Titan's Smooth Surface Baffles Scientists 319
JazMuadDib writes "Scientists expected a few rough spots when their space drone snapped close-range images of Titan, Saturn's largest moon. Instead, the planetlike moon appears to have a bizarre, mysteriously smooth surface, and Tuesday's images have left them in a state of wonder. Read more at the Tucson Citizen." NASA's Cassini pages have a wide assortment of images and analysis. Cassini's data has already thrown scientists for loop.
I must be missing something.... (Score:5, Informative)
Am I missing something? The title of the slashdot entry discusses the smooth surface, but I RTFA, and scientists don't KNOW... period?
Re:Not quite as the summary says (Score:5, Informative)
Re:I must be missing something.... (Score:5, Informative)
No information about X doesn't mean X is false (Score:1, Informative)
Extract:
The data show a variation in height of only about 150 meters (490 feet) over the 400-kilometer-long (250-mile-long) track, indicating that in this region Titan is remarkably flat.
Re:Seems like radar passes coul dprovide elevation (Score:5, Informative)
Looking at some of the preliminary radar data (here [nasa.gov]), there's a strip 400km long, with no more than 100 meters of height variation. That's flatter than the state of Kansas!
Re:A Little Perspective (Score:5, Informative)
Actually it was on Europa in 2010. This premise (well, at least the premise of a liquid ocean) was backed up by the Galileo space probe when it reached Europa. Ganymede might also have a liquid ocean, but Europa still looks like the best place to look for life, IMHO. Granted, I'm not holding my breath.
landing on titan (Score:5, Informative)
clickable link to radar data... (Score:5, Informative)
fascinating stuff. shows titan flat as a pancake for 100's of kilometers.
Chemistry of Titan's atmosphere (Score:4, Informative)
Among the recent images provided by NASA is a graph showing data from the ion and neutral mass spectrometer [nasa.gov] as Cassini sniffed Titan's upper atmosphere (far away from the cloud at the southern pole, if I understand it correctly). Some compounds have been identified by mass and labelled, such as hydrogen (2 Da), methane (16 Da) and nitrogen (28 Da).
However, I wonder what that unlabelled band at 7 Da (between hydrogen and methane) represents. What molecule could possibly have a mass of 7? I haven't taken a chemistry class since 1980, so please help me decode this. Are we seeing lithium ions or something?
As for the speculation that the clouds contain some "organic goo", didn't someone long ago suggest that the moon was made of cheese..?
Re:Chemistry of Titan's atmosphere (Score:3, Informative)
Re:Excellent news!! (Score:5, Informative)
-kaplanfx
Re:so you got a smooth landscape... (Score:5, Informative)
Titan is a moon of Saturn, not Jupiter.
Re:Seems like radar passes coul dprovide elevation (Score:5, Informative)
If they're doing Synthetic Aperture interferometry (i.e., multiple pass analysis), they can get range, azimuth, and phase, which can give outstanding accuracy (see, for example, Zebker and Goldstein's Topographic Mapping From Interferometric Synthetic Aperture Radar Observations, Journal of GEOPHYSICAL RESEARCH, Vol. 91, NO. B5, pp. 4993-4999, Apr., 1986)
There's a decent online summary of the technique at http://www.gisdevelopment.net/aars/acrs/1997/ts6/
Now, since it's a spaceship fly-by, there's not as much chance for doing interferometry. You still have pretty good ranging signals. I don't know the accuracy in terms of meters, though.
I think they'll be doing SAR interferometry at some point in the project, but not yet. I think they'll do it from orbit, like Magellan did over Venus.
Re:They didn't quite say it was smooth... (Score:5, Informative)
Many people are confusing two separate issues here: visual imaging and radar topography. On this one pass, and on each of the other passes, Cassini will get A) visual image data on large parts of Titan's surface and B) radar topography on a SMALL PART. The radar sequence is very short -- they just get a little strip of radar data at closest approach and then that's it for that pass.
OVER MONTHS AND YEARS, they will gather enough to put it together and form a complete body of INTEGRATED visual and topographic data, and then we'll get the cool flyover renderings that make us all wet our pants.
But for now they have lots of visual data, which they CAN NOT use for determining topographic details due to the lack of shadowing, and a tiny bit of radar which they CAN.
Re:Tucson, Titan (Score:5, Informative)
As in, University of Arizona, in Tucson. Which happens to be a leader in planetary science.
Re:Seems like radar passes coul dprovide elevation (Score:2, Informative)
http://saturn.jpl.nasa.gov/spacecraft/inst-cassini -radar-details.cfm
This link has a complete description of the RADAR instrument (along with the other instruments), which has a SAR built in but for height measurements is using a straight radar altimeter with "resolution between 90 and 150m"
Re:No.... (Score:3, Informative)
But it's been twenty years since I read it, and the fog of time may cloud my memory.
Re:A Little Perspective (Score:4, Informative)
But to answer your questions:
1. Yes, it could have a liquid core and probably does but also just as likely that the core is no where near as large as our own.
2. Not true. An extremely small liquid core (a few thousand miles across) would not be large enough to case the crust to move. Parts under the crust maybe - but not the crust itself. And even then the movement would be constrained well below the surface.
3. Untrue again. It is composition of the core and not whether the core is liquid or not which would give the moon/planet/whatever a magnetic field. A world made of balsa wood the size of Jupiter would not have a magnetic core - but it would have a gravitational field. A world made up almost entirely of metallic molecules would have both a magnetic as well as a gravitational field.
Or, possibly, by Saturn (Score:2, Informative)
b) A major collision is in no way necessary, sorry.
c) What you've written about gravitational stress is correct - tidal forces (difference in pull on various parts of planet due to varying radial distance from Saturn) cause the entire planet to be mildly deformed - think about tides on earth - if the sun, which is millions of miles away, can pull our water around (and the entire earth, a little, actually), think how magnified the forces must be that much closer to a massive body. This is the primary mechanism for liquidity and internal energy in any planetary body.
d) Fission is likely in any sufficiently dense object. Due to the great heat in the core, denser elements (such as uranium, plutonium, other radioactive elements) will sink to the bottom, where they will reach critical masses and fiss. In addition, fusion is likely, because electron degeneracy can be overcome in planetary cores.
e) If the core is ferrous, there will be a magnetic field. This will result in a 'dynamo' effect, causing further heating.
Wrong moon of saturn (Score:3, Informative)
Re:A Little Perspective (Score:3, Informative)
Jupiter has a bigger gravity well than Saturn, and the surfaces of Ganymede and Callisto are heavily cratered. Europa has some craters, but would seem to be resurfaced by water gushing/oozing onto the surface. Io has very few craters, not unexpected for the most active surface in the solar system.
It's not like the central planet hoovers all imactors away from its moons. In fact, the greater number of objects falling into the system would likely increase the number of impacts on the moons. Yes, the majority hit Saturn, but that still leaves a lot to hit Titan. Look at the other heavily cratered moons of Saturn like Dione and Mimas.
The jury is still obviously out on the degree of activity on Titan's surface. There are some hints of linear markings visible in the latest data that some of the science team are tentatively labeling as possible evidence of tectonics.
Re:A Little Perspective (Score:3, Informative)
Actually, that's not true at all. Among the objects that don't generate a real, structured magnetic field, we have Venus [campusprogram.com], The Moon [ucsb.edu], Io [sciencedaily.com], Europa [google.ca], and Mars [nasa.gov]. Of course, *why* some planets have fields and some don't is still up in the air (rotation of the Earth's core generates our magnetic field, or so it is assumed, and yet Mercury, which almost certainly has a solid core, possesses a planetary magnetosphere).
Re:A Little Perspective (Score:3, Informative)
In the desert, when a sandstorm comes along it can kill and both humans and animals hide from it. This is not only because the storm makes it hard to breath, but because of the sand blast effect. The flesh can be literally stripped from the bones by the force of the sand hitting you.
Again, it may take millions of years, but if the atmosphere is doing this it will slowly but surely reduce mountains to hills and fill valleys. This is also true of any impact craters which were formed. The real question becomes - when was the last time something actually slammed into Titan's surface? Not that we watch it day and night 24/7/365 - but I suspect it is about as long ago as when our planet was last smacked into by a fairly large asteroid. Which, if I recall correctly, was a few million years ago. Without a lot of geologic upheavel it is quite possible that everything has just been worn down.