That’s right folks! As of today, this blog has moved over to the AGU Blogosphere! So, head over to check out my new digs and update your bookmarks and RSS feeds While you’re there, take a look at the other excellent blogs that are part of the network.
I’ll keep cross-posting here for a little while to give you a little time to make the switch, but pretty soon this version of the blog will be retired.
There’s a new post up at the new home of The Martian Chronicles about a recent study that suggests that one in four sun-like stars had earth-sized planets. Head on over and check it out, and update your bookmarks and subscriptions for the new site! I won’t be posting here for much longer…
Last week was my birthday, and I unexpectedly got a gift in the mail from my cousin. We don’t normally exchange birthday gifts, but she came across a t-shirt called “Tubes of Mars” and just had to buy it for me. Apparently, this line of shirts is capitalizing on various wacky conspiracy theories and they decided to use one of my favorites, the “glass tubes on Mars” idea.
The shirt itself has a swirly-looking abstract design on it, but then down in the corner it has a caption in fine print explaining:
Photographs taken from Martian orbit reveal what appear to be miles and miles of ribbed ‘tubes’ on the surface of the red planet. It is estimated that these tubes have diameters of close to 600 feet. Some have tried to explain these formations as a the result of geological processes. Others believe they are organic in nature. Yet some are convinced the tubes may have been constructed.
If you’re not familiar with this hoax, let me explain, starting with a picture.
Here's a HiRISE view of some channels on Mars full of aeolian ripples.
See the numerous light-toned ridges arrayed along that canyon floor? There is a group of people who claim that these features are actually the support struts of transparent tubes that crisscross the martian surface. I’ll grant that if you have no idea what you’re looking at, these things might sort of look like a tube of some sort, but it’s actually an illusion. The light-toned ridges are ripples of wind-blown material, likely coarse sand or gravel. These are seen all over the place on Mars, and they don’t always look so tubular. Heck, the Opportunity rover has been driving across ripples like these for years! The thing that is confusing people is that these ripples are extremely common in canyons, and because the canyons funnel the surface winds so that they blow down the length of the trough, the ripples are oriented perpendicular to the canyon walls. If you look closely you can see that these are clearly wind-blown ripples. Take this HiRISE image for example:
Here's a HiRISE view of some channels on Mars full of aeolian ripples.
The channels in this image are filled with aeolian ripples. If you were really determined to see a tube, I suppose you could at the scale shown above, but if we zoom in even more that explanation disintegrates:
You can see here that the larger ripples break up into more complicated ripples toward the edges, and that there is a secondary wind direction forming small ripples perpendicular to the big ones.
I’ve always found the belief that these features are some sort of glass tubes on Mars to be both funny and sad at the same time. It shows a complete lack of understanding of the very interesting geology at work on Mars (and Earth), along with a somewhat disturbing willingness to see evidence of outlandish claims and conspiracies everywhere. Those of us in Mars science are all too familiar with this. There’s a long tradition of seeing what you want to see on Mars, going all the way back to the famous “canals”. These days, no scientists really think there’s macroscopic evidence of life on Mars, but I think there is still a very strong desire among scientists and the public for early Mars to have been “warm and wet” (a.k.a. Earth-like). Maybe it really was earth-like, but maybe it wasn’t. We all need to be vigilant and make sure the way we want Mars to be doesn’t cloud our conclusions.
The Outpost Tavern burned down Friday night. The Outpost was a rickety little tavern in Houston a couple miles from Johnson Space Center, famous as a hang-out for astronauts and other NASA folks. It went out of business earlier this year and it has apparently now met its fiery demise.
I first visited the Outpost when I was in the 2006 Goddard NASA Academy. 20 of us showed up without notice at this little bar with one bartender and a couple of regulars. They were completely overwhelmed by the sudden burst of business, but amazingly, the regulars got up and lent the bartender a hand in the kitchen, and we all got our burgers and beer in impressively little time. We followed the tradition and signed our names to a dollar bill and posted it on the wall along with all the other signed bills and various astronaut paraphernalia.
Future NASA heroes enjoying dinner at The Outpost.
But I mention the end of the Outpost not just so I can share that anecdote with you. I mentioned it because I came across an interesting commentary on the Outpost as a metaphor for NASA in general over at Elliott Potter’s blog Implementation, Detail.
This excerpt really stood out to me:
Now it’s 40 years later. Our cell phones have more computing power than the Apollo moon landers, yet the Space Shuttle’s proposed successor has barely more computing power than the one on the desk in front of me. Why? Not because it’s hard to put electronics into space, or because spacecraft design somehow excludes modern technology – it’s because small-minded people won’t let science fiction become reality.
Those are the people who I think will most lament the passing of The Outpost. Those are the people who bow to the supposed wisdom of yesterday’s paper heroes – Shuttle astronauts who can’t bear to just be scientists or engineers because scientists and engineers aren’t viewed as heroes.
I agree with most of this, but I think more than just the Old Guard lament the loss of the Outpost and the era that it stood for. I certainly am sad to see it go even though I share Potter’s disappointment with the tendency for NASA to cling to the past. The early days of NASA have become almost mythological precisely because there were heroes, and it’s very difficult for people to imagine a different type of NASA with different types of heroes. But that’s exactly what we need. The tendency has always been to try to recreate those glory days of NASA, but we live in a different world and we have to accept there are other ways for space exploration to advance.
I sincerely hope that as NASA attempts to move forward and send humans to Near Earth Objects and other destinations beyond low-earth orbit, it also remembers how to get the world excited again. I’ve talked about this before and Potter puts his finger on it: NASA needs heroes again, and people need to be comfortable with scientists and engineers being those heroes rather than Buck Rodgers-style steely-eyed missile men. You can show the average person all the spectacular pictures of space that you like, but they won’t truly get excited about what NASA does unless there is a human element to connect with. Human space exploration is perfect for building this connection with the public, but somehow NASA has lost the ability or the willingness to play on the inherent human drama of what it does.
I’ll close with the eloquent conclusion to Elliott Potter’s post because it sums things up better than I can:
America already has the resources to achieve greatness in the future. We already have the knowledge and power to go to the Moon, Mars, and Beyond. It doesn’t require additional support from the President or senators or congressmen or contractors. All it requires is that we learn from the past without being bound by it – that we respect the heroes of our youth without requiring all future heroes to be the same. My children should aspire to be astronauts not through feats of strength or military training, but through preparation, knowledge, and ability – the strengths that make humanity most unique and powerful and able to deal with the unknown.
Let The Outpost rest in peace; with it, let our past heroes rest in peace. Let new heroes arise from the ashes: the engineers and scientists who can actually perform the technical miracles we expect from NASA.
Big news folks! Sometime next week, this blog will be moving over to the American Geophysical Union‘s new blog network! AGU is the organization responsible for the Journal of Geophysical Research – Planets, which is one of the most important journals in planetary science, particularly for the terrestrial planets. AGU also hosts the enormous “fall” meeting each December, causing 16,000 scientists to descend on downtown San Francisco like over-educated locusts.
I’m really excited to be representing planetary science as part of the AGU blog network, and I’ll be in very good company. Here is a list of the other geobloggers who will be joining me in the move:
Dave’s Landslide Blog by Dave Petly
Dan’s Wild Wild Science Journal by Dan Satterfield
Mountain Beltway by Callan Bently
Magma Cum Laude by Jessica Ball
Terra Central by John Freeland
Outdoor Science by Vivienne Raper
I’ll keep you posted as the transition occurs, and I should be able to cross-post to both versions of The Martian Chronicles for a while to give you time to update your subscriptions. Stay tuned!
Over the weekend I learned that observational cosmologist John Huchra passed away on Friday. I only met him once, when I was a summer intern at the Harvard-Smithsonian Astrophysical Observatory. He very graciously gave the group of summer interns an hour and a half of his time and told us about his research, and about the interplay between observation and theory in astronomy. But more than that he also shared his passion for discovery and learning about the universe. Hearing him talk got me much more excited at the prospect of becoming a scientist. Even though my scientific interests have drifted toward planets rather than cosmology, that morning spent with Dr. Huchra still sticks in my mind as one of the highlights of my first summer doing real research.
I jotted down this quote when Dr. Huchra was sharing the excitement of his research with a bunch of wide-eyed interns. It spoke to me then and I think of it every time I find myself burning the midnight oil for the sake of something I’m passionate about:
“The best sunrises are the ones you see as you’re going to bed.” -John Huchra
My condolences go out to his friends, families and colleagues who knew him much better than I did. Astronomy has lost a passionate leader. He will be missed.
I always found the contrast between Soviet and US engineering fascinating. The goals were generally similar, but while the US seemed to aim for elegant, lightweight, optimized designs, Soviet spacecraft always look like they’re bolted together out of cast iron or something. That’s why I love this gallery of photos of the Soviet lunar lander that they developed during the space race. This thing looks like it should be used for deep sea exploration! Between this, and the always-awesome Lunokhod rovers, I’m pretty sure the Russians inadvertently started the steampunk movement. 
We wrapped up the landing site workshop on wednesday afternoon by revisiting each of the four sites and discussing them in turn. Unfortunately, the way that we did this was very disappointing, and made for a frustrating afternoon.
The discussion was centered around a word document that was projected up on the screen in the room. Over lunch, the meeting leaders had conferred and listed what they thought were the key points for each site that everyone agreed with, along with areas of future work. But they should have known that getting a room of 200 scientists to agree with something is nearly impossible, and it didn’t help that their list of points was a mish-mash of actual, irrefutable observations (e.g. “there are strong clay mineral signatures at Mawrth”, or “there is a huge layered mound at Gale”) and complete speculations (e.g. “the delta at Eberswalde preserves organic molecules” or “the layered rocks at Holden are likely lake deposits”) and everything in between.
The result was that we spent most of the afternoon going through this document line by line and debating word choices and phrasing and grammar. It was incredibly frustrating, to the point where I almost had to leave the room. By the end, there were probably only five or so people actively participating, while everyone else in the room silently suffered through watching this document being written by committee.
After the discussion, we did end up with a central hypothesis for each of the sites, along with a list of future work.Gale was the first site we discussed, so a lot of the time was spent figuring out how we were going to do this document editing as a group. I also was on the edge of my seat because my adviser was off the the side telling me that I should chime in. I always get stressed out when I’m expected to comment or ask a question when I don’t really have a comment or question to make. In the end I asked about the wording of one of the bullets that said Gale has a “relative paucity of fluvial channels”. Because it actually has tons of them. But apparently “relative paucity” meant “there is more volume in the mound than could have come from those channels” so the sentence was not edited. Those two things mean different things to me, but I didn’t press the point.
Anyway, all of that meant that I didn’t take careful notes for Gale, but the final hypothesis was something along the lines of “how do the environmental and mineralogical signatures preserved in the layered rocks reflect the aqueous processes in the crater?” Although someone else suggested a more concise and to-the-point version: “Did the big-ass mound form in a lake?” Future work for Gale included getting a better handle on the age of the deposits and identifying specifically where MSL would go to look for organics.
For Mawrth the process was a little smoother, but still painful. I don’t know how professional scientists can have so much trouble stringing together a coherent set of words. in the end, the hypothesis they came up with was: “Mawrth records geologic processes during early martian history when aqueous phyllosilicate-forming processes were pervasive and persistent and provides the opportunity to understand early habitability.”
Future work for Mawrth was to figure out the timing of the formation of the stratigraphy and the mineralogy, and just generally getting a better grasp on the possible depositional settings. There was also the question of what MSL would do on an extended mission, and Jean-Pierre Bibring called for astrobiologists to take a look at the site and try to fill in that part of the story.
By the time we got to Holden, the process for the discussion was in place, and the site advocates had had time to write down a hypothesis. unfortunately, it was wordy and awkward and immediately had to be edited, but in the end it boiled down to: “Holden preserves evidence of a fluvial-lacustrine system that provides the opportunity to apply a systems approach to evaluating a sustained, habitable environment.”
For Holden, the future work was to see if we can learn anything more about the light-toned layered deposits to see if they were formed in a lake. Also, looking at the orientation of the layers in the site was mentioned specifically.
Finally, Eberswalde benefitted from watching all of the other sites go first, and the fact that it has the clearest hypothesis to test of any of the sites. Sanjeev Gupta delivered this hypothesis: “Eberswalde crater’s stratigraphy, geomorphology and mineralogy records the evolution of a crater lake and associated fluvio-deltaic systems and additionally represents a habitable sedimentary environment that is favorable to the preservation of organics.” This one was clear enough and well worded enough that people actually applauded when they realized we wouldn’t have to agonize over the wording.
I don’t have notes for future work for Eberswalde, but I am pretty sure it included looking more carefully at the minerals seen from orbit and identifying specifically where to go to access the “bottomset” beds, which should have the best chance of preserving organics (the Eberswalde presenters repeatedly answered this question – you go the the bottom of any preserved stratigraphy – but people seemed determined not to hear this answer)
There was also a repeated call for all of the sites to identify specific targets for MSL to investigate, which can be fed into the rover drivers’ attempts at estimating how long it will take to get to the primary targets of each site.
So, that wraps up the 4th MSL landing site workshop. We didn’t vote any of the sites “off the island” this time, but I can tell you the impression that I got. I think Eberswalde is the clear leader among the four sites because, if you’re going to look for organics on Mars, it is the only place where we can be confident that there was a low-energy depositional environment that would concentrate and preserve organics. Based on the vibe in the room, I think Mawrth would come in second place if we had voted. Even though we have no idea how the rocks there formed, they have the undeniable advantage that you land on your primary target. Also, their team has always been a very cohesive and outspoken group at these meetings. They can be annoying in their fanaticism over their site, but I think their disciplined messaging may have had some influence.
I think Gale crater would come in just behind Mawrth. It has a lot of great qualities: including clear detections of both phyllosilicates and clays, and a very thick stratigraphic sequence that would tell you about a lot of environments. But Gale is a go-to site, and even though I showed a lot of cool stuff in the ellipse, people are a bit uncomfortable with the go-to sites. Gale particularly worries people because driving up a big mound sounds risky. We saw that based on slopes, there looks to be a clear path up the mound, but i wouldn’t be surprised it the rover drivers end up telling us it’s going to be extremely slow to climb it. The other issue is that we can’t say for sure what the mound is made of. It might have formed in a lake, but then again it might not have. This is true for all the sites except Eberswalde, which is pretty clearly a delta, but it seems to be emphasized most for Gale.
Finally, I think Holden would come in last. The Holden presenters did a great job highlighting all the good science that can be done on the alluvial fans in Holden, and with the go-to targets. But Gale has many similar features, only more-so. At both sites you land on an alluvial fan and then drive to layered rocks. Except the rocks at Holden are 100s of meters thick and the rocks at Gale are 1000s of meters thick. Holden does have nice examples of pre-impact breccia as well as the flood deposits, neither of which you would get to see at Gale, but those targets are toward the end of a long traverse at Holden, and may not tell us much about habitability.
So, that’s how I think the voting would go if we had voted at this meeting. My own ranked order shuffled around throughout the meeting: each site made a very convincing argument, so tended to jump higher on my list until the next site presented its case. Now, with a few days of perspective, I would rank the sites in this order: 1. Eberswalde, 2. Gale, 3. Mawrth, 4. Holden. I personally put Gale ahead of Mawrth because even though we don’t know the depositional setting for either site, at Gale there is enough stratigraphy that you get multiple chances to find a habitable environment.
Of course, there are caveats to this. If Eberswalde really did form from melted runoff caused by the Holden impact, that might knock it down on the list. If we can figure out the depositional environment at Mawrth and it’s not just impact ejecta, that might bump it up in the ranking.
The bottom line coming out of this meeting is that there is still a lot we can learn about all of these sites. Some of it can only be learned by a rover, but some of it just requires a deeper look at the data we already have. MSL is a phenomenally powerful (and phenomenally expensive) machine, and we only get one. I hope this meeting gets people digging deeper to learn about these sites so that we send MSL to the best place possible, whatever that may be.
With the details of all four landing sites on the table, we started day 3 of the meeting by hearing from the engineers and several scientists about the properties of the ellipses, the risks for landing and the capabilities of the landing system. First on the schedule was Mike Watkins, who explained why MSL is so unique in terms of assessing the risk for the landing site because the landing safety is essentially the same for the sites, so the tradeoff becomes more science-oriented and requires a lot more knowledge of the possible targets and traverse distances.
After Watkins, Ashwin Vasavada – the deputy project scientist – told us about the atmospheric simulations that his team has been doing to make sure the weather at the sites won’t mess up the landing system. He pointed out that we are one mars-year away from landing: “The next time Mars goes around the sun, we’ll be there to meet it.” That means that measurements being made right now will be really important in predicting the conditions when MSL arrives. It turns out that unlike previous missions, MSL will actually fly for about 100 km at a pretty constant altitude. This guided flight is what shrinks the ellipses down to nearly circular, but it means that we need to understand the weather for that whole distance. It sounds like the weather at the sites shouldn’t be a problem: Vasavada said that MSL should be able to land even if there is a dust storm occurring at the landing site.
Vasavada also showed this interesting plot of day and night temperatures at each landing site, along with an extreme "test case".
Next up, Ken Herkenhoff gave a summary of all the processing that goes into making the high-resolution elevation maps based on HiRISE stereo images. It is incredibly complicated to make these things, but they’re extremely important for planning the landing and traverses. Luckily, the folks at USGS have a lot of really clever techniques to make the products possible. The DTMs are available at the HiRISE website.
Matt Golombeck then gave his first of two presentations. This one was about counting rocks in the landing ellipses to make sure they’re safe. For the purposes of his talk, he defined a “rock” as anything that we don’t want to land on or get in the way. Rock counting has been done for all the previous landing sites on Mars, so we have some good “ground truth” to compare with the rock counts from orbit with HiRISE. They use an automated algorithm to count the rocks and then fit the size distribution to a model based on previous sites to predict the number of dangerous rocks that are too small to count. In the past it has been very successful, and they’re confident that all the MSL sites are safe enough. Golombeck said that Holden is especially safe in terms of rocks: “I think there’s maybe one rock in Holden.” There were a couple of very good questions after this talk. Rob Sullivan asked whether a small softball-sized rock would be a danger if we landed right on it with a wheel, and the answer was basically no. The engineers said that the biggest risk was getting a rock in the belly that would damage the rover and/or prevent it from moving. A second question from Steve Ruff was more generally, “how concerned should we be about landing with a hobbled rover?” The engineers said, again, don’t worry about it. They’ve been investigating some scenarios where the landing system might get stressed beyond the point where the materials have a linear behavior, but they aren’t worried about breaking the rover.
Next up, Robin Fergason presented about the thermal inertia of the sites. Thermal inertia is a measurement of how resistant a surface is to heating. Bedrock takes a long time to heat up and cool down so it has a high thermal inertia. Dust has a low thermal inertia. Fergason said that all the sites look safe in terms of thermal inertia and then discussed some of the details of each site. One thing that sort of bothered me was that she kept saying that lower thermal inertia might suggest alteration. It’s true, it might, but I would never bet a $2.3 billion rover on the fact that altered rocks have slightly lower thermal inertia. The values seen could just as well be
unaltered bedrock with a dusting of sand or dust on top. Of course, we see other evidence that the rocks at the landing sites are altered, but for the rocks with no clear spectral signatures, I don’t think it’s safe to assume they’re altered based on thermal inertia.
A thermal inertia map of the Gale Crater ellipse. I love how the alluvial fan pops right out in the thermal data!
After the thermal inertia discussion, Golombeck got up and gave a presentation with 83 slide in 30 minutes, flashing rapid-fire views of lots of different data-sets used to characterize the ellipses. He also told us that the orientation of the ellipses has changed a little bit so that now their long axis is due east-west. Taking a look at the 5 meter slopes he said that Mawrth and Eberswalde were significantly rougher than Gale and Holden (which makes sense, since Gale and Holden both land on top of nice flat alluvial fans). The topography at Mawrth and Eberswalde would be comparable to that seen in the Columbia hills, where Spirit has been exploring. Golombeck also showed that there are very few “inescapable hazards” such as craters in which you could land but then couldn’t escape. At this point he jokingly made fun of engineer Gentry Lee who had been worried about a big crater in the Mawrth ellipse, saying that the crater was not a target rather than an obstacle! There was also the amusing mention of a small mesa in Eberswalde where MSL would land but would have to go down some pretty steep slopes to escape. This possibility was later refferred to as the “Lion King” scenario by Rob Sullivan. It’s incredibly unlikely, but still hilarious to picture the rover greeting the sunrise from atop this viewpoint, which would, of course, be called Pride Rock.
MSL at Pride Rock. I spent too much time making this, but it had to be done.
At the end of this talk, Sullivan asked whether there is any concern that dust kicked up by the rockets could confuse the landing radar. The engineeres said that yes, there is some concern, but they are doing tests with the radar on helicopters to learn more. Basically, the engineer responding said “We could probably fly through the blowing stuff. We might not like it, but we could do it.”
Next, Devin Kipp, one of the engineers on the entry, descent and landing teams gave a presentation that took a look at all the things that could go wrong and basically said “we don’t think these things are going to happen”. He said that the chances of landing success in all of the sites are about 98-99%. Kipp also made the biggest understatement and the best example of NASA engineering-speak all day. When discussing the transition from wheel touchdown to actual roving he said: “hopefully the rover-surface interaction perpetuates for the rest of the mission.” I certainly agree with that!
Finally, Paolo Belutta, a rover driver, gave a presentation detailing how the traverse times for each site are going to be predicted. I suspect that these traverse times are going to be the deciding factor for which site is selected. Since landing on the sites is equally safe, the risk gets pushed into the traverse portion of the mission. Belutta is making detailed maps of the sites using HiRISE images and terrain models to estimate how long it will take to drive in any given location. Then, with input from the scientists, he will compute the traverse durations for several options in each of the landing sites. At that point we’ll come to the tough part where we decide whether the cost of a long traverse is worth the possible payoff.
Overall, it was an extremely positive morning and I think it laid to rest a lot of concerns that the science community had, based on rumors and partial information that had spread around the science teams. That said, I think it was also presented with full knowledge that this was a public meeting, and that word might get out if they admitted to any major problems. NASA has this mentality where it is afraid to acknowledge the difficulty of what it does until it has done it successfully. Personally, I think NASA should play up the risks and the difficulties ahead of time: they’re really interesting, and they make the final successes that much more exciting, and prepare people for the worst if it happens.
In any case, it was a fascinating morning. I’ll post about the big afternoon discussion of all the sites tomorrow. Stay tuned!
Ryan shoots rocks with lasers, looks for good places to land future Mars missions, and helps keep the MER cameras healthy.
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The Martian Chronicles 