[HN Gopher] Astronomers Find Cosmic 'Superhighways' for Fast Tra...
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Astronomers Find Cosmic 'Superhighways' for Fast Travel Through
Solar System
Author : bookofjoe
Score : 93 points
Date : 2020-12-13 11:30 UTC (1 days ago)
(HTM) web link (www.sciencealert.com)
(TXT) w3m dump (www.sciencealert.com)
| FlyMoreRockets wrote:
| See also: https://news.ycombinator.com/item?id=25410192
| sxp wrote:
| Note that "fast" is a relative term in this case. E.g, "On
| average, these particles reached Uranus and Neptune 38 and 46
| years later, respectively, with the fastest reaching Neptune in
| under a decade."
|
| It's more accurate to say that these are "cheap" paths rather
| than fast ones since the primary saving will be fuel. These paths
| will be too slow for humans to use and any dramatic improvement
| in human travel through the solar system will require a
| technological breakthrough like a high-powered torch drive [1] or
| laser-powered solar sails [2]. Otherwise, we'll still be stuck
| with multi-year trips to anything beyond Luna [3]
|
| [1] http://www.projectrho.com/public_html/rocket/torchships.php
|
| [2] https://www.youtube.com/watch?v=oDR4AHYRmlk
|
| [3] See the Impulse vs Brachistochrone table at
| http://www.projectrho.com/public_html/rocket/appmissiontable...
| moonbug wrote:
| [3] It's called the moon, not Luna.
| hinkley wrote:
| Is that entirely true though? Many of our highest impulse
| engines have fewer problems with the tyranny of the rocket
| equation, but also have low thrust. The beginnings of trips are
| going to be slow even if the end is not.
|
| Using these paths for the beginning and end of journeys may
| make a lot of sense, even if they make no sense at all in the
| middle.
| dmitrygr wrote:
| > The beginnings of trips are going to be slow even if the
| end is not.
|
| Endings too. You cannot just slow down. No brakes in space.
| And if your engine is low thrust, you'll need a while to slow
| down too, unless your goal is kinetic impact unto your
| target.
| dragonwriter wrote:
| > You cannot just slow down.
|
| If you engineer to survive it, aero- and even litho-braking
| are alternatives where you can "just" slow down, without
| using onboard reaction mass.
| JPLeRouzic wrote:
| So in the worst case the average speed is half of the
| maximum speed. Still something attractive.
| xwdv wrote:
| We can reach Mars in a couple months. Beyond that, the only
| further places I could imagine humans wanting to go is Europa
| or Titan, maybe Ceres.
| FlyMoreRockets wrote:
| There are lots of gravitationally attractive resoures
| scattered throughout the asteroid belt.
| warent wrote:
| In a couple months like, what, once every 10 years or
| something when it's closest to earth? Otherwise iirc it takes
| much longer
| paledot wrote:
| Only 26 months in the Earth/Mars system, in fact. And
| that's still the fastest way to go, which is the only thing
| that's relevant for crewed spaceflight. Doesn't matter how
| much you're saving on gas if you still need to bring enough
| snacks for the drive.
| ummonk wrote:
| Dude Hohmann transfer to Mars is less than a year.
| jagger27 wrote:
| I think "trade winds" is better analogy than "super highway".
| chrisweekly wrote:
| Yes, by far! And to extend it, we're at the "canoes" (or
| maybe "swimming and surfing") stage regarding our technology
| for exploring those horizons.
| weego wrote:
| Feels more like we threw someone in and watched to see if
| they could doggy paddle back.
| ben_w wrote:
| For interplanetary, I think it's more like we looked at
| some flotsam in the water spinning around and wondered if
| we could make a canoe based on that principle get to the
| next island, having only just tippy-toed into the water
| up to our ankles just to prove it wasn't immediately
| lethal.
|
| (Scale difference: Uranus is 7800 times further than the
| moon [0], so if wading to ankle depth is 1m from the
| shore, then the metaphorical island is 7.8 km away --
| pretty close of the distance between the closest parts of
| Portsmouth and the Isle of Wight [1]).
|
| [0] http://www.wolframalpha.com/input/?i=Distance%20to%20
| Uranus%...
|
| [1] https://goo.gl/maps/rvV5cXeb8i8xbVwr9
| aquova wrote:
| To put that into perspective, it took Voyager 2 8.5 years to
| reach Uranus, and 12 years to reach Neptune.
| backtoyoujim wrote:
| I wonder if these gravitational jetstreams explain the weird
| acceleration that was written about `Oumuamua's path.
| rdlecler1 wrote:
| If you had a propulsion system in one of these highways, could
| you move quicker (or at least use less energy?)
| ArnoVW wrote:
| I am trying to understand. Is this not the same thing as the
| Interplanetary Transport Network, dating from a paper in the 90s?
|
| https://en.m.wikipedia.org/wiki/Interplanetary_Transport_Net...
| HenryKissinger wrote:
| "Supreme Chancellor, delegates of the Senate. A tragedy has
| occurred. It started right here with the taxation of the trade
| routes, and has engulfed our entire planet in the oppression of
| the Trade Federation."
| awinter-py wrote:
| they should have sent a poet
| scionthefly wrote:
| So...did Omuamua follow a path like this, or...
| jagger27 wrote:
| No
| slowmovintarget wrote:
| Gravitational "sweet spots" (label mine) produce orbital tracks
| that cause movement of things in the solar system in decades
| instead of centuries or millennia.
|
| No FTL claims here (whew).
| kiliantics wrote:
| > Gravitational "sweet spots"
|
| a G-spot, if you will
| desireco42 wrote:
| I want to point out and give a shout-out to Belgrade Observatory
| and their team.
|
| These people work without huge telescopes or excessive equipment
| and we should celebrate major contributions when they come from
| smaller teams like this.
| hguant wrote:
| I was under the impression that this was common knowledge among
| the astrophysicist set, going back, well, according to Wikipedia,
| to the 1890s when Poincare figured out you could do zero-energy
| orbit transfers[0].
|
| I suppose the novelty here is that someone identified a subset of
| 'fast' paths along the Interplanetary Transport Network.
|
| [0]
| https://en.wikipedia.org/wiki/Interplanetary_Transport_Netwo...
| jefurii wrote:
| I am not an astronomer but these seem to be a different thing.
| paledot wrote:
| Bingo. This is a classic case of pop science misunderstanding
| half of a paper and sensationalizing the other half.
|
| > This network can transport objects from Jupiter to Neptune in
| a matter of decades, rather than the much longer timescales, on
| the order of hundreds of thousands to millions of years,
| normally found in the Solar System.
|
| By "objects" they mean asteroids and particles. "A matter of
| decades" is still a ridiculously long time by human spaceflight
| standards.
| tzs wrote:
| > "A matter of decades" is still a ridiculously long time by
| human spaceflight standards.
|
| That's true when you are just exploring. When you start more
| long term projects, such as colonization, things are
| different.
|
| Say you want to colonize something that is 30 years away
| using the cheap but slow network. What you do is 30 years
| before you want to start the colony you start sending regular
| loads of supplies via the slow cheap network.
|
| Once those are near starting to arrive at the destination,
| you send your colonists the expensive but fast way.
|
| You can also do this to speed up exploration. Suppose we know
| we are going to want to send a manned exploration mission to
| someplace eventually, but we've got other more important
| targets to occupy us for the next few decades.
|
| Send fuel and other supplies to that place by the cheap and
| slow method. Then when it finally comes time to send a round
| trip manned mission, you only need to include enough fuel and
| other supplies for a one way trip. They can use the fuel and
| supplies that were sent the slow way for their return trip.
|
| This way your exploration rockets only need to carry half the
| mass of fuel and supplies that they would otherwise need.
| This will allow higher acceleration and thus shorter travel
| time.
| deepsun wrote:
| >need to carry half the mass of fuel and supplies
|
| Not just half, but can be much more than that, because it's
| exponential.
| bluGill wrote:
| That only works when only a couple of governments are
| involved. Once (big if!) it becomes a free for all there is
| risk that you will send supplies and someone else will use
| them. Or maybe they just charge a ransom before you can get
| at your supplies - just send a robot out to where those
| supplies are going, "hide them", and ???. There are too
| many risks to trust that someone doesn't think of this.
|
| I hope the rocket scientists are not caught as off guard as
| us computer people have been by ransomware and the like
| (note that viruses have been doing evil things for over 30
| year and we still don't have a handle on it)
| dflock wrote:
| Fairly high barrier to entry, for stealing shit from the
| Jovian system, though.
| shdc wrote:
| sciencealert.com seems very peak HN to me.
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