Slashdot Mirror
Titan Photos and Sounds
ahsile writes "NASA and the ESA have released the first images
from Titan. The ESA also has available sounds from the surface." Reader ZZip writes: "Apparently a bunch of enthusiasts has compiled the first mosaics from the raw data delivered by the Huygens probe. Meanwhile space.com has more coverage and pictures from NASA/ESA." Say a silent thank-you to the persistent troubleshooters of the world, without whom none of this would be possible.
All of the very very short samples were taken at various times, hence the differences in volume.
but am I the only one who sees what looks like small craters in in the "water"?
It may be dust particles or condensation in the cameras. When contrast is enhanced, such camera artifacts tend to really stick out.
Table-ized A.I.
If you look at the caption for the photograph on that page, you'll see: "I have bumpmapped the image for clearer details: (the "craters" you might see are photographing artefacts that only seem to be craters)" Still it was a very good observation to notice those... and maybe there's something to it?
Not everything liquid is water!
"What surprised me was what looked like river deltas. I thought Titan was way too far out for there to be water, unless its rivers of liquid gas?"
The general belief is that hydrocarbons (ethane and methane) comprise most of the atmosphere and possibly exist in liquid phase. This image and others (rounded ice "rocks" seem to imply erosion) seem to confirm the hope of liquids running on the surface.
Keep the lighting conditions in mind: the Sun is MUCH dimmer out there, even without such a thick, cloudy atmosphere to dim it further. And no, maybe they didn't have a much better camera: there might be severe bandwidth and weight limitations involved.
I think the whole titan mission is fascinating, but they really need to release some higher quality pictures.
Have some patience people. We are mostly seeing raw dumps with quicky contrast enhancement. It will take a while before it is put together and cleaned up.
I would note that Huygens was not designed to be a high-resolution photographic mission. Many were not even sure if the surface would be visable when launched. Plus, such an atmospheric desent probe cannot have directional antennas (other than maybe "not down"), reducing the bandwidth. For example, the mars rovers only send high-res images when they are sitting still and focusing their narrow-angle directional antennas at specific locations in the sky for the receivers to pick up (either at earth dishes or in Mars orbit).
Table-ized A.I.
I was a little saddened after seeing the pictures and getting all stoked for ultra-high-res pictures like what Spirit and Opportunity are sending back, but I don't think it's in the cards.
The uplink from Huygens to Cassini was only 8kb (don't remember if it was bit or bytes, in any case, not a wide channel) and there was only about a 2 hour window to transfer to data before the batteries on Huygens went dead. I consider 2 hours pretty remarkable given the extreme conditions is going in to and the fact that the batteries have been waiting for seven years. The technology also dates to at least 1997, probably earlier (to provide time to check for reliability against radiation fun from space).
Supposedly there are some 350 or so pictures, so at 32Kb a piece (at least what the ESA is putting up), I don't think we're going to see anything much higher.
My Slashdot account is old enough to drink...
I'd love to see NASA spend some of its new $billions running a planetary probe on the Earth, exactly like those to our neighbors....we'd also get a way to interpret the results of those other missions, by comparing the "probe" picture of the Earth with our other pictures of the Earth, including firsthand experiences here at home.
Do you mean testing the cameras on Earth targets?
Table-ized A.I.
It has to do with resolution. With B&W, one pixel measures the gray-level, whereas with RGB, you need three pixels to measure each primary color. So while the images are not as 'colorful', they contain more (acurate) information. The rover missions use B&W for just this reason.
As for the cripsness of the images, I don't know. Perhaps the atmosphere has a lot of haze, or these are just preliminary low-res images. Maybe the hi-res images are coming later. Again, the Rover mission did the same thing initially.
Unlike Mars the surface of Titan has not been mapped. The portion of the surface that was revealed is less than 1% and Titan has probably 1/2 of Earth land surface area (33million square miles). Any probe that we send to the surface is flying blind just as Huygens did. When we descended we did not know what surface features we were going to discover. Unless radar and ground telescopes technologies advances enough so that we could "pick" a landing site for the next lander/rover we can only hope that the terrain is navigable. I also hope we return to Titan in the next 50 years.
Are you telling me you are living in a world without exposure settings on cameras?
You dont need daylight to create bright pictures, you know?
They didnt know the exact luminosity, too, so they chose settings that would give pictures even if it was darker than it oviously was.
Better to bright than too dark...
HI O WISE PRINCE. WHT TOOK U SO DAM LONG?
Those "craters" you see are photgraphic artefacts, as is said in the caption of the web site.
--- Sigmentation Fault - Comments Dumped
No need for a math PhD. Orbital mechanics is pretty straightforward. Sophomore-level physics for the baseline calculations. The real challenge is in getting the engineering of the spacecraft to be so robust, and to account for more subtle effects (e.g. small changes to trajectory and spin rate due to outgassing and radiation pressure).
I think the technology dates back even further than 97, it was designed in the late 80's. There was an interview with one of the guys who worked on it on UK TV last night. It was 17 years ago that he started work on the project, 10 years design, building & testing then 7 years waiting for it to get there. :-)
They only had a data rate of 8Kb/sec to work with, and the probe wasn't going to be able to broadcast for long. So the pictures had to be very low res.
They could have easily taken better pictures, but the data wouldn't have been able to make it back to Cassini with the throughput and amount of time they had.
Its because the normal way of taking colour pictures (Si photocells with wideband colourfilters) is only good at taking pictures for human eyes, not for any kind of spectral analysis.
Plus in this case, there were 3 reasons:
a) There wasnt enough space for multiple cameras/spectrometer
b) Most of the pictures were planned to be taken in rapid descent/being shaken around (they hoped it would land, but werent sure), so filter changing wouldnt be so good (plus too time consuming, they only had so little)
c) There isnt much light there, so narrowband spectral filters would have made the exposure matter even worse(by factor of 50 or so, and even wideband filters would block 2/3s of the light) (especially combined with the moving viewpoint)
At least they had very cool ccds (little noise), so they could take such bright pictures in that short time.
HI O WISE PRINCE. WHT TOOK U SO DAM LONG?
Interestingly, the probe passed close to the Sun and twice close to Venus to use their gravity for acceleration. The kind of precision they use for these calculations is truly fascinating - I mean you have to know the gravity and "course" of Venus pretty exactly to send a probe around Venus for acceleration!
Sebastian
No, not because of him. It appears (though no one wants to say anything really substantiative) that someone forgot to send a command to cassini to turn on the reciever for one of the channels. ESA is accepting full responsibility though since it was them who were supposed to give the command to NASA to send up I think.
- "Hear that?! The percolations are imminent! Cease your ingress!"
Yes, to our eyes methane, like practically all aliphatic hydrocarbons, is a crystal clear liquid.
But we don't know which wavelenghts the used camera records, so what is clear to us isn't necessarily clear to the camera in question.
Thanks to all slashdotters to help test whether our box is capable of coping with the /. effect.
I hope you all like the pictures we created and published before ESA came out with theirs.
Much kudos to ESA, NASA and uni of Arizona for having those pictures out for the world to enjoy
--- Sigmentation Fault - Comments Dumped
Google is your friend. For example, look here.
This is all Newtonian physics. It's not like they're just flinging the spacecraft out there and hoping that it hits the right spot. Knowing Cassini's current position and velocity, they can calculate to very high precision where it will be six months from now. It's still an amazing technological achievement, though, to be able to guide the spacecraft through seven years' worth of maneuvers to get to this point!
I watched conference at 2am pacific time. I believe they mentioned that 350 pictures were lost because software did not have a command to receive from a channel B. Someone forgot to implement command to start receiving data. Investigation in progress. So we got 1/2 of the pictures were were supposed to get. Because of that we lost lots of panoramic pictures which are now missing lots of pieces. NASA channel coverage was a pure shame. They stop transmitting conference after 1 hour. Cameras instead of showing data graph were showing wide angle with scientist pointing to the graph and a graph 20 meters away. So you could not make out what parts of the graph he was talking about!
So, why do we keep sending only B&W cameras on these things?
Because that's just how cameras (even film) work. Your $100 webcam only senses brightness, not color, just like the cameras on Huygens and the Mars rovers. With the rovers, they have filters which only allow certain frequencies (colors) to hit the sensor, just like your digicam/webcam/film camera. The difference is the filters on the consumer camera are fixed on the CCD (or film), while NASA's are in front of the lens, so you can mix and match.
If your goal is *only* to make pretty pictures, sure, send up a digicam. If your goal is science, you use interchangeable filters, or just a single, fixed filter across all pixels.
This is not only better science, but also higher resolution. Your digicam (say, 4MP), has 2million green pixels, 1 million red, and 1 million blue (in one common configuration, there are other mixes and colors), and the raw image is processed to simulate 4 million RGB pixels. But using a 4MP sensor with filters over the lens, you get all 4 million pixels at the selected wavelength. This provides more information, and science is all about information.
History books for sure, but you must be forgetting asteroid Eros, landed on by NEAR in 2001; and (depending on your definition of "land") Jupiter, whose atmosphere was visited by Galileo.
One might add the "bombing" of Tempel 1 in a few months by Deep Impact
They explained in the press conference.
They didn't have the bandwith to send back complete sound, so they've averaged the amplitude and frequency of the sound. I assume that they've then used this to modulate some white noise to produce the sound that they've posted.
Batteries add mass, and mass adds cost. Even if you shut down the lander until Cassini is back in range, you have to warm it up (from about 70K). Since it's not mobile, there isn't a lot you can do over time with a payload of its size. You'd just end up taking the same readings over and over. It might be nice to have data on the landing site over time, but you're not going to be able to power the lander for such a period. I don't think even an RTG would be of much use.
""Directional receiver" and not needing pointing are mutually exclusive by definition."
I don't think so...Imagine a fixed simple small whip antenna that would stick out the side of the craft. As the probe spins the signal strength varies regularly (synodically) by knowing your spin rate and the time you can determine where the signal is coming from (roughly) by looking at when the signal strength is highest.
Yagi antennas are different from phased arrays. When I said phased array I mean computer controlled phased array. These weren't really available until the '70's-'80's.
- "Hear that?! The percolations are imminent! Cease your ingress!"
The landing was basically a bonus - it was designed as an atmospheric probe, and used a heatshield to decelerate to subsonic velocity, then a series of parachutes to float down relatively slowly over the course of two hours. It was calculated to impact the surface at 10m/s or so, around 20mph, so they designed the instruments to survive that sort of shock so that some data could be returned if a landing was successfully made.
"Studies have shown that people who eat peanuts live longer than those who do not eat."
You mean like the Mission to Planet Earth?
General Relativity: Space-time tells matter where to go; Matter tells space-time what shape to be.
Warning. That is actually a redirect page on the fark server to a rather annoying page that oppens up about 8 billion constantly resizing windows. It pw03n3d my computer! I had to restart X to kill it.
"The war in Iraq is spending about that much every 20 days. Cassini's cheap." .2 Billion dollars a day, or about... $4,100,000,000 every twenty days.
Are you sure about that? The war in Iraq is and has been phenomenally expensive and wrongheaded, but I'm not sure about that figure. Quick math: According to costofwar.com, the cost is up to about 150 billion right now. It's been not quite two years since March 20, 2003, so we take 150/365 and divide that by two for the two years, and find that the war in Iraq costs a little over
Holy crap, that's about right.
If my math is screwed up anywhere, somebody correct me.
Eh?