Want to read Slashdot from your mobile device? Point it at m.slashdot.org and keep reading!

 


Forgot your password?
Close
typodupeerror
×
Space

Cassini Probe Has Camera Problems 143

Posted by chrisd from the chris-knight-school-of-optics-clarity dept.
xX_sticky_Xx writes "The BBC is reporting that the last billion dollar NASA probe, Cassini, (enroute to Saturn) is suffering from an unknown source of contamination on its narrow field camera. NASA has attempted to alleviate the contamination, which is causing a haze to appear around images, by "defrosting" it, with so far limited success. Another attempt will be made in January. If this problem can't be resolved this will be extremely disappointing. Cassini is set to expand our knowledge of Saturn more than Galileo did for Jupiter."
This discussion has been archived. No new comments can be posted.

Cassini Probe Has Camera Problems More

Cassini Probe Has Camera Problems

Comments Filter:
  • just take off the glass lens, and use the bottom part of your t-shirt to clean it off!

    of course, putting 100,000 miles between the two of them could cause a problem...
  • I read the article, but it wasn't too clear what exactly would be. There isn't much in the way of dust for the thing to run into I would think. There isn't water to condense on the lense either. Would this be dust that the probe has brought along with it for the ride that happened to settle on the wrong part?
    • Would this be dust that the probe has brought along with it for the ride that happened to settle on the wrong part?

      dust doesn't really settle in zero G...

    • probably outgassing (Score:5, Informative)

      by Anonymous Coward on Sunday December 16, 2001 @01:32AM (#2710424)
      when you take something from earth pressure to zero pressure you'd be surprised at what will boil off. this is called outgassing, as polymers, etc... lose mass to vapor. the stuff outgassed can then condense on your optics and ruin your pictures. The usual practice is to put everything in a vacuum chamber and get it all out before flight, but this won't always be enough. Also, you can coat surfaces that will outgass, but you need to use anyway (such as electronics circuit boards) with a non-outgassing coating (such as uralane). If some electronics overheat and melt away some of that coating, the materials underneath might, you guessed it, outgass. It is a difficult problem to avoid and it is unfortunate that it might ruin the mission. hopefully not.
    • You're assuming the contamination is on the outside of the lens. It could be some component within the camera "off gassing" and forming sludge on the inner lens surface.
    • I don't agree with the BBC's claim that this is a "major" problem... the narrow angle camera still works - the contaminent just effectively reduces the resolution of the NAC. But from what I understand, the NAC resolution is nominally very, very high and even with the contamination it still will produce amazing pictures.

      As far as what the contaminent is... the best guess so far is that it is outgassing from some part of the spacecraft... probably the camera. Something got heated up, vaporized and then condensed on the lens (either the inside or the outside of the lens). When they see if the stuff cooks off and what temperature it cooks off at, they'll have a better idea where the contaminent came from.

      Cassini has already had larger problems (the reaction wheel last December, and the probe relay problem) that have been overcome and Cassini is still on track to make all of its mission objectives and then some. This problem is minor by comparison and will probably be fixed.

      Cassini was launched in 1997, and arrives at Saturn in 2004... seven years later. Then its primary mission ends 4 years after that... and it is hoped Cassini can fly a 4 year extended mission after that... So this spacecraft will fly 15 years in deep space without any possibility of any repairs more sophisticated than commanding a motor back and forth to jiggle something loose or turning on a part to heat it up. Things are bound to break... hopefully, these things will be small and not cause the spacecraft to blow up when it turns on its engines the next time.... we all want to see the pictures of the pterodactyls flying on Titan, don't we?

  • space dust? (Score:4, Informative)

    by moniker_21 ( 414164 ) on Sunday December 16, 2001 @12:55AM (#2710346)
    Worryingly, the origin of the contamination is unknown

    What about plain old space dust? According to this [nasa.gov] article there's enough of it out there to hamper astronomists when viewing celestial objects from earth. More closer to the point this [spacedaily.com] article describes how people involved in space exploration are concerned with peices of space dust, too small to be tracked, causing serious damage to orbiting satelites. The Cassini article says they're pretty sure that it's related to the deep cold of space, which is why they equipped it with heaters. But if it's not related to the cold, it's not out of the realm of posibility that maybe Cassini simply encountered some of this dust? Although you'd have to think the makers of the satelite thought of this already, but who knows.

    • Re:space dust? (Score:1, Informative)

      by Anonymous Coward
      In short, no. When you hit dust at 10 km/s, it doesn't "contaminate", it drills holes.

      • If dust got on the lens, or inside, most likely the fuzz pattern would be even or random. The fact that it is on the edges of the image suggests that something is condensing.

        If the camera was hit by a speck of space dust, perhaps the impact could have created a little cloud of dust when it penetrates (assuming it did not hit the lense or image sensor chip itself. If it did hit one of those, I doubt it would be just the edges.)

        The fact that a little heat reduced the problem is also kind of against that theory.

        Condensation of something is the most likely exlanation IMO.
    • The BBC article refers to the "Stardust" project as though everyone knows about it...

      Stardust project, which had a similar problem that was much worse. In that case, Stardust's team were able to completely remove the contamination

      You can read more about that mission at http://stardust.jpl.nasa.gov [nasa.gov].

      What a name.
      • Do you have any links to the problem about camera? I checked the site but didn't see an obvious link to quoted problem or a link to "mission log of stardust" kind of thing.
    • What about plain old space dust? According to this [nasa.gov] article there's enough of it out there to hamper astronomists when viewing celestial objects from earth. More closer to the point this [spacedaily.com] article describes how people involved in space exploration are concerned with peices of space dust, too small to be tracked, causing serious damage to orbiting satelites.
      First of all, the stuff in orbit that's hampering astronauts is not "space dust", in the astronomy sense of the term. It's simply "space junk" - i.e. leftovers from stuff we've created.
      And while it's very true that clouds of space dust proper can create enormous blind spots for Earth-based astronomers, on a human level, it's actually quite sparse. Something on the order of one-part-per-million (billion?). As my astro professor put it, one single particle of dust per that many parts is equivalent to a single tennis ball in the state of Missouri. It's simply that sparse, and that's why only lightyears of it will have any noticeable effect on visibility.
      Yes, there are variations from location to location, but in general, space dust is simply not dense enough to cause this particular problem.
      • It's easy to visualise 1-in-a-million if you think of a 1 metre cubed volume, and imagine a 1 centimetre cubed sugar cube in it. This brings 1-in-a-million into distinctly human-sized terms. 1-in-a-billion* is easily visualised as a 1-millimeter cube of dirt in a 1 metre volume of space. Using Volumes rather than lengths or areas to visualise "large" numbers brings them to comprehensible scales - Think of filling a medium sized cupboard with sugar cubes for an approximation to one million....

        * 1000-million == 1000 000 000 == 1 "amercian" billion. Note that most British people now pretty much exclusively use the american definition of a billion (many people will still tell you that the British Billion is a million million, but if a British person says a billion, he now tends to mean an american billion, just to confuse you).
      • Perhaps it actually could be space dust.

        I seem to remember one of the Apollo missions (8 or 9, not certain which) had reported a problem during lunar insertion...pilot reported that the window was "foggin up".

        Turns out that NASA had plotted their course through one of the moon's Lagrange points (a more-or -less natural "parking space" for dust), and the "fogging" was the window being sandblasted!

        I know, I'm showing my age here...
    • I'll tell you who did it. It's that damn sasquatch.
    • If it were a known phenomenon like space dust, then it should have been caught during the assembly/testing process. If it really happens to be so, then that would be a serious lapse on the NASA's part, wouldnt be it? On the other hand, we need to think about why this did not happen in any of the previous probes, and only specifically this?

  • Wipers? (Score:1, Funny)

    by mberman ( 93546 )
    Maybe it's time to start intalling windshield wipers on spacecraft?

    • Re:Wipers? (Score:2, Funny)

      by xinit ( 6477 )
      Unfortunately, that was an optional feature and they opted not to install the wipers at the factory, planning to get an after market add-on.

      See, the factory version would have added $5.7 million to the before tax cost, and this guy on the project knew a guy whose brother found the exact same component at a flea market for $10. NASA's trying to come in closer to budget now, after all, so...

  • I mean, given the size of space and all, the amount of dust it has passed through is probably negligable, let alone what could have stuck to the camera. I can't imagine it is anything other then frost and judging by the fact that the warming did help, it seems that is really the most likely answer.


    I would only begin to worry if heating it a few more times doesn't clear it up totally.

    • I mean, given the size of space and all, the amount of dust it has passed through is probably negligable, let alone what could have stuck to the camera...

      Shuttles get hit by stuff all the time. Cassini has gone a lot further, and is going a lot faster. It has occupied a couple of trillion cubic meters so far, and that's a lot of space. Ample opportunity to hit dust particles.

      At interplanetary space speeds, a grain of sand is a serious collision. 15 to 20 times the speed of a rifle bullet. Ouch!

      ...laura

  • So after reading the article (I know, rare for a slashdotter) I started wondering who they named the probe after. Turns out they named it after a 17th century astronomer who was the first to observe Saturn's four moons.

    Some more info on the man behind the name of the probe can be found here [st-andrews.ac.uk].
    • IF you had read the article, you would have realised that Galileo was the first to observe JUPITER'S four (largest) moons and SATURN'S rings.

      Galileo is one of the world's most famous names. How could you have gotten far enough in life to be able to post on Slashdot without having heard of the guy?

      You Fucktard.

  • Last Cassini report (12/12) indicated normal. (Score:3, Informative)

    by snStarter ( 212765 ) on Sunday December 16, 2001 @01:02AM (#2710367)
    This is from the report sent out:

    Cassini Weekly Significant Eventsfor 12/06/01 - 12/12/01The most recent spacecraft telemetry was acquired from the Goldstonetracking station on Wednesday, December 12. The Cassini spacecraft is in anexcellent state of health and is operating normally. "Present Position" webpage, http://www.jpl.nasa.gov/cassini/english/where/ .Recent instrument activities included two Radio and Plasma Wave Science HighFrequency Receiver calibrations. Engineering activities taking place onboardthe spacecraft this week include an Attitude Control Subsystem high-watermark clear and the uplink of the Mission Sequence Subsystem (MSS) D7.6.1Modules.
    • The BBC article is from the 15th and says that this is a very recent development. And that also sounds like general health, not picture quality.
      Not sure this applies to the current problem.
    • From the 10/25/01 - 10/31/01 [nasa.gov] weekly status report:

      The Imaging Science Subsystem (ISS) post-warm-up images were downlinked for analysis. The 15 images were planned in support of the UVIS Spica observation, and were examined for potential changes relative to the pre-warm-up images. Preliminary results show a change in the character of the anomaly with the halo gone but more spreading of the star image than before. ISS also performed a scattered light observation, in an effort to resolve an anomaly observed in C25 when an ISS observation received far more light than expected. This current observation included a series of scans across the sky to see how much scattered light ISS gets at different distances from the sun for a selection of different orientations, to see if reflection off another part of the spacecraft is causing the extra light seen by ISS.
  • When I was 6, my mom bought this balloon for me. I accidentally let it go and it went higher and higher, never to be seen again.

    Sorry NASA.
    • When a friend and I were about 11-12, we went to this trade fair where different booths were handing out helium balloons. We must have grabbed 50 or so each. So what else do you do with 100 helium balloons? We slitted a garbage bag, made a huge black sheet of low-weight plastic, and tied the balloons to it. We also attached a note to it (hey, we were kids) to the effect of: "If you find this, call me @ xxx-xxxx".

      The sucker was visible for a LONG time as it rose (very little wind that day). We promptly forgot about it, until about 6 months later. Turns out it ended up in some farmer's field about 200 miles away!

      Yeah, completely offtopic, but further proof of just how geeky I was in those days. Thoughts like this are what inspires people to send probes to other planets, I guess.

  • Man that sucks... (Score:2, Interesting)

    by bteeter ( 25807 )

    After all the risks that were taken to put this thing in space - it would be a shame for it to go to waste. (Risk = putting 75 LBS of plutonium within a few miles of crashing down onto the earth.)

    NASA is having a rough time with it lately. There have been a lot of pretty expensive and embarasing failures. If NASA were a private enterprise I'd suspect a management shakeup. Since it is a government body - I'm not sure what can be done. Clearly something should be done...

    Take care,

    Brian
    --
    We are almost out of Free Palm m100's... [assortedinternet.com]
    --

    • Do we have to hear MORE of these people??? Geez, as if caring about an INTERNATIONAL Spacecraft such as Cassini (the probe which will go to the moon Titan was made by the European Space Agency) makes us forget the terrorist attacks. What Flamebait... Anyway, that probe's had problems too, but they fixed it.
    • If NASA were a private enterprise I'd suspect a management shakeup.

      There is a "management shakeup" occurring right now. Daniel Goldin, the longtime administrator of NASA, has retired (see what he's up to and his new computers at the L.A. Times Celebrity Setup [latimes.com]).

      Dr. Daniel Mulville [nasa.gov] is the current Acting Administrator while Sean O'Keefe is waiting for confirmation [slashdot.org].

    • It is the ONLY thing I LOVE about USA. I guess many foreigners feel the same way. There is bound to be problems, after all, it is rocket science. That is the agency brought Apollo 13 crew back, how hard could it be to clean a camera lens? Or just bring amazing amount of information with a faulty cam. It is one of two, after all, and there are other data collectors. Have some faith, NASA will solve... Unless your stupid president and idiotic congress cut their budgets further, not leaving enough staff to maintain the lonely probe. Remote possibility? No, just look what had happened to voyagers and pionners.
    • bteeter wrote:
      After all the risks that were taken to put this thing in space - it would be a shame for it to go to waste. (Risk = putting 75 LBS of plutonium

      What would you quantify the risks as?

      -Chris

  • Lens cap... (Score:5, Funny)

    by arsaspe ( 539022 ) on Sunday December 16, 2001 @01:23AM (#2710412)
    In news today, Nasa scientists spent all last week trying to find the source of the contaminant on the Lens. After many hours of brainstorming, one of the engineers spilt coffee on a button labeled "Lens Cap". Shortly after, the camera apeared to be functioning correctly. Head NASA Scientists are trying to work out the function of this "Lens Cap" button, but the British designer of the button cannot be contacted, and Nasa officials are still unsure what has happened.
    • roflmao.

      The function of the "Lens Cap" button has now been determined by Nasa officials. It appears to be an emergency overide to remove the Lens protection device in the event of a failure to remove it automaticly. When asked why the Cover failed to be removed in the first place, the Nasa spokesperson told us that instead of making the cover 6" wide, the manufacturing company made the cover 6cm wide instead, and it was a very tight fit.

    • A Jovian toddler mistook the probe for a scooter. Unfortunately, her parents forgot to put the toddler's diapers on.

      Or, they forgot to turn on the No Smoking sign.

    • Re:Lens cap... (Score:2, Interesting)

      by Feng ( 63571 )
      Slightly offtopic but there have been cases of space probes having lens cap problems. In the 70's a Russian probe (Venera, IIRC) landed on Venus and returned photos of complete darkness. In the end it was determined that its lens cap melted on to the camera.

      A subsequent Venera had an improved lens cap which popped off on landing. The funny part is the lens cap landed in front of the probe, where a spring loaded arm called a "penetrometer" was supposed to spring out from the probe and sample the soil around it...

      ...You guessed it. The penetrometer ended up sampling the lens cap which was lying where the arm was supposed to plunge in.

  • January's too soon... (Score:3, Funny)

    by Carl Jacobsen ( 23360 ) on Sunday December 16, 2001 @01:25AM (#2710417)
    it'll still be winter -- if we waited 'til spring and maybe it'd thaw out on its own.
    • That very much depends on which hemisphere you're in... January's the second hottest month of the year for us... coming close behind Feb...

  • something really needs to be done (Score:5, Funny)

    by mj6798 ( 514047 ) on Sunday December 16, 2001 @01:35AM (#2710431)
    This just keeps happening--the Vogon interstellar starliners keep illegally flushing their toilets into space in the vicinity of solar systems. I think we should file a complaint with the local authorities on Alpha Centauri.
  • Maybe it's about time for some fancy inter-stellar windshield wipers. I suppose it's hard to refill wiper-fluid in space though ;-)
  • I told ya we shouldn't have let that guy with the squeegee wash the lens on the way to Saturn!
  • Oh no! It's sounds like the return of the dreaded space fungus [slashdot.org] that was eating Mir!

    Seriously though, one wonders if this could be even remotely related. I doubt it highly, but it is an interesting thought...

  • I'm not quite sure what the big deal is. They said in the story that not only were they optimistic that it would be fixed, but that the lenses and optics are designed with heaters for this kind of thing. Shouldn't we be happy that finally one of those "just-in-case" prevention measures that NASA spends millions on finally might be the difference between a successful and, well, not-so-successful mission?

    It sounds to me like a lot more information needs to come out before we start saying that the mission is even in danger...we do have 2+ more years.
    JoeRobe

  • Source of contamination (Score:5, Insightful)

    by chazR ( 41002 ) on Sunday December 16, 2001 @04:29AM (#2710703) Homepage
    The source of contamination *has* to be the spacecraft itself.

    If the contamination were external, it would have had a signifigant (measurable) effect on the momentum of the spacecraft. The space through which it is travelling is pretty much completely empty anyway.

    That leaves one plausible possibility: Cassini is leaking something that is condensing on the cold (*very* cold) bits. The most likely cause is a small propellant leak. As far as I know, the spacecraft has three propellants on board, N2O4, N2H4 an monomethyl hydrazine. I'm too lazy to look up the charecteristics of these, but their boiling points differ.

    A heating cycle of the lens seems to have helped. I would be *very* surprised if the data from the heating cycle didn't give them a good clue as to the exact contaminant by looking at the amount removed by a known heat input (latent heat of vapourisation)

    The big worry is that the leak will leave the spacecraft with insufficient fuel for orbital insertion (unlikely - it's almost entirely a gravity-assist trajectory) or for manoeuvering. That would be bad.

    I may, of course, be completely wrong.

    • If the contamination were external, it would have had a signifigant (measurable) effect on the momentum of the spacecraft...That leaves one plausible possibility: Cassini is leaking something that is condensing on the cold (*very* cold) bits.

      Call me stupid, but wouldn't a leak also cause a significant change in momentum? Maybe you're just used to using some method of inertialess propulsion to get around, in which case we'd all be really interested to hear about it. :)

      • Yes. Of course it would affect the momentum. But if the leak is slow enough for the vapour to remain close to the spacecraft for it to condense in large enough amounts to obscure a lens, I doubt that the velocity of the escape is enough to have much effect on a six-tonne spacecraft.
      • Maybe you're just used to using some method of inertialess propulsion to get around, in which case we'd all be really interested to hear about it.

        Check woodward engine, you might find interesting. See http://www.grc.nasa.gov/WWW/bpp/ (sorry I don't know how to make those clickable, look for research proposal about mach's principle) for credibility, james woodward's homepage http://chaos.fullerton.edu/Woodward.html for more info.

        For all too lazy to floow links guys out there, woodward claims to have detected transient mass effects, which might be used for propellantless propulsion. The idea is sound and experimental confirmation is present, but the experimental values are a few orders of magnitude less than predicted. It is unclear whether the theory or experiment design is incorrect right now. Both NASA and Mr. Woodward is looking into it, though the results have been painfully slow to arrive.

        • Learn basic HTML, then submit in 'HTML Formatted' mode.
          <A HREF="http://www.nasa.gov/";>More info on NASA</A;> as an example of a link More info on NASA [nasa.gov]
          Also <BR> for line breaks and <P> for paragraph breaks.
          • Opps; there shouldn't be a semi-colon between just before the >, I got a bit confused with the &lt; & &gt; ligatures needed for to escape angle brackets ( & is done using &amp; )
            Doh! Serves me right for not previewing.
          • And <ul> gives you a short-cut for the <blockquote> effect (N.B., not semantic, just the rendering effect) LIke:
            • this
            Compared to
            this
            .

            Have you ever wanted to add a long "pause" or separation between paragraphs? Use clusters of <p> <br> <p>.

            I always like seeing people stretch the limits of allowed HTML here on /.
            Sometime ago a poster A poster created
            created "call out" segements cool callouts...
            to her/his posts using /. tags. Neat effect. I tried to imitate it and found that
            the preview process mangled the Comment-box contents. Moral: becareful.

    • would be *very* surprised if the data from the heating cycle didn't give them a good clue as to the exact contaminant by looking at the amount removed by a known heat input (latent heat of vapourisation)

      I would be *very* suprised if they had enough variables for that:
      -They don't know what part of the camera is contarminted. (ccd, ot what lense)
      -They don't seem to measure the "haze", it seems hard to detect, and they are much more intersted in calculting it away.

      And, if something is leaking, there is very little they can do since there is no service point/ R2d2 robot. They will have to rely on backup devices.

      --By the way instead of *very* you can use <B> for bold or the html <I> italic </I>

  • They have three YEARS to solve the problem (Score:3, Informative)

    by Zarhan ( 415465 ) on Sunday December 16, 2001 @05:28AM (#2710802)
    Okay, most of the folks here seem to be bashing NASA and jumping to conclusions that the probe is lost. No damn way. They'll come up with a solution soon enough - for one thing, a similar incident occured with the Stardust [nasa.gov] probe earlier this year. Just take a look at the status reports [nasa.gov].

    Start at somewhere aroud May 4,2001 and go backwards (by that report, the problem had been fixed). I bet the glitch on Cassini will be fixed just as easily. Note that the problem occured just before christmas, so they probably just tried a "quick fix" to see if it just went away. Like said, they have until 2004(!) 'till Cassini is at its destination to try a number of things. They'll probably get rid of the contamination just by turning on the heaters for a couple of months, but they don't want to start the operation and immediately leave for a christmas vacation (in case something comes up).
    • Okay, most of the folks here seem to be bashing NASA and jumping to conclusions that the probe is lost.

      Regardless, this is an *experiment* - we leaned *something* here. Either about materials in extreme cold and vacuum for years, if it is a NASA "error", or about the nature of interplanetary space if it is some sort of dust. Grant you, it's not pretty pictures, but I don't think the public even cares about pretty pictures anymore.

      --
      Evan

  • Does anybody remember there were protests against the launching of the Cassini probe? Some environmentalists were afraid about the nuclear materials aboard or something like that...

Slashdot Top Deals

Let's organize this thing and take all the fun out of it.

Close