Using Pulsars As GPS For Starships 103
cold fjord writes with an excerpt from Science Codex: "CSIRO scientists have written software that could guide spacecraft to Alpha Centauri ... Dr George Hobbs (CSIRO) and his colleagues study pulsars — small spinning stars that deliver regular 'blips' or 'pulses' of radio waves and, sometimes, X-rays. Usually the astronomers are interested in measuring, very precisely, when the pulsar pulses arrive in the solar system. Slight deviations from the expected arrival times can give clues about the behaviour of a pulsar itself ... 'But we can also work backwards,' said Dr Hobbs. 'We can use information from pulsars to very precisely determine the position of our telescopes.' 'If the telescopes were on board a spacecraft, then we could get the position of the spacecraft.' Observations of at least four pulsars, every seven days, would be required. ... A paper (paywalled) describing in detail how the system would work has been accepted for publication by the journal Advances in Space Research."
(Here is a related story from the same source.)
Paywalled? (Score:2, Interesting)
My taxes paid for it!
Re:Paywalled? (Score:5, Informative)
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So his taxes paid for salaries that provide those IP or services ...
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As stated, only partially.
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I demand partial access to the papers!
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I WANT EVERY FOURTH WORD!
Am I doing this right?
Also, filter error.
Unpaywalled (Score:5, Informative)
The paper is available free from the arXiv (http://arxiv.org/abs/1307.5375)
The past called.. (Score:5, Insightful)
This is so 1970's...
http://en.wikipedia.org/wiki/Pioneer_plaque [wikipedia.org]
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It should not come as a surprise to anyone. That doesn't mean it shouldn't be here, only that the summary sucks. It should have something new and interesting in it.
It should be obvious to anyone who is familiar with both GPS and DtoA. Which should be all of you by now, goddamn it.
Re:The past called.. (Score:5, Informative)
The abstract of the paper (unpaywalled version [arxiv.org]) has a better summary.
We demonstrate how observations of pulsars can be used to help navigate a spacecraft travelling in the solar system. We make use of archival observations of millisecond pulsars from the Parkes radio telescope in order to demonstrate the effectiveness of the method and highlight issues, such as pulsar spin irregularities, which need to be accounted for. We show that observations of four millisecond pulsars every seven days using a realistic X-ray telescope on the spacecraft throughout a journey from Earth to Mars can lead to position determinations better than ~20 km and velocity measurements with a precision of ~0.1 m/s.
In other words, they're not just saying that it's a theoretical possibility. They're saying "this is the type of telescope you need", "this is how you have to process the data", and "this is how precisely you can measure your position". Next step, I guess, is building the hardware.
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It should be obvious to anyone who is familiar with both GPS and DtoA. Which should be all of you by now, goddamn it.
I'm fully familiar with Decimal-to-ASCII, but I don't see how that helps.
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It should be obvious to anyone who is familiar with both GPS and DtoA. Which should be all of you by now, goddamn it.
I'm fully familiar with Decimal-to-ASCII, but I don't see how that helps.
OGHIHA (Oh, God, How I Hate Acronyms!)
Re: The past called.. (Score:1)
Because sick poor people dying from preventable diseases is the mark of a successful society. I know super geniuses like you think the developed world should be like Victorian Britain but luckily most places have progressed since then.
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I suppose that depends on what you think is "progress"
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I suppose that depends on what you think is "progress"
I don't suppose the GP post had in mind MDR [wikipedia.org] bugs. Maybe the (real AD) 1984 was better than nowadays in this concern, but... thanks God we got out of their hair style.
(my point... feel free to mod OT: exemplifying the "that depends" - even when right, I find quite pretentiously stupid an "It depends" answer on its own - i.e. with no details on the "dependency variables". Even, "So... it has come to that" is more to-the-point).
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Also doubling the population, while curing those sick people, and using up all our resources is the mark of a great society!
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This is so 1970's...
http://en.wikipedia.org/wiki/Pioneer_plaque [wikipedia.org]
The Pioneer plaque showed the position of the Earth's solar system. It wasn't for human navigation on a moving space vessel. (Although in a sense the Earth is a moving space vessel.)
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Go back and read the section titled Relative position of the Sun to the center of the Galaxy and 14 pulsars, which has this sentence in particular:
If the plaque is found, only some of the pulsars may be visible from the location of its discovery. Showing the location with as many as 14 pulsars provides redundancy so that the location of the origin can be triangulated even if only some of the pulsars are recognized.
Given the distance of the pulsars, it is a pretty good bet that at least 4 would be visible by a hypothetical finder of the plaque.
For a moving spacecraft, you could easily seed it with these 14 pulsars, and run a SLAM[1] algorithm to add new ones and fix their position as you move. Localization with an initially unknown set of point beacons is well studied.
Now,
Really? (Score:1)
1980s? Try the '60s or '70s at least. (Score:2)
My dad had some "Best of" Analog and Astounding collections dating back to the mid-'50s. Those omnibus editions got me hooked on sci-fi at a very young age.
I remember reading more than one story out of those where using pulsars to determine a ship's current position was a key plot point. According to Wikipedia, the first pulsar was discovered in 1967. Given the intense interest that most sci-fi writers and readers had in astronomy, I would be very surprised if that information wasn't common knowledge wit
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Yeah, it's totally boring that these guys are now able to calculate the observer's position anywhere in the galaxy to within several metres and velocity to within less than a meter per second, something previously only imagined in the realm of sci-fi. Next thing you know they'll be building a working warp drive, holodeck, transporter or something else equally trite and unoriginal.
Warp drive, transporter, all good. (Warp drive now considered theoretically possible, according to previous articles on Slashdot.) I have mixed feelings about the holodeck. We've already seen in other types of entertainment (cough-tv-cough) that people tend to immerse for longer and longer periods of time, eventually becoming a kind of meat-based houseplant. I'm concerned that a holodeck would accelerate the process.
Oliver's retort to Fermi's Paradox: A civilization progresses to the point where it inve
Good work Dr Hobbs! (Score:4, Funny)
Re:Good work Dr Hobbs! (Score:4, Funny)
When you've located a person with that name, here is a link to Warp Field Mechanics 101, by NASA:
http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20110015936_2011016932.pdf [nasa.gov]
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Apple maps will still screw it up and show Alpha Centari in the Andromeda galaxy
Done a long time ago (Score:2)
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Brass (copper/zinc)? or is it bronze(copper/tin), the popular literature says copper. On that copper is plated gold, and aluminum plated on the cover. over the aluminum is plated very pure U-238 so if the thing were ever found (which would be tens or hundreds of thousands of years from now) an alien civilization could measure the decay product ratio and determine when craft launched.
Hopefully, our descendents don't end up having to rue our decision and do the "Independence Day" thing
ridiculous (Score:3)
This is like Karl Benz figuring out road signs.
If we currently do not have a way to travel to the stars, then what does it matter how we find our way among them?
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If we currently do not have a way to travel to the stars, then what does it matter how we find our way among them?
You'd need an excellent politician to be able to build ways to travel to the stars, not a scientist. As in:
"I'm a space flight engineer, Jim! Not a politician with space travel plans!"
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This is like Karl Benz figuring out road signs.
If we currently do not have a way to travel to the stars, then what does it matter how we find our way among them?
Knowing the position of artificial objects in space with great precision might be useful if you enter the realm of the unknown.
e.g.: Imagine we launch a number of solar satellites and the information they return about their position doesn't match with the position we're seeing them at. Maybe it's a problem with our equations.
Maybe some defects of space curvature are only observable over long distances but cancel each other perfectly so as to disallow us from detecting them by their impact on the light comin
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That would be great if pulsars were fixed points in space. But the universe is expanding, and so their position changes even for objects in our own solar system.
Too complicated (Score:1, Interesting)
Just add a cross hair to the "windscreen" of the space ship and point it at the damn star that you are going to pay a visit.
There will be plenty of time for fine tuning. As a matter of fact, it would be a real good recreational job for the 10.000 year long trip.
As the star got bigger you would simply change the velocity accordingly. Not such a big deal. I know, because i used to play Elite on a C64.
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Stars move. You'd be adding hundreds of years to your travel time by taking a curved path. Better to go in a straight line to where the star will be in 10,000 years, for which purpose you'd need... navigation.
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>Stars move. You'd be adding hundreds of years to your travel time by taking a curved path
You could bring a sniper to do the aiming.
Beside 100, plus minus compared to 100.000 years wouldn't be my biggest concern.
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> You could bring a sniper to do the aiming.
You would have to take into account the one variable he doesn't... the speed of light. Even at distances where the curve and spin of the earth matter, the latency caused by light itself is not an issue.
Thing is, aiming at where the target will be is exactly what a sniper would tell you to do...that is what he does when leading a target.
Then you have to take into account another variable thats simpler for him: Fuel. Straight line accleration is easy, you just ac
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>You would have to take into account the one variable he doesn't... the speed of light.
I just watched "The shooter" on Netflix yesterday.
Lee Swagger would hit his target across the galaxy without any booster corrections, taking into account, the heat radiation, electromagnetic forces, space and time warping, gravity shearing, gravity pull from black matter, resistance from the microscopic amounts of hydrogen gas. Boom shaka laka.
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I do something similar in Kerbal Space Program, when I get lazy during a rendevous maneuvre :)
But, sometimes I do it "properly", and try to figure out what the funk a hofman transfer is, and where my target will be when I get to where it will have been... Pain the in the Rear!
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You realize of course that stars are moving.
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Yeah, aim for where Alpha Centauri was FOUR YEARS AGO... eventually you will be chasing the star and there is a good possibility it will be moving faster than you are so you will simply watch it recede from you as you slowly starve/suffocate.
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you know, we have these things called computers that can compensate and calculate the right answer
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sorry, but your view is too simplistic. You wish to end up in an orbit about interesting planet of the target star. No amount of pointing your craft at anything will get you the correct solution.
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You know, they have these things called original posts that actually explain what the fuck is being discussed.
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Then i would turn the ship around and go the other way around the galaxy and set the cryo-beds and the alarm clock for an other 250 million years, or what ever it takes for the galaxy to revolve.
Second star to the right... (Score:2)
Visibility (Score:3)
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Are the pulses from pulsars visible from all directions, or just from the plane of rotation?
Not from all directions, but not always from the plane of rotation either. The pulse sweeps around at a fixed angle from the plane of rotation, which may not be 90 degrees.
But you're right: if we went far enough, we'd stop seeing some pulsars, and start seeing some new ones. So if we start travelling more than a thousand light years or so, we'll need another means of navigation.
The original paper [arxiv.org] only talks about using it as a means of navigation within the solar system, though, for which it's perfectly f
Acquiring Satellites (Score:1)
Seven days to get a read on current position? Still better than NeverLost :)
Only works (Score:2)
If you're going slower than the speed of light
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if you are going at the speed of light all events in time happen simultaneously
Nav Aids (Score:1)
Pulsars: The Nav Beacon's of the Universe. Been that way since they were discovered - just like VOR beacons for Airports
Talk about putting the cart before the horse! (Score:2)
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Trek thought of it (Score:1)
I seem to remember an episode of Star Trek where they ended up in the armpit of space such that they couldn't get a Federation navigation signal. They used pulsar triangulation to get a fix on their location.
Now, of course, implementation of this theory in the 21st century is a different matter!
Old hat for Minecraft fans... (Score:2)
"Notch," the developer behind the famous Minecraft game, also ostensibly proposed pulsars as navigation beacons for his now-defunct game "0x10c." He used (generated) data collection from a pulsar as part of a series of puzzles related to PR for the game.
Don't pulsars have a narrow emission beam? (Score:2)
I thought that pulsars emitted a beam of energy that was very narrow in angular size and located on a specific rotation axis.
What if you travel off the beam's axis while traveling large distances between astronomical objects?