Monday, May 28, 2012

Vastly Different Worlds (WW114 - Season One Finale!)

Season One of Western Worlds clues up tonight with my interview of Dr. Jaymie Matthews (pictured above) of the University of British Columbia. We'll be back on Monday, July 30th for Season Two, starting off with a discussion of the Mars Science Laboratory.

In his work as an anthropologist, the famed scientist Jared Diamond is known to express his fondness for the idea of a "natural experiment." What he means by this is that some systems are so large and complex and the ramifications of changing variables so severe that it would be impossible to simulate these systems in the laboratory or the real world. So, instead, what we do is to look at the world around us and its history. For significant events, if we can determine their proximate and ultimate causes and understand the variables in play we can understand the relationship between cause and effect. For instance, we don't need to go out and remove all the trees from an island to understand what deforestation does to the culture living there - the history of Easter Island tells us this.

Similarly, in Astronomy we are lucky that there are examples of just about every structure that exists both today and, through the finite speed of light, in the past. We didn't have to reconstruct the positions of all the near stars to understand what a galaxy looks like from all angles, there are examples of every type in every orientation out there, just waiting to be observed. And we understand the life-cycle of stars from birth to death even though the process requires more time than life has been on Earth because we can see examples of every stage out there.

Similarly, we can use Exoplanets to tell us what our own solar system and our own planet would be like were the conditions a little bit different. Earlier this year we heard from Nikku Madhusudhan about what might happen if Carbon exceeded Oxygen in abundance. This episode, we explore the full gamut of possibilities from planets both nearer and further from their parent stars than we, some with highly eccentric orbits that give them phenomenal seasons. This tells us about climate in general and its ability to regulate planetary temperature and weather. For that reason, this episode is entitled "Vastly Different Worlds." And like what we have learned from studying the clouds on Jupiter and, yes, the dunes on Mars, it can improve our understanding of our own planet and the processes that affect the world we experience.

It's a great way to cap off our season! And like the interview with David Southwood, there's a little something for everyone in the work of Dr. Matthews. As usual, my on-air intro is under the cut. After you listen to this episode, be sure to head on over to our Survey and help to pick out what episodes we'll air over the summer. Have a great couple of months and don't forget to make World Enough and Time for us again the week before Curiosity lands on Mars 10 PM EDT on Monday, July 30!

Thursday, May 24, 2012

A Puzzle of Winds

The composition "Seasonal Winds" by my favourite artist and photographer Greg Martin imagines what 400 km/h would look like ripping down Chasma Borealis on Mars. It's too bad such atmospheric phenomena don't exist since they make for such great art and literature. However, the story of how this misconception has propagated itself is an interesting study in the history of planetary science. Go to http://www.experiencetheplanets.com/ to download a high resolution version of the above image.

This spring I set myself a puzzle to solve. As an atmospheric scientist working on Mars, you get used to hearing from other disciplines about the tremendous winds that this planet has to offer. "They happen twice each year as the winter hemisphere moves from North to South and back again - all that CO2 sublimates and rushes towards the other pole." If not this story, then it is tales of some kind of a self-sustaining instability in the global dust storms which occur periodically. However it happens, this tremendous wind has been invoked to explain all manner of features on the surface of Mars.

By the mid 1990s, the existence of such winds was common knowledge extending even into the Science Fiction world. Two highly awarded novels - Greg Bear's "Moving Mars"and Kim Stanley Robinson's "Red Mars" - both have major plot points where such winds are important. In the former, a large pressure wave kicked up by a dust storm and featuring supersonic winds disturbs Casseia Majumdar and her new husband on their honeymoon and, temporarily, provides the environmental conditions necessary for reviving past martian life. In "Red Mars" colonists Nadia and and Arkady are nearly killed when their dirigible is thrown off course in an intense dust storm. When they go outside to repair damage, they can barely stand up, even though the pressure is only 12 milibars (hence the winds must be enormous!) Both of these occurrences are significant because they postulate Mars as it exists today, not some distant terraformed future.

That would be all well and good except these winds don't actually exist! The highest windspeed recorded by our landed missions, our best determinant of ground level windspeed on Mars, was 16 m/s (~58 km/h or 36 mph) for the Phoenix Lander. You might say: "that's all well and good, but Phoenix only lasted 152 sols during northern summer, a fairly quiescent time." You would be right, however, the much longer 2245-sol (~7 Earth Year/3.5 Martian Year) Viking Lander missions saw the entire seasonal cycle several times over and were operating during the two "great dust storms of 1977." Their record shows no windspeed in excess of 19 m/s (68 km/h or 43 mph).

Tuesday, May 22, 2012

Vote for your favourite episodes!

Next week is the season one finale of Western Worlds! We're taking a break until July 30 when season 2 begins. But until then we'd like to know what episodes you liked best and which ones you would like to hear rerun over the break. To vote for your favourites, click on the link below:


Thanks again for listening and I'm looking forward to season two.

Monday, May 21, 2012

Practice makes Perfect (WW113)


Dr. Dean Eppler, space suit expert and 2011 Science Lead for the NASA Desert RATS Team sat down with our own Marianne Mader at LPSC this year and you'll have the chance to hear that interview later on tonight. Much of what they talked about focused on something called "Analogue Missions" which are practice space missions completed on Earth. Why would you want to hold such an exercise? Well, for one thing it's much cheaper to conduct a space mission on the Earth and much safer for the astronauts. That means that you can try lots of different tools and techniques to figure out what works and what doesn't.


This is important because astronaut time is extraordinarily valuable. Say you could design, build and deliver a capable lunar rover for ~$1b and that the median expected lifetime on the lunar surface was something like 5 years. With 8 hours of ops per day (average), that gives us an hourly cost of something like $100k/hour. However, a mission to the moon for two weeks (~70 hrs EVA) might cost something like ~$10b/astronaut. So that's about $100m/hour for humans. If we assume a Phoenix-like multiplier, i.e. that 152 sols of operations could have been conducted in a couple of hours by humans, you get that human time is ~600 times more productive than is robot time. Call it an even 1000 times. Thus, the cost per datum gathered is about the same, but an hour of human time wasted is equivalent to over four months of robot time wasted, so even a small cost in human time is extremely expensive. Worse, you loose the contemplation time that robots give you to convince yourself and the rest of the science team that you are making the correct decisions.


One of the focuses for D-RATS is to find ways to make that human time more productive through innovative use of technology. Often they test combinations of different tools, rovers and humans working cooperatively and so on. It's a challenging problem on many levels and D-RATS aren't the only team trying to improve our knowledge here. We've done a couple of analogue missions here at Western for the CSA which I am proud to say I've been a part of as a Co-Investigator (and have written about before in this space). You can read more about our activities at our "Anablog" and our first paper discussing how we ran mission control can be found here. If you're in the D.C. Area, why not go and listen to WW Co-Host Raymond Francis talk a little bit about how rovers and humans interacted at the GLEX Conference?


Want to know more? My intro is under the cut and don't forget to tune into Western Worlds on Astronomy.fm at 10PM tonight after 365 Days of Astronomy and the News.

Wednesday, May 16, 2012

Swords into Plowshares (WW112)

Ralph Mcnutt 

Ralph McNutt (pictured above) has had a long and successful career working as a scientist on a great many missions from Voyager through Cassini to New Horizons and his current role as project scientist for Mercury Messenger. Like previous guest David Southwood, his specialty is space physics, a field with broad applicability across the solar system.

However, when Dr. McNutt spoke with our co-host Raymond Francis at this year's LPSC, it was on a different, yet no less important topic. What Voyager, Cassini and New Horizons have in common is a reliance on nuclear power to provide electricity to their computers, scientific instruments and onboard systems. You just can't do deep space exploration without these nuclear batteries, powered by Plutonium 238. However, production of Pu-238 stopped many years ago in the United States and current stocks to run spacecraft have been purchased from the Russians.

However, the lack of Pu-238 is starting to approach crisis levels. This is an issue that the DPS has spoken out strongly about for several years. As such, the US Congress has sought ways to restart the production of this material domestically for spacecraft usage. Unfortunately, agreements between the DoE and NASA have kept falling through. For many years the language Authorizing NASA to restart production was set-out in law, but no money was Appropriated for that purpose (The US has a two-stage budget process in which not everything an agency is legally permitted to do is actually funded). This year, it looks like things might be changing with NASA expected to receive approximately $15 million for plutonium restart in the president's budget request.

In the meantime, the plutonium shortage has helped spur the interest of engineers to try to improve the efficiency of Nuclear Batteries. Interestingly, the decay energy of Pu-238 goes almost entirely into creating heat which means that they are particularly helpful when thermal energy is what is ultimately desired. But the main problem is that by moving around heat to keep components warm, or to increase the efficiency (such as with a sterling cycle) you introduce moving parts with non-infinite duty cycles. Just like the human heart, all such components will ultimately stop beating, bringing the missions they power to an end.

We don't always focus on the technical aspects here at WW, but this episode is a fascinating study of a critical technology for space exploration and is not to be missed. You can find a copy of the episode here and, as usual, my intro is under the cut.

Monday, May 7, 2012

Diamonds on the Blackest Velvet (WW111)


Tonight's guest on WW is Nikku Madhusudhan (shown above in a photo by Beverly Schaefer) as we return once more to the topic of extrasolar planets. It's a fascinating field that has grown in leaps and bounds since the first planets were observed around pulsars in the ealy 1990s and around a main sequence star in 1995. Since that time our techniques have expanded and the variety of planetary systems is added to almost daily.

Astoundingly, we can now deduce details about the atmospheres of some of these extrasolar planets, but only the ones relatively large and relatively close-in around brighter stars. But even in this small subset of the infamous "hot jupiters" there is amazing variety. A good part of Dr. Madhusudhan's fame comes from confirming the existence of planets for which Carbon is more abundant than oxygen. Such places were long theorized to exist because Oxygen and Carbon are produced in similar quantities by the proceses in stars that create elements heavier than hydrogen. This "nucleosynthesis" produces a characteristic pattern that we can observe in the abundances of elements within our own solar system (from wikipedia and shown below):


Take a close look. You'll notice a few things. First, the elements created in the big bang, Hydrogen and Helium Dominate - we have not yet come close to processing all of the material in the universe through stars. Secondly, you'll notice the stair-step pattern favoring even-numbered elements. This comes from the relative ease of building up heavier nucleii from "alpha particles," helium-2 nucleii and the greater stability of the nucleii thus formed. But the abundances fall off as the atomic number increases because it gets harder and harder to form larger and larger nucleii since more energy is required. In particular, beyond Iron, nuclear fusion does not yeild any energy, and so you get a pile-up that allows Iron to stand up above the pack.

What about Carbon and Oxygen? Well, these are synthesized largely through an efficient nuclear fusion process called the CNO-cycle in stars a bit more massive than the sun and up. Depending on the specific circumstances of the stellar furnace in question, either one of Carbon or Oxygen can come out a bit ahead. In the building of our own solar system, it was Oxygen. And so we have a solar system whose solids are composed mainly of ices (H2O) and silicate-bearing rocks (SiO4). By weight, Oxygen is not just a significant part of our atmosphere but comprises nearly 60% of the Earth's solid matter too.

Had the balance been different, a system of carbon compounds with different properties would have resulted. By showing that such systems do, in fact, exist Dr. Madhusudhan has expanded our view of the universe and the kinds of variety that exists out there. I hope you enjoy listening to his interview as much as I did. As always, a transcript of my intro is under the cut.