact in the area.

Either way, it’s great to see the small-scale geological activity in action as well as huge Mars avalanches…

Source: HiRISE

April 2, 2008December 24, 2015 by Tammy Plotner

Meteor Shower… On Mars!

What’s that? Another meteor shower we can’t possibly see? Of course you can. All you need to view this meteor shower is a backyard on Mars! A team of scientists led by Armagh Observatory have, for the first time, detected a storm of shooting stars on Red Planet.

What happens when the orbit of Mars intersects with debris from comet 79P/du Toit-Hartley? Scientists were hard at work making predictions. The detections were then cross-referenced with observations of activity in the Martian ionosphere by NASA’s Mars Global Surveyor (MGS) satellite. Says Dr. Apostolos Christou:

“Just as we can predict meteor outbursts at Earth, such as the Leonids, we can also predict when meteor showers are going to occur at Mars and Venus. We believe that shooting stars should appear at Venus and Mars with a similar brightness to those we see at Earth. However, as we are not in a position to watch them in the Martian sky directly, we have to sift through satellite data to look for evidence of particles burning up in the upper atmosphere.”

We’re all familiar with the cause of most meteor showers. They happen when a planet (and not always ours!) passes through the debris trail left by a comet as it moves along its orbital path. The material lets us glimpse into the age, size and composition of particles ejected from the comet’s nucleus, the speed at which it was thrown off, as well as general information about the structure and history of the comet itself. Oh, to be a comet watcher on Mars! About four times as many comets approach the orbit of Mars than the Earth’s and the greatest majority of these are Jupiter Family Comets.

Studying Martian meteor showers can definitely improve our understanding of meteor showers and the Jupiter Family Comets as well. JFC are short period comets with an orbital period of less than 20 years. Their orbits are controlled by Jupiter and many are believed to originate from the Edgeworth-Kuiper Belt, a vast population of small icy bodies that orbit just beyond Neptune. Famous JFCs include Comet 81P/Wild 2, which was encountered by the Stardust spacecraft in January 2004 and Comet Shoemaker-Levy 9, which broke up and collided with Jupiter in July 1994.

When meteor particles burn up in a planet’s atmosphere, metals contained within them are ionised to form a layer of plasma. On Earth, this layer has an altitude of approximately 95-100 kilometres and on Mars the layer is predicted to be around 80-95 kilometres above the Martian surface. Meteor showers leave a narrow layer of plasma superimposed on top of the main plasma layer, caused by meteors that are general debris from the Solar System. Dr. Christou and his colleagues developed a model to predict meteor showers caused by the intersection of Mars with dust trails from comet 79P/du Toit-Hartley. From the model, the team identified six predicted meteor showers since the MGS satellite entered into orbit around Mars in 1997. Although the metallic ions cannot be observed directly by MGS instruments, evidence for the plasma layer can be inferred by monitoring electron density in the Martian atmosphere using the spacecraft’s radio communication system.

Just like earthly meteor showers, we can predict all we want – but sometimes we draw a blank. In this instance only one of the six predictions came true. In the April 2003 data, the team found that an ionospheric disturbance appeared at the exact time of the predicted meteor outburst. The height of the disturbance corresponded with the predicted altitude for the formation of the metallic ion layer and its width and multi-peaked shape were similar to structures observed in the Earth’s ionosphere linked to the Perseid meteor shower.

For the 2005 data, no features were observed near or immediately after the predicted meteor shower. Dr Christou says, “We speculate that we don’t see anything in the 2005 data because the meteors burned up deeper in the atmosphere where their ionisation is less efficient. If we are going to get a clear picture of what is going on, we need more optical and ionospheric observations of meteor showers at both the Earth and Mars so we can establish a definitive link between cause and effect. Equally importantly, we need further observations of Martian meteor showers, either from orbit or from the planet’s surface, to confirm our predictions. Finally, we need to improve our prediction model by tracking more comets that might cause meteor showers on Mars.”

Dr Christou is now investigating the possibilities of making observations with Europe’s ExoMars mission, which is due to land on Mars in 2015.

April 2, 2008December 24, 2015 by Tammy Plotner

Venus’ Variable Evolution

For every backyard astronomer, we know 4.5 billion years ago, both Venus and Earth were formed with nearly the same radius, mass, density and chemical composition. Venus is like Earth’s evil twin, but why is the climate on both worlds so widely varied? Scientists analysing the data from the orbiting European Venus Express spacecraft are finally putting the pieces of the geological and climatological puzzle together as they take a closer look at Venusian evolution.

Today, Professor Fred Taylor of Oxford University presented the scenario in a talk at the Royal Astronomical Society National Astronomy Meeting in Belfast. According to the studies, Venus appeared to have evolved very rapidly compared to the Earth during the early formation of the solar system. Thanks to data obtained from the Venus Express, it would appear our wicked sister planet once had significant volume of water covering the surface… Oceans which were lost in a very short geological timescale. As the water disappeared, the geological evolution of the surface of Venus slowed quickly – unable to develop plate tectonics like the Earth. Biological evolution could never happen. If, at one time, Venus mirrored Earth in climate and habitability terms, then it evolved too quickly at first, then too slowly.

‘They may have started out looking very much the same,’ said Professor Taylor, ‘but increasingly we have evidence that Venus lost most of its water and Earth lost most of its atmospheric carbon dioxide.’

Here on Earth, carbon dioxide is captive plant life, minerals and the crust itself. Not to harp on global warming, but the release CO2 back into the atmosphere is a source of climatic change. On Venus, the majority of the carbon dioxide resides it its atmosphere, leaving the surface temperature at a searing 450 degrees Celsius. This slows or stops geological as well as biological evolution.

‘The interesting thing is that the physics is the same in both cases’ said Prof Taylor. ‘The great achievement of Venus Express is that it is putting the climatic behaviour of both planets into a common framework of understanding.’

But, we haven’t heard the last from Venus Express just yet. Due to operate until May 2009, scientists involved in the project are already busy applying for an extension until 2011.

‘We have plans for joint operations with the Japanese spacecraft called Venus Climate Orbiter that will arrive in December 2010’, said Taylor. ‘Together, we can do things neither could do alone to crack some of the remaining puzzles about Venus.’

April 2, 2008December 24, 2015 by Nancy Atkinson

New Search Technique May Lead to Discovery of Extra-solar Earth-Like Planets

The Holy Grail in the search for extra-solar planets would be to find an Earth-like world orbiting another star. A group of UK astronomers believe they have good chance of being the first to find such a planet with a revolutionary new camera called RISE. With RISE, scientists will search for extra-solar planets using a technique called â€œtransit timing,â€ which may provide a short-cut to discovering Earth-like planets with existing technology.

The two primary techniques to find extra-solar planets are usually only sensitive to massive, gas giant planets in close orbit around their parent star, so-called â€œHot Jupiters.â€ Firstly, planets can be found through their gravitational pull on the star they orbit – as the extra-solar planet moves the star wobbles back and forth, and by measuring this movement astronomers can deduce the presence of a planet. Secondly, the transit search technique looks for the changes in a starâ€™s brightness as a planet passes in front of it.

But neither of these techniques is currently good enough to find small extra-solar planets similar to the Earth. With the new transit timing technique, the RISE camera will look for Earth-mass planets in orbit around stars already known to host Hot Jupiters.

Transit timing works on the principle that an isolated hot Jupiter planet orbiting its host will have a constant orbital period (i.e. its ‘year’ remains the same) and therefore it will block out the light from its parent star in a regular and predictable way. During the planet’s transit events, RISE can very accurately measure the rise and fall in the amount of light reaching the Earth from the parent star – the camera can be used to pinpoint the time of the centre of the event to within 10 seconds. RISE is a fast-read camera. It has a fixed “V+R” filter and reimaging optics giving a 7 x 7 acrminute field of view to maximize the number of comparison stars available. An e2V frame transfer detector is used to obtain a cycle time of less than 1 second.

By observing and timing their transits, astronomers hope to detect small changes in the orbital periods of known hot Jupiters caused by the gravitational pull of other planets in the same system. In the right circumstances, even planets as small as the Earth could be found in this way.

â€œThe potential of transit timing is the result of some very simple physics, where multi-planet systems will gravitationally kick one another around in their orbits – an effect often witnessed in our own Solar System,â€ said PhD student Neale Gibson of Queen’s University Belfast. â€œIf Earth-mass planets are present in nearby orbits (which is predicted by current Hot-Jupiter formation theories) we will see their effect on the orbit of the larger transiting planets. RISE will allow us to observe and time the transits of extrasolar planets very accurately, which gives us the sensitivity required to detect the effect of even small Earth-mass planets.â€

RISE was designed by astronomers at Queen’s University in collaboration with Liverpool John Moores University and is now installed on the 2 meter Liverpool Telescope on the Canary Island of La Palma. For more information about the RISE Camera, see Neale Gibson’s homepage.

Original News Source: NAM Press Release

April 1, 2008April 6, 2008 by Fraser Cain

Virgin/Google’s Mission to Mars: Virgle

Set your April jokes on fool, dear reader because it’s April 1st. That means there’ll be a non-stop barrage of April Fools Jokes coming at you from all directions. We had to join in the fun, but we’re not the only ones. Check out this “offering” from Virgin Galactic and Google. They’re going to be setting up a colony on Mars and they’re looking for volunteers. You’ve got to know it’s serious because Google founders Sergey Brin and Larry Page make the offer personally. I like how they mentioned the one-way trip idea. Is someone reading Universe Today?

And Branson’s version is here: