Archive for the ‘Astrobiology’ category

Can Life Survive in Space?

August 12, 2010

I’ve got a new post up at The Science of Starcraft! This time I tackle the question of whether unprotected living things could ever survive in the vacuum of space. Go check it out!

New Deep Sea Vents Discovered in the Caribbean

July 22, 2010

The hybrid robotic vehicle Nereus is recovered after searching for new hydrothermal vents along the Mid-Cayman Rise. Image credit: Woods Hole Oceanographic Institution

Here’s the second of my recent Universe Today Articles: scientists have discovered new deep sea vents in the Caribbean that will teach us more about sunless ecosystems. Good to know if we ever want to look for life in the oceans of Europa some day! Check out the article here.

Ice Caves on Mars!

June 9, 2010

Hey, guess what? There might be caves with ice in them on Mars! You should go check out my post about this cool new possibility over at Universe Today!

Carnival of Space 152

May 2, 2010

Welcome to The Martian Chronicles and the 152nd edition of the Carnival of Space! As always, we’ve got a great bunch of space-related posts from across the blogosphere, ranging from life on Mars to the age of the universe to Science Ninjas!

I’ll get things started with a pair of posts from right here at The Martian Chronicles. A couple weeks ago I went on a cool geology field trip in the El Paso/Carlsbad area along with a whole bunch of other martian and terrestrial geologists. Among other things, we learned that printed Mars panoramas make good raincoats, that graduate students are ideal for menial labor like counting hundreds of thousands of layers of rock, and that ancient reefs have a surprising amount to teach us about stratigraphy on Mars. Check out my summaries of Day 1 and Day 2 of the field trip! Day three is coming soon, with lots of pretty pictures of Carlsbad Caverns!

Speaking of rocks and Mars, Paul Scott Anderson at Planetaria has a post about another Mars meteorite that might have evidence of life! He includes a few very nice electron microscope images of the meteorite for your consideration. Personally, I’m not convinced, but I’m also not an expert on this corner of Mars science. Take a look for yourself!

Ian O’Neill at Discovery News also has been thinking about martian microbes, and whether germs from Earth might have hitched a ride on our rovers, set up camp on Mars and wiped out the locals. It would sure be disappointing if we discover life on Mars only to learn that someone at JPL forgot to wash their hands! Of course, there are also those who think we should stop bothering with all this planetary protection business and deliberately seed Mars with Earth life. What do you think?

While we’re on the topic of our potentially infectious little rovers, Stuart Atkinson has some beautiful pictures from the Opportunity rover. Oppy is slowly making her way across the Meridiani Plains, and has a tantalizing view of the distant hills that are her ultimate destination. As Stu says, “The far horizon is calling…

But this is the Carnival of Space, not the Carnival of Rocks and Bugs and Rovers, so let’s get on to the more “spacey” stuff! I’m a big fan of stuff, and so is Steve Nerlich at Cheap Astronomy! This week they have a great podcast about “stuff” in space and the surprisingly limited number of shapes in which it can be found.

A radar "image" of an asteroid and its two tiny moons. Credit: NASA / JPL / GSSR / Emily Lakdawalla

While we’re on the topic of stuff and its various shapes, I should point out that radar is a great way to find out the shape of stuff in space like asteroids. If you’ve ever seen one of the “images” of an asteroid taken by a telescope like Arecibo and wondered how a radar antenna can be used to take a picture, then wonder no longer! Just take a look at Emily Lakdawalla’s post about radar imaging and all your questions will be answered.

If radar images are not your cup of tea, then maybe you’d prefer to learn about an old-school optical telescope: the Radcliffe 1.9 meter telescope. Markus shares the joy of handling the massive old wrought iron telescope in this post at Supernova Condensate.

Not a fan of old school ‘scopes? Well, perhaps I can interest you in some futuristic¬† Hypertelescopes? Next Big Future also has some cool posts about even more far-out ideas like Dyson Swarms and Dyson bubbles and “statites” – structures that hover above a star by balancing its gravitational force with its radiation pressure.

We’re a long way from that level of engineering, but solar sail technologies are getting more advanced. Centauri Dreams has a post about the Japanese IKAROS mission: an interplanetary solar sail that also uses its sail as a solar panel to generate electricity! I hadn’t heard of this mission, but it sounds really cool!

Whether you’re talking about star-enveloping Dyson spheres or relatively simpler missions, you have to wonder what drives exploration, particularly since big steps forward like the Apollo program come so rarely. Well, 21st Century waves talks about the idea that what we’re really dealing with is a chaotic system in this post on how complexity drives exploration.

Of course, sometimes it’s just the brilliance of one person that makes the difference, and lights the path forward, and Robert Goddard is a great example. Over at Music of the Spheres, there’s a great post about Goddard that takes a look as some of his earliest thoughts on space and also some of his inventions, which are now available online thanks to Google Patents.

Weird Sciences contributed three posts this week: First up, some thoughts on why Stephen Hawking is wrong about aliens and the threat they pose. Also, some thoughts on the implications of self-replicating machines. And third, visualizing the fourth spatial dimension.

Speaking of weird, what does Weird Warp have for us this week? Why it’s a nice, informative (and actually not very weird!) post all about the ins and outs of comets, everyone’s favorite icy visitors to the inner solar system.

While we’re back on the subject of “things that are in the inner solar system”, let’s take a look at Astroblogger Ian Musgrave’s post about how to use the moon to find stuff in the night sky. Ian even provides some scripts for the free programs Celestia and Stellarium!

Once you have rounded up your friends and family and taken them on a tour of the night sky using the moon as your guide, you’re bound to start getting pelted with questions. Luckily, “We are all in the gutter” has started a new “how do we know” feature. Their first post in the series is an answer to the question: “How do we know how old the universe is?” Do you have other “how do we know”-type questions? Contact the “We are all in the gutter” folks and get your answer!

Our penultimate post is from Steinn Sigurdsson, who reports on the unfortunate incident of the Nuclear Compton Telescope: a balloon-borne telescope that crashed in Australia during an attempted launch earlier this week. Condolences for those on the telescope team; it’s painful to watch so much work fall apart at its culmination.

And finally, on a (much) lighter note, what you’ve all been waiting for. Toothpaste ingredients! Which of course, logically, lead us to discover Amanda Bauer’s secret alter ego: the Science Ninja. This post makes me wish that a) all products had ingredient lists like the one on that toothpaste, and b) that I, too, was a science ninja.

Update: one late addition to the carnival! Nancy Atkinson at Universe Today is working on a series of posts entitled “13 Things that Saved Apollo 13“. The main article has link to the rest of the articles. Very interesting stuff!

Update 2: One more latebreaking addition! Out of the Cradle has a nice review of the book “The Big Splat, or How the Moon Came to Be”.

Phew! Well, that does it for this week’s Carnival of Space! It’s been a wild ride, as always. Thanks again to Fraser for letting me host, and thanks to all the space bloggers who contributed!

TED Talk: Why we need to go back to Mars

March 25, 2010

I recently started subscribing to the TED talk RSS feed, and I really love coming home every day after work and listening to smart people talk about cool ideas. If you aren’t familiar with TED, you should be. Most of the talks are fantastic and very thought-provoking. So you can imagine I was excited when I saw that today’s talk was about Mars!

The talk was given by Joel Levine, the principal investigator for the proposed ARES mission, which is a rocket-powered airplane that would fly for a couple of hours on Mars and study the atmosphere, surface and subsurface.

He starts off with an overview of Mars exploration history, describing the Mariner flyby in 1965, followed by images from the Viking orbiters and landers. He says that the Viking landers returned the first images ever from the surface of another planet, but that’s actually not true! That achievement actually belongs to Venera 9, which, astoundingly, returned photographs from the surface of Venus in 1975! Everyone forgets poor Venus.

Levine goes on to talk about some of the stunning topographic features on Mars, highlighting Olympus Mons, Valles Marineris and the Hellas basin as the largest volcano, canyon and impact crater in the solar system, respectively. If you really want to be pedantic, Olympus Mons is the tallest volcano, not the largest, but it’s not really a big deal because Mars also has the largest one (Alba Patera). But what really made me pause for a moment was that Hellas is not the biggest crater in the solar system: the South Pole Aitken Basin on the moon has a diameter of 2500 km, 400 km larger than Hellas!

He continues and talks about the mysterious crustal magnetism on Mars and the fact that all of the water on present-day Mars is in the form of ice, and all of this is fine, but then a slide comes up which Levine claims shows “recent” photos from the Mars rovers with evidence of very fast-flowing water on the Martian surface. The only problem is, the images on the slide are all orbital images! I can’t say for sure but I think they are from the MOC camera, which stopped functioning in 2006, three years before this talk was given. Yes, the images show features that could be due to ancient flowing water, but they are certainly not from the rovers, and they’re not very recent either.

I got even more suspicious when Levine showed this picture of a crater filled with ice and claimed that it was taken a few weeks ago and had not yet been publicly released. The only problem is, I remember seeing that picture years ago. A quick web search reveals that it was released in a 2005 press release. Levine also misspeaks and says that the crater is filled with liquid water, but immediately corrects himself so I’ll let that slide. I’m baffled by his claim that it is a never-before-seen image though.

Credit: ESA/DLR/FU Berlin (G. Neukum); Image released: 2005

Shortly after the icy crater image, Levine makes a very strong claim that Mars once had oceans. He doesn’t equivocate at all, he states this as a fact. I find this to be very misleading. Yes, there are some hypotheses about a northern ocean on Mars, but the evidence just is not there to make such a definitive claim, and to pretend that it is gives people an incorrect impression about the Mars community’s consensus.

Even worse, later on in the talk, he claims that the northern lowlands are smooth because they were protected from impacts by an ocean. This is patently false. Oceans are not an effective protection against impacts and if you think about it, you’ll see why. The average ocean depth on earth is 2.3 miles. For comparison, the object that killed the dinosaurs was at least 6 miles in diameter and was traveling at tens of miles per second. It went through the ocean like it wasn’t even there.

Also, there is evidence for craters in the northern plains. They have been buried but they still are just barely visible in elevation data. Of course, an ocean would be one way to bury a huge expanse of the surface, but if the ocean isn’t thick enough to block impacts, then the burial must not be very old, and all evidence points to the water on Mars being a very ancient phenomenon.

Ok, oceans aside, Levine goes on to talk about the recent detections of methane on Mars. He summarizes the results well enough, but draws a misleading parallel with the earth. He says that 99.9% of Earth’s atmospheric methane is biogenic, which may well be true. But that doesn’t mean that life is the only possible source of methane on Mars! I don’t know the exact numbers involved but it would have been much more informative if he had compared the estimated amount of methane on Mars to the estimated amount from abiotic sources on the earth.

The second half of the talk focuses on the ARES Mars airplane mission. I have actually visited the lab in Langley that works on this concept and seen the models of the plane. It is undeniably really cool, but I am not convinced it is the best way to explore Mars. The problem with an airplane is that you need active control to keep it from crashing. Of course the technology exists to fly planes automatically, but to do so on Mars could be difficult. And even assuming that you can get the plane to fly automatically, it would only last for a couple of hours at most. It would collect some fantastic atmospheric and magnetic field data, and some very nice images and video, but it would only be able to cover a few hundred kilometers.

I think if you want to fly something on Mars it should be a balloon. The thin atmosphere is not ideal for a balloon, but they have the advantage that they fly without any active control: they’re lighter than air! It would be a slower ride, for sure, but it could last much longer than an airplane, and the winds could carry the balloon long distances.

In case you couldn’t tell, I was disappointed in this talk. For most people, it will be very enjoyable and they will probably learn something about Mars and about a cool proposed future mission, but the talk also had a lot of misinformation in it. Some was very minor and innocent, but the certainty with which the ocean hypothesis and the biogenic origin of methane were presented struck me as misleading.

I am all in favor of getting people excited about exploring Mars, but we should not give them the wrong impressions about the current state of knowledge. There’s plenty to get excited about without distorting the truth, whether it is intentional or not. That’s why I decided to write this blog entry. Is some of it pedantic? Yes. But I wanted to set the record straight so that maybe a few people get a more accurate picture of the red planet.

LPSC 2010 – Day 4: Mars Oceans, Titan Lakes, Astrobiology and Asteroids

March 6, 2010

Thursday started off with a couple of talks about the possibility of oceans on Mars. The first one, given by Gaetano DiAchille looked at possible locations of deltas all over Mars to try to figure out the water level of a past ocean. Deltas form when a river hits a standing body of water and drops its sediment, so they are a reliable marker of the water level. DiAchille found that “open deltas” – that is, deltas that do not end in a closed basin like a crater, all appear at the same elevation. This might mean that they all fed into a large northern ocean.

A map of valley network density on Mars and the possible extent of a northern ocean.

In the second talk, Wei Luo described his work mapping where all of the valley networks on Mars are and found that the northern limit of the networks fits with elevations that had previously been considered as possible ocean shorelines. The valley networks also matched with locations that atmospheric models predict would get the most precipitation.

Neither of these studies is conclusive evidence for a northern ocean on Mars, but they are interesting and they suggest that the “ocean hypothesis” is becoming popular again after years of little interest.

Later that day I saw a talk by Nick Warner describing the possible thermokarst lakes that he discovered in Ares Vallis on Mars. I wrote an article on Universe Today about this discovery when it was first announced a couple months ago.

I ducked out of the Mars talks to go see a talk by my friend Debra Hurwitz about a lava channel in a crater in Elysium Planitia. The channel was formed when lava breached the rim of the crater, flowed down the inner wall and ponded in the bottom. She calculated that the lava probably flowed at about 17-35 meters per second and that 6,000 cubic meters per second flowed down the channel for about 15 days. She also found that the channel could have been eroded mechanically without the need for the lava to actually melt the underlying rock very much.

A sketch of the lava channel filling the crater in Elysium Planitia.

After that, I headed over to the Titan session to hear a talk by Ralph Lorenz about waves on Titan lakes. Most of what we know about the surface of Titan, including the presence of liquid hydrocarbon lakes, is based on radar images from Cassini that measure roughness. The lakes show up as perfectly smooth (and therefore dark) surfaces, which is weird because radar images of lakes on earth usually have slight roughness due to waves. On Titan the gravity is lower, so you would expect bigger waves. It’s possible the lack of waves is due to the viscosity of the lakes, which might be increased by bigger “tar-like” molecules dissolved in the thinner ethane and methane, but it might also be due to a lack of wind. The Cassini mission will be watching as the seasons at Titan change to see if the wind changes and kicks up any waves.

A (suggestively colored) radar map of lakes on Titan.

I did a lot of session hopping on Thursday! The next stop was the astrobiology session. Oleg Abramov presented some results of his investigation of what intense impacts might have done to early life on the earth or Mars. He found that even during the Late Heavy Bombardment, the crust is not sterilized by the impacts, and in fact it might be more habitable for early life because impacts deliver organic molecules and cause widespread hydrothermal activity!

The talks I was really interested in were two talks on the magnetite crystals discovered in the famous ALH84001 meteorite. I posted a while back about a new paper that claims these crystals are evidence of life on Mars, and these two talks were focused on the claim. The first talk, by Allan Treiman gave some good background on the debate over whether ALH84001 preserves evidence of life and then addressed some of the new claims about the magnetite crystals. He said that most of the attributes of biological magnetite crystals, such as their size, lack of flaws, and precise crystal structure were not observed in the ALH84001 crystals. The big question is why the crystals are so pure. Allan argued that you can get pure crystals just from the heating of iron carbonate, which is found in the meteorite.

The following talk was by Kathy Thomas-Kleptra, whose paper Treiman was responding to. She showed that Treiman had probably made an error in calculating the breakdown temperature for iron carbonate. She also pointed out that the crystals are found in carbonates without much iron and that there is no graphite observed, but it is also a byproduct of heating the carbonates.

I don’t know enough about petrology and geochemistry to know who is right here, and I was very disappointed that both Kathy and Allan used up all of their time talking, so there was no chance at all for questions! I wasn’t the only one. When the moderator said that there was not time for questions and that they had to get on with the next session, most of the room groaned and protested. But alas, the talks pressed onward.

Biogenic magnetite crystals inside a bacterium one Earth.

I zipped back over to the Titan talks in time to catch the end of one pointing to features that they claimed were “deltas” in one of the lakes. I was very skeptical of this because the quality of the radar images is so low. What they avtuall observe is a dark branching channel that ends at a peninsula in one of the lakes. That’s not evidence for a delta in my book. This talk made me realize how spoiled I am with HiRISE, CTX, MOC and other high-resolution data on Mars!

Finally, I stopped by the asteroid session for two talks. The first was by Dan Scheeres and he talked about the role that tiny forces might play in holding asteroids together. He showed that Van Der Waals forces, normally ignored for all but the tiniest particles, actually might be important in holding particles together in asteroids. He made the analogy to powders like flour or cocoa powder on earth. These can clump together and when they are stressed the form fractures even though they are made of loos grains. The same thing might happen on a much bigger scale with the gravel and boulders in low-gravity asteroids!

It's possible that the fractures in objects like Phobos are more like the cracks you see in flour than like cracks in a solid, fractured rock.

The last talk I caught on Thursday was by my friend Seth Jacobson, who showed some simulations of asteroids that spin so fast they break apart. He showed that the ratio of sizes between the two bodies make a big difference in how the binary asteroid evolves. In some cases, the secondary asteroid even swings so close to the primary that it splats apart and forms a short-lived three-body system!

How to Cook Primordial Soup, with Julia Child

February 1, 2010

(Courtesy of Amanda Bauer’s blog, astropixie)


Get every new post delivered to your Inbox.

Join 61 other followers