Posted on by Nancy Atkinson

Phoenix Lander Team: It Snows at Night on Mars

Data from the Phoenix lander's LIDAR instrument showing precipitation falling on Mars. Credit: Whiteway, et al.

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It snows on Mars. This occurs, at least in the northern arctic region where the Phoenix lander set up camp in 2008. Science teams from Phoenix were able to observe water-ice clouds in the Martian atmosphere and precipitation that fell to the ground at night and sublimate into water in the morning. James Whiteway and his colleagues say that clouds and precipitation on Mars play a role in the exchange of water between the ground and the atmosphere and when conditions are right, snow falls regularly on Mars.

“Before Phoenix we did not know whether precipitation occurs on Mars,” Whiteway said. “We knew that the polar ice cap advances as far south as the Phoenix site in winter, but we did not know how the water vapor moved from the atmosphere to ice on the ground. Now we know that it does snow, and that this is part of the hydrological cycle on Mars.”

Phoenix landed at the north arctic region on Mars (68.22°N, 234.25°E) on May 25th, 2008. On Mars, this was just before the summer solstice. Phoenix operated for 5 months, and was able to observe conditions as the seasons changed from summer to winter, giving science teams an unprecedented look at the planet’s changing weather patterns, including frost and precipitation.

The science team used the light detection and ranging instrument, known as LIDAR, and observed clouds that are similar to cirrus clouds here on Earth.

The LIDAR instrument emits pulses of laser light upward into the atmosphere, and then detects the backscatter from dust and clouds. The researchers were able to observe that water-ice crystals grow large enough to precipitate through the atmosphere at night and sublimate into water in the morning. The water vapor on the ground is then mixed back up through the air by turbulence and convection – reaching a height of about two and a half miles (four kilometers) – before again forming clouds at night.

Movie of clouds on Mars. Credit: NASA/JPL/UofA
Movie of clouds on Mars. Credit: NASA/JPL/UofA

Fall streaks in the cloud structure traced the precipitation of ice crystals toward the ground.

“Frost was predicted, but snowfall was quite a welcome surprise,” said Phoenix principal investigator Peter Smith. “In summer there was a lot of dust in the atmosphere. As we neared fall, the dust cleared, and all of a sudden there were water ice clouds forming at about 4 km (2.5 mi.) above the surface. We could see the clouds scud by, moving through the camera field, and once we saw snow coming out of the bottom of a cloud. It was very exciting to watch the daily weather changes. No one has ever had this experience.”

Using the LIDAR, the team could measurement atmospheric dust in the planetary boundary layer (PBL), the lowest part of the atmosphere which is directly influenced by its contact with a planetary surface.

Whiteway and his team said the PBL on Mars is quite interesting. “The PBL on Mars was well mixed, up to heights of around 4 kilometers, by the summer daytime turbulence and convection,” the team wrote in their paper, which is published today in the Journal Science. “The water-ice clouds were detected at the top of the PBL and near the ground each night in late summer after the air temperature started decreasing. The interpretation is that water vapor mixed upward by daytime turbulence and convection forms ice crystal clouds at night that precipitate back toward the surface.”

The clouds didn’t begin forming until around sol 80 or 90 – the number of days from when Phoenix landed on Mars — when air temperatures were cool enough for water vapor in the atmosphere to condense. In the early morning hours on sol 109, the LIDAR observed clouds and precipitation that extended all the way to the ground.

The science team said the clouds and precipitation keep the water confined within the PBL. Eventually, the ice clouds would have persisted within the PBL throughout the daytime, and water ice would have remained deposited on the ground. As the depth of the PBL decreased in late summer, the atmospheric water vapor would decrease, and the process would eventually stop as winter progressed.

Source: Science

Posted on by Anne Minard

Messier 87 Shows Off for Hundreds of Earth-bound Astronomers

Artists's Conception of M87's inner core: Black hole, accretion disk, and inner jets. Credit: Bill Saxton, NRAO/AUI/NSF

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When the giant radio galaxy Messier 87 (M 87) unleashed a torrent of gamma radiation and radio flux, an international collaboration of 390 scientists happened to be watching. They’re reporting the discovery in this week’s issue of Science Express.

Large-scale VLA image of M87: White circle indicates the area within which the gamma-ray telescopes could tell the very energetic gamma rays were being emitted. To narrow down the location further required the VLBA. CREDIT: NRAO/AUI/NSF
Large-scale VLA image of M87: White circle indicates the area within which the gamma-ray telescopes could tell the very energetic gamma rays were being emitted. To narrow down the location further required the VLBA. CREDIT: NRAO/AUI/NSF

The results give first experimental evidence that particles are accelerated to extremely high energies in the immediate vicinity of a supermassive black hole and then emit the observed gamma rays. The gamma rays have energies a trillion times higher than the energy of visible light.

Matthias Beilicke and Henric Krawczynski, both physicists at Washington University in St. Louis, coordinated the project using the Very Energetic Radiation Imaging Telescope Array System (VERITAS) collaboration. The effort involved three arrays of 12-meter (39-foot) to 17-meter (56-foot) telescopes, which detect very high-energy gamma rays, and the Very Long Baseline Array (VLBA) that detects radio waves with high spatial precision.

“We had scheduled gamma-ray observations of M 87 in a close cooperative effort with the three major gamma-ray observatories VERITAS, H.E.S.S. and MAGIC, and we were lucky that an extraordinary gamma-ray flare happened just when the source was observed with the VLBA and its impressive spatial resolving power,” Beilicke said.

“Only combining the high-resolution radio observations with the VHE gamma-ray observations allowed us to locate the site of the gamma-ray production,” added R. Craig Walker, a staff scientist at the National Radio Astronomy Observatory in Socorro, New Mexico.

Peering Deeper Into the Core of M87: At top left, a VLA image of the galaxy shows the radio-emitting jets at a scale of about 200,000 light-years. Subsequent zooms progress closer into the galaxy's core, where the supermassive black hole resides. In the artist's conception (background). the black hole illustrated at the center is about twice the size of our Solar System, a tiny fraction of the size of the galaxy, but holding some six billion times the mass of the Sun. Credit: Bill Saxton, NRAO/AUI/NSF
Peering Deeper Into the Core of M87: At top left, a VLA image of the galaxy shows the radio-emitting jets at a scale of about 200,000 light-years. Subsequent zooms progress closer into the galaxy's core, where the supermassive black hole resides. In the artist's conception (background). the black hole illustrated at the center is about twice the size of our Solar System, a tiny fraction of the size of the galaxy, but holding some six billion times the mass of the Sun. Credit: Bill Saxton, NRAO/AUI/NSF

M 87 is located at a distance of 50 million light years from Earth in the Virgo cluster of galaxies. The black hole in the center of M 87 is six billion times more massive than the Sun.

The size of a non-rotating black hole is given by the Schwarzschild radius. Everything — matter or radiation — that comes within one Schwarzschild radius of the center of the black hole will be swallowed by it. The Schwarzschild radius of the supermassive black hole in M 87 is comparable to the radius of our Solar System.

In the case of some supermassive black holes — as in M 87 — matter orbiting and approaching the black hole powers highly relativistic outflows, called jets. The matter in the jets travels away from the black hole, escaping its deadly gravitational force. The jets are some of the largest objects in the Universe, and they can reach out many thousands of light years from the vicinity of the black hole into the intergalactic medium.

Very high-energy gamma-ray emission from M 87 was first discovered in 1998 with the HEGRA Cherenkov telescopes. “But even today, M 87 is one of only about 25 sources outside our galaxy known to emit [very high energy] gamma rays,” says Beilicke.

The new observations now show that the particle acceleration, and the subsequent emission of gamma rays, can happen in the very “inner jet,” less than about 100 Schwarzschild radii away from the black hole, which is an extremely narrow space as compared with the total extent of the jet or the galaxy.

In addition to VERITAS and the VLBA, the High Energy Stereoscopic System (H.E.S.S.) and the Major Atmospheric Gamma-Ray Imaging Cherenkov (MAGIC) gamma-ray observatories were involved in these observations.

Lead image caption: Artists’s Conception of M87’s inner core: Black hole, accretion disk, and inner jets. Credit: Bill Saxton, NRAO/AUI/NSF

Second image: Large-scale VLA image of M87: White circle indicates the area within which the gamma-ray telescopes could tell the very energetic gamma rays were being emitted. To narrow down the location further required the VLBA. CREDIT: NRAO/AUI/NSF

Collage: At top left, a VLA image of the galaxy shows the radio-emitting jets at a scale of about 200,000 light-years. Subsequent zooms progress closer into the galaxy’s core, where the supermassive black hole resides. In the artist’s conception (background). the black hole illustrated at the center is about twice the size of our Solar System, a tiny fraction of the size of the galaxy, but holding some six billion times the mass of the Sun. Credit: Bill Saxton, NRAO/AUI/NSF

Sources: Science and the National Radio Astronomy Observatory, via Eurekalert.

Posted on by Nancy Atkinson

Test-Bed Rover is Now Stuck — Which is a Good Thing!

With a slope of about 10 degrees and a pointy rock under the test rover's belly, this sandbox setup at NASA's Jet Propulsion Laboratory, Pasadena, Calif., is ready for engineers to use the test rover to assess possible moves for getting Mars rover Spirit out of a patch of loose Martian soil. Credit: JPL

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Engineers at the Jet Propulsion Laboratory have intentionally driven their engineering rover into soft soil in a sandbox testbed, to simulate how the Spirit rover is stuck on Mars. And they did a good job of it, too, as the test rover, called SSTB1, is stuck, as well, with its wheels spinning and going nowhere. The science team has confirmed a rock on Mars, underneath Spirit is touching the underside of the rover, so engineers have placed a similar looking rock in the test sandbox, as seen above.

“We want to experiment with different extraction techniques down here on Earth before we actually do them for real on Mars,” said John Callas, project manager for the Mars rovers. “Our expectation is that it will some time to get Spirit out, so we will be able to get a better feel for that here in this facility to see how well the techniques work and how long it will take for them to work.”

The rover team spent several days of preparing a sloped area of soft, fine soil to simulate Spirit’s current sandtrap on Mars. On June 30 they maneuvered the test rover around, driving the wheels to the loose soil where the rover would sink and slide to the side, with a slope of about 10 degrees, as engineers believe Spirit has done on Mars.

You can follow the work being done to free Spirit from her predicament at the Free Spirit website. JPL regularly posts updates and videos showing what the rover teams are doing, and currently you can see a movie of how the test rover was driven in the sandbox to get stuck.

A test rover rolls off a plywood surface into a prepared bed of soft soil. Credit: JPL
A test rover rolls off a plywood surface into a prepared bed of soft soil. Credit: JPL

There are actually two test vehicles, and the folks at UnmannedSpaceflight.com have a page explaining the differences, as well as other FAQs about the attempts to free Spirit. The one being use for this current test, SSTB1 is a full size replica of the MER vehicles, but it has a few differences such as no solar panels, and a few other minor missing parts. It has the same mass as the ones on Mars, which means it has a higher weight on Earth than the MERs have on Mars.

The other test rover, SSTB Lite, is a stripped down vehicle with same wheel size, actuators and suspension system, but has other major components missing which gives it a weight on Earth that is similar to the weight of MER on Mars. However, when the Opportunity rover was stuck a couple of years in the Purgatory dune, engineers found that SSTB1 behaved more similarly to the MER vehicles, possibly because both the SSTB1 and the soil were subject to the same gravity vector.

Mosaic of the area around Home Plate where Spirit remains stuck was made especially for Spaceflight Now (Used by permission). Credit: Kenneth Kremer, Marco DiLorenzo, NASA/JPL/Cornell/Spaceflight Now. Click for larger image.
Mosaic of the area around Home Plate where Spirit remains stuck was made especially for Spaceflight Now (Used by permission). Credit: Kenneth Kremer, Marco DiLorenzo, NASA/JPL/Cornell/Spaceflight Now. Click for larger image.

So, just where is Spirit on Mars? Take a look at this great image created by Ken Kremer and Marco DeLorenzo of UnmannedSpaceflight.com, showing Spirit’s current location. It shows smooth area in the foreground, that concealed slippery water related sulfate material where rover became stuck. Once free, Spirit will drive to area near the unusually capped hill ahead designated Von Braun to sample water related evidence there. Let’s hope the engineer’s work here on Earth will “Free Spirit” and enable explorations of Von Braun, and beyond.

Caption for mosaic above: Mosaic of the area around Home Plate where Spirit remains stuck was made especially for Spaceflight Now (Used by permission). Credit: Kenneth Kremer, Marco DiLorenzo, NASA/JPL/Cornell/Spaceflight Now. Click the picture for a larger image.

Sources: “Free Spirit” website, Unmanned Spaceflight, Spaceflightnow.com

Posted on by Nancy Atkinson

WiFi in Space Coming Soon?

Mike Massimino, AKA Astro_Mike on Twitter, works on his computer during the STS-125 mission. Credit: NASA

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Although current astronauts are Twittering and blogging from space, it’s a cumbersome process as the ISS, shuttle and Soyuz do not have internet access. Instead, they have to downlink their information to mission control, where someone posts it to the web. But if future commercial space travelers or astronauts living on the Moon want to blog, Tweet and share their experiences real-time, will it be possible? Well, a group of engineers are working on applying the same wireless systems that keep our mobile phones, laptops and other devices connected to the web to a new generation of networked space hardware. They say that wireless technologies will likely be important part of future space exploration, not only for human communication but for transfer of data and commands.

The Wireless Working Group (WWG) of the Consultative Committee for Space Data Services (CCSDS) is a group of engineers that coordinates wireless research among global space agencies and promotes interoperability of spacecraft data systems.

Multiple microsensors like this one could be scattered across planetary surfaces to gather more information than a single lander could provide. The microsensors would then configure a wireless network to assemble data for its relay back to Earth. Credit: ESA
Multiple microsensors like this one could be scattered across planetary surfaces to gather more information than a single lander could provide. The microsensors would then configure a wireless network to assemble data for its relay back to Earth. Credit: ESA

They say that wireless sensor nodes placed throughout a spacecraft might function as a networked nervous system, yielding a wealth of currently inaccessible structural or environmental data to mission controllers. Similar nodes scattered across a planetary surface would generate a much higher scientific return than a single lander could, configuring a network to combine their findings for relaying to Earth.

And establishing ‘plug and play’ wireless networking between multiple spacecraft could enable the seamless transfer of data and commands. This would work for formation-flying satellite constellations and orbiter-lander-rover combinations , but proximity networks could be set up by any spacecraft within signal range as easily as a laptop plugs into a WiFi network.

Of course, the technology is still being developed and having Wifi in space isn’t going to happen anytime soon, but engineers say the underlying technologies are already with us, in the protocols delivering wireless connectivity to homes, offices and public places.

“This research is an example of us ‘spinning in’ technology developed elsewhere into the space sector,” said ESA data handling engineer Jean-François Dufour, who is part of the CCSDS. “Commercial wireless protocols such as the IEEE 802.11 family of standards for computer WiFi or sensor networking standards such as IEEE 802.15.4 are already available so we are assessing how they might transfer to the space environment.”

Source: ESA

Posted on by Nancy Atkinson

Where In The Universe #60



Ready for another Where In The Universe Challenge? Here’s #60! Take a look and see if you can name where in the Universe this image is from. Give yourself extra points if you can name the spacecraft responsible for the image. As usual, we’ll provide the image today, but won’t reveal the answer until tomorrow. This gives you a chance to mull over the image and provide your answer/guess in the comment section. Please, no links or extensive explanations of what you think this is — give everyone the chance to guess.

UPDATE: The answer has now been posted below. Don’t peek before you make your guess!

This is an image of clouds in Earth’s atmosphere, taken by the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite. The features here are called “cloud streets,” this type of cumulus clouds form when cold air from the ice blows over the open ocean, chilling the moist air. As the temperature drops, water freezes into tiny clouds, which are arranged in neat rows in line with the powerful sweep of the wind. The clouds from this image are forming over the Bering Sea, and although some clouds form over the cracking sea ice on the right side of the image, most are over the unfrozen water.

To see a larger version of the image and to learn more about it, see NASA’s Earth Observatory website.

Check back next week for another WITU Challenge!

Posted on by Anne Minard

Astronomers Discover Medium-Sized Class of Black Holes

HLX-1 in the periphery of the edge-on spiral galaxy ESO 243-49. Credit: Heidi Sagerud.

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It’s the Goldilocks variety of black holes: not too big and not too small.

The new source HLX-1,  the light blue object to the top left of the galactic bulge, is the ambassador for a new class of black holes, more than 500 times the mass of the Sun. It lies on the periphery of the edge-on spiral galaxy ESO 243-49, about 290 million light years from Earth.

The discovery, led by Sean Farrell at Britain’s University of Leicester, appears today in the journal Nature.

Until now, identified black holes have been either super-massive (several million to several billion times the mass of the Sun) in the center of galaxies, or about the size of a typical star (between three and 20 solar masses).

The new discovery is the first solid evidence of a new class of medium-sized black holes and was made using the European Space Agency’s XMM-Newton X-ray space telescope. At the time of the discovery, Farrell and his team were working at the Centre d’Etude Spatiale des Rayonnements in France.

A black hole is a remnant of a collapsed star with such a powerful gravitational field that it absorbs all the light that passes near it and reflects nothing.

“While it is widely accepted that stellar mass black holes are created during the death throes of massive stars, it is still unknown how super-massive black holes are formed,” Farrell said.

It had been long believed by astrophysicists that there might be a third, intermediate class of black holes, with masses between a hundred and several hundred thousand times that of the Sun. However, such black holes had not been reliably detected until now.

One theory suggests that super-massive black holes may be formed by the merger of a number of intermediate mass black holes, Farrell said.

“To ratify such a theory, however, you must first prove the existence of intermediate black holes. This is the best detection to date of such long sought after intermediate mass black holes. ”

Using XMM-Newton observations carried out in 2004 and 2008, the team showed that HLX-1 displayed a variation in its X-ray signature. This indicated that it must be a single object and not a group of many fainter sources. The huge radiance observed can only be explained if HLX-1 contains a black hole more than 500 times the mass of the Sun. The authors say that no other physical explanation can account for the data.

Lead image caption: Artist’s impression of HLX-1 in the periphery of the edge-on spiral galaxy ESO 243-49. Credit: Heidi Sagerud.

Sources: Nature and the University of Leicester

Posted on by Nancy Atkinson

Your New Guide to the Inner Galaxy

Colour-composite annotated image of part of the Galactic Plane seen by the ATLASGAL survey, divided into sections. Credit: ESO

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All you galactic hitchhikers take note: a new atlas of the inner regions of the Milky Way was released today, showing thousands of previously undiscovered dense knots of cold cosmic dust — the potential birthplaces of new stars. This new map of the home galaxy was made using observations from the APEX telescope in Chile, showing the Milky Way in submillitere wavelengths. “ATLASGAL gives us a new look at the Milky Way. Not only will it help us investigate how massive stars form, but it will also give us an overview of the larger-scale structure of our galaxy”, said Frederic Schuller from the Max Planck Institute for Radio Astronomy, leader of the ATLASGAL team.

So, grab your towels and let’s head out!

This is the largest map available of cold dust, and astronomers say it will provide an invaluable map for observations made with the forthcoming ALMA telescope, as well as the recently launched ESA Herschel space telescope.

The area of the new submillimeter map is approximately 95 square degrees, covering a very long and narrow strip along the galactic plane two degrees wide (four times the width of the full Moon) and over 40 degrees long. The 16,000 pixel-long map was made with the LABOCA submillimeter-wave camera on the ESO-operated APEX telescope. APEX is located at an altitude of 5100 m on the arid plateau of Chajnantor in the Chilean Andes — a site that allows optimal viewing in the submillimeter range. The Universe is relatively unexplored at submillimeter wavelengths, as extremely dry atmospheric conditions and advanced detector technology are required for such observations.

And click here to see an annotated pan of part of the galactic plane.

Highlights of the map include the center of the Milky Way, the nearby massive and dense cloud of molecular gas called Sagittarius B2, and a bubble of expanding gas called RCW120, where the interstellar medium around the bubble is collapsing and forming new stars.

Colour-composite image of the Galactic Centre and Sagittarius B2 as seen by the ATLASGAL survey. Credit: ESO
Colour-composite image of the Galactic Centre and Sagittarius B2 as seen by the ATLASGAL survey. Credit: ESO

“It’s exciting to get our first look at ATLASGAL, and we will be increasing the size of the map over the next year to cover all of the galactic plane visible from the APEX site on Chajnantor, as well as combining it with infrared observations to be made by the ESA Herschel Space Observatory. We look forward to new discoveries made with these maps, which will also serve as a guide for future observations with ALMA”, said Leonardo Testi from ESO, who is a member of the ATLASGAL team and the European Project Scientist for the ALMA project.

The interstellar medium — the material between the stars — is composed of gas and grains of cosmic dust, rather like fine sand or soot. However, the gas is mostly hydrogen and relatively difficult to detect, so astronomers often search for these dense regions by looking for the faint heat glow of the cosmic dust grains.
Submillimetre light allows astronomers to see these dust clouds shining, even though they obscure our view of the Universe at visible light wavelengths.

The newly released map also reveals thousands of dense dust clumps, many never seen before, which mark the future birthplaces of massive stars. The clumps are typically a couple of light-years in size, and have masses of between ten and a few thousand times the mass of our Sun. In addition, ATLASGAL has captured images of beautiful filamentary structures and bubbles in the interstellar medium, blown by supernovae and the winds of bright stars.

Source: ESO

Posted on by Nancy Atkinson

Mars Will NOT Look as Big as the Full Moon, But You Can Watch it Get Closer

Mars and the Moon -- NOT. Credit: Scientific American

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For criminy’s sake, I just got one of those “Mars as big as the full Moon in August” emails. For one more time: this is completely false and it couldn’t possibly happen. Besides, in 2009 Mars is all but unobservable until the end of the year, and even next year it won’t be much better. So can we please see an end to these erroneous emails???

But Mars is coming closer to Earth (it happens like clockwork every 26 months) and the folks at Emory University have created a real-time distance calculator that shows Mars’ geocentric distance from us. It’s really fun to see how quickly Mars is coming closer to Earth (but pleeeeease it is not going to look as big the full Moon!!!) The distance is calculated in miles (sorry rest of the world) and shows up in blue when Mars is approaching and red when Mars begins to move farther from Earth. Very fun!

And if you need to know why Mars will not look as big as the full moon, see below.

Even at its closest approach, which happened back in 2003, Mars was 35 million miles (56 million km) away from Earth. You would have to magnify Mars 75 times to make it look as big as the full Moon, without a telescope. Mars won’t come this close again until 2287.

Here’s a graph from Robin Scagell at Popular Astronomy (below) which shows how the distance from Earth to Mars varies over the next few decades, shown as the size that Mars will appear in the sky. 25 arc seconds is about half the apparent size of Jupiter in the sky, which is the largest that Mars appeared in 2003.

Apparitions of Mars 2003-2042. Credit: Popular Astronomy
Apparitions of Mars 2003-2042. Credit: Popular Astronomy

Mars as big as the full moon just ain’t gonna happen, folks.

We’ve discussed the Mars Hoax email every years since 2003. Here are the UT articles for 2008, 2007, 2006, and 2005. And if you need more there are a few from Phil Plait the Bad Astronomer: here, here , here, and here’s the original one back in 2003.

And while I’m at it, I also recently got a “North Pole at Sunset” email. Another NOT.

Posted on by Nancy Atkinson

Get Your Own Personal UFO


I’m always amazed at what you can find on You Tube. Type “UFO” in the search panel, and you get all sorts of wacky stuff. But this one is really quite cool. It’s called the X-Jet and was created by the US Air Force. It is kind of like your own personal flying Segway. For everyone who has wondered where the flying cars are, here’s your answer.

Posted on by Nancy Atkinson

Faster, Cheaper (and Better?) Way to the Moon


The word this morning from several NASA Twitterers is that the stacking of the new Ares I-X rocket for its upcoming test flight is temporarily on hold. Everyone is waiting for word from a NASA executive session reconsidering the plan. And perhaps it might have something to do with an alternative plan to return to the Moon, submitted by shuttle program manager John Shannon to the Augustine Commission, the independent panel that is reviewing NASA’s current vision, including the Constellation program. Interestingly, Shannon says he was strongly encouraged by a top NASA administrator to present his idea to the panel. Shannon’s option would be faster – perhaps eliminating at least a year of the projected 5-year gap between the shuttle and Constellation. It would be cheaper: $6.6 billion vs. $35 billion for Constellation. But would it be better? Take a look at this video that Shannon presented to the Augustine Commission.
Continue reading “Faster, Cheaper (and Better?) Way to the Moon”