8 ms·

I wonder if we'll someday launch a Voyager 3 & 4.

• planteen 7y ago
  It would be pretty neat if we launched Voyager 3 & 4 around 2150, following the same 175 year cycle "Grand Tour" of the original Voyagers. I also wonder if the power source in 2150 would still need to be a RTG or if we will have an alternative by then.
• sp332 7y ago
  New Horizons is heading out of the solar system too. But it's moving about half as fast as the Voyagers and won't hit the heliopause until after 2050. https://en.wikipedia.org/wiki/List_of_artificial_objects_leaving_the_Solar_System https://en.wikipedia.org/wiki/List_of_artificial_objects_lea...
  • pmoriarty 7y ago
    Not only that, but according to the article, when New Horizons "runs out of power in the 2030s, it’ll fall silent more than a billion miles short of the heliosphere’s outer edge."
• mdorazio 7y ago
  Do you mean interstellar probes? The Voyager missions were primarily planetary exploration missions, which NASA and other space agencies continue to run with new probes every few years. The interstellar exploration piece was kind of a secondary feature of the missions taking advantage of high speeds from all the gravity assists along the way. I don't think we'll see a dedicated interstellar probe for a long time. It just takes too much energy to get out that far in a reasonable amount of time without radical designs or a big leap in propulsion technology.
  • pierrebai 7y ago
    Wouldn't it be possible if we launched from the moon instead? Most of the trust of rocket is loss to get out of the earth gravity well. (Not that we're anywhere near having a rocket factory on the moon... but maybe one could be assembled and fueled in orbit?)
    • ars 7y ago
      The only reason to land on the moon would be if you could find fuel there. Which you can't. So that's a no for the moon, but something from orbit could make sense. Have a staging area and just accumulate tons of fuel from multiple launches.
      • outworlder 7y ago
        > Which you can't Of course you can. > By atomic composition, the most abundant element found on the Moon is oxygen. It composes 60% of the Moon's crust by weight, followed by 16-17% silicon, 6-10% aluminum, 4-6% calcium, 3-6% magnesium, 2-5% iron, and 1-2% titanium. You have oxygen. You have aluminum. You can now make a solid rocket. There's some magnesium there too if you want to use that instead.
        • rbanffy 7y ago
          And aluminium, magnesium and titanium are great for building spacecraft, if we can get the mining and manufacturing capability there.
        • saalweachter 7y ago
          It's kind of hilarious that the hardest thing to find in the inner solar system, off Earth (and, of course, the Sun), isn't precisely water but hydrogen.
        • seppel 7y ago
          > You have oxygen. You have aluminum. Not exactly. You have aluminium oxide, which you could split into aluminium and oxygen using huge amounts of energy, like we do on earth. Helium-3 could be interesting, though.
          • behringer 7y ago
            Energy isn't a problem when you can build nuclear power plants without worry.
  • HarryHirsch 7y ago
    The propulsion technology for an interstellar mission is available today, there are proposals for probes powered by RTGs or even nuclear reactors and driven by ion engines. Jupiter-Saturn conjunctions that can be exploited for gravity assists happen every 20 years or so: https://en.wikipedia.org/wiki/Interstellar_probe#Proposed_interstellar_probes https://en.wikipedia.org/wiki/Interstellar_probe#Proposed_in... It's entirely a political problem. There is no will to fund such a mission, and what's worse is that in the US funding is approved year by year.
    • Jeff_Brown 7y ago
      In nuclear engines the fuel and propellant is separate. I keep wondering how much gas a rocket needs to take with it in order to have something to push against. Nuclear fuel is incredibly energy-dense, but the density of the gas used for propulsion in a nuclear rocket can't be much different from what's used in conventional rockets.
      • HarryHirsch 7y ago
        The JIMO mission was supposed to have 12 tons of xenon on board, a substantial amount of the yearly production (~ 70 tons). You do wonder how Elon Musk's Starlink madness will affect the xenon price.
        • tlb 7y ago
          The StarLink satellites use krypton thrusters instead of xenon [0]. They need more electic power to run, but produce higher specific impulse [1]. And krypton is cheap. [0] https://www.spacex.com/sites/spacex/files/starlink_press_kit.pdf https://www.spacex.com/sites/spacex/files/starlink_press_kit... [1] http://ngpdlab.engin.umich.edu/electric-propulsion/krypton-HET http://ngpdlab.engin.umich.edu/electric-propulsion/krypton-H...
  • jandrese 7y ago
    With launch costs plummeting it may be possible to launch a bigass booster and give an interstellar probe a real kick even without a magical planetary alignment. The question then becomes: what instruments would you put on this that would tell us something the Voyager probes have not? What is your mission beyond "making something go even further away from us"?
    • tempestn 7y ago
      As per the article, exploring the trailing edge of the heliopause would be interesting and is something that hasn't yet been done. But yes, presumably instrumentation has also improved over the last 50 years, so hopefully we could get better data as well.
  • blacksmith_tb 7y ago
    There's a (partly funded!) project to send a 'chain' of probes to α Centauri[1], as long as they don't need to slow down when they get there, they can shoot right through and relay results back, as I understand it. 1: https://www.skyandtelescope.com/astronomy-news/100-million-for-probes-to-alpha-centauri-yes-really/ https://www.skyandtelescope.com/astronomy-news/100-million-f...
    • marcoseliziario 7y ago
      Russian Billionaires just got a lot more respect in my book. This looks like just something right from a Jules Verne book.
• NeedMoreTea 7y ago
  We may have to wait a while - Voyager relied on a rare once every 175 year planetary alignment for gravitational slingshotting. It's only a shame the whole Grand Tour that Voyager had once been intended to be a small part of never happened. Depending on the mission there's no doubt other alignments that would give the gravity assist. https://en.wikipedia.org/wiki/Grand_Tour_program https://en.wikipedia.org/wiki/Grand_Tour_program
  • kylek 7y ago
    Do we have any newer propulsion methods that would make a difference in these super-long-running missions? (I am not a rocket scientist... but I'm thinking along the lines of something like a low-impulse ion thruster that uses a relatively small amount of fuel but can run for a very, very long time)
    • thekingofh 7y ago
      Yes, the new missions now have a Delta-V of something like 11 kilometers per second, which is insane. For instance, the New Horizons which only took 9 years to get to Pluto had thrusters with a Delta-V of only like 0.27 kilometers per second, so most of the trip was done using gravity assists. Missions now can do some crazy things like orbit two separate bodies. To put it into perspective, Voyager 1 has a current speed of 17 kilometers per second. So the Dawn craft has most of that trip covered without gravity assists if it wanted. AFAIK there's nothing stopping us from loading up some craft with more fuel and larger ion engines except for launch weight. And even then, if we mastered orbital refueling we could surpass that. As it stands, the craft can carry approximately the same amount of Delta-V that the rocket that got it into space. Equivalent to tons of fuel from chemical rockets.
      • CydeWeys 7y ago
        > To put it into perspective, Voyager 1 has a current speed of 17 kilometers per second And the Earth has 30 km/s, yet we don't get Voyager "for free" and then some just from LEO. You can't compare speeds in different parts of the gravity well against each other because then you're ignoring the dv required to get from here to there.
• dadarepublic 7y ago
  There's a quote I thought of when you said this. It's from a very old Wired article (back when Negroponte was a part of it) titled "The Millennium Clock" by Danny Hillis: "I think of the oak beams in the ceiling of College Hall at New College, Oxford. Last century, when the beams needed replacing, carpenters used oak trees that had been planted in 1386 when the dining hall was first built. The 14th-century builder had planted the trees in anticipation of the time, hundreds of years in the future, when the beams would need replacing. Did the carpenters plant new trees to replace the beams again a few hundred years from now?" I sincerely hope we do launch more deep space probes in the near future, for our collective far future selves.
  • baking 7y ago
    The original builder felt strongly enough about the oak beams to plant replacements. The restorers, or whoever hired them, did not. Perhaps they knew that 500 years in the future there would be better alternatives and were not as locked into the original design as the first builder was. Not all such decisions are short-sighted. Edit: I think it's been shown elsewhere that it is not the date that you launch the next probe that is important, but the speed at which it travels.
• bpodgursky 7y ago
  One of the biggest problems is that NASA's Plutonium-238 stockpile is running low, and is only barely being replenished (it was an artifact of nuclear weapon production, at the time). Each of Voyager 1 and 2 used something like 15kg of it for their RTGs. Because they were so heavily powered, the half-life won't power the craft down for decades. The availability of Pu-238 is why European missions can't go past Jupiter without coordinating with NASA -- politically is impossible for them to produce nuclear spacecraft, but solar power becomes ineffective farther from the sun. But given that NASA has a limited Pu-238 stockpile, they're only stocking new craft with the minimum necessary to hit the key science objectives. There's (finally) a new program to produce more if it, but in very limited quantities: https://www.businessinsider.com/nasa-nuclear-battery-plutonium-238-production-shortage-2017-8 https://www.businessinsider.com/nasa-nuclear-battery-plutoni...
  • jandrese 7y ago
    This was a mostly political problem with Congress kicking the can down the road for 20 years. According to the article they've restarted production although a bit slower than they wanted. Of course you can't stockpile radioactive materials for too long. Their very nature limits their shelf life. So constant production is necessary if you want to use it on missions.
  • baking 7y ago
    Do you know if the new designs proposed using thermophotovoltaics and silicon-carbide pellets are more efficient than traditional RTGs in their use of plutonium? Eli Yablonovitch mentions work being done at Berkely: https://www.youtube.com/watch?v=lDxJsa8miNQ&t=3280 https://www.youtube.com/watch?v=lDxJsa8miNQ&t=3280
  • marcoseliziario 7y ago
    Wouldn't kilopower (https://en.wikipedia.org/wiki/Kilopower https://en.wikipedia.org/wiki/Kilopower) be an alternative? It used U-235.
    • theandrewbailey 7y ago
• LinuxBender 7y ago
  That would be cool. Can we still build hardware as reliable as v1/v2?
  • AnimalMuppet 7y ago
    The Mars rovers tell me that the answer is probably yes.