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Space

Busy Signals for Deep Space Experiments 138

Posted by chrisd from the time-for-a-very-long-extension-cord dept.
lionchild writes "Just when you hated getting those 'Network Busy' signals on your Cell Phones..imagine what it's like to deal with communications in deep space after all these years of putting satellites and probes out there into the space lanes. Check the article out on space.com " The saddest part is the poor state that the deep space network of dishes is in, with some of the 70 meter antennae approaching their fifth decade with no repair funds on the horizon.
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Busy Signals for Deep Space Experiments More

Busy Signals for Deep Space Experiments

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  • So when your communication with your space probe doesn't make it, tell him you've seen him on commercials.
  • Someone ought to tell those folks over at Space.com that the word antennae applies only to the sensory projections of an insect.

    When you're talking about radio receivers, the plural of antenna is antennas.

    It's in the dictionary [dictionary.com] if you don't believe me.
    • English is a living language.
      If you don't like that, I suggest Latin.
      • Scientists are detail-oriented by nature, and for them to miss a small detail such as the proper pluralization of a word they use constantly is out-of-character.

        Oh, right. The article was written by a journalist, not a scientist. I take back my statement.

        • >>
          Scientists are detail-oriented by nature, and for them to miss a small detail such as the proper pluralization of a word they use constantly is out-of-character.
          >>

          I have to respectfully disagree with you here. *Some* scientists are detail-oriented, but others are more "idea people" and hate getting bogged down with trivial details. Often times, you'll see a lot of two author papers where one author is "the idea guy" and the other author is "the detail guy". True story.

          Also... as far as (detail-oriented == proper spelling)... again I have to disagree. I just finished refereeing some conference papers and one of them sticks out in my mind as having wonderfully detailed proofs, but also as being an atrocity commited against the English language. Attention to detail in one's research doesn't always carry over into other areas... (for example, I try to be very detailed in my research... but if you read through some of my slashdot posts, you'll find that I'm pretty much unable to spell and often abuse English grammar.)

          Really though, the true thesis of your post was journalist-bashing; to which I can only respond: "Rock on, brother" =)

    • Re:Call me a pedant but... (Score:2, Informative)

      by mph ( 7675 )
      Someone ought to tell those folks over at Space.com that the word antennae applies only to the sensory projections of an insect.
      Or, at least, to a famous pair of interacting galaxies.
      When you're talking about radio receivers, the plural of antenna is antennas.
      It's in the dictionary [dictionary.com] if you don't believe me.
      The real dictionary (the OED) makes no such distinction.
  • +1 informative?

    The gravitational force is proportional to mass, but goes inversely squared with distance. So any local effect of a gravitational field on a light beam will diminish very quickly with distance. There is no 'light horizon' for the solar system. You could just as easily say that there's enough stuff out there to pull the light beam away from us.

    Complete bunk.


    • Funny how a bunk statement is bunked by another bunk statement :).

      (a) Photons are massless, so you can't use newtonian gravity F=GmM/r^2 to compute gravitation effects on it.

      (b) There is no such thing as "stuff" out there to pull light beam away from us. That is even more completely bunk. According to your logic, the planets will be pulled away from us too.

      (c) There is a light horizon from the solar system. It is but the future light cone of the event called the 'solar system' now in a space-time diagram. The word you want to use is "event horizon".

      The more correct answer is that the curvature of space-time caused by the sun's mass is not enough to curve space upon itself, i.e. start with a photon, and the
      photon will follow the curvature back onto the source. (Roughly speaking of course.)

      • Is it really so much bunk?
        (a) Photons are massless, so you can't use newtonian gravity F=GmM/r^2 to compute gravitation effects on it.
        I trust that you are not saying that light is not affected by gravity? The mass of photons is debatable, but it is a well known, observed fact that light is indeed affected by gravity.
        (b) There is no such thing as "stuff" out there to pull light beam away from us. That is even more completely bunk. According to your logic, the planets will be pulled away from us too.
        Sure there is. Everything that has mass exerts a gravitational pull. It may be small and far away, but that don't mean it doesn't exist! As for the planets, well, they don't crash into 'us' do they? It ain't just centripital force keeping them out there...
        (c) There is a light horizon from the solar system. It is but the future light cone of the event called the 'solar system' now in a space-time diagram. The word you want to use is "event horizon".
        A light horizon exists in 3 dimensions and only because of the curvature of the earth (or other solar body). An event horizon exists in 4 dimensions. They are two different things. The same goes for a future light cone [caltech.edu]. It exists in the 4th dimension. The bunk debunker has been debunked...
        • "(a) Photons are massless, so you can't use newtonian gravity F=GmM/r^2 to compute gravitation effects on it.
          I trust that you are not saying that light is not affected by gravity? The mass of photons is debatable, but it is a well known, observed fact that light is indeed affected by gravity."

          It is indeed observed. In fact, this was one of the first things that 'proved' the Theory of Relativity. An expedition to Africa was made to observe the sun during an eclipse. If photons were affected by gravity, then the light passing near the sun (which is normally drowned out by the sun's light, but isn't drowned out during an eclipse) would be distorted. Well, the distortion was observed. :>
          • The funny thing about the Africa expedition (carried out by I think eminent astrophysicist Eddington, though I am not sure) is that it measures what it expects.

            It turns out that their measurements was wrong, but wrong in the right way to get the expected result :). It was hailed at that time as a "confirmation of a German Theory (einstein) by a British astronomer (eddington)", in 1919 I think, as a nice "reconciliation" after WWI. Well, Eddington got it wrong. Maybe that's why WWII happened :).

        • >(a) I trust that you are not saying that light is not affected by gravity? The mass of photons is debatable, but it is a well known, observed fact that light is indeed affected by gravity.

          Light is bent by gravity. But not according to Newton's Law. Light follows null geodesics (a technical term : imagine space-time being curved and the shortest line between two points, called the null geodesics). To compute gravitational lensing effects, one has to use the full general relativistic equation of motions, where Newton's gravity is just an approximation.

          >(b) Sure there is. Everything that has mass exerts a gravitational pull. It may be small and far away, but that don't mean it doesn't exist! As for the planets, well, they don't crash into 'us' do they? It ain't just centripital force keeping them out there...

          Of course they exist, just not strong enough to have an effect on us. Now you ask : why don't everything crash into us. The answer is twofold : stuff in a galaxy (and in fact around the local galactic cluster) will eventually crash onto each other. That includes all the stars in our galaxy. However, the other stuff outside a certain distance scale (larger than a few 10s of Mega Parsecs : depending on the matter content of the universe), *might* not collapse if the universe keeps on expanding forever. The search for the exact scale is an area of ongoing research.

          >(c)A light horizon exists in 3 dimensions and only because of the curvature of the earth (or other solar body). An event horizon exists in 4 dimensions. They are two different things. The same goes for a future light cone [caltech.edu]. It exists in the 4th dimension.

          Everything you said is roughly correct (plus/minus semantics). Although it is completely unhelpful to think of light cones and horizons existing in 3/4 dimensions (eg : a light cone is defined by the zero norm of the metric, which has both time and spatial coordinates in them). So what's your point?

          >The bunk debunker has been debunked..

          Are you sure? :)

          • >Everything you said is roughly correct (plus/minus semantics). Although it is completely unhelpful to think oflight cones and horizons existing in 3/4 dimensions (eg : a light cone is defined by the zero norm of the metric, which has both time and spatial coordinates in them). So what's your point?

            I take that back. *Not* everything you said is roughly correct. In fact saying that light cones exist in 3D 'because' of the curvature of earth is completely wrong. Light cones exist, period.
            • My dear sir, Please re-read my post. I never once made the claim that light cones exist in 3d or because of the curvature of the earth. What I did say was that light horizons exist in 3 dimensions and are caused due to the curvature of the earth. We are in complete accord regarding the temporal nature of 'light cones' and 'event horizons.' My objection to your original post was due to the fact that you equated light cones with light horizons.
              • >What I did say was that light horizons exist in 3 dimensions and are caused due to thecurvature of the earth.

                Which is wrong too, I am afraid.
                • What definition of light horizon are you using?
                  • A light horizon of an event A is the spatial distance travelled by photons (or any massless particle) sent at opposite directions, from event A at time t_0 to some time later t_1. The horizon traces out the light cone in a spacetime diagram.

                    There are other horizons (this is semantics though). Send a couple of particles from event A, but if these have mass, they will travel at a slower velocity than light, they will trace out a smaller horizon.

                    Essentially, the light horizon defines the causal "reach" of event A. So you might hear people call it the "causal" horizon of some event.

                    The curvature of the earth, of which I take what you mean is the curvature of spacetime caused by an object of one earth mass, does not define any horizon, except for the fact the earth is there. So its existence traces out a future light cone. For example, if the earth blows up at event A, then people within the future light cone of A will eventually realizes the earth is gone. This is not as obvious as it sounds, since spacetime itself is not static (as in special relativity), but itself has dynamics (for example the expansion of the universe). There will be regions in spacetime where the light cone from event A will never reached. The line which separates the region "reachable" by event A and those that is "not-reachable", for eternity or at least to the end of time if the universe is a close universe, is called the "event horizon of A".

                    A more common "event horizon" is the event horizon of a black hole (i.e. some event that occured within the event horizon will never reach the "outside"). But we don't need black holes to have event horizons.

                    All this discussion, of course, have nothing to do with the my original post on the completely wrong statement of the debunker.

                    • Ahh, now I see why we were not understanding each other. I was thinking of a completely different definition of light horizon. I was assuming that you were speaking of THE horizon (ie the sun is on the horizon). Calling it a light horizon I though was a little odd, but oh well. If I understood the original poster of whom you were debunking, I believe that is the type of horizion that he was referring to as well. As for your assertion that photons are massless, it is my understanding that this is only a theory, and though well recieved is certainly not universally accepted. I only wish that you would present it as such. :) And lastly, in reference to this discussion having nothing to do with the original post, I say 'so what?'. Isn't the intent of any discussion board to stimulate interaction? This has been a most enlightening experience, I thank you for your time.

    • Whoops (Score:2)

      by HEbGb ( 6544 )
      Meant as a response to http://slashdot.org/comments.pl?sid=33380&cid=3606 402

      re-posted there. Parent = -1 redundant
  • Organisations putting up stuff that can potentially become space junk should have to pay a decommissioning fee upfront so that if they are unable to maintain the craft it gets taken down.
    • To whom is the fee to be paid? Since there doesn't seem to be an organization with the available means/authority for decommissioning I suggest the fee be remitted to myself.

      I think a more plausible less big-brotherly approach would be an international agreement where all parties would design their spacecraft to burn up/leave orbit/whatever. Part of it could be technology sharing where the more developed space programs share the how's and whatnots involved with ensuring a controlled re-entry that won't squish anyone.
  • I'm breaking up? ... Can you hear me now? ... Can you hear me now?
  • I know stuff breaks down, but these satellites are just up there. There's no wind or water to wear down the antennas. How much do these things actually break?
    • Imagine a million particles of dust flying a million miles an hour hitting an object day in and day out.

      Tors have become polished stone for less than that.
      • Try to imagine all life as you know it stopping instantaneously and every molecule in your body exploding at the speed of light...

        Important safety tip, thanks Egon...

        -- Sorry, couldn't resist.

    • The antennas on the satellites are fine. The antenna dishes *on the ground* have been out in the weather for decades and need renovation.
    • KE = .5mv^2 The mass of a dust particle may be small, but it sure travels fast. Guess where the energy goes?

      • space shuttle (Score:3, Interesting)

        by BlueboyX ( 322884 )
        The space shuttle is well armored. Yet when the thing was origionally designed, nobody knew how common high velocity (but tiny) rocks would be up there. It turned out that the shuttle had insufficient armor to deal with micrometeorites for very long. That is why you see clips of the shuttle 'flying backwards' while in orbit. There is more armor on that side...

    • Re:how do antennas break? (Score:5, Informative)

      by nygeek ( 66352 ) on Wednesday May 29, 2002 @09:51PM (#3606922)
      I worked on the DSN back in the late 1970s out at JPL and I spent many days and nights in the control room for the 70m antenna, so this article brings back some memories.

      You asked how often these antennas break down. While I don't know any statistics, I can give you an idea of what sorts of things make up one of these installations.

      First of all, the antenna has to be pointed at the satellite that it's tracking. This is not an easy task, since the satellite is moving and it's a long way away. To make matters worse, the beam width of the antenna is damn small, so you have to point it very accurately. Doing this involves some tricky work, when you consider how much a 70 meter antenna weighs. And you can't ignore the wind in the desert, though to be fair they do stow the antenna when the wind gets above 20 or 30 miles per hour, as I recall. So in addition to having to move a lot of steel, you have to position it very accurately. Take a complex polynomial to describe the trajectory in azimuth and elevation (or is it right ascension and declination? I don't remember) and servo all that steel to track.

      OK, that's the mechanics.

      Now let's talk about the transmitter. The satellites you're talking to are rather far away. Remember our friend one-over-r-squared? Well, when r is large, the energy falls of a hell of a lot. So when transmitting you try to have as much power as possible. Think megawatts. Megawatts at microwave frequencies. How do you generate such power at those frequencies? You take a vacuum tube that stands about six feet high and you put a lot of current into it. You cool that sucker with a lot of water. Did I mention that the antenna is out in the middle of the desert?

      OK, now you have an idea about the transmitter.

      Ah, yes, the receiver. Well, the satellite can't afford to transmit a megawatt of power. If it's lucky, it can muster ten or twenty watts. At planetary distances, the energy arriving at the antenna is comparable to the amount of energy that arrives at the moon when you hold up a lit match. Not much!

      How do you make a receiver that will detect a signal that weak? This is a very complicated topic, but let me summarize by noting that the key component is a superconducting maser. This is basically a chunk of copper hollowed out, evacuated, and then cooled down to a very cold temperature. In the desert.

      To coordinate all of this you have to have some computers. When I last visited the control room at Goldstone it seemed pretty darn big to me. It had something like six or seven rows of 19" racks, each row with something like thirty or forty racks. That was over 20 years ago, so I might be off by a factor of two or more.

      Oh, yes, how about some facilities for the people who support the installation and the project people from JPL.

      And it's out in the desert. The control electronics at the big antenna are in one building and the people who drive the antenna sit in another. There's a long tunnel between the two. You're out in the desert, so keep an eye out for scorpions when you go into the tunnel. I never saw a live one, though I did see several dead ones.

      So in answer to your question about maintenance, yes, there is some stuff that needs maintenance.

      • Re:how do antennas break? (Score:1, Informative)

        by Anonymous Coward
        azimuth and elevation (or is it right ascension and declination? I don't remember)

        It's azimuth and elevation. At least those're the only terms I've ever heard used to locate something in the night sky.

        • RA and declination (Score:3, Informative)

          by Iron Sun ( 227218 )
          No, it isn't. Azimuth and elevation are simple up-and-down, left-to-right figures, useless in finding an object if you move or even wait a while, like saying "go west 2km and then north 1 km" is not much use on Earth unless you know exactly where to start from. Right ascension and declination are the celestial version of latitude and longitude. They require an accurately aligned platform to be of any use, but once you've done it you can look up coordinates in a star atlas, point it at the sky, and bingo!
          RA and dec are also mounted on what is commonly called an equatorial platform, meaning that the platform is offset so it can turn in synch with the rotation of the earth via a single drive while pointing at the same object. I'm not sure, but I think it's the declination axis that does this. Altitude (elevation) and azimuth must both alter at varying rates to track a celestial object. That being said, equatorial mounts are much larger and more expensive than alt/az ones, so many big scopes nowadays use the simpler mount with computer control to do the tracking.

          In short, both alt/az and equatorial (RA/dec) are pointing strategies, but RA/dec is a coordinate system.

          • Re:RA and declination (Score:3, Informative)

            by MaggieL ( 10193 )
            Azimuth and elevation are simple up-and-down, left-to-right figures, useless in finding an object...

            Well, since I have an amateur radio satellite earth station, I can tell you a little about this. The pointing commands to the antenna array *are* in terms of azimuth and elevation. For quickly-moving spacecraft, like those in low-earth orbit, I use software that calculates directly to az/el in real time from the satellite's Keplerian orbital elements. While I don't currently track anything that's not in Earth orbit, given RA and Dec, the equivalant az and el for a given point on the Earth can be calculated.

      • So in answer to your question about maintenance, yes, there is some stuff that needs maintenance.

        I believe that the original poster was asking about the antennas of satellites in space. (Of course, your post was a very interesting read on what happens here on Earth.)

        Though there is no wind or water, I'd believe that dust and micrometeorites wear down the stuff in space somewhat. But I'm no expert. If somebody could elaborate on this as well as the parent....? =)
    • There's no wind or water to wear down the antennas. How much do these things actually break?

      You've got plenty of meteors and orbiting space-junk up there... you also need to worry a LOT more about radiation because there isn't an atmosphere protecting the satellite.
    • The article is about antennas on the ground, but I'll give one example. You're right, the antenna is not likely to break. However, most antennas are dishes, pointed mechannically. It is certainly possible for the pointing mechanism to seize due to lubrication issues.

      Spacecraft have multiple antennas -- usually a high or medium gain antenna, and at least one low gain antenna, used when the spacecraft is in a "safe" mode. There are switches to control which antenna to use; these can break or fuse, especially if they are switched while in a high-current state.

      The electronics that 1)control the antenna or 2) receive/transmit the signal might break. For example, on SOHO [nasa.gov], the phase-lock-loop (PLL) component of one of our receivers malfunctioned somehow (possibly due to tin whiskers [nasa.gov]), causing the uplink frequency (the frequency received by the spacecraft) to shift 400 kHz.

      The antenna on Galileo [nasa.gov] failed to deploy properly, and could not be used. Galileo now has to use their low gain antenna and some compression techniques [nasa.gov] to downlink its images and data.

      Returning to the article, the DSN antennas (or their ground systems) break frequently. In 2001, SOHO recorded about 500 ground anomalies. Fully half of them were due to some problem at the antenna site. (yes, boys and girls, that means almost one problem per day, and that's just SOHO) Most of the other half were network problems between the DSN site and the mission control center at GSFC [nasa.gov].

      To give specific examples of stuff that has broken (or had a glitch that caused a problem): hydraulics (failure), pointing motors, brakes (when the brake is on, the antenna stops moving and you very quickly are not pointing at the spacecraft), power amplifiers (transmitter), low-noise amplifiers (receive), telemetry systems (usually software crashes, have to reboot the system), ground receivers, exciters ... too many to list here.
  • How many can be suprised about this phenomenom? We live in a very self-centric society that is more concerned about our own interests, unless if those interfere with ours. This is a widespread attitude in this country, reaching from the common man concerned about the television programming that those satellites are beaming down and obscuring some of the DSN antennas to those at NASA and the NSA, who have also put a great many objects into orbit, including those that are taxing the system beyond its capacity.

    Scientists could continue to exacerbate the problem, as many have personal ideas about what is more important, their future NASA rovers or an improved method of keeping in contact with other projects. Funds diverted to repair and upgrade generally means that funds are diverted away from their projects, and few would readily give up funding. One of the ways to gain support for expansion and repair would have to convince people that investing in this now will have definite benefits in their projects later.

    • How many can be suprised about this phenomenom? We live in a very self-centric society that is more concerned about our own interests, unless if those interfere with ours.
      While blaming the whole thing on Society is fashionable, and easy, in this case it's mostly wrong.

      NASA has a bad habit of not even requesting funds for facility maintenance.

  • Amateur Radio (Score:4, Funny)

    by lostchicken ( 226656 ) on Wednesday May 29, 2002 @08:30PM (#3606539)
    Just put Ham equipment on those things, and let us do the rest...

    I'm sure we could get something to work.
    • I can see the news reports now... "A group of rogue Ham radioers have taken control of NASA's satellites. They are reportedly playing freeze-tag with them. Still pending investigation..."
    • Radio hams can do some pretty amazing things, but I dunno how they can overcome the fact that receiving weak signals from that far out requires a really big dish to collect enough signal.

      Of course, you wouldn't put it past ham radio people to build their own 70-metre dish if they really put their minds to it :)

  • Hi,

    At least here in Australia the big CSIRO-owned Parkes radio-telescope (also a 70-m dish, featured in the recent movie `the Dish' [imdb.com]) supplements the NASA DSN when needed. Last time I visited the site they were communicating with the Galileo Jupiter probe.As far as I know this antenna is well maintained, as it is also used for radio-astronomy research.

  • TDRS etc. (Score:3, Informative)

    by apsmith ( 17989 ) on Wednesday May 29, 2002 @08:44PM (#3606599) Homepage
    The number of options for contacting a deep-space spacecraft (which includes anything beyond geo-synchronous orbit) are surprisingly limited - basically NASA's Deep Space Network, NASA's Tracking and Data Relay satellites, and then whatever time can be purchased on the various radio telescopes and ground stations around the world. For a spacecraft at Mars the signal is weakened by an inverse square factor of billions relative to near-Earth satellites, so you need highly directed large and sensitive receivers to hear anything. NASA has been upgrading the TDRS satellites but they aren't much use for really deep space missions because of their limited size. Except for commandeering Arecibo, the 70-meter DSN antennas are about all that's available right now...
    • TDRS aren't much use for deep space missions because their single access parabolic dish and multiple access phased array antennas point at the Earth and Earth-orbiting satellites, most of which are below the TDRS altitude. The TDRS space-to-ground link antenna has a limited gimbal range, so you can't just flip the spacecraft over to point away from the Earth. The antennas on TDRS HIJ do have enough azimuth gimbal range to see significantly past the limb of the Earth, but even a three-axis stabilized satellite is not a very stable platform for the extremely accurate pointing required to talk to very small spacecraft very far away with limited transmitting power. Using TDRS for deep space missions is an unlikely proposition at best.
    • I think we all just started to face up to the fact that, except for technology that can commercialised, such as medical, transport, etc, the end is here for pure science.

      The Australian government funded organisation, the CSIRO, has been told to become more commercially viable while funding in many areas has been slashed.

      The end result of all this is a similar cycle that has happened to the world many times before when scientific advancement has ground to a halt, the money men run everything and science for the sake of it stops.

      This is despite the fact that pure science research has ultimately been the basis for all pratical science.

  • Hmm... (Score:3, Funny)

    by Loki_1929 ( 550940 ) on Wednesday May 29, 2002 @08:48PM (#3606620) Journal
    "We're sorry, please try your call again later."

    "The number you are trying to reach, 3-0-5-1-3-4-5-2-3-5-2-4-6-2-1-6-3-7-4-4-8 ... is not valid. Press 0 if you need assistance."

    "We're sorry, the number you are trying to call has been disconnected."

    "All circuts are busy, please try your call again later."

    "Please wait... while the NASA subsciber you are trying to reach is located..."

    "That number, 5-4-7-2-7-1-0-8-6-2-3 .. has been changed .. to an unpublished number."

    "You have reached .. mailbox number 2,942,213. At the tone, please leave your name and telephone number."

    "Your call could not be completed as dialed, please check the number and try again."

    "Hello, Verizon information. What City and State please?" ... "3rd ring of Jupiter."

    • You don't have an e-mail or a web site, so I thought I'd ask:


      How is ColdFusion and SQL server treating you? I read it in you bio.


      • CF is ok, and I'm experimenting with MySQL, which seems to be fairly nice. I need to do some side-by-side comparisons to be sure, but it looks as though on most things, it's much faster than M$ SQL. Anyway, there are plenty of jobs available for those who know SQL, so if you don't know it now, learn it. Have fun, folks :)

  • This has made me think(what a wonderful new feeling)... Where is the site where you can buy property on the moon? if I could get a nice plot of dust on the far side, prefferably in a crater, I could FINALLY be free of USELESS SPAM! Of course, I wouldn't be able to receive any kind of communication, but maybe it's worth it?

  • Dang... (Score:5, Funny)

    by FrostedWheat ( 172733 ) on Wednesday May 29, 2002 @08:52PM (#3606636)
    How's ET supposed to phone home now?
  • "Just when you hated getting those 'Network Busy' signals on your Cell Phones.."

    I have never gotten this message on my cellphone when using any service (regular calling, wireless web, instant message.) What is it? Is the phone service provider's internet bandwidth saturated or something?

    • IF you get a fast busy, its the network saying it doesnt have any open voice channels, too congested. Only happens in areas where there's heavy usage.
      Every tower only has so many channels available, or if it's CDMA, the ability to support only so many calls. If it runs out, it just tells your phone "No go", and your phone generates a fast busy.

  • /. effect (Score:2, Funny)

    by cascino ( 454769 )
    "We call it the traffic jam," said Bill Blume, mission design manager
    We call it the slashdot effect.

  • Can you hear me now?

    Gooooood...

    ;-)

  • "We are concerned that our 70-meter antennae are getting quite old," Miller said. "Late in the next decade, they'll be 50 years old."

    What an interesting way to say "Right now, they're 30 years old."

  • The DSN has options.... (Score:3, Interesting)

    by mbone ( 558574 ) on Wednesday May 29, 2002 @09:37PM (#3606852)
    The Deep Space Network (DSN) works well in a crisis mode, or when a spacecraft is doing something spectacular. It's not so good at the mundane day to day.

    I used to work there, and then I worked for its "competition" in the US government. The DSN does a lot of non-criticial stuff that could be done cheaper elsewhere, either by other parts of the US government, or abroad, or by private industry. It has always been unwilling to off-load any of these routine tasks, even if the charge would be a fraction of what it costs the DSN to do it.

    So I am not entirely sympathetic, at least until the DSN restructures and reinvents itself.
  • "Huston, we have a...aww crap"
  • The Soviets had a similar system to DSN. If I remember correctly they had 2 land stations and a ship in the Atlantic [svengrahn.pp.se]. They used it to track, among other missions, the Venera [nasa.gov] missions to Venus... that still hold the record as the only human missions to ever transmit from the surface of Venus!

    Assuming that the antennae (note English spelling) are the expensive part, they why not buy up one or two from the Russians and stuff new signal processing equipment (aka computers) in them?

    -AD

  • They must be using AOL.

  • Relays (Score:3, Informative)

    by Fastolfe ( 1470 ) on Wednesday May 29, 2002 @11:09PM (#3607234)
    I once read an article about how much of this was going to be solved by the use of a real deep-space communications network. The idea was to have them launch some relay satellites at some stable orbital points in the solar system, and instead of having ground stations here dedicated to communicating over these great distances, you'd ideally have a relay near your probe relay its transmissions back to earth. Once you get into deep space, you can start using more efficient optical methods for communicating between relays, and communication from earth basically just relies on your ability to get the message to the nearest relay satellite and let it route your message appropriately.

    All of this has the added benefit of allowing all of the various probes and interplanetary craft to be in communication at the same time.

    Unfortunately, aside from the original paper I read, I haven't heard of anything more about these ideas. It's possible they've been tabled as too expensive for now.. :/

    It's a shame because I think this project would be really fascinating and could probably save a ton of money in the long run.
  • Hate to state the obvious, but always beating our chests with the "there is no money for science" theme is not bound to generate sympathy, especially when the poor and old DSN has just received the money to build a new 34m dish at the Madrid station.

    Why not reading the article before spitting out the old song about money and science? Have you considered what state is the Russian deep space network now ? tracking is available only above Russia (which is probably 14 timezones, but is still barely 1/2 of what the DSN can do) and the mighty fleet of tracking ships has been sold for scrap metal. Heck, Russia can't even track objects in Earth orbit for the full span of the orbit! So think before posting!


    -Muad'Dib

    PS: If instead you told me that some of the 400bln tossed by Bush IInd in the Pentagon's budget could be spent better than just in funding the "military/industrial combine" Eisenhower was scared of, I totally agree. There is no match militarily for the US, but they *have* to spend 400bln in things that do not increase homeland security - why ? well, simply because the weapons/defense industry is filling the pockets of a congressman near you.... :-(

  • is gonna be screwed.

  • Light buckets (Score:3, Interesting)

    by foniksonik ( 573572 ) on Thursday May 30, 2002 @02:59AM (#3607812) Homepage Journal
    "Laser light buckets could allow faster data rates than the biggest radio antennae on Earth, Miller said, but it does have its drawbacks.

    "The concept looks very promising from a cost standpoint...but it can't get through clouds at all," he said, adding that to be effective, a number of ground sites would be needed to account for bad weather. "And it would all have to be developed from scratch, but it's possible that sometime in the next decade we could be using optical instead of radio frequencies."

    "

    "but it can't get through clouds at all"

    Why can't we just use satellites to receive the 'optical' data and retransmit via radio or whatever the last 'mile' kinda like a DSL for deep space transmissions...

    • Or why not just build it on a mountain? If you find a high enough one, then cloud aren't normally a problem, apart from the really high ones like cirrus, cirrostratus, cirrocumulus etc. But if you were to build a tower on top of the said mountain, you may be able to avoid the clouds altogether.
  • "We're sorry -- the space probe you have reached is not in service. Please check the coordinates and try again." *click*
  • Two tin cans and a reeeeeeeeeeeeeeally long ball of string, perhaps?

  • Arrays (Score:1)

    by vinn ( 4370 )
    I remember working on an RFP that involved some DSN communication. From what I remember, the 70m dishes are going away. Yeah, a huge dish kicks ass, and the amount of bandwidth you can get is phenomenal (hundreds of kilobits on an interplanetary mission!!). However, you can get pretty much the same bandwidth by using the smaller 34m dishes in parallel. The 70m dishes were the old NASA approach of using a sledgehammer on a thumb tack. Modern electronics lets you do some fancy stuff, and it's a lot easier to install a few racks of equipment and use smaller dishes then keep the mechanics on the 70m dishes running. We're likely to not see many infrastructure improvements on the current DSN soon - they did a huge upgrade in the early/mid nineties.

    Another real problem is acquiring enough bandwidth at the right time of day. DSN has three main locations because this little blue sphere we're on spins so fast. Scheduling all that communication isn't exactly easy.
  • For those to young to remember, the ALOHA protocol was the inspiration for the Ethernet protocol.
  • Late in the next decade, they'll be 50 years old
    Isn't that just a silly way of saying they're a little over 30 years old?

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