Slashdot Mirror

← Back to Stories (view on slashdot.org)

Interplanetary Network (IPN) Tested

Posted by michael on from the token-ring dept.

CETS writes "Slim on detail but...USA Today reports of the first test of an Interplanetary Network. 'In a sign of cosmic communications to come, last week mission controllers sent signals to a Mars-orbiting European spacecraft, which relayed the instructions to NASA's Spirit rover on the surface, and a signal was returned to Earth back along the same path.'" NASA also has a press release.

14 of 138 comments (clear)

  1. Isn't that a bit early? by locknloll · · Score: 5, Interesting

    I mean, good intentions, and kudos to NASA to get that infrastructure up and running, but it will probably take some more years before this really starts to make sense.

    I guess it won't be used for routing traffic to gameservers...

    --
    -- Power corrupts, but PowerPoint corrupts absolutely.
    1. Re:Isn't that a bit early? by Anonymous Coward · · Score: 1, Interesting

      Well, part of this idea was to place a small number of satellites around planets esp. mars and let them handle communications, CPU processing, GPS, etc. W's group has killed the system that was to be sent to Mars to do this, but the technology is still doable so that NASA can help others and visa-versa. If all the others use it, it will allow for more info to be received from other planets and possibly save a mission or 2.

  2. I'm kind of surprised... by TWX · · Score: 4, Interesting

    ...that they haven't implemented some form of relay satellite over Mars already. I'd think that one satellite in space would remain viable longer than a ground craft, and since it's in space it wouldn't have the dust-on-the-solar-panels problem, the atmospheric barrier problem, or the temperature variance problem. The ground craft wouldn't need to be built to transmit to Earth, just to an orbiting Mars satellite, which would handle the rest, so the landing craft could have engineering to make it more suited to its task rather than concentrate on radioing home.

    --
    Do not look into laser with remaining eye.
    1. Re:I'm kind of surprised... by Skyshadow · · Score: 4, Interesting
      that they haven't implemented some form of relay satellite over Mars already.

      Well, they *are* using existing orbiters to communicate with the current generation of orbiters. You know, just like the headline there says.

      I suspect that before any serious Mars exploration ramps up, a set of satellites in martian geosync would be a good idea. Not only would that facilitate communiation with anything actually on the planet, but it could also provide for a global positioning system.

      The real issue up to this point is that we just haven't needed that sort of thing yet. If/when we send people (especially if we follow Zubrin's advice and send them for 500+ day stays, or my advice and just build a colony and get on with it), that will change. If nothing else, just increasing the amount of bits you can push by sending a constant stream of lower-power 1's and 0's to a satellite instead of screaming data at the DSN here on earth a few hours a day would probably be a big benefit to future missions.

      --
      Every year during my review, I just pray the words "slashdot.org" aren't mentioned.
    2. Re:I'm kind of surprised... by I+don't+want+to+spen · · Score: 5, Interesting

      Geostationary orbit satellites only last about 10-15 years before the satellites run out of fuel. I don't know if a Martian equivalent would need more or less fuel due to the lower gravity. The current orbiters can also do useful planetary observation as well as acting as a communication relay, precisely because they do orbit over the planet's surface and can see the whole of it from close range. I doubt that 3 aerostationary, or whatever the correct Martian term is, satellites would adequately perform observations for their much higher orbit as well as providing blanket comms coverage for the planet. Plus power considerations etc. I'm sure it will happen, but not for a good while yet.

      --
      Don't go to a brothel if you want to buy broth
    3. Re:I'm kind of surprised... by Anonymous Coward · · Score: 2, Interesting

      Actually, that was suppose to happen. the current admin was trying to kill it. Now, that they are supposedly going after the moon and mars, who knows? Perhaps, W's people will quit trying to kill good stuff.

  3. USATODAY.com for all your science needs... by John+Seminal · · Score: 2, Interesting
    Radio signals take several minutes, travelling at the speed of light, to traverse the void between the two planets

    Hmmm. Funny, NASA does not say anything about that.

    Anyways, I guess it is good to have an article which might stirr up support in the community as a whole.

    So, what is next? Will every planet in the solar system have a series of satelites that can form a solar system wide network? If this experiment of launching rovers is a success on mars, as it looks to be, then I can see a day when we have rovers on all the planets, perhaps even a manned station on different planets.

    Too bad Gene Roddenberry is not alive to see the begenning...

    --

    Rosco: "If brains were gunpowder, Enos couldn't blow his nose."

    1. Re:USATODAY.com for all your science needs... by AeroIllini · · Score: 5, Interesting

      USA Today, is right, though. The lag time between Earth and Mars is anywhere between 3 and 22 minutes when Earth and Mars are clostest and farthest away from each other in their orbits.

      And I think NASA has had plans to incorporate signal relay satellites for some time. Of course, NASA plans to build many more probes/satellites than actually get launched, so we're just now seeing satellites with relay capabilities. There were plans as far back as 1997 to launch a series of satellites whose only purpose was to relay signals from other spacecraft. Interplanetary routers, if you will. However, due to budget cuts, the capability was instead built into satellites with otherwise scientific payloads.

      --
      For security, the MD5 hash of this message and sig is 09f911029d74e35bd84156c5635688c0.
  4. KA9Q by bigattichouse · · Score: 3, Interesting

    Just a dressed up store-and-forward packet radio, right? KA9Q was written well over 10 years ago, and can route IPv4 traffic over such a connection.

    --
    meh
  5. Re:Not really by Anonymous Coward · · Score: 1, Interesting

    The window of opportunity for communication isn't that much better. In fact, it's worse if you use the network. The MGS, Mars Express, etc are in low Mars orbit (LMO?), so they can't see Earth for much longer than the rovers themselves. Maybe an extra 20 minutes when the rovers are just out of sight of Earth (just before Earthrise and after Earthrise).

    And on top of that, the orbiters have to have LOS to the landers. They only have LOS for (wag) about 30 minutes. And that's not taking into account the fact that the ground track of the oribiters change, so they only see the landers a few orbits a day.

    Nah, the network isn't good for much except a few high-rate data transfers. Everything else is still a matter of the traditional point-to-point lander-Earth communications. Now if we put some "ares-centric" comm relay satellites in orbit, we'd be looking good!

  6. Not even that good. by Civil_Disobedient · · Score: 4, Interesting

    The lag time between Earth and Mars is anywhere between 3 and 22 minutes when Earth and Mars are clostest and farthest away from each other in their orbits

    And just to make matters worse, you've got to deal with some serious high-gain amplification to "dial them up". Beaming cable over a satellite's easy -- sending it millions of miles away means a lot more power (a scarce commodity on a satellite to begin with) or a much more sensitive antenna on the recieving end. I don't know what the current data transmission rates with the things we sent to Mars, but for reference, the Magellan probe back in the 90's had a transmission rate of 115 - 268.9 kilobits/sec.

    It is really amazing to consider that we now have a "spy" satellite orbitting Mars relaying images of the surface back to us on Earth, and that it's sensors are good enough to show us photos of the landing of the rover on the surface. Just incredible. But this technology is still in its infancy -- we've still got decades before we land a man on the planet. This is an amazing page about the Soviet exploration of Venus that may also be of interest.

    1. Re:Not even that good. by dvd_tude · · Score: 5, Interesting

      They do have one thing that helps (as it turns out, quite a bit): no in-band background noise to interfere with the communication.

      Anyway, yes their data rates are lower than diect broadcast TV satellite. It's all about the relative S/N owing to inverse square law and the greater distance to the deep space vehicle. The rover and orbiter link rates are on par with Magellan's - 128~256 kb/s, compared with about 30mb/s for a DTV satellite transponder channel.

      Read this chapter in JPL's Space Flight Primer for more information about how their space vehicle comms work. A tidbit I found in there: they use coherent (phase-locked) transmission and Doppler to very accurately measure the remote vehicle's position. That's a neat hack.

      Both things are amazing when you look at them, for different reasons. Deep space communication is amazing because it's possible. Direct broadcast satellite is amazing because it's so cheap!

      A nitpick: the 'milestone' stated in the article, which was apparently overlooked by many of the posters here is the fact that, for the first time, a non-NASA spacecraft (in this case the ESA's Mars Express Orbiter) got into the act as a data relay for the rovers. This is more a statement about cooperation than it is about outright technical achievement. It is a political milestone, much the same as our (America's) cooperation with Russia in the ISS and in developing new rocket booster technology. Yet while it is political, it is a good thing in that it's another step toward recognizing that for space exploration to be fully realized it needs to be global endeavor, not a national one.

      This is very much at odds with Bush's election-year 'man to the moon' pipe dream that serves no real scientific end and is more about beating the collective American wiener on the table with China.

    2. Re:Not even that good. by Civil_Disobedient · · Score: 2, Interesting

      the 'milestone' stated in the article, which was apparently overlooked by many of the posters here is the fact that, for the first time, a non-NASA spacecraft (in this case the ESA's Mars Express Orbiter) got into the act as a data relay for the rovers

      It's also neat that some of these satellites are doing double-duty -- that is, they have certain bandwidth limitations that act as a bottleneck to all the data they could be sending from their normal scientific operation modes. The Mars Express orbiter had to juggle data from both its scientific instruments and all the recon for the rovers. In effect, distributing bandwidth like an ISP.

      Yet while it is political, it is a good thing in that it's another step toward recognizing that for space exploration to be fully realized it needs to be global endeavor, not a national one.

      Definately. I often wonder how much more advanced our space program would be (our=mankind's) if the Russians and Americans had been working cooperatively in the 60's instead of reinventing each other's work. I realize that the anatagonism of the cold war certainly helped get a lot of the movement underway, but I can't help but look at some of those older Russian probes and think, "Damn, what a clever bunch of guys they had."

      Russia had been working on rockets long before the Germans were buzzing Britain; think of where we'd be now if we'd paired a guy like Goddard with guys like Glushko and Korolev. Sucks that Russian's pre-eminent rocket designers were later arrested and tortured under Stalin's terrors.

      ---
      A small aside (Karma to burn...) why are we wasting our limited resources on sending probes to distant planets? It seems absurd to me, that you would send a probe halfway across the solar system, then wait (and pray) that all the instruments survived the trip, then wait for the results to come back as weak sputtering data. Think about it, folks -- How did they do in Star Trek? You assemble one big ship in space , then have it go out and get your research.

      Everyone's talking about landing people on Mars, living on Mars... it's insane! The requirements to land on a planet are a lot more restrictive than travelling to a planet. Just concentrate on a ship with enough power (it would probably have to be nuclear, like our nuclear subs are today). Once you're power solution is found, you can build it as big and un-aerodynamic as you want! Need some extra O2, or food? No problem, just tack on another cargo hold.

      I realize Ion propulsion isn't very efficient right now, but with enough power you wouldn't have to carry around all that stupid compressed air. Anyway, my point is that we could accomplish so much if we just got some people out there, but we don't have to have people living on other planets for this to happen. Just build a ship, people. You can figure out the other stuff as you go. /rant.

  7. Re:Answered my own question. by Civil_Disobedient · · Score: 2, Interesting

    I also read somewhere that one of the new systems that is going to be tested is the use of the Ka Band for data transmission instead of what they normally use (X-Band), which I believe increases the amount of data that can be sent an order of magnitude or so. The X-Band tops out at 400 kbps, I believe.