Tag: science

A comet picture taken by Philae on the way down

1:06 pm

Comet 67P/C-G as seen by Philae during its descent

I am not sure if the actual landing site is visible in this image. I don’t think so as nothing seems to match what was on the earlier close-up. Moreover, the Rosetta website does not say.

No images on the surface have yet been released. There are also issues that could prevent a full success.

However, while the lander has touched down on the comet using its harpoons, scientists said that it had not yet deployed its anchors which meant that it was not completely attached to the surface. The surface was much softer than they expected, so there were some concerns that it was not securely fixed on the comet – although from a software point of view things seemed to be fine. Engineers will attempt to fire the anchors again soon in order to keep Philae attached to the surface of the comet.

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Philae has landed successfully!

9:14 am

Philae has landed successfully on Comet 67P/C-G.

Philae is on the surface, its harpoons have fired and the landing gear has been moved inside, and Philae is in contact. It’s incredible! Massive smiles on everyone’s faces. The room went mad. Twice — when we first had the hint, and then when Stephan Ulamec and Andrea Accomazzo confirmed it. Unbelievable.

More information and data will be coming in a few hours. Stay tuned.

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Philae is go for separation, despite problem

12:25 am

Engineers have given a go for the separation of the Philae lander from Rosetta, despite the failure of a thruster to operate.

During checks on the lander’s health, it was discovered that the active descent system, which provides a thrust upwards to avoid rebound at the moment of touchdown, cannot be activated.

At touchdown, landing gear will absorb the forces of the landing while ice screws in each of the probe’s feet and a harpoon system will lock Philae to the surface. At the same time, the thruster on top of the lander is supposed to push it down to counteract the impulse of the harpoon imparted in the opposite direction. “The cold gas thruster on top of the lander does not appear to be working so we will have to rely fully on the harpoons at touchdown,”says Stephan Ulamec, Philae Lander Manager at the DLR German Aerospace Center. “We’ll need some luck not to land on a boulder or a steep slope.”

Update: Separation has occurred and signal reacquired from Philae. We wait for landing.

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Close-up image of Philae’s landing site

9:32 am


Agilkia landing site for Philae

Inset of landing site

In the preparation to Wednesday’s landing of Philae on Comet 67P/C-G, Rosetta’s science team has released a great image of the landing site, shown above. To the right is a higher resolution inset of the site itself, with the smallest object visible about 8.5 feet across.

Looking at this inset, there are some obvious worries that we all should be aware of prior to the landing attempt. Though the Agilkia landing site is generally more smooth than most of the comet’s surface, it still has significant hazards. The lower part is strewn with boulders and rocks, many of which are quite large. Any one of these could do serious harm to Philae should it land on them.

Even more interesting is the upper part of the landing site. Though very smooth, the image suggests to me that this is a very thick pile of softly packed material. Philae might land there and quickly sink below the surface, where its cameras will be able to see nothing.

Nonetheless, the science team has also released this outline of Philae’s science timeline after landing. The lander will also be taking images of both Rosetta and the comet during its descent, so even if the landing is a failure we will still get some worthwhile data.

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Comet Siding Spring’s fly-by of Mars changed the planet’s atmosphere

8:57 am

Data obtained by the various Mars orbiters during the close fly-by of Comet Siding Spring of Mars has revealed that the comet created a new temporary layer in the planet’s atmosphere.

The European Space Agency’s Mars Express spacecraft detected an increase in electrons in Mars’ upper atmosphere, partly ionising it. This was attributed to fine cometary dust penetrating the atmosphere, which led to a meteor storm of thousands of meteors per hour. The increase in electrons led to the creation of a temporary new layer of charged particles in the ionosphere, which runs from an altitude of 120 kilometres to several hundred kilometres above. This is the first time such an event has been seen, even on Earth the extra density of electrons was measured to be five to ten times higher than normal by NASA’s Mars Reconnaissance Orbiter. Another NASA spacecraft, MAVEN, which also observed the new layer in the ionosphere, will monitor for any long-term events as it goes about its regular duties of studying Mars’ atmosphere.

MAVEN’s Imaging Ultraviolet Spectrograph was able to ascertain the species of ions that flooded into the ionosphere from the comet, the first time a comet that has come direct from the distant Oort Cloud has been sampled in this way. It detected the signal of magnesium, iron and sodium ions following the meteor shower, a signal that dominated Mars’ ultraviolet spectrum for hours afterwards, taking two days to dissipate.

The chemistry that MAVEN detected appears superficially somewhat similar to the chemistry that Rosetta is detecting at Comet 67P/C-G, though there are differences.

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The November 12 timeline of events for Philae’s landing on a comet

10:16 am

ESA has released a detailed timeline of events on November 11-12, when Rosetta’s Philae lander will be released and land on Comet 67P/C-G. They have also released a much more readable summary of the most critical events, describing what will be happening.

For Americans, these events will be occurring from around 3 pm (Eastern) November 11, when the process begins, to 12 pm (Eastern) November 12, when Philae will send back the first signals after landing. Much of the most critical events will take place in the wee hours of the morning.

Meanwhile, one of Rosetta’s instruments has confirmed the presence of water vapor and carbon dioxide in the jets seen near the comet’s narrow neck.

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The best image yet of the birth of a solar system

8:43 am

HL Tau

The new ground-based telescope ALMA has taken an amazing image of a baby star and the planet-forming accretion disk that surrounds it.

ALMA uncovered never-before-seen features in this system, including multiple concentric rings separated by clearly defined gaps. These structures suggest that planet formation is already well underway around this remarkably young star. “These features are almost certainly the result of young planet-like bodies that are being formed in the disk. This is surprising since HL Tau is no more than a million years old and such young stars are not expected to have large planetary bodies capable of producing the structures we see in this image,” said ALMA Deputy Director Stuartt Corder.

ALMA has just been completed and is only in its initial shake-out period. It is also not an optical telescope, but observes in longer wavelengths above infrared. Thus, it can peer through dust clouds to see details like this. And these details confirm that the most accepted theory of planetary formation appears to be right.

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Signs of a sunspot ramp down

1:39 pm

The monthly update by NOAA of the solar cycle is out, showing the sunspot activity for the Sun in October, As I do every month, I am posting it here, with annotations to give it context.

Despite the appearance last month of the largest sunspot in almost a quarter century, the number of sunspots in October dropped significantly, bringing overall activity back to levels seen in 2012, prior to the second peak in the solar maximum. If things go as expected (not something I would bet much money on), the overall ramp down of sunspot activity should now continue over the next few years. There will obviously be jumps periodically, but the general output of sunspots should steadily decline.

I also want to reiterate what I noted last month, that the 2009 prediction of the solar scientist community is looking better and better with time. Other than over-estimating the total activity somewhat while missing the dip between the two peaks, their overall curve, indicated by the red line, is reasonably close to what has actually happened.

October 2014 Solar Cycle graph

The graph above has been modified to show the predictions of the solar science community. The green curves show the community’s two original predictions from April 2007, with half the scientists predicting a very strong maximum and half predicting a weak one. The red curve is their revised May 2009 prediction.

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A geological score for Curiosity!

10:25 pm

Spectroscopy from Curiosity’s most recent drilling has been found to match and thus confirm the spectroscopy of the same spot taken years ago from orbit.

In observations reported in 2010, before selection of Curiosity’s landing site, a mineral-mapping instrument on NASA’s Mars Reconnaissance Orbiter provided evidence of hematite in the geological unit that includes the Pahrump Hills outcrop. The landing site is inside Gale Crater, an impact basin about 96 miles (154 kilometers) in diameter with the layered Mount Sharp rising about three miles (five kilometers) high in the center.

“We’ve reached the part of the crater where we have the mineralogical information that was important in selection of Gale Crater as the landing site,” said Ralph Milliken of Brown University, Providence, Rhode Island. He is a member of Curiosity’s science team and was lead author of that 2010 report in Geophysical Research Letters identifying minerals based on observations of lower Mount Sharp by the orbiter’s Compact Reconnaissance Imaging Spectrometer for Mars (CRISM). “We’re now on a path where the orbital data can help us predict what minerals we’ll find and make good choices about where to drill. Analyses like these will help us place rover-scale observations into the broader geologic history of Gale that we see from orbital data.”

This is a significant finding. Not only does this data now prove that the orbital data is correct, it demonstrates that scientists can now use that orbital data to direct Curiosity to even more interesting geological surface features. In fact, this ground-based data will help them calibrate all their orbital data more precisely, thus making our geological knowledge of Mars more accurate and reliable.

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Mathematical models badly overstate ebola numbers

8:33 am

The uncertainty of science: New evidence suggests that the on-going ebola epidemic in Africa is beginning to ease, contrary to the predictions made by computer models.

The Ebola outbreak in West Africa has infected at least 13,567 people and killed 4,951, according to figures released on 31 October by the World Health Organization (WHO). Now, in a rare encouraging sign, the number of new cases in Liberia seems to be flattening after months of exponential growth. Scientists say it is too soon to declare that the disease is in retreat: case data are often unreliable, and Ebola can be quick to resurge. But it is clear that mathematical models have failed to accurately project the outbreak’s course. [emphasis mine]

The creators of these mathematical models should switch fields and go into climate change modeling. At least in that field the journal Nature would never trumpet the failure of their models to work. In climate science, the major journals do whatever they can, for political reasons, to hide these failures.

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How a big impact gave Vesta its grooves

3:30 pm

New data suggests that when a large impact hit Vesta’s Rheasilvia basin sometime in the past, the entire asteroid was shaken up, producing ripples that eventually surfaced as the giant grooves that circle the asteroid’s equator.

“Vesta got hammered,” said Peter Schultz, professor of earth, environmental, and planetary sciences at Brown and the paper’s senior author. “The whole interior was reverberating, and what we see on the surface is the manifestation of what happened in the interior.”

The research suggests that the Rheasilvia basin on Vesta’s south pole was created by an impactor that came in at an angle, rather than straight on. But that glancing blow still did an almost unimaginable amount of damage. The study shows that just seconds after the collision, rocks deep inside the asteroid began to crack and crumble under the stress. Within two minutes major faults reached near the surface, forming deep the canyons seen today near Vesta’s equator, far from the impact point.

Essentially, for a very very short period of time, immediately after the impact, the solid material of the asteroid acted more like a liquid, producing ripples that immediately settled down as the solid deep equatorial grooves we see today.

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G2 survives Milky Way center fly by

3:08 pm

The uncertainty of science: The gas cloud, dubbed G2, that was going to be eaten by the supermassive black hole at the center of the Milky Way as it did a close fly-by this summer has instead turned out to be a massive star formed when the star’s of its binary system merged.

G2 survived the fly-by, produced no big fireworks which were what was predicted if it has been a gas cloud. The data now suggests that the object is instead a very big star formed when two stars merged.

Massive stars in our galaxy, [astronomer Andrea Ghez] noted, primarily come in pairs. When the two stars merge into one, the star expands for more than one million years “before it settles back down,” Ghez said. “This may be happening more than we thought; the stars at the center of the galaxy are massive and mostly binaries. It’s possible that many of the stars we’ve been watching and not understanding may be the end product of a merger that are calm now.”

Be warned that this new hypothesis about G2 has its own uncertainties. Better data might eventually find it to be something else again.

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First chemical results from Rosetta

9:24 am

Spectroscopy from Rosetta has identified the make-up of a single dust grain captured by the spacecraft.

For the convenience of communications the science team had dubbed this single grain “Boris.”

[T]hese first results show that among the grain’s components are magnesium and sodium. Since 95 percent of the known observed minerals in comets resemble olivine and pyroxenes – containing a lot of magnesium – the detection of this element is not a big surprise. But, finding sodium in the dust grain, in a refractory mineral phase, has sparked our interest considerably.

The coma and tails of other comets are already known to contain sodium; it was observed in the dust samples returned from Comet Wild 2 by NASA’s Stardust mission, and a prominent example was also the sodium tail of Comet Hale-Bopp that flew past the Sun in April 1997 and which could be seen in the night sky for many weeks. However, by contrast, neither sodium nor magnesium were observed in Comet 67P/C-G dust grains before sampling the inner coma dust. But our dust grain Boris has showed off with clear sodium and magnesium mass peaks in the secondary ion mass spectra that we obtained.

Their next goal is to identify where on the surface of Comet 67P/C-G this sodium came from.

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Avalanches on an asteroid

9:12 am

A new analysis predicts that when the asteroid Apophis flies past the Earth in 2029, the close fly-by will cause avalanches on the asteroid.

If asteroids pass close to Earth, they begin to experience the effects of our planet’s gravity. Just like the moon pushes and pulls the oceans, creating the tides, asteroids are susceptible to tidal forces from our planet. To judge what effect this will have on Apophis, scientists need to know what it’s made of. Their best guess is based on photos taken by a Japanese spacecraft named Hayabusa, which took detailed pictures of an Apophis-sized asteroid named Itokawa. Those images revealed that the asteroid wasn’t a solid mass of rock spinning through space, but rather a giant clump of debris held together loosely by gravity. “You look at the [Hayabusa] pictures and you’re like, ‘Uh, that’s a pile of rocks, dude.’ It’s very likely that Apophis is similar,” says astrophysicist Derek Richardson of the University of Maryland, College Park.

To show that Earth’s gravity could cause some of these rocks to tumble, Richardson and his colleagues developed a computer model that allowed them to place virtual sand piles across the surface of a model asteroid with roughly the same dimensions as Apophis. By factoring in the gravity from the asteroid, the tidal force from Earth, centrifugal force caused by the asteroid’s rotation, inertial forces, and other effects, the team was able to predict how the particles on the surface of the asteroid would behave on approach. The results confirm that Earth’s tidal forces would be strong enough to cause tiny avalanches on the asteroid, the team reported online ahead of print in Icarus.

Need I note that there are a lot of uncertainties here? Because they are using what is known about a different asteroid, all of their assumptions about Apophis’s properties in their computer model could be very wrong.

Still, this is interesting, because it does demonstrate that an asteroid could be significantly disturbed simply by flying past a planet.

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LADEE impact site located

8:47 am

Lunar Reconnaissance Orbiter has spotted the impact crater formed when engineers sent the probe LADEE crashing into the lunar surface in April 2014.

Compared with asteroid and meteoroid impacts on the moon, LADEE was actually traveling pretty slow, ‘only’ 3,800 miles per hour (1,700 meters per second). That combined with the relatively low mass and density of the spacecraft, a fairly neat crater of only 10 feet (3 meters) across was created. The crater barely registered in LROC’s image resolution, making it a very difficult task to identify the fresh man-made divot.

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Sierra Nevada announces an X-37B version of Dream Chaser

9:29 am

The competition heats up: In a press release today, Sierra Nevada has announced plans to build a version of Dream Chaser optimized for science research.

The Dream Chaser for Science, or DC4Science, spacecraft is designed to fly independently for short and extended durations to provide customers in such fields as biotech and pharmaceuticals, biology and life science, and material and fluid science with a flexible and evolvable vehicle easily suited for individual mission requirements.

More details here.

I call this version of Dream Chaser a variation of the X-37B because that is essentially what it would be, an unmanned reusable robot vehicle capable of taking experiments into space for periods of time and then bringing them safely back to Earth on a runway.

What Sierra Nevada is doing by announcing this now, shortly after the landing of the X-37B, is selling the concept in an effort to drum up customers who will then invest in the vehicle and thus help fund its construction.

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Comet 67P/C-G smells!

5:07 pm

Instruments on Rosetta have determined that the various molecules coming off Comet 67P/C-G have a strong aroma.

You might expect a rock that spends all its time in a vacuum to be fairly inoffensive, but in fact exposure to sunlight is causing it to give off quite an aroma: hydrogen sulfide, ammonia, formaldehyde, hydrogen cyanide, and other caustic gases would make it smell “suffocating,” like a cross between a filthy barn, an embalming room, and a rotten egg.

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Problems at the National Weather Service?

9:29 am

According to this news report, since Tuesday the National Weather Service has lost access to some of its satellite data.

The story is very unclear and might not be accurate. For example, it does not state where the problem is. Has a specific satellite failed? Or is the problem on the ground, preventing the NWS from processing data from any of its satellites? It also seems puzzling for such a significant failure to occur on Tuesday and only now on Thursday does anyone notice. I have seen no other news stories about this outage.

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Increasing activity at Comet 67P/C-G

8:49 am

Data from Rosetta in the past month has been showing a steady and gradual increase in dust emissions from the surface.

While images obtained a few months ago showed distinct jets of dust leaving the comet, these were limited to the ‘neck’ region. More recently, images obtained by Rosetta’s scientific imaging system, OSIRIS, show that dust is being emitted along almost the whole body of the comet. Jets have also been detected on the smaller lobe of the comet. “At this point, we believe that a large fraction of the illuminated comet’s surface is displaying some level of activity,” says OSIRIS scientist Jean-Baptiste Vincent from the Max Planck Institute for Solar System Research (MPS) in Germany.

The last two images at the link compare the same location with one image overexposed to make the jets visible. What is interesting is that the source of the jet is not evident in the other normally exposed image. It is almost as if surface material is simply heating up and then using that extra energy to simply throw itself off the surface. Why that then forms jets however is puzzling.

More info here.

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Titan’s atmosphere is unexpectedly unbalanced

5:15 pm

The uncertainty of science: New data from the ground-based telescope ALMA suggest that certain organic molecules in Titan’s atmosphere are not evenly distributed through the atmosphere as expected.

At the highest altitudes, the pockets of organic molecules were shifted away from the poles. These off-pole concentrations are unexpected because the fast-moving, east-west winds in Titan’s middle atmosphere should thoroughly mix the molecules formed there. The researchers do not have an obvious explanation for these findings yet.

I would not take these results too seriously, as the data are very sketchy. With better data many of these questions will vanish, replaced by new questions that are better based on reality.

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India begins tests of larger rocket engine

8:45 am

The competition heats up: Indian engineers have successfully completed their first tests of a new more powerful upper stage engine for their biggest launch rocket.

Taking a big step forward in the development of bigger and more powerful locally-built rocket engines, the Liquid Propulsion Systems Centre (LPSC) on Monday successfully conducted the first ‘cold flow test’ on the CE-20 cryogenic engine, which will power the upper stage of the Geosynchronous Satellite Launch Vehicle-Mk III (GSLV-Mk III). “It’s a milestone,” LPSC director Dr K Sivan told ‘Express’ here on Tuesday, confirming that the test had gone as planned at the LPSC facility in Mahendragiri, Tamil Nadu. The first ‘hot test’ – where the engine will be fired for a few seconds- will be performed in three weeks’ time, Sivan said.

In a cold test, the propellants are not ignited. On Monday, the fuel, Liquid Hydrogen (LH2), and the oxidiser, Liquid Oxygen (LOX), were injected into the chambers for the checking of various parameters.

In related news, Mangalyaan has taken another global view of Mars.

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