Changing seasons on Titan


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Since entering Saturn orbit in 2004, Cassini has seen the seasons on Titan shift through half a Saturn year.

As Titan approaches its northern summer solstice, NASA’s Cassini spacecraft has revealed dramatic seasonal changes in the atmospheric temperature and composition of Saturn’s largest moon. Winter is taking a grip on the southern hemisphere and a strong vortex, enriched in trace gases, has developed in the upper atmosphere over the south pole. These observations show a polar reversal in Titan’s atmosphere since Cassini arrived at Saturn in 2004, when similar features were seen in the northern hemisphere.

Sadly, there will not be any spacecraft at Saturn during the second half of this Saturn year. After Cassini ends its mission in 2017 it will likely be many decades before another spacecraft arrives, since at this moment none has even been proposed.

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9 comments

  • wodun

    Too bad planetary scientists can’t figure out how to build more than one satellite at a time. Everything is a one off special purpose project that supports a limited set of goals and audiences.

  • Alex

    Wodun: Your critics are correct, it is too expensive and it needs too long to probe the (outer) planets. We should send out a larger number of S/C to the planets in a continuous approach, which are built up in modular manner and share more common already qualified components, even if the S/C mass is not optimized.

  • Edward

    Alex and wodun,
    It is a matter of resources and priorities. If we spend more of our limited resources (read: “money”) on additional Saturn probes, then we won’t have those resources for sending probes to Mars or Jupiter. Rather than concentrate on Saturn, we have prioritized Mars as the planet that we want to send the most probes. This makes sense, as we are eager to send humans there in the next couple of decades.

    Another — and a higher — priority is to spend our limited resources on people who do not contribute to the economy. Rather than have these people work for their food, housing, Xboxes, and Obama Phones ( http://www.obamaphone.com ), the US government (and many others) sends these sloths money that could have been more wisely used on other projects, such as sending humans to Mars. Had these layabouts been productive — rather than a drag on the economy — they would be providing additional goods and services that exceed the goods and services that they consume, and would be able to pay taxes (rather than receive other people’s money) to provide even more resources for those other projects, such as sending humans to Mars. (It is when people make more than they take that we get greater wealth and prosperity, such as more houses, buildings, roads, and bridges than a century ago.)

    The seasons are not just changing on Saturn and Titan, we on Earth seem to have entered into a political winter, where people are encouraged to live labor-free off the labor of others, rather than a political spring, where almost everyone makes more than he takes, and some small portion of that – but more than we do now – can go into exploration and expansion.

    We elect the people who set these priorities and assign the government’s portion of the resources. Use your vote only on those whose priorities are wisest. Otherwise you are bound to get more of the same messed up priorities and limited exploration and expansion.

  • wodun

    It is a matter of resources and priorities. If we spend more of our limited resources (read: “money”) on additional Saturn probes, then we won’t have those resources for sending probes to Mars or Jupiter.

    I disagree a little. Missions are chosen from the decadal science survey. The missions support a single objective and are constructed with a narrow set of requirements. So one mission is Mars, the next Saturn, then Pluto, Europa, and on and on. There isn’t any commonality between these missions and they don’t support any larger goal other than a nebulous search for knowledge.

    There are limited resources but those resources are spent schizophrenically in terms of priorities. There are a lot of people and groups who make demands on the use of government money.

    There is an endless list of worthy things to spend money on to research.

    What could drive costs down, while possibly sacrificing some individuality, is constructing more than one planetary probe that would be sent to more than one planet. Same is true for space based telescopes. Instead we get one telescope or one planetary probe and other specialized experiments to measure gravitational waves or something to land on Europa.

    None of these science missions support human settlement. Even the rovers on Mars only tangentially support this because they build general knowledge. These types of missions should be scouting landing locations and resource extraction points.

    In my view, limited resources and priorities are both being misapplied. I think part of the problem is that the people making the decisions are disassociated from the people who make academic life possible. They don’t respect the people who give them the money to spend and so they don’t spend the money wisely or represent the interests of the taxpayers.

  • wayne

    wodun/Edward/alex-
    You all 3 bring up interesting points, in a number of competing areas.
    I bet if we drew the Venn diagrams, it would be enlightening.

  • Edward

    wodun,
    You wrote: “These types of missions should be scouting landing locations and resource extraction points.

    Isn’t it a little early for this? When we went to the moon, landing locations were not scouted out decades in advance but only about half a decade in advance. It wasn’t until 1966 that the US sent mapping satellites to orbit the moon. And yes, if we could free up some of the money spent on layabouts, we could spend a tiny portion of it on finding where additional Martian resources are located. In the meantime, despite Musk’s talk last month, we are planning manned missions with limited stays, not colonies. Musk only told us of an idea, not a plan; much must be done before we begin to consider locations, especially we must figure out all the resources that are available and that we will need for our colonies. A more general knowledge of Mars will help us figure out what may be available for us.

    Earthly colonists have usually been able to count upon there being trees for construction, fresh water for drinking, and arable land for crops, but Mars has none of that without some form of processing.

    You wrote: “None of these science missions support human settlement.

    Human settlement of Europa or the rest of the universe is far too early to consider, at this point. Unless you suggest that we ignore the rest of the solar system and universe until after we have settled Mars or the Moon or both. Building general knowledge has proved very useful in the past. It is why we are able to get into space in the first place. Without general knowledge of chemistry, aerodynamics, metallurgy, optics, and other sciences, we would still be on the ground looking up at wandering stars.

    With the possible exception of putting people on Mars and back on the Moon, we do not have any larger goal other than to gain general knowledge. For the most part, the people who seem most committed to humans on Mars and the Moon seem to be private companies, not governments.

    You wrote: “There are a lot of people and groups who make demands on the use of government money.

    Yes there are. About half the US government’s money goes to people who are not working. That is about 100 times as much money as is spent by all of NASA, not just the planetary sciences parts of NASA.

    You wrote: “What could drive costs down, while possibly sacrificing some individuality, is constructing more than one planetary probe that would be sent to more than one planet.

    A nice thought, but different planets have different things that we want to explore. A probe to Europa, for example, would not be adequate for Titan. We sent two duplicate probes on the “Grand Tour” of the solar system*, back in the 1970s, and we discovered the differences from planet to planet that have caused us to tailor subsequent satellites to explore the different attributes of each planet.

    We make one telescope because these telescopes are expensive, so we expect a yeoman’s work from the one telescope that we do make. Making 10 Hubble telescopes would still be an expensive endeavor, and we would have to ask ourselves which other missions to never launch in order to get Hubble quality information a little sooner that if we only had the one Hubble.

    Another factor is that duplication has its limits. The Viking landers and the Mars Exploration Rovers, Spirit and Opportunity, were limited in what they could look for. The majority of what we learned from them came during their designed lifetimes, and we have found that we get similar information in different locations. It is a case of diminishing returns, so we may not get reasonable value for the cost of additional duplicate probes, rovers, landers, and satellites. This is why we tend to send up to two of the same design while the next one(s) is designed with different instruments and sent to different landing sites or orbits. If we were to try wildcat drilling for underground water, we may have to send up a lot of such rigs, unless underground water is ubiquitous.

    Launch costs are another part of the equation. These do not decrease much with increased launch rate, and the limited supply of launch vehicles each year limits the number of probes and other space hardware that can be launched each year. Do we spend it all on duplicate probes, or do we save some launch slots for commercial satellites?

    There is a limited amount Deep Space Network availability. Already there are complaints from those who are operating the US DSN that it is being stressed, as we saw when some data collection was delayed for another probe while a recent problem was fixed on the Juno satellite. Adding more deep space probes will require more ground bases to receive their data and give them instructions. Although this could be done, it is not a priority among those who hold the purse-strings.

    Which brings us to another problem involved: the political priorities of Congress. A lot of money is spent on SLS that could be spent on making more probes, but it is instead ill spent on poor priorities — keeping people employed working on an expensive rocket that could be obsolete before it gets a productive mission to perform.

    You wrote: “In my view, limited resources and priorities are both being misapplied.

    That was my point. Be sure to elect politicians who have your priorities in mind. Otherwise you are bound to get more of the same messed up priorities and limited exploration and expansion.

    * In reality, in advance of the Voyagers, we sent Pioneer 10 to Jupiter and sent Pioneer 11 to Jupiter and Saturn. The Pioneers performed a quick survey of the planets in order to give the Voyagers a better sense of where to concentrate their instruments. Incremental exploration of each planet has been NASA’s strategy, over the decades.

  • wodun

    Isn’t it a little early for this?

    Considering transit time, communications delays, and the lifetime of a rover, this is the perfect time to perform exploration in support of settlement. Even if you toss out the word settlement, these missions should support future human missions. In all likelihood, many of these prospecting missions need to take place for good site selection.

    IMO, things could be done faster and closer on the timeline to humans landing on Mars if we had people within the cognitive horizon of Mars performing the prospecting. But this would still require more than one or two rovers and a focusing of activities in support of a common goal.

    Unless you suggest that we ignore the rest of the solar system and universe until after we have settled Mars or the Moon or both.

    No, but why does studying Europa have to take the form of the current proposal? We could learn a lot just by observing Europa for an extended period of time.

    but different planets have different things that we want to explore. A probe to Europa, for example, would not be adequate for Titan.

    Yes, with standardization comes some sacrifice in individuality. But it is easier than ever to pack in lots of different types of cameras and remote sensing equipment. The useful part of standardization could come in the form of propulsion, power generation, and structure that would allow for commonality while also providing for some modularity.

    The reason why a probe for Titan and Europa would be radically different is the mission profile. Landing on either would require something radically different but observing either from a long term orbit wouldn’t. Working on one off landers is counterproductive to long term goals. Standardization of landers would work great for places we intend to send many landers to, like Mars or the Moon.

    This would require NSF participants to think of a larger audience than themselves. Restrict some areas of activity for a time to focus on something different.

    Its not a halt to random scientific experiments but rather looking at long term generation of knowledge from a different perspective.

    There is a limited amount Deep Space Network availability.

    Building up infrastructure like this could be a beneficial use of satellite commonality. But would NSF participants delay gratification a cycle to do this?

    Everything has trade offs. IMO, when talking about government money, those funds should support having the largest impact for the most people rather than the narrow set of interests from the NSF, which drastically change every cycle. NSF should work with the society that makes their lifestyle possible to do what is most beneficial for that society. There is plenty of good science to be done this way and there will always be a never ending list of worthy endeavours to spend money on.

    At the very least, there are enormous inefficiencies in how the NSF spends money. They could make changes that would allow them to do more science for the same amount of money, even it that means skipping things like drilling to the core of Europa.

    I am sure there are some NSF participants who would view what I am saying as very threatening and restrictive but they way around that is for scientists and researchers to get their funding from sources other than the government. Then I wouldn’t care how they spend their money and cheer on random science for the sake of general discovery.

  • wayne

    wodun/Edward–
    You both bring up many good points.

    The elephant (donkey) in-the-room: We have a $20 trillion dollar debt with $200 trillion in non-funded liabilities. Those are real claims on real resources, and all of it is borrowed money, and all of it is coming due now, not some nebulous point in the future.

    Our Leaders don’t make real-choices anymore, they have all morphed into Santa Claus and huge numbers of our fellow citizens see nothing wrong with that & will ride the gravy-train right over the cliff.

  • Edward

    wodun,
    You asked: “why does studying Europa have to take the form of the current proposal?

    Because Congress, not the planetary science team, declared that there would be a lander. This is what I mean when I say “Be sure to elect politicians who have your priorities in mind. Otherwise you are bound to get more of the same messed up priorities and limited exploration and expansion.

    Speaking of the decadal science survey, they have a lot of science that wants to be performed and a limited amount of resources in which to perform them. While you see schizophrenia in their priorities, each planetary scientist see less exploration of the planet that he wants explored. New Horizons only went to Pluto because that planet’s atmosphere was about to condense onto the surface, and it would be two centuries before any study of its atmosphere would be possible. Pointing out this timing was what put it higher on the priority list.

    With Congress’s priority currently on encouraging people to be layabouts, this limited amount of resources can only become more limited. If we concentrate on Mars, then Europa would necessarily become a lower priority and would likely not be studied until after Mars becomes lower on the priority list.

    You wrote: “it is easier than ever to pack in lots of different types of cameras and remote sensing equipment.

    Getting to space is still expensive, and if we don’t send the appropriate instruments to the appropriate locations, then we don’t investigate the unique attributes of each location. Different locations on the Moon and on Mars will want different science. This is why the instruments on Curiosity were designed to study a location that was once wet. That task was accomplished, but if its twin is sent to a location that was always dry, are the same instruments going to be as useful there, or do we want instruments that are better able to explore that region?

    Sending a probe that does not learn anything new is not a valuable scientific endeavor. The probe may have cost a little less (although launch and operational costs remain the same), but if it does not add enough value, then it was a waste of resources. Penny wise but science foolish.

    Even if SpaceX’s optimistic timeline is correct and they put someone on Mars in a decade, Their first choice is going to be for a safe site to land and take off again, not a scientifically or colonially interesting site. The primary objective will be to not get anyone killed, as that could put us off human exploration for a long time. Lower on the priority list will be bringing back scientific knowledge.

    You wrote: “The reason why a probe for Titan and Europa would be radically different is the mission profile.

    This is my point. Each mission is different. The reason that Juno started with a high orbit was to get an overview before going in for more detailed science. In essence, they will get two missions out of one adjustment maneuver. Rosetta did much the same thing as it adjusted its trajectories and orbits at comet Comet 67P/C-G. Rovers move from one spot to another, essentially becoming multiple probes. Each has its own mission profile for reasons that are specific to the location. We already try to get the most out of the limited resources, and new methods are continually being developed.

    For instance, rover engineers are working on software that can more autonomously guide rovers from location to location reducing human interaction, reducing DSN usage, and getting to new locations faster — thus adding to the science that can be obtained withing the (extended) lifetimes of the rovers.

    We spend incremental amounts of additional resources on successful missions by extending their missions and getting additional science. Opportunity is a classic example. We didn’t have to send additional probes in order to look at a couple of craters, because Opportunity has managed to do that for us. (Yay, Opportunity!)

    You wrote: “Landing on either would require something radically different but observing either from a long term orbit wouldn’t.

    Except for the differing chemistries; the clouds that have to be looked through; the mountains, rivers, lakes, and oceans on the one that are not on the other; the water plumes on the other but not the one; that sort of thing, sure, they are practically the same, and [*** Sarcasm Alert! ***] the same instruments would easily handle the differing conditions enough to support future manned missions.

    You can’t have it both ways. If you want to prioritize on one thing, then others must suffer. If you send identical instruments that turn out to be virtually useless, then you have spent a lot of scarce resources on launch and operational costs only to waste an opportunity for studying a phenomenon unique to that location. If you send the same probe to Pluto that you sent to the Moon, then you spend a billion dollars and still don’t learn about its atmosphere.

    An excellent example are the Ebb and Flow probes. They were designed for a specific task that generic probes couldn’t have accomplished.

    If we only build the same probes for all locations for all time, then we miss out on advancements in technologies, the ability to make lighter weight instruments in order to include more instruments on the next probe, and the science that could have been studied due to the unique attributes of each unique situation.

    It is like sending a Bathyscaphe to study the plants or a space probe to study the Mariana Trench. Design time may cost a little more, but you get far more science from using the right hardware in the right places. You may be able to use a saw blade to tighten a screw, but a screwdriver would be the better choice (and I don’t even want to think about using a screwdriver for cutting a board to the right length, but the image is in my head now).

    You wrote: “Building up infrastructure like this could be a beneficial use of satellite commonality.

    You are preaching to the choir (almost literally, as I am figuratively singing the praises of scientific research and agree with you on this point), but Congress’s priorities are not for this, they are for encouraging sloth. In fact, if the other half of income earners paid a little income tax too (not even their fair share), then there would be plenty of money to expand the DSN, but Congress has different priorities. The president, too.

    You wrote: “Everything has trade offs.

    You are talking to an engineer; this is practically my job description. I and the scientists in the decadal science survey are willing to trade off a little extra money in order to get the proper science at each location being studied.

    You wrote: “IMO, when talking about government money, those funds should support having the largest impact for the most people rather than the narrow set of interests from the NSF

    Paying people to stay at home seems to have the largest impact for the most people. And it ignores the narrow set of interests from the NSF or the decadal science survey, too. This seems to be the priority of We the People, too, as this is the government we have elected.

    You wrote: “NSF should work with the society that makes their lifestyle possible to do what is most beneficial for that society.”

    Few people think that space sciences has any benefit for society — which is why it has such low priority — so this would eliminate all but the (ignored) aviation portion of NASA, and we would go back to the NACA (National Advisory Committee for Aeronautics). However, because of space sciences, we have weather satellites, GPS, various medical devices and knowledge, wide area communications (even in remote locations), and quite a few other benefit to daily life. NASA’s Spinoffs Magazine was supposed to highlight these everyday benefits, but it quickly turned into an engineering magazine sent only to technical types.

    You wrote: “They could make changes that would allow them to do more science for the same amount of money, even it that means skipping things like drilling to the core of Europa.

    But isn’t drilling into Europa far more interesting and educational science than merely looking at it from orbit for years on end? How else are we supposed to learn for certain what is down there rather than speculate and try to deduce from insufficient knowledge?

    You wrote: “I am sure there are some NSF participants who would view what I am saying as very threatening and restrictive but they way around that is for scientists and researchers to get their funding from sources other than the government.

    Back in the good old days, government funded very little research. Mostly what they funded were areas in which they wanted something specific. Come to think of it, they still prioritize that way when funding research. This might explain why the laser was the last major invention — research has moved away from the general, basic, fundamentals and into directed goals. Wait until the directed goal becomes putting people on Mars — then we will see some serious prioritization for Martian research at the expense of other planetary research. Of course, if government does not direct that goal, then we will have to settle for whatever SpaceX can do.

    Be sure to elect politicians who have your priorities in mind. Otherwise you are bound to get more of the same messed up priorities favoring neediness over productivity while limiting exploration and expansion.

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