The case for a Titan rover mission

[mikejz]

I think the $64,000 question is if Cassini could even enter into orbit around Titan---lets start to look into that one!

 

[yurkin]

I Think I remember hearing somewhere that at this point Cassini cannot orbit Titan.

 

[rlb2]

<font color="orange">Bring a tank of Oxygen along, and burn Titan's methane for fuel.<font color="white"><br /><br />That’s a good thought, however liquid Oxygen per gallon weighs more than water it then becomes a transportation thing. There was a paper written to tap the Martian sloped Hills for wind energy, a large vertical axis Darius windcharger. <br /><br />This next idea takes it to a new level as it is applied to Titan. How about a balloon or Dirigible dragging a rover over the surface with its wheels turning a generator, like you use on a bicycle………Or a balloon or Dirigible dragging a water turbine over a large lake of methane to produce energy.... Or a balloon or Dirigible with counter rotating blades carrying Darrious type blades on its teather line that is made out of light weight material…………..<br /><br />That is all in the Windsurfer paper I mentions above.<br /><br />Here is a look at what it may look like......The amazing thing about all this is - look how it predicted the Titan surface to look; the paper was written in 2003. There is plenty of light on the surface, it isn't engulfed in the dark featureless world they claimed it to be......<br /><br /></font></font> <div class="Discussion_UserSignature"> Ron Bennett </div>

 

[mcbethcg]

http://www.sfgate.com/cgi-bin/article.cgi?f=/c/a/2005/01/16/HUYGENS.TMP&type=science<br /><br />I guess it is not certain that there are seas there.

 

[najab]

><i>An irrelevancy, as usual. I don't have to go to Madrid to know it's hot in the summer and freezing in the winters. Good reports by knowledgeable and reliable observers tell us that.</i><p>Exactly who is your 'reliable observer' when it comes to what lies under the ice on Europa? Did you launch an orbiter or lander to do a thorough study while we weren't looking? I do not know what's on Europa and neither do you. Stop acting as if you know - you're neither omnipresent, nor omniscient - you're just another SGOTI (some guy on the Internet).</p>

 

[rogers_buck]

>> Hovercraft would work very well, but are tricky things to operate and use lots of power. Mich more than a boar, rover or airship.<br /><br />True, but a hot lump of Plutonium unleashed upon a ground saturated with dry ice, liquid methane, etc. would produce a large volume of gas. Trapped under a skirt it could be used for hover and thrust.<br /><br />I was pondering in another thread if there was any evidence of a "quench" event from the warm spacecraft landing on the surface of Titan. I saw on the Science channel today and interview with one of the investigators who reported seeing a large methane signature moments after landing that dissipated. He was speculating that it was a "quench" event - though he didn't use those words.<br />

 

[rogers_buck]

An inverse ram-jet would work well on Titan. By inverse ram-jet I mean a ram jet where an oxidizer is introduced as opposed to a fuel. <br /><br />A nuclear ram-jet might also work well at Titan. Given the low temperature of the ingress gas not too much heat would be required for a lot of expansion. Maybe a low flying survey mission with a lifetime of a few weeks could cover much of the planet.<br /><br />Drone aircraft can criss-cross the globe, automatous vehicles can't even go 10km at 35kph without turning over. The current state of autonomous navigation would be better suited to an aircraft with a constellation of relay and positioning satellites overhead.<br />

 

[arobie]

Methane <br />Freezing Point: -182*C<br />Boiling Point: -161.5*C<br /><br />Ethane<br />Freezing Point: -183.2*C<br />Boiling Point: -88.6*C<br /><br />Titan's Average Temperature: 94*K or -179.15*C<br /><br />Steve, as you can see, both methane and ethane's freezing point falls below Titan's average temperature. Therefore, they can both exist in liquid form on Titan. Yes, I know that this does not prove that there are sea's, and that was not my intention. I just wanted to make it clear that there can be liquid on Titan.<br /><br />Methane's Stats<br />Ethane's Stats<br />Titan's Stats

 

[rogers_buck]

Are those at 1 atmosphere pressure? I think the higher pressure on Titan makes the phase diagram even more likely for liquid on the surface. <br /><br />The apparent drainage channels into the flat dark areas seems convincing to many of the experts I have seen interviewed. But, for proof of liquid on the surface, the most compelling "PROOF" is the methane "fart" emitted after Huygens plopped onto the surface. That was measured by the onboard gas analysis and quickly dispersed. It is most probably the warm lander flashing methane in the "wet" surface material. What saturates also flows and pools.<br /><br />Given that the dark areas of the moon are referred to as "seas" I think they should outright call the dark areas on Titan "seas" even if they turn out to be some strange dark albedo material that mimics liquid to a degree.<br />

 

[vogon13]

Let's go just a little crazy for a minute.....<br /><br />How about a follow on JIMO derived carrier vehicle, bristleing with all kinds of goodies: Micro penetrators for all of Saturn's icy moons, Saturn atmospheric probe, ring particle collector/earth sample return module, Titan multi-atmospheric probes, multiple surface rovers, liquid capable probes, seismic probes, cameras, scanners, tricorders, etc. I know we have to get a JIMO/Prometheus first, but once you get the basic hardware in earth orbit, subsequent launches can bring up huge additional tanks of reaction mass and extra payload/equipment for on orbit assembly. The basic Prometheus engine, once it is in space, can really be loaded down and still carry out its mission.<br />Too bad I'm not Bill Gates, I'd just write you out a check and you could all have what you want, as it is, NASA, JPL, SDC, etc. just have to be real clever in laying out what we want and then cajoling congress into thinking they're getting a deal..... <br /><br /><br />Work as though your job depended on it. <div class="Discussion_UserSignature"> <p><font color="#ff0000"><strong>TPTB went to Dallas and all I got was Plucked !!</strong></font></p><p><font color="#339966"><strong>So many people, so few recipes !!</strong></font></p><p><font color="#0000ff"><strong>Let's clean up this stinkhole !!</strong></font> </p> </div>

 

[impfetus]

I think the idea of a rover with inflatable wheels would be the best solution: it can float, crawl and fly.<br /><br />the idea has been laid out by JPL already:<br />http://www.space.com/scienceastronomy/solarsystem/aerover_for_titan_001020.html<br />http://www.lpi.usra.edu/meetings/outerplanets2001/pdf/4023.pdf

 

[JonClarke]

I think a JIMO class mission to Saturn would be most desirable. Since Saturn has only one big moon, how about it drops a Saturn entry probe, and then goes into a polar orbit round Titan equipped with a mapping radar. If an airship isn't feasible, than several small probes could be dropped.<br /><br />Jon <div class="Discussion_UserSignature"> <p><em>Whether we become a multi-planet species with unlimited horizons, or are forever confined to Earth will be decided in the twenty-first century amid the vast plains, rugged canyons and lofty mountains of Mars</em>  Arthur Clarke</p> </div>

 

[titanian]

Yes, the higher atmospheric pressure on Titan is a positive factor for liquid methane or ethane at those temperatures but you forget the low gravity of Titan ( 7 times lower than on Earth ) which is a negative factor.<br />Do we have a diagram for ethane and methane taking both factors into account?<br /><br />www.titanexploration.com

 

[bobvanx]

>>forget the low gravity of Titan<br /><br />Gravity isn't a factor in a substance's phase. Just pressure and temperature. The pressure at the surface is not even twice that of Earth, so the phase diagram is going to look substatiantially the same.

 

[arobie]

I would assume that the measurements where taken at the standard atmospheric pressure.<br /><br />Doesn't higher pressure cause a higher freezing point?

 

[rogers_buck]

I'm not following you on gravity being a factor. Are you suggesting that the atmosphere keeps its rain aloft? That's the only aspect I can think of where gravity enters the picture.

 

[rogers_buck]

Yes, that is why your cigarette lighter has liquid in it. Same for LP gas, etc.<br /><br />That's why a hovercraft would work on Titan. Just warm up under the skirt and you would get several hundred to one expansion of trapped surface liquid into gas.

 

[thalion]

My two bits:<br /><br />1.) Air-breathing craft: I don't think we know enough about the atmosphere to be sure if one of these would be effective. For instance, what if there are substantial tarry aerosols in the atmosphere, like the theorized tholins? Might they gunk up an engine? Ditto for using Titan's atmosphere for fuel; we don't know how "pure" the air is, yet. Hopefully Huygens's data will help clear this up. I expect that we'll have some answers in a year or so, once the initial proprietary period is over.<br /><br />2.) Airships: These are highly desirable, IMO. The coldness of the atmosphere would make it easy to float at various levels with only minimal amounts of heating--I'm thinking along the lines of a hot-air craft. However as someone else mentioned, we need to know more about the turbulence of the atmosphere.<br /><br />3.) Planes: If the atmosphere proves to be conducive to it, I think these would be a great second choice to airships. I'm thinking along the lines of a prop-powered "flying wing."<br /><br />Excluding a JIMO-class mission--I'm going to wait until they start actually laying the keel for this thing (so to speak) before I even think of being too enthusiastic--I'd favor a slower approach:<br /><br />1.) Determine the surface properties: Using a combination of Huygens and Cassini data, characterize the surface and learn just where the flattest and safest areas to land are.<br /><br />2.) Start broad: send a multiprobe mission that can deliver multiple objectives. If I had to choose, I'd pick two "dumb" descent probes like Huygens with similar instrumentation, two balloon probes, and a single robust, nuclear-powered lander similar the proposed (solar-powered) Phoenix craft, with a seismometer, met boom and package, trenching tool, and various on-board analyzing packages. Future missions would depend on what this mission would find.

 

[phaze]

<blockquote><font class="small">In reply to:</font><hr /><p>>An irrelevancy, as usual. I don't have to go to Madrid to know it's hot in the summer and freezing in the winters. Good reports by knowledgeable and reliable observers tell us that.<br />Exactly who is your 'reliable observer' when it comes to what lies under the ice on Europa? Did you launch an orbiter or lander to do a thorough study while we weren't looking? I do not know what's on Europa and neither do you. Stop acting as if you know - you're neither omnipresent, nor omniscient - you're just another SGOTI (some guy on the Internet). <p><hr /></p></p></blockquote><br /><br />I'm pretty sure there are still quite a few things we have yet to discover in this universe. And, I'm pretty sure there are quite a few things we think we know, that we'll discover in the next hundred years or so, we didn't know as well as we thought we did. Seems to be the way things work, no?<br /><br />Steve seems to be very good at reciting what we know now. But very poor at imagining varying possible outcomes. <br /><br />LIFE (as we know it) is pretty stubborn. This isn't to say that if we dropped a monkey on the surface of Mars, Titan, or Europa it would fare very well.... but if LIFE ever did exist in any of those places, it seems plausible it might've adapted and figured a way to endure... perhaps miles below the surface... perhaps in a form alien to Earth... etc. <br /><br />OK - that's not what this thread is about. <br /><br />How about a hover-craft rover? Seems like it might be the perfect craft for navigating the surface... skimming over any pools of goop and whatnot.<br /><br /><br /><br />

 

[rogers_buck]

Humm, a propeller, I hadn't considered that simple device. I don't think there would be any problems from a nuclear ramjet gunking up since anything entering the engine would quickly vaporize. There is one other feature that a nuclear ramjet can do for you that nothing else can. With some creative plubing (jettosoned of course) it can be your rocket engine as well. With the addition of some solid boosters, you might even be able to land it on the surface, collect a sample, and then climb out of Titan's gravity well on its swollen atmosphere. You might even be able to garner enough energy in the outter atmosphere to escape Saturn's gravity for a sample return.<br /><br />Airships are everybodies favorite victim. It is hard to keep them in the air here on earth with humans at the controls. Seems like autonimous but directable flight would be superior and have the advantage of adapting quickly given the unknown conditions at play.<br />

 

[bobvanx]

>>hard to keep [airships] in the air here on earth<br /><br />It is!?<br /><br />Goodyear, then Fuji, Sanyo, Monster, and now many others use inflatables to tool around the sky. Airships help with logging and reconnaissance. You could even fill a semi-rigid structure with hydrogen and not worry about it going up in flames.<br /><br />Since the lifting power in relationship to Titan's gravity is so great, the lifting part of an airship would be smaller than anything we have familiarity with. I'd bet you could construct a cryogenic composite material tank, have it hold a vacuum, and that would be sufficient to do the lifting.<br /><br />Let's see... a liter of Earth air, 78% Nitrogen, is over a gram, a kilogram of lift is provided by displacing about 800liters. On Titan, that 800liters lifts about 7kg, so a 300kg Huygens type probe needs a lifting displacement of roughly 35,000liters. That's only, what, 35 cubic meters of displacement? That's a relatively small tank!<br /><br />In fact, I think the LH2 tank for the X-33 was in that range. <br /><br />[edit]<br /><br />I just checked Thalion's Titan facts. The atmospheric density at the surface is about 5x that of Earth, at only 1.5x the pressure. Density figures into bouyancy, doesn't it? Would our airship be 5x smaller yet? Would it be only 7 cubic meters to lift 300kg?<br /><br />[anotehr edit]<br />clearly I should go to bed. Titan's atmosphere is 5.5 kg/m^3, so to lift 300kg is the simple equation 300/5.5 = 54m^3 of displacement. Still relatively small, but not crazy small.<br /><br />[morning edit]<br />That's a sphere 4.7m in diameter. My friend at l'Garde says they can make an inflatable one of these in practically no time.

 

[centsworth_II]

<i>"...you forget the low gravity of Titan ( 7 times lower than on Earth ) which is a negative factor." -- Titanian</i><br /><br />On a molecular level, gravity is such an impossibly miniscule force that it has no effect, whatever its strength. Ok, maybe on a neutron star or black hole.<img src="/images/icons/smile.gif" /> <div class="Discussion_UserSignature"> </div>

 

[titanian]

Thanks for your answers.So, the gravity has a very marginal impact on the boiling point of methane or ethane.Nevertheless, gravity played a key role to retain this fantastic atmosphere.<br /><br />www.titanexploration.com

 

[rogers_buck]

It was my thinking that airships tend to want to be flown in benign atmospheric conditions here on earth. GoodYear liked to base out of Arizona and the blimps used to fly over my elementary school on their way to the barn. That was cool. Perhaps this is no more so for airships than any other aircraft. Maybe the legacy of the crumpled giants of the 20s lives on to prejudice.<br /><br />On Titan, there is evidence of strong buffeting of the Huygens even in the low atmosphere. At the surface a 10 mph wind would have the energy of a 50 mph wind on earth due to the higher density. I dunno, seems like an airship could be at risk of being downdrafted into the ground or simply carried off to the south pole, and stuffed into a cloud forever.

 

[robnissen]

I agree that flying an airship in the thick, cold, windy and mostly unknown atmosphere of Titan is not a trivial task. Especially considering that we have no maps of the surface. Another problem with most of the proposals here, is that they look like the multi-billion dollar projects that have gone the way of the Dodo bird. (Don't forget that Cassini was the last of the multi-billion dollar projects.) I'm not sure that any of the proposals here can be done under Nasa's new motto: "Cheaper, Cheaper, Cheaper." (Please note that in Nasa-Speak both Better and Faster are synonyms for Cheaper. <img src="/images/icons/smile.gif" /> ) But then again, we can always dream.