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NASA Space Science

Nasa's Voyager 2 Probe 'Leaves the Solar System' (bbc.co.uk) 151

The Voyager 2 probe, which left Earth in 1977, has become the second human-made object to leave our Solar System. From a report: It was launched 16 days before its twin craft, Voyager 1, but that probe's faster trajectory meant that it was in "the space between the stars" six years before Voyager 2. The news was revealed at the American Geophysical Union (AGU) meeting in Washington. And chief scientist on the mission, Prof Edward Stone, confirmed it.

He said both probes had now "made it into interstellar space" and that Voyager 2's date of departure from the Solar System was 5 November 2018. On that date, the steady stream of particles emitted from the Sun that were being detected by the probe suddenly dipped. This indicated that it had crossed the "heliopause" -- the term for the outer edge of the Sun's protective bubble of particles and magnetic field. And while its twin craft beat it to this boundary, the US space agency says that Voyager 2 has a working instrument aboard that will provide "first-of-its-kind observations of the nature of this gateway into interstellar space".

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Nasa's Voyager 2 Probe 'Leaves the Solar System'

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  • Maybe not (Score:5, Funny)

    by Impy the Impiuos Imp ( 442658 ) on Monday December 10, 2018 @01:17PM (#57780560) Journal

    second human-made oblect to leave the solar system

    I wonder if there isn't some chunk of arrowhead embedded in an asteroid smashed off the Earth in some titanic collision.

    • by Anonymous Coward

      Not even a remote possibility. Last time that happened was long before humans existed (think dinosaurs) let alone humans who had advanced to making stone into an arrowhead.

    • Yeah, it is possible that in the 8,000 years of Earth's history that happened at least once.
      • But given Earth's escape velocity and dense atmosphere, it's extremely unlikely.
        • Re: (Score:3, Funny)

          Well maybe. I'll check the Bible to see if there is any record of it occurring.
          • The story of the destruction of Sodom and Gomorrah? Turns out there is evidence of a midair meteorite explosion on the north end of the Dead Sea around 5000 BC. In other words, many biblical stories may be based at least partially on actual events. There is also evidence of a meteor crater in Greenland from around 14,000 years ago. So far, no evidence of a collision strong enough to knock man-made items into space, but it is still possible, albeit extremely unlikely.
            • That's odd. I searched for "meteorite" in the Bible and there weren't any results.
              • by SWPadnos ( 191329 ) on Monday December 10, 2018 @03:10PM (#57781388)

                That's odd. I searched for "meteorite" in the Bible and there weren't any results.

                Did you search the original Hollerith version, or were you using the updated Unicode version?

                You've got to remember that there have been several translations (through EBCDIC and ASCII, with a short diversion through UTF8), and there's no direct translation for "meteorite" (the closest would be "comet" (U+2604, U+FE0F) or "shooting star" (U+1F320)).

                Gotta be careful when electronically searching ancient texts!

              • Genesis 19:24-25: Then the Lord rained on Sodom and Gomorrah sulfur and fire from the Lord out of heaven. And he overthrew those cities, and all the valley, and all the inhabitants of the cities, and what grew on the ground.
                That doesn't sound like a meteorite burst to you?
                • by quenda ( 644621 )

                  Genesis 19:24-25:
                  Then the Lord rained on Sodom and Gomorrah sulfur and fire from the Lord out of heaven.

                  That doesn't sound like a meteorite burst to you?

                  You'd have to be quite delusional to think that referred a meteorite rather than a volcano. "Sulphur" FFS!

                  Also, 5000BC is far too early for any biblical influence. The Hebrew language itself only goes back to around 1000BC.

                  • Quite a lot of stories in the Ancient Testament are basically lifted from older stories from the Middle East. Like how Noah's Ark is taken from an episode in the Epic of Gilgamesh.

                    In another example, the Vedas (Hindu sacred teachings), used to be transmitted orally for several thousand years until they were written down much later.

                    A lot of the knowledge we have from Greek myths is also a transcription of oral transmitted stories including Homer's Illyad and the Trojan War. The Indian Mahabharata may be anot

              • by Tablizer ( 95088 )

                That's odd. I searched for "meteorite" in the Bible and there weren't any results.

                You didn't use the GoogleWebs properly. I found about a dozen. [openbible.info]

        • by quenda ( 644621 )

          But given Earth's escape velocity and dense atmosphere, it's extremely unlikely.

          "unlikely" just means it happens less often. The dinosaur-killer would have sent countless tonnes of earth-rock, some life-bearing, to Mars and beyond.
          Maybe none in the last 100ky to carry arrow-heads?

          BTW, Earth's escape velocity is not the limiting factor. To escape the solar system, allowing for earth's orbital velocity, you need to be expelled from the surface at more than double that speed.
          The Voyager probes reduced this by doing gravity-assist flybys.

          • To escape the solar system, allowing for earth's orbital velocity, you need to be expelled from the surface at more than double that speed.

            That's actually almost meaningless. You can no more achieve 17 km/s than you can achieve 11 km/s. Basically the problem is that the combination of high velocity and dense atmosphere at low altitude AND passive flight after ejection means you need to reach a HIGH initial velocity with a LARGE solid object (to survive the atmospheric exit), but that's only possible with a truly massive impact as you point out. In addition, besides hitting Earth in the first place, it would also probably have to hit a place wh

    • Re:Maybe not (Score:5, Interesting)

      by Gravis Zero ( 934156 ) on Monday December 10, 2018 @01:52PM (#57780806)

      I wonder if there isn't some chunk of arrowhead embedded in an asteroid smashed off the Earth in some titanic collision.

      1) A collision of that magnitude (large enough to create ejecta) would likely be a mass extinction event. Humans have yet to experience one of those (from an asteroid).
      2) Other planets (especially Jupiter) would likely ensnare the newly created asteroid. Getting past them once is very unlikely to start with but getting past them, being just the right size to not cause a mass extinction event but large enough to create ejecta, then have the ejecta (now asteroid) getting past those same planets and all in the span in the last 100k years (hell, I'll give you all 400k years for proto-humans) and there being no recognizable evidence? Finding a unicorn being ridden by a leprechaun seems more likely.

      The chances of this happening are slim to start with but the chances of this happening while humanity existed and there being no clear evidence of it are beyond infinitesimally small. It's a neat thought experiment but that's all it is.

      • Other planets (especially Jupiter) would likely ensnare the newly created asteroid.

        This incredibly stupid. The chances of a random object shot out from earth being caught in Jupiter's gravity well is essentially zero. Space is big!

        • The chances of a random object shot out from earth being caught in Jupiter's gravity well is essentially zero. Space is big!

          Sure, space is big but planets are moving very fast (relatively). It's like trying to stick your finger in an active industrial fan and pulling it out before a fan blade gets you. You're going to lose a digit.

      • I think OP was thinking of the few martian rocks which have fallen to Earth as meteors [wikipedia.org]. Those were ejected from Mars via meteor or asteroid impacts, and eventually found their way to Earth.

        However, the delta-v [wikipedia.org] needed to barely traverse from Mars to Earth is only 2.9 km/s. The delta-v needed to leave the solar system from Earth is a minimum 12.3 km/s, or 18x as much energy. And that's on top of the higher ejecta velocity needed to escape Earth's gravity well (more than twice that of Mars).
      • I have heard other arguments claiming it was a volcanic eruption, kinda like the one in Pompey, and that the description makes more sense that way.

        • s/Pompey/Pompeii

        • A assuming a volcanic eruption provided enough energy to escape Earth's gravity, whatever was being ejected would be subjected to a huge amount of frictional heat. Also, it's not going to have a whole lot of velocity and it has billions of miles to travel, so this would need to happen a LONG time ago (and what the hell were they doing atop a mountain/volcano?). Since ancient arrowheads are made of rock, the frictional heat of the atmosphere would cause them to explode, much like meteorites do entering Ear

    • I wonder if there isn't some chunk of arrowhead embedded in an asteroid smashed off the Earth in some titanic collision.

      Pretty sure that's all at the bottom of the ocean.

  • 41 years (Score:5, Interesting)

    by 110010001000 ( 697113 ) on Monday December 10, 2018 @01:20PM (#57780586) Homepage Journal
    41 years to exit the solar system. 13 billion miles. Max speed 36,000 mph. 0.00005% the speed of light. Pretty cool!
    • Re:41 years (Score:5, Interesting)

      by k6mfw ( 1182893 ) on Monday December 10, 2018 @01:36PM (#57780688)
      You have summed up just how big our Solar System is and yet puny compared to the Milky Way galaxy (nice post). Though a screamer at 36K mph, a fraction of a snail's pace in terms getting to another star. Overall to think it was launched so many years ago, and think about various items on the spacecraft with company tags with model and serial numbers, and many of these companies no longer existing.
      • by jd ( 1658 )

        The oldest company in the world was founded some time around 750 AD. That any company involved in building Voyager no longer exists is abysmal.

      • Re:41 years (Score:4, Interesting)

        by Kjella ( 173770 ) on Monday December 10, 2018 @03:40PM (#57781658) Homepage

        Though a screamer at 36K mph, a fraction of a snail's pace in terms getting to another star.

        Yeah. The moon was hard. Mars is hard. But going interstellar... even if SpaceX built the BFR, boosted it to the max in a high elliptic orbit, put another stage on top instead of the BFS and sent it on the Grand Tour of gravity slingshots (which won't happen again until 2150, but that's still a small problem) it'll go from 40000 years like Voyager to what, like 10000 years? Chemical rockets are almost like breeding horses to reach the moon. But I do hope they'll limp humans to Mars in my lifetime...

    • Elon is right it is high time to abandon internal combustion engine. Newer engine designs will hopefuly translate into more options for space travel.
  • Not fare well,
    But fare forward, voyagers.

    -- TS Eliot, The Dry Salvages

    [Ed Stone added this quote to the last slide of his Voyager-Neptune talk, at the Fall 1989 AGU meeting.]

  • ... to join with The Creator (in endless CG cloud scenes...)
  • Amazing! (Score:4, Insightful)

    by gosand ( 234100 ) on Monday December 10, 2018 @01:43PM (#57780748)

    This really is an amazing thing. And I mean that in the truest sense, not in an OMG-this-pumpkin-spice-frappachino-is-amazing kind of way. Sadly, I am guessing most people won't even read this story because it's not trash news.

    I really liked this from the article: "Voyager 1 will not approach another star for nearly 40,000 years, even though it is moving at such great speed. "

    It's fascinating and hard to comprehend.

  • by northbrae ( 1775792 ) on Monday December 10, 2018 @02:04PM (#57780902)
    Voyager 2 has entered interstellar space (i.e. crossed the heliopause, the boundary where the Sun's solar wind is stopped by the interstellar medium), but it hasn't left the solar system (the spherical area of space gravitationally bound to the Sun). The Oort Cloud, by current estimates, extends 10-2,000 times farther out than Voyagers 1 & 2 are now. The probes are expected to reach the inner edge of the Oort Cloud in ~300 years. The popular idea of the solar system ends at Pluto, but we know of many objects orbiting far beyond that.
    • I've always been curious about how the sun's gravity can affect objects so far away from itself as the Oort cloud. Consider that I am thinking in terms of distance versus force where the intensity of the force decreases with distance, at such distances the intensity of the gravitational force should be really really small right?
      • I've always been curious about how the sun's gravity can affect objects so far away from itself as the Oort cloud. Consider that I am thinking in terms of distance versus force where the intensity of the force decreases with distance, at such distances the intensity of the gravitational force should be really really small right?

        It probably doesn't matter how small the force is as long as it is stronger than the other outside forces of gravity from other bodies. One billionth of a G in force is still stronger than nothing and if it is competing with "statistically" nothing it wins the tug of war.

        • Inertia doesn't care about the gravity from the 'void' beyond the solar system. Out in the oort, objects are orbiting so slowly that the micro-gravity from the sun still keeps them. The gravity from the void beyond is a tiny fraction comparatively. So this is about inertia vs gravity, not local gravity vs interstellar gravity.

          Also consider that the oort cloud has not been observed. 'cloud' might be a very optimistic description of what orbits out there, if anything. A single icy body out there could be

  • Voyager 2 will have some catching up to do to leave the solar system as many times as Voyager 1. :) https://xkcd.com/1189/ [xkcd.com]
  • by Anonymous Coward

    Have either of them made it past the Oort cloud?
    No? When will that happen?
    So you're saying there's some distinction between "leaving the solar system" and "leaving the neighborhood of objects which orbit the sun"?

    • Have either of them made it past the Oort cloud?
      No? When will that happen?
      So you're saying there's some distinction between "leaving the solar system" and "leaving the neighborhood of objects which orbit the sun"?

      They probably won't be the first past the Oort cloud. I'm sure we will have vessels that can travel fast enough to overtake Voyager in time to beat them past that distance.

    • So you're saying there's some distinction between "leaving the solar system" and "leaving the neighborhood of objects which orbit the sun"?

      Yes.. Interstellar space is defined as being beyond the Solar Wind's reach; Where the particles ejected by the Sun reach equal pressure with Interstellar space. Gravity influences objects at much greater distances. So you can orbit the Sun in Interstellar space.

  • by Tablizer ( 95088 ) on Monday December 10, 2018 @03:01PM (#57781336) Journal

    Voyager 2 has an additional instrument [nasa.gov] that Voyager 1 lacked during its crossing:

    The most compelling evidence of Voyager 2's exit from the heliosphere came from its onboard Plasma Science Experiment (PLS), an instrument that stopped working on Voyager 1 in 1980, long before that probe crossed the heliopause.

  • comments from reddit about Voyager 2 leaves the Solar System https://old.reddit.com/r/news/... [reddit.com]

    FactualNeutronStar writes:

    It didn't actually leave the Solar system. It entered "interstellar space" which means the Solar wind is basically negligible, but it is still well within the influence of the Sun's gravity. It's similar to saying that a rocket has left Earth because it escaped the atmosphere, despite the fact that it is still very much influenced by the Earth.

    Classified0 writes:

    Voyager 2 is travel

  • by giampy ( 592646 ) on Monday December 10, 2018 @05:26PM (#57782444) Homepage
  • In the late 1960s, I was employed as a programmer by a subcontractor at the Jet Propulsion Lab in Pasadena, California. That was before the Voyager satellites were launched. I wrote part of the software that would later be used to track and collect data from the Voyager ssatellites. I also wrote part of the software used by the project management to schedule tasks in the development and launches of the satellites.

    Is there anyone else reading this who participated in the Voyager project before they were l

  • As far as I know, the probe did not actually ever attain solar escape velocity, which means it will continue to slow down and eventually be pulled back, entering into an extremely long and skinny elliptical orbit around the sun.

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